series dresbus ii final report · a low pass filter – eq4..... 45 fig. 4.21 walls deformations...

SEVENTH FRAMEWORK PROGRAMME Capacities Specific Programme

Research Infrastructures

Project No.: 227887

SERIES SEISMIC ENGINEERING RESEARCH INFRASTRUCTURES FOR

EUROPEAN SYNERGIES

Workpackage [WP10/TA6 – IFSTTAR Centrifuge]

DRESBUS II Investigation of the Seismic Behaviour of Shallow Rectangular

Underground Structures in Soft Soils Using Centrifuge Experiments

User Group Leader: Dr. E. Rovithis Revision: Final

May, 2013

SERIES 227887 TA Project: DRESBUS II

i

ABSTRACT

This report contains centrifuge recordings and data interpretation as the outcome of the

Transnational Access project DRESBUS II “Investigation of the seismic behavior of shallow

rectangular underground structures in soft soils using centrifuge experiments” that was

performed under SERIES Research Program. DRESBUS II was designed, compiled and

completed on December 2012, as a collaborative project between the Institut Français des

Sciences et Technologie des Transports, de l'Amménagement et des Réseaux, France (IFSTTAR)

(acting as the Access Provider), the Earthquake Planning and Protection Organization, Greece

(EPPO-ITSAK) and the Laboratory of Soil Mechanics, Foundations and Geotechnical

Earthquake Engineering of Aristotle University of Thessaloniki, Greece (AUTH), both of them

acting as the main Transnational Access Users.

Seven centrifuge test sequences were carried out in total referring to flexible or rigid tunnel

sections, smooth or rough soil-tunnel interface (smoothed aluminium surface and grooved

aluminium with depth equivalent to sand D50) and dry or saturated Fontainebleau sand N34 with

ID = 70%. Novel techniques for the sand pluvation, models saturation and waterproofing of the

tunnel sections were used during centrifuge tests set-up. Each soil-tunnel system was excited by

the same input sequence: a real recording from Northridge earthquake scaled to three levels of

peak acceleration (0.1g, 0.2g and 0.3g) followed by a sine wave at 0.3g. A dense monitoring

scheme was employed to record soil-tunnel response comprising of miniature piezoelectric

accelerometers within the soil or attached to the tunnel section and the ESB container,

displacement sensors to record the surface ground settlement and pore pressure sensors to

measure pore pressure dissipation, for the saturated cases. Furthermore, specially designed

extensometers were used to record the racking deformations of the tunnel section and diagonal


ii

“blade” extensometers were installed along the longitudinal axis of the tunnel to verify the

homogeneity of deformation and control out of plane response of the structure.

Experimental recordings obtained from each test are reported herein in detail followed by a

preliminary interpretation of the experimental data. Seismic response of the tunnel sections is

commented as affected by the model parameters under investigation. In this regard, the acquired

datasets offer valuable experimental evidence on fundamental aspects of seismic behaviour of

soil-tunnel systems, providing a well-documented basis for validating numerical models and

design methods that are commonly employed in practice.

Keywords: Dynamic centrifuge tests, Rectangular tunnels, Racking deformations


iii

ACKNOWLEDGMENTS

The research leading to these results has received funding from the European Community’s

Seventh Framework Programme [FP7/2007-2013] under grant agreement n° 227887.


iv

REPORT CONTRIBUTORS

AUTH (Greece) Grigorios Tsinidis

EPPO (Greece) Emmanouil Rovithis

AUTH (Greece) Kyriazis Pitilakis

IFSTTAR (France) Jean-Luis Chazelas


v

CONTENTS

List of Figures ............................................................................................................................... viii

List of Tables .................................................................................................................................. xv

1 Introduction .............................................................................................................................1

2 DRESBUS II experimental program..........................................................................................3

2.1 IFSTTAR Centrifuge facility ...........................................................................................3

2.2 Centrifuge Scaling laws..................................................................................................4

2.3 Fontainebleau sand properties ......................................................................................4

2.4 Tunnel models ................................................................................................................5

2.4.1 Models dimensions ............................................................................................5

2.4.2 Soil‐tunnel interface rugosity............................................................................6

2.4.3 Aluminium mechanical properties ....................................................................7

2.4.4 Flexibility ratios..................................................................................................8

2.5 Models preparation ........................................................................................................9

2.5.1 Sand pouring......................................................................................................9

2.5.2 Saturation procedure.......................................................................................10

2.5.3 Treatment of model tunnels boundaries ........................................................12

2.6 Model layout ‐ Instrumentation scheme .....................................................................14

2.6.1 Miniature accelerometers ...............................................................................15

2.6.2 Displacement sensors......................................................................................16

2.6.3 Pore pressure cells ...........................................................................................17

2.6.4 Walls deformations extensometers ................................................................17

2.6.5 Diagonal extensometers .................................................................................20


vi

2.7 Testing program...........................................................................................................22

2.8 Experimental procedure ..............................................................................................22

2.9 Input motion characteristics ........................................................................................24

3 Data processing .....................................................................................................................25

3.1 Accelerations ................................................................................................................25

3.2 Effect of filtering technique on tunnel distortion recordings .....................................27

3.3 Water Pore pressures ...................................................................................................27

4 Experimental data..................................................................................................................28

4.1 Test DRESBUS_2_1_1 ..................................................................................................28

4.2 Test DRESBUS_2_2_1..................................................................................................50

4.3 Test DRESBUS_2_3_1 ..................................................................................................65

4.4 Test DRESBUS_2_4_1..................................................................................................80

4.5 Test DRESBUS_2_4_2 .................................................................................................81

4.6 Test DRESBUS_2_5_1 ..................................................................................................99

4.7 Test DRESBUS_2_6_1................................................................................................113

4.8 Test DRESBUS_2_7_1 ................................................................................................129

5 Interpretation of experimental data.....................................................................................145

5.1 CPT data during test sequence ..................................................................................145

5.2 Recorded soil amplification .......................................................................................145

5.3 Tunnels racking deformations ...................................................................................147

5.3.1 Input motion amplitude effect ......................................................................147

5.3.2 Tunnel stiffness effect ...................................................................................151

5.3.3 Soil‐tunnel interface effect............................................................................151

5.3.4 Soil saturation effect .....................................................................................154

6 Conclusions ..........................................................................................................................155

References ....................................................................................................................................156


vii


viii

List of Figures

Fig. 1.1 Daikai Station. (a) Settlements of the overlaying roadway caused by the subway collapse, (b) Collapse of the central columns of the station (Special Issue of Soil and Foundations, 1996) ......................................................................................................................... 2 Fig.2.1 (a) Geotechnical Centrifuge at IFSTTAR, (b) Earthquake Actidyn QS 80 actuator, (c) ESB container ................................................................................................................................. 3 Fig. 2.2 Tunnels sections ................................................................................................................ 5 Fig. 2.3 Definition of roughness ..................................................................................................... 6 Fig. 2.4 Relation between the sand grain size and the grooves dimensions ................................... 6 Fig. 2.5 Device for the deformation tests of the tunnel specimens................................................. 7 Fig. 2.6 Small strain shear wave velocity profiles according to Hardin and Drenvich model ....... 8 Fig. 2.7 Model preparation.............................................................................................................. 9 Fig. 2.8 Installation of the waterproof rubber membrane on the ESB container .......................... 11 Fig. 2.9 Schematic representation of the saturation system setup ................................................ 12 Fig. 2.10 Saturation system setup ................................................................................................. 12 Fig. 2.11 Typical connection of the tunnel with the ESB box for the dry sand tests.................... 13 Fig. 2.12 Details of the tunnels – ESB box connections (a) Dry sand tests, (b) Saturated sand tests; first solution, (c) Saturated sand tests; final solution........................................................... 13 Fig. 2.13 Typical model layout for a dry test................................................................................ 15 Fig. 2.14 Typical model layout for a saturated test....................................................................... 16 Fig. 2.15 “Fork” system extensometer.......................................................................................... 18 Fig. 2.16 Design sheet of the fork extensometers......................................................................... 19 Fig. 2.17 Calibration device for the fork extensometers - Representative calibration curves of a fork system.................................................................................................................................... 20 Fig. 2.18 Diagonal extensometers................................................................................................. 20 Fig. 2.19 Design sheet for the diagonal extensometers ................................................................ 21 Fig. 2.20 Calibration device for the diagonal extensometers........................................................ 21 Fig. 2.21 Shaking table base configuration................................................................................... 23 Fig. 2.22 Relative position of the CPT with respect to the tunnel (top view) .............................. 23 Fig. 2.23 Nominal input motions .................................................................................................. 24 Fig. 4.1 Test DRESBUS_2_1_1 model set up and instrumentation scheme ................................ 28 Fig. 4.2 Accelerometers vertical arrays ........................................................................................ 30 Fig. 4.3 Processed acceleration time histories – EQ1................................................................... 33 Fig. 4.4 Processed acceleration time histories – EQ2................................................................... 34 Fig. 4.5 Processed acceleration time histories – EQ3................................................................... 35 Fig. 4.6 Processed acceleration time histories – EQ4................................................................... 36


ix

Fig. 4.7 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1......................................................................................................... 37 Fig. 4.8 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2......................................................................................................... 37 Fig. 4.9 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3......................................................................................................... 38 Fig. 4.10 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4......................................................................................................... 38 Fig. 4.11 Typical transfer functions along vertical accelerometers arrays – EQ1........................ 39 Fig. 4.12 Vertical accelerations – EQ2 ......................................................................................... 39 Fig. 4.13 Stress-strain loops – EQ1 .............................................................................................. 40 Fig. 4.14 Stress-strain loops – EQ4 .............................................................................................. 40 Fig. 4.15 Shear wave velocity profiles computed along vertical accelerometers arrays; comparison with Vso computed according to Hardin and Drenvich (1972) formulation.............. 41 Fig. 4.16 Walls deformations obtained using a low pass filter – EQ1.......................................... 42 Fig. 4.17 Walls deformations obtained using a low pass filter – EQ4.......................................... 43 Fig. 4.18 Walls maximum deformations obtained using a low pass filter.................................... 44 Fig. 4.19 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1.................................................................................................................. 45 Fig. 4.20 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ4.................................................................................................................. 45 Fig. 4.21 Walls deformations obtained using a band pass filter – EQ4........................................ 46 Fig. 4.22 Walls maximum deformations obtained using a band pass filter.................................. 47 Fig. 4.23 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a band pass filter – EQ3................................................................................................................ 48 Fig. 4.24 CPT test results.............................................................................................................. 48 Fig. 4.25 Soil surface settlements ................................................................................................. 49 Fig. 4.26 Test DRESBUS_2_2_1 model set up and instrumentation scheme.............................. 50 Fig. 4.27 Processed acceleration time histories – EQ1................................................................. 53 Fig. 4.28 Processed acceleration time histories – EQ2................................................................. 54 Fig. 4.29 Processed acceleration time histories – EQ3................................................................. 55 Fig. 4.30 Processed acceleration time histories – EQ4................................................................. 56 Fig. 4.31 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1......................................................................................................... 57 Fig. 4.32 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2......................................................................................................... 57 Fig. 4.33 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. – EQ3................................................................................................................ 58 Fig. 4.34 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4......................................................................................................... 58 Fig. 4.35 Shear wave velocity profiles computed along vertical accelerometers arrays; comparison with Vso computed according to Hardin and Drenvich (1972) formulation.............. 59 Fig. 4.36 Walls deformations obtained using a low pass filter – EQ2.......................................... 60 Fig. 4.37 Walls maximum deformations obtained using a low pass filter.................................... 61 Fig. 4.38 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ3.................................................................................................................. 62 Fig. 4.39 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a band pass filter – EQ4................................................................................................................ 62


x

Fig. 4.40 Walls maximum deformations obtained using a band pass filter.................................. 63 Fig. 4.41 CPT test results.............................................................................................................. 64 Fig. 4.42 Soil surface settlements ................................................................................................. 64 Fig. 4.43 Test DRESBUS_2_3_1 model set up and instrumentation scheme.............................. 65 Fig. 4.44 Processed acceleration time histories – EQ1................................................................. 68 Fig. 4.45 Processed acceleration time histories – EQ2................................................................. 69 Fig. 4.46 Processed acceleration time histories – EQ3................................................................. 70 Fig. 4.47 Processed acceleration time histories – EQ4................................................................. 71 Fig. 4.48 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1......................................................................................................... 72 Fig. 4.49 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2......................................................................................................... 72 Fig. 4.50 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3......................................................................................................... 73 Fig. 4.51 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4......................................................................................................... 73 Fig. 4.52 Shear wave velocity profiles computed along vertical accelerometers arrays; comparison with Vso computed according to Hardin and Drenvich (1972) formulation ............ 74 Fig. 4.53 Walls deformations obtained using a low pass filter – EQ1.......................................... 75 Fig. 4.54 Walls deformations obtained using a low pass filter – EQ4.......................................... 76 Fig. 4.55 Walls maximum deformations obtained using a low pass filter.................................... 77 Fig. 4.56 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ2.................................................................................................................. 78 Fig. 4.57 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a band pass filter – EQ4................................................................................................................ 78 Fig. 4.58 Walls maximum deformations obtained using a band pass filter.................................. 79 Fig. 4.59 CPT test results.............................................................................................................. 80 Fig. 4.60 Soil surface settlements ................................................................................................. 80 Fig. 4.61 Test DRESBUS_2_4_2 model set up and instrumentation scheme.............................. 81 Fig. 4.62 Processed acceleration time histories – EQ1................................................................. 85 Fig. 4.63 Processed acceleration time histories – EQ2................................................................. 86 Fig. 4.64 Processed acceleration time histories – EQ3................................................................. 87 Fig. 4.65 Processed acceleration time histories – EQ4................................................................. 88 Fig. 4.66 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1......................................................................................................... 89 Fig. 4.67 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2......................................................................................................... 89 Fig. 4.68 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3......................................................................................................... 90 Fig. 4.69 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4......................................................................................................... 90 Fig. 4.70 Walls deformations obtained using a low pass filter – EQ2.......................................... 91 Fig. 4.71 Walls deformations obtained using a low pass filter – EQ4.......................................... 92 Fig. 4.72 Walls maximum deformations obtained using a low pass filter.................................... 93 Fig. 4.73 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1.................................................................................................................. 94 Fig. 4.74 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a band pass filter – EQ1................................................................................................................ 94


xi

Fig. 4.75 Walls maximum deformations recorded by fork extensometers; low pass filter .......... 95 Fig. 4.76 Water pore pressures during and after shaking – EQ1 .................................................. 96 Fig. 4.77 Water pore pressures during and after shaking – EQ2 .................................................. 96 Fig. 4.78 Water pore pressures during and after shaking – EQ3 .................................................. 97 Fig. 4.79 Water pore pressures during and after shaking – EQ4 .................................................. 97 Fig. 4.80 CPT test results.............................................................................................................. 98 Fig. 4.81 Test DRESBUS_2_5_1 model set up and instrumentation scheme.............................. 99 Fig. 4.82 Processed acceleration time histories – EQ1............................................................... 102 Fig. 4.83 Processed acceleration time histories – EQ2............................................................... 103 Fig. 4.84 Processed acceleration time histories – EQ3............................................................... 104 Fig. 4.85 Processed acceleration time histories – EQ4............................................................... 105 Fig. 4.86 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1....................................................................................................... 106 Fig. 4.87 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2....................................................................................................... 106 Fig. 4.88 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3....................................................................................................... 107 Fig. 4.89 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4....................................................................................................... 107 Fig. 4.90 Walls deformations obtained using a low pass filter – EQ1........................................ 108 Fig. 4.91 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1................................................................................................................ 109 Fig. 4.92 Walls maximum deformations obtained using a low pass filter.................................. 110 Fig. 4.93 Walls maximum deformations obtained using a band pass filter................................ 111 Fig. 4.94 CPT test results............................................................................................................ 112 Fig. 4.95 Soil surface settlements ............................................................................................... 112 Fig. 4.96 Test DRESBUS_2_6_1 model set up and instrumentation scheme............................ 113 Fig. 4.97 Maximum Processed acceleration time histories – EQ1 ............................................. 116 Fig. 4.98 Processed acceleration time histories – EQ2............................................................... 117 Fig. 4.99 Processed acceleration time histories – EQ3............................................................... 118 Fig. 4.100 Processed acceleration time histories – EQ4............................................................. 119 Fig. 4.101 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1....................................................................................................... 120 Fig. 4.102 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2....................................................................................................... 120 Fig. 4.103 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3....................................................................................................... 121 Fig. 4.104 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4....................................................................................................... 121 Fig. 4.105 Walls deformations obtained using a low pass filter – EQ1...................................... 122 Fig. 4.106 Walls maximum deformations obtained using a low pass filter................................ 123 Fig. 4.107 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1................................................................................................................ 124 Fig. 4.108 Walls maximum deformations obtained using a band pass filter.............................. 125 Fig. 4.109 Water pore pressures during and after shaking – EQ1 .............................................. 126 Fig. 4.110 Water pore pressures during and after shaking – EQ2 .............................................. 126 Fig. 4.111 Water pore pressures during and after shaking – EQ3 .............................................. 127 Fig. 4.112 Water pore pressures during and after shaking – EQ4 .............................................. 127


xii

Fig. 4.113 Soil surface settlements ............................................................................................. 128 Fig. 4.114 Test DRESBUS_2_7_1 model set up and instrumentation scheme.......................... 129 Fig. 4.115 Processed acceleration time histories – EQ1............................................................. 132 Fig. 4.116 Processed acceleration time histories – EQ2............................................................. 133 Fig. 4.117 Processed acceleration time histories – EQ3............................................................. 134 Fig. 4.118 Processed acceleration time histories – EQ4............................................................. 135 Fig. 4.119 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1....................................................................................................... 136 Fig. 4.120 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ2....................................................................................................... 136 Fig. 4.121 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ3....................................................................................................... 137 Fig. 4.122 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ4....................................................................................................... 137 Fig. 4.123 Walls deformations obtained using a low pass filter – EQ1...................................... 138 Fig. 4.124 Walls maximum deformations obtained using a low pass filter................................ 139 Fig. 4.125 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1................................................................................................................ 140 Fig. 4.126 Walls maximum deformations obtained using a band pass filter.............................. 141 Fig. 4.127 Water pore pressures during and after shaking – EQ1 .............................................. 141 Fig. 4.128 Water pore pressures during and after shaking – EQ2 .............................................. 142 Fig. 4.129 Water pore pressures during and after shaking – EQ3 .............................................. 142 Fig. 4.130 Water pore pressures during and after shaking – EQ4 .............................................. 143 Fig. 4.131 Soil surface settlements during swing up .................................................................. 143 Fig. 4.132 Soil surface settlements during shaking .................................................................... 144 Fig. 5.1 CPT test results for the dry sand tests............................................................................ 145 Fig. 5.2 Maximum horizontal acceleration at the soil free field (Array 2) for the dry tests....... 146 Fig. 5.3 Maximum horizontal acceleration at the soil free field (Array 2) for the saturated tests..................................................................................................................................................... 147 Fig. 5.4 Maximum racking deformations for different input motion amplitudes – rough flexible tunnel in dry sand (DRESBUS2_1_1) ........................................................................................ 148 Fig. 5.5 Maximum racking deformations for different input motion amplitudes – smooth flexible tunnel in dry sand (DRESBUS2_2_1) ........................................................................................ 148 Fig. 5.6 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in dry sand (DRESBUS2_3_1) ........................................................................................ 149 Fig. 5.7 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in saturated sand (DRESBUS2_4_2) ............................................................................... 149 Fig. 5.8 Maximum racking deformations for different input motion amplitudes – smooth rigid tunnel in dry sand (DRESBUS2_5_1) ........................................................................................ 150 Fig. 5.9 Maximum racking deformations for different input motion amplitudes – smooth rigid tunnel in saturated sand (DRESBUS2_6_1) ............................................................................... 150 Fig. 5.10 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in saturated sand (DRESBUS2_7_1) ............................................................................... 151 Fig. 5.11 Maximum racking deformations for different input motion amplitudes – rough vs. smooth flexible tunnel in dry sand (DRESBUS2_1_1 vs. DRESBUS2_2_1)............................ 152 Fig. 5.12 Maximum racking deformations for different input motion amplitudes – rough vs. smooth rigid tunnel in saturated sand (DRESBUS2_6_1 vs. DRESBUS2_7_1) ....................... 153


xiii

Fig. 5.13 Maximum racking deformations for different input motion amplitudes – effect of sand saturation (DRESBUS2_3_1 vs. DRESBUS2_7_1)................................................................... 154


xiv


xv

List of Tables

Table 2.1 Scaling laws for geotechnical centrifuge tests (Schofield, 1980)................................... 4 Table 2.2 Fontainebleau sand NE 34 physical properties.............................................................. 4 Table 2.3 Mechanical properties of the aluminum alloy used ........................................................ 7 Table 2.4 Tunnels flexibility ratios based on Wang (1993) method............................................... 8 Table 2.5 Pouring parameters ....................................................................................................... 10 Table 2.6 Calibration parameters of the fork systems .................................................................. 18 Table 2.7 Calibration curves for the diagonal extensometers....................................................... 22 Table 2.8 DRESBUS II testing program....................................................................................... 22 Table 2.9 Extensometer systems used during each test ................................................................ 23 Table 2.10 Input motions characteristics (bracketed values: values in prototype scale) .............. 24 Table 4.1 Sensors numbering and exact positions ........................................................................ 29 Table 4.2 Extensometers numbering............................................................................................. 30 Table 4.3 Sensors numbering and exact positions ........................................................................ 51 Table 4.4 Extensometers numbering............................................................................................. 52 Table 4.5 Sensors numbering and exact positions ........................................................................ 66 Table 4.6 Extensometers numbering............................................................................................. 67 Table 4.7 Sensors numbering and exact positions ........................................................................ 82 Table 4.8 Extensometers numbering............................................................................................. 83 Table 4.9 Measured vs. theoretical water pore pressure at P1...................................................... 84 Table 4.10 Sensors numbering and exact positions .................................................................... 100 Table 4.11 Extensometers numbering......................................................................................... 101 Table 4.13 Sensors numbering and exact positions .................................................................... 114 Table 4.14 Extensometers numbering......................................................................................... 115 Table 4.12 Sensors numbering and exact positions .................................................................... 130 Table 4.13 Extensometers numbering......................................................................................... 131


xvi


1

1 Introduction

Large underground structures such as tunnels and metro stations possess a vital socio-economic

role being a crucial part of the transportation and utility networks in an urban area. The

associated impact in case of earthquake induced damages denotes the paramount importance of a

safe seismic design, especially in seismically active areas.

Although recent earthquake events (Kobe 1995, Duzce 1999, Chi-Chi 1999 and Wenchuan 2008)

have demonstrated that underground structures may undergo extensive deformations or even

collapse (Sharma and Judd, 1991, Wang, 1993, Iida et al., 1996 among others), their seismic

response has been little explored compared to aboveground structures due to lack of

experimental data and well-documented field evidence (Cilingir and Madabhushi, 2011). In this

regard, design specifications for underground structures in modern seismic codes are based

primarily on simplified methods (Wang, 1993, Penzien, 2000, Hashash et al., 2001, ISO 23469,

2005, FWHA, 2009), the implementation of which may lead to a substantially different seismic

design for this type of structures (Pitilakis and Tsinidis, 2012).

A substantial contribution to the knowledge of seismic behavior of underground structures may

be accomplished by means of well-focused experimental data, allowing investigation of crucial

response parameters such as seismic earth pressures distribution on the side walls of the

structure, seismic shear stresses distribution around the perimeter of the structure and definition

of impedance functions to be implemented in simplified Winkler models for underground

structures.


2

(a)

(b)

Fig. 1.1 Daikai Station. (a) Settlements of the overlaying roadway caused by the subway collapse, (b) Collapse of the central columns of the station (Special Issue of Soil and

Foundations, 1996)

The above research objectives motivated the realization of the collaborative experimental

Transnational Access project DRESBUS II “Investigation of the seismic behavior of shallow

rectangular underground structures in soft soils using centrifuge experiments” offered by the

SERIES research project. More specifically, DRESBUS II TA project dealt with the

investigation of shallow rectangular tunnels seismic response by means of dynamic centrifuge

testing. The experimental study was elaborated in the geotechnical centrifuge facility of

IFSTTAR under a centrifuge acceleration of 40g. Well-documented experimental data was

recorded for a wide set of soil-tunnel systems allowing a better understanding of the seismic

behavior of underground structures, as affected by salient parameters such as soil-structure

relative flexibility, soil-tunnel interface properties, soil saturation and amplitude of excitation.

Following a detailed description of DRESBUS II project set up, the herein report provides (a) a

representative set of experimental recordings obtained from each centrifuge test case and (b)

comparisons between selected soil-tunnel systems to highlight important aspects of the physical

problem within a preliminary interpretation of the recorded data.


3

2 DRESBUS II experimental program

2.1 IFSTTAR CENTRIFUGE FACILITY

DREBSUS II TA project was hosted by the centrifuge facility of IFSTTAR in Nantes, France.

IFSTTAR centrifuge has a radius of 5.5m and a capacity of two tonnes under a centrifugal

acceleration of 100g. The dimensions of the swinging basket supporting the model are 1.4m ×

1.1m.

Earthquake input motions were applied at the base of the soil-tunnel model, using the specially

designed actuator Actidyn QS 80 (Chazelas et al., 2008) being able to impose both sinusoidal

and real record input motions up to 400kg of payload mass. It is designed to work under a

centrifugal acceleration up to 80g, while it can apply input motions of peak acceleration at 0.5g,

allowing modeling of a wide frequency range (30-300Hz for real earthquakes).

A large Equivalent Shear Box (ESB) was employed to mount the models, having inner

dimensions 800mm in length, 340mm in width and 409mm in depth. The box is designed to

match the shear stiffness of the contained soil for the range of shear strains of interest, in order to

minimize spurious boundary effects arising from soil-container interactions.

Fig.2.1 (a) Geotechnical Centrifuge at IFSTTAR, (b) Earthquake Actidyn QS 80 actuator, (c) ESB container

(a) (b) (c)


4

2.2 CENTRIFUGE SCALING LAWS

The tests were performed under a centrifuge acceleration of 40g, implying a scaling factor at

1/40 (N = 40). As the centrifuge gravity is not constant with depth, the reference level for the

tuning of the centrifuge acceleration (40 g) was defined at the bottom soil-tunnel interface. The

relevant parameters are scaled down to the model level following standard scaling laws for

centrifuge testing (Table 2.1).

Table 2.1 Scaling laws for geotechnical centrifuge tests (Schofield, 1980)

Parameter Dimensions (*) Model / Prototype Length L 1/N Mass M 1/N3 Stress ML-1T-2 1 Strain 1 1 Force MLT-2 1/N2

Time (dynamic loading) T 1/N Time (Seepage) T 1/N2

Frequency 1/T N Acceleration LT-2 N

Velocity LT-1 1 Seepage Velocity LT-1 N

Displacement L 1/N *where: L is the length, T is the time, M is the mass and N is the scaling factor

2.3 FONTAINEBLEAU SAND PROPERTIES

Soil deposit was composed by Fontainebleau sand NE34 D50 = 200 μm, with a relative density at

70%. The main physical properties of the sand are summarized in Table 2.2.

Table 2.2 Fontainebleau sand NE 34 physical properties

ρs (g/cm3) emax emin d50 (mm)

Fontainebleau sand NE34 2.64 0.86 0.55 0.200


5

2.4 TUNNEL MODELS

2.4.1 Models dimensions

Models dimensions were specifically chosen on the basis of reflecting desirable soil-to-tunnel

relative flexibility and interface characteristics. Four model sections were manufactured and

tested referring to a rigid section with a rough interface, a rigid section with a smooth interface, a

flexible section with a rough interface and a flexible section with a smooth interface,

respectively.

Models sections are shown in Fig. 2.2. The inside dimensions of the models were kept constant

allowing use of identical extensometers (described in the ensuing). Based on the scaling factor

employed (N=40), the flexible tunnel models correspond to 1.88 × 2 (m) sections having an

equivalent concrete thickness equal to 8 cm for the walls and 32 cm for the slabs in prototype

scale (assuming E = 30 GPa for the concrete). Accordingly, the rigid tunnel models correspond

to 2.16 × 2 (m) sections having an equivalent concrete thickness equal to 27 cm for the walls and

30 cm for the slabs.

6mm

6mm 1.5mm

1.5mm50mm

47mm

Model 1

50mm

Model 2

54mm

6mm

5mm

6mm

5mm

Fig. 2.2 Tunnels sections


6

2.4.2 Soil‐tunnel interface rugosity

The tunnel sections were manufactured from 2017 A aluminum alloy (equivalent to old reference

AU4G T4), by implementing an electro-erosion technique to avoid any manufacturing or

assembly pre-stressing.

Referring to soil-tunnel interface rugosity two cases were investigated: (i) a smooth interface and

(ii) a rough interface, by changing the models external face roughness. Roughness is defined by

(Figs. 2.3 and 2.4):

0

1( )

L

aR f x dxL

(2.1)

0

1²( )

L

qR f x dxL

(2.2)

where Ra refers to an algebraic mean of the relief height around a mean line (grooves height) and

Rq, stands for a quadratic mean of the relief height around a mean line. Referring to the tunnel

sections with a rough soil-tunnel interface, (R) and (AR) were set at 100μm and 200μm,

respectively.

Fig. 2.3 Definition of roughness

Fig. 2.4 Relation between the sand grain size and the grooves dimensions

AR

R

AR

R

AR

R

Rt

L

f(x)


7

2.4.3 Aluminium mechanical properties

The elastic modulus of the specific fraction of aluminum was back-calculated from a series of

deformation tests performed on small length pieces of the tunnel models (3 cm). A specially

designed device was employed for these tests (Fig. 2.5), consisting of two brackets, connected

with each other, through the tunnel specimen. The top bracket was fixed, while the bottom was

supporting a plate to introduce the masses producing a tensional load to the model. The diagonal

deformation of the model was measured by two LVDTs (black cylinders in Fig. 2.5). The loads

(masses) were incrementally increased, reaching to a diagonal deformation equal to 1 mm.

Several circles of loading and uploading were conducted to examine the reversibility of the

phenomenon and to make sure that no hysteresis loops were observed. For the back analysis the

system was numerically modeled implementing an elastoplastic constitutive law, assuming a

yield stress at 400 MPa. The elastic modulus was calibrated based on the recorded deformations.

The metal stirrups were considered to be elastic (E=200 GPa), while the friction coefficient

between the stirrups and the model was assumed equal to 0.3. The comparisons indicated an

elastic modulus equal to 71 GPa. Table 2.3 summarizes the mechanical properties of the

aluminum alloy.

Fig. 2.5 Device for the deformation tests of the tunnel specimens

Table 2.3 Mechanical properties of the aluminum alloy used

Elastic modulus (GPa) 71 Poisson v 0.33

Yield stress (MPa) 400 Density (t/m3) 2.7


8

2.4.4 Flexibility ratios

Mention has already been made to the variable of tunnel stiffness employed in the centrifuge

experiments. The above parameter was quantified by means of the soil-tunnel flexibility ratio as

reported in Wang (1993). According to this simplified procedure, the flexibility ratio for

rectangular tunnels is estimated as:

mG WF

S H

(2.3)

where, Gm is the soil shear modulus, W is the width of the structure, H is the height of the

structure and S is the required force to impose a unit racking deflection of the structure. The

latter can be estimated through a simple static frame analysis of the tunnel. Soil shear modulus

was estimated herein, according to the Hardin and Drenvich (1972) model (Fig. 2.6), leading to

the flexibility ratio values that are summarized in Table 2.4.

‐14.4

‐10.8

‐7.2

‐3.6

0

0 100 200 300 400Vs (m/s)

z(m)

Saturated sand Dry sand

Fig. 2.6 Small strain shear wave velocity profiles according to Hardin and Drenvich model

Table 2.4 Tunnels flexibility ratios based on Wang (1993) method

Tunnel model Saturated sand Dry sand model-1 (flexible tunnel) 14.7 11.6

model-2 (rigid tunnel) 0.72 0.55


9

2.5 MODELS PREPARATION

An automatic hopper system was employed to form the sandy soil deposit of the centrifuge

models in a piecewise manner. During model formation, tunnel section and recording devices

were embedded at the desirable locations (Fig. 2.7).

2.5.1 Sand pouring

The device implemented for sand pouring is a linear curtain hopper that moves automatically

back and forth over the experimental container. A slot at the bottom of the hopper is actually

forming the sand curtain. The tuning parameters for a given (desirable) density are:

the width of the slot,

the falling height (distance between the sand layer and the hopper slot)

the movement velocity of the device and

the number of back and forth journeys over the container before changing the hoppers

height.

These tuning parameters were accordingly selected (Table 2.5) to achieve the desirable soil

density at 70%.

Fig. 2.7 Model preparation


10

Table 2.5 Pouring parameters

Sand type

Slot (mm)

Falling height (cm)

Horizontal frequency

(Hz)

Height tuning

ID (%)

γd

(kN/m3)

Fontainebleau sand NE34

4 60 32 Every two back

and forth journeys 70 15.82

2.5.2 Saturation procedure

During shaking, the water pore pressures in a granular soil increase. These pore pressures will

slowly decrease after the earthquake as water will dissipate within the soil from high- to low-

pressure subsoil regions. The above dissipation mechanism is governed by the Darcy’s law. To

respect the similitude laws for both the fundamental equation of the dynamics and the Darcy’s

law, viscous liquid is preferred rather than water. In centrifuge experiments it is common to add

Hydroxy-methyl-propylcellulose (HPMC) into water to obtain a liquid of viscosity N times

higher than water, with N being the reduction factor of the experiment (.e.g. N = 40). The HPMC

quantity is usually negligible (around 2%) so that the density of water is not changing. The above

technique is quite efficient as it can easily be implemented and has a low cost. However, the

water-HPMC mixture has some drawbacks. The viscosity of the mixture is temperature-

depended and it is affected by the development of bacteria. Moreover, the mixture is not

completely Newtonian as the viscosity is slightly depending on the velocity of the flux. To avoid

the development of bacteria, an antiseptic additive (2 to 4 % of the HPMC) is used. As the

preparation of a soil bed can take 10 to 15 days (pluvation, saturation, delay for centrifuge

availability, final set up) the weather conditions must be accounted. Although the liquid viscosity

may not affect the soil behavior during shaking (undrained conditions), it affects the time of the

pore pressures dissipation and should therefore be taken into account.

To avoid any water leakage from the sides of the ESB container, a waterproof rubber membrane

was installed on the container walls. In order to flatten the membrane against the box walls an

additional jacket was added at the external face of the container and a partial void was applied

between jackets. During the saturation phase, a lid was added on top of the box, over the jackets,

and the liquid (water of increased viscosity) was injected by the bottom plate of the box. The


11

saturation of the whole soil deposit was made under a partial vacuum. The whole procedure was

controlled by specially designed software. The saturation process is summarized in the following

steps:

The liquid mixture for the saturation is prepared diluting about 2% of Hydroxy – Propyl –

Methyl – Cellulose (HPMC) into water. The mixture is then sterilized with antiseptic (~6%

of HPMC) and de-aired for 8 hours in a tank under a partial vacuum decreased progressively

to 0.2 bars.

The sand deposit in the ESB container is put under 0.3 bar vacuum for 3 hours.

Then the atmospheric pressure is restored by injection of CO2 for 10 minutes and

subsequently the vacuum is restored.

The bottom level of the tank is set 30 cm higher than the bottom plate of the ESB container

to fill the capillarity layer with the liquid. This procedure takes about 12 hours.

To fill the whole sand model, the level of the tank is consecutively adjusted so that the water

level in the tank is 30 cm over the water level in the ESB container. This difference is

maintained by a control system. Approaching the sand surface, the height difference is

reduced progressively to avoid under-pressure on the surface sand grains.

The saturation procedure continues until the water table reaches 2 cm over sand surface.

Fig. 2.8 Installation of the waterproof rubber membrane on the ESB container

Jacket vacuum pump

1 bar

Metallic flanges

1 bar

0.2 bar Wooden protection of membrane

External jacket Internal jacket


12

Fig. 2.9 Schematic representation of the saturation system setup

Fig. 2.10 Saturation system setup

2.5.3 Treatment of model tunnels boundaries

The tunnels ends were properly designed to ensure a plain strain model behavior. For this reason,

low friction Teflon plates were glued on the ESB container in the case of dry sand (Fig. 2.12a).

The tunnel ends were equipped with knobs made of soft rubber foam. An aluminum plate was

stuck on the external face of the knob being in contact with the Teflon plate. In this manner the

foam knob could be compressed without limiting the in plane deformation of the tunnel near its

ends.

Jacket vacuum pump

1 bar

0.2 bar

Box & Tank Vacuum Pump

Float and magnetic water level gauge

Table height gauge

CO2

Sand saturation set up

Table height motor

0.3 bar

Float and magnetic water level gauge


13

Fig. 2.11 Typical connection of the tunnel with the ESB box for the dry sand tests

Tunnel

Soft rubberfoam

Aluminum plate

Teflon plate

ESB container aluminum frame

ESB containerrubber layer

Tunnel

Soft rubberfoam

Aluminum plate

Teflon plate



Soft rubberplate

Waterproof rubbermembrane

Tunnel

Soft rubberfoam

Aluminum plate

Teflon plate



PVC cap

Waterproof rubbermembrane

Soft silicon joint

(a) (b)

(c)

Fig. 2.12 Details of the tunnels – ESB box connections (a) Dry sand tests, (b) Saturated sand tests; first solution, (c) Saturated sand tests; final solution


14

For the test cases with saturated sand a thin rubber membrane covering the inside of the ESB

container was employed to waterproof the box. The Teflon plates were glued on this membrane

using double face tape. The foam cap was modified to glue a soft rubber plate on the tunnel slabs

and walls ends. The principle of the compressible foam was kept to contribute to the link

between this rubber layer and the aluminum of the tunnel (Fig. 2.12b). Unfortunately, this set up

did not manage to resist the water pressure, leading to water leakage inside the tunnel for a test

case (DRESBUS2_4_1). The connection was then redesigned to resist both positive and negative

relative pressures, since at those locations the pressures were significantly changing during

model construction and experiment. A stronger PVC cap was stuck on the tunnel using a thick

soft silicone joint resisting positive and negative pressures, thus limiting slightly the tunnel

deformations (Fig. 2.12c). The effect of this limitation was checked by diagonal extensometers

installed at the middle and the end sections of the tunnel-models.

All the strain gauges wires were settled inside the tunnel model and exited near the extremity of

the model through the top slab.

2.6 MODEL LAYOUT ‐ INSTRUMENTATION SCHEME

Fig. 2.13 and 2.14 present typical model layouts of the centrifuge tests referring to a dry and a

saturated sand case, respectively. A particularly dense instrumentation scheme was designed and

installed to record soil-tunnel response comprising of miniature piezoelectric accelerometers in

vertical arrays within the soil or attached to the tunnel section and the ESB container,

displacement sensors to record the surface ground settlement and pore pressure sensors to

measure pore pressure dissipation, for the saturated cases. Furthermore, specially designed

extensometers were used to record the racking deformations of the tunnel section and diagonal

“blade” extensometers were installed along the longitudinal axis of the tunnel to verify the

homogeneity of deformation and control out of plane response of the structure.


15

250mm

400mm240mm

360mm

180mm326mm

355mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

125mm

A14A15

20mm

100mm

A23

A24

A21

A22

A25A26F5

F1F5

F10

D1 D2D3

D4

S1 S3

800mm

Dry Fontainebleau Sand(Dr=70%)

50mm

47mm

Model

14mm

y

x

z

S2

Accelerometer Laser displacementsensor

Diagonal extensiometer Transversal "fork"extensiometer

1.5mm6.0mm

A16

A17

A18A19

Fig. 2.13 Typical model layout for a dry test

2.6.1 Miniature accelerometers

Miniature piezoelectric accelerometers were used to measure the acceleration in the soil, on the

tunnel and on the ESB box. The transducers were installed in vertical arrays within the soil to

capture base-to-surface amplification of soil response in the horizontal direction and the tunnel

effect on the induced wave field.


16

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

14mm

y

x

z

S2

Accelerometer Laser displacement sensor

Diagonal extensiometer

Transversal "fork"extensiometer

50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19

Pore pressuresensor

A27

P3P1

P2 P4 P5

P6

Fig. 2.14 Typical model layout for a saturated test

2.6.2 Displacement sensors

Soil surface settlements were measured by displacement sensors installed at three locations along

the ground surface. Laser sensors were used for the dry sand tests, while potentiometer sensors

were used for the saturated tests, as the water table was set above the soil surface (2cm above).


17

2.6.3 Pore pressure cells

For the saturated tests pore pressure cells were utilized, to measure the water pore pressures at

several locations near the tunnel and at the free field during and after shaking.

The final positions of the instruments (accelerometers, pore pressure cells) were defined during

installation as well as after the test to measure the actual soil settlement caused by the centrifuge

spin up and the subsequent shaking.

2.6.4 Walls deformations extensometers

The tunnel-models deformations were measured in terms of side-walls deformations at the

middle section and diagonal deformations of the model at several locations. For this purpose,

special designed extensometers were installed.

To determine and measure the racking deformations of the tunnels side-walls a special device

was designed, comprising of 2x5 “teeth”, capable of measuring, independently, the deformations

of the walls relatively to the bottom slab. The device was fixed at the middle section of the invert

slab of the tunnel. Fig. 2.15 displays one of these extensometer devices. Each “tooth” is equipped

with two strain gauges mounted in half-bridge, forming a bending deformation sensor. These

sensors can measure deformations up to 1 mm, and withstand a force up to 10N, without

yielding. The design sheet with the main characteristics of this system is given in Fig. 2.16.

A special mechanical system was used for the calibration of these sensors (Fig. 2.17). During the

calibration procedure, each tooth was plugged to the system and subjected to 2 mm

displacement, controlled be a micrometer. The calibration curves denote linear response, with a

different offset. Table 3.5 summarizes the corresponding calibration factors.


18

Fig. 2.15 “Fork” system extensometer

Table 2.6 Calibration parameters of the fork systems

Fork system 1

a mm/mmV

b mm/mmV

Fork system 2

a mm/mmV

b mm/mmV

Fork system 3

a mm/mmV

b mm/mmV

Fork 1-1 0.352 0.1754 Fork 2-1 0.345 -0.189 Fork 3-1 0.361 -0.115 Fork 1-2 0.348 0.187 Fork 2-2 0.347 -0.138 Fork 3-2 0.367 -0.197 Fork 1-3 0.355 0.116 Fork 2-3 0.347 -0.167 Fork 3-3 0.364 -0.028 Fork 1-4 0.349 0.083 Fork 2-4 0.348 -0.182 Fork 3-4 0.363 -0.283 Fork 1-5 0.358 -0.164 Fork 2-5 0.347 0.062 Fork 3-5 0.368 -0.178 Fork 1-6 0.358 -0.112 Fork 2-6 0.346 -0.131 Fork 3-6 0.389 -0.220 Fork 1-7 0.353 -0.232 Fork 2-7 0.351 -0.204 Fork 3-7 0.366 -0.264 Fork 1-8 0.363 -0.050 Fork 2-8 0.350 0.017 Fork 3-8 0.367 -0.156 Fork 1-9 0.355 -0.416 Fork 2-9 0.349 -0.089 Fork 3-9 0.369 -0.357

Fork 1-10 0.351 -0.142 Fork 2-10 0.347 -0.316 Fork 3-10 0.369 -0.041


19

Fig. 2.16 Design sheet of the fork extensometers


20

Fig. 2.17 Calibration device for the fork extensometers - Representative calibration curves of a fork system

2.6.5 Diagonal extensometers

To measure diagonal deformations and control the plain strain behavior of the tunnel, diagonal

extensometers were installed at several locations along the longitudinal axis of the models. These

sensors are made of a pre-stressed steel blade, forming an arch in the diagonal of the rectangular

section of the tubes. They are equipped with strain gauges mounted in half bridges placed at mid

span to evaluate the deformation of the arch. The main design characteristics of the sensors are

conforming to the following limitations:

the lateral walls can have a displacement equal to 1 mm, so the diagonal can range from

58.14 mm to 59.67 mm.

the force applied by the extremities of the extensometers to the tubes should be limited to

10N.

Fig. 2.18 Diagonal extensometers


21

Fig. 2.19 Design sheet for the diagonal extensometers

For the calibration of these sensors, a specific device was designed (Fig. 2.20). During the

calibration the extensometer is stressed until the cord length is equal to the diagonal of the tunnel

at rest. Displacement steps are then imposed with a micrometer to obtain ± 1.25 mm around the

original position. Although the response shown in Fig. 2.20 is not linear, a similar trend is

obvious between the different extensometers tested. To this end, it was concluded that a fourth

degree polynomial fits better the specific calibration curves.

Fig. 2.20 Calibration device for the diagonal extensometers


22

Table 2.7 Calibration curves for the diagonal extensometers

Regression law – Chord length = f(x in mV) CL 1 to 4 4 3 2y 0.1231x 0.2434x 0.3237x 2.6624x 8.637

CL 5 to 8 4 3 2y 0.0784x 0.2153x 0.4352x 2.6842x 9.3893

CL 9 to 12 4 3 2y 0.0965x 0.2222x 0.4134x 2.68x 8.9683

2.7 TESTING PROGRAM

Seven centrifuge tests were carried out in total, by combining flexible or rigid tunnel sections,

smooth or rough soil-tunnel interface and dry or saturated sand. The test cases are tabulated in

Table 2.8. It is noted that Dresbus_2_4_1 test failed due to water leakage inside the tunnel. Table

2.9 summarizes the extensometer systems used for each test.

Table 2.8 DRESBUS II testing program

Test case

# Test name

Structure flexibility

Soil Dr (%)

Soil saturation

Culvert surface

Test month

1 Dresbus_2_1_1 Flexible Dry Rough April 2012 2 Dresbus_2_2_1 Flexible Dry Smooth May 2012 3 Dresbus_2_3_1 Rigid Dry Rough July 2012 4* Dresbus_2_4_1 Rigid Saturated Rough July 2012 5** Dresbus_2_4_2 Rigid Saturated Rough December 2012 6 Dresbus_2_5_1 Rigid Dry Smooth August 2012 7 Dresbus_2_6_1 Rigid Saturated Smooth October 2012 8 Dresbus_2_7_1 Rigid

70

Saturated Rough October 2012 * failed

** repetition test of Dresbus_2_7_1 to check the repeatability

2.8 EXPERIMENTAL PROCEDURE

During each flight, the centrifuge was spun up to 40g and swing down to 1g three times

(consolidation – stabilization circles) to check the proper function of the monitoring scheme.

Once the consolidation cycles completed, a CPT test was conducted at a surface location away

from the tunnel (Fig. 2.22). During the main dynamic tests, acceleration, tunnel deformations and

pore pressures data were firstly recorded at a sampling frequency of 51 kHz and were then re-


23

sampled at 12.8 kHz by means of a fast acquisition system that is available at IFSTTAR (DAS).

Soil surface settlements were recorded at a lower sampling frequency.

Table 2.9 Extensometer systems used during each test

Test case

# Test name

Fork system

Diagonal extensometers

1 Dresbus_2_1_1 F3 CL5-8 2 Dresbus_2_2_1 F3 CL5-8 3 Dresbus_2_3_1 F3 CL5-8 4 Dresbus_2_4_1 F2 CL9-12 5 Dresbus_2_4_2 F2 CL9-12 6 Dresbus_2_5_1 F2 CL9-12 7 Dresbus_2_6_1 F2 CL9-12 8 Dresbus_2_7_1 F2 CL9-12

Fig. 2.21 Shaking table base configuration

Fig. 2.22 Relative position of the CPT with respect to the tunnel (top view)

Tunnel

CPT

~ 37 cm

22 cm

13 cm

Tunnel

Sand

Container

Centrifuge pivot side

Shaking table

Centrifuge room door side

DAS

X

Y

Z


24

2.9 INPUT MOTION CHARACTERISTICS

Four input motions were successively introduced at the base of the model referring to a record

from the Northridge earthquake (1994) scaled to 0.1 g, 0.2 g and 0.3 g peak acceleration

followed by sine wavelet having a frequency equal to 85 Hz and an amplitude equal to 0.3 g

(Table 2.10 and Fig. 2.23).

0 0.25 0.5 0.75 1−0.35

−0.175

0

0.175

0.35

t(s)

A/4

0g

EQ1

0 0.25 0.5 0.75 1−0.35

−0.175

0

0.175

0.35

t(s)

A/4

0gEQ2

0 0.25 0.5 0.75 1−0.35

−0.175

0

0.175

0.35

t(s)A

/40g

EQ3

0 0.16 0.32 0.48 0.64−0.35

−0.175

0

0.175

0.35

t(s)

A/4

0g

EQ4

Fig. 2.23 Nominal input motions

Table 2.10 Input motions characteristics (bracketed values: values in prototype scale)

Nominal amplitude (g) Nominal Duration (s)

Input type Model scale Prototype scale Model scale Prototype scale

EQ1 4.0 0.10 1.0 40 EQ2 8.0 0.20 1.0 40 EQ3

Northridge record 12.0 0.30 1.0 40

EQ4 Pseudo-Harmonic

(85Hz) 12.0 0.30 0.64 25.6


25

3 Data processing

3.1 ACCELERATIONS

Filtering – Displacements computation

The acceleration-time histories were band-pass filtered between 20 to 400 Hz (model scale),

before double integrating them to obtain the corresponding displacement signals. Using the

filtered data, the maximum horizontal acceleration was computed for all the locations and plotted

along vertical acceleration arrays (i.e. free field array, tunnel array etc).

Transfer functions

To identify possible soil-structure interaction and wave field effects, pertinent transfer functions

were computed by utilizing available recordings along vertical arrays within the centrifuge

apparatus. Based on the corresponding Fourier spectra soil amplification is defined by the ratio:

1

2

TF

(3.1)

where 1 and 2 refer to the Fourier spectra of the two recordings.

Shear strain-stress loops

Having computed the displacement time histories, shear strains may be evaluated by means of

the procedure proposed by Zeghal and Elgamal (1994) as reported in Brennan et al. (2005) for

centrifuge testing. More specifically, using a first order approximation, shear strain between two

instruments in the same vertical array is:


26

2 1

2 1

u u

z z

(3.2)

According to the above procedure, the shear stress τ may be computed from the integration of the

acceleration time histories with respect to depth z:

0

zz a z dz (3.3)

Alternatively, the following simplified formulation may be adopted:

10

2z z u u z (3.4)

For surface acceleration, a linear fit was performed, using the adjacent pair of instruments

(Brennan et al., 2005).

2 1

1 12 1

u uu z u z z

z z

(3.5)

Having the shear strain and the shear stress, soil shear stiffness was estimated for each τ-γ loop

by means of (Brennan et al., 2005):

max min

max min

G

(3.6)

where τmax, τmin, γmax, γmin correspond to the maximum and minimum shear stress and strain,

respectively, in each loop. Shear wave propagation velocity may then be estimated through

standard elastodynamic considerations.

sV G (3.7)

with ρ being the sand density.


27

3.2 EFFECT OF FILTERING TECHNIQUE ON TUNNEL DISTORTION RECORDINGS

Residual values of deformation recorded in some tests should be attributed to sensor drifts during

shaking and to some minor extend to permanent response due to the soil yielding and

densification. Using a band pass filter those permanent values are vanished. However, if a low

pass filter is adopted, these residual values are not minimized. For this reason, both a band pass

(20-400 Hz) and a low pass filters (400Hz) were used to obtain relevant comparisons with the

numerical analyses. An 8th order Butterworth type was employed for both filtering schemes.

3.3 WATER PORE PRESSURES

The pore pressures time histories were filtered using a 8th order Butterworth type low pass filter

for frequencies up to 400 Hz (in model scale).


28

4 Experimental data

4.1 TEST DRESBUS_2_1_1

Fig. 4.1 presents the model set up along with instrumentation scheme.

DRESBUS2_1_1: Flexible tunnel ‐Rough surface ‐ Dry Sand

250mm

400mm240mm

360mm

180mm326mm

355mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

125mm

A14A15

20mm

100mm

A23

A24

A21

A22

A25A26F5

F1F5

F10

D1 D2D3

D4

S1 S3

800mm


50mm

47mm

Model14mm

y

x

z

S2

Accelerometer Laser displacementsensors


1.5mm6.0mm

A16

A17

A18A19

Fig. 4.1 Test DRESBUS_2_1_1 model set up and instrumentation scheme


29

Tables 4.1 and 4.2 summarize channels and sensors locations before and after the main test. The

coordinates refer to the reference system presented in Fig. 2.21. The settlements estimated for

each instrument by the direct measurements are also reported.

Table 4.1 Sensors numbering and exact positions

Real coordinates at set-up

Real Position after shocksA/A

DAS Channel

Sensor #

Position Positive Direct X

cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

cm A1 1 68 End table + pivot A2 2 69 Bottom plate + pivot 17 40 A20 3 79 Bottom plate +top A3 4 73 Above plate + pivot 16.5** 40 39.6 34.1 39.6 0 A4 5 96 +13 cm/bottom + pivot 16.5** 40 28.1 22.6 28.1 0 A12 6 74 +13 cm/bottom + pivot 16.3 17.5 28.0 22.5 28.1 0.1 A9 7 101 + pivot 16.5** 16.5 15.5 10 15.9 0.4 A6 8 97 + pivot 17.6** 35.1 15.5 10 15.9 0.4 A13 9 75 + pivot 17.6 32 15.5 10 15.9 0.4 A7 10 98 + pivot 16.8** 36 12.7 7.2 13.6 0.9 A10 11 102 + pivot 16.5** 33 10.5 5 11.1 0.6 A8 12 99 + pivot 16.5** 35.7 10.5 5 11.1 0.6 A14 13 76 + pivot 17.3 17.5 10.5 5 10.9 0.4 A11 14 93 + pivot 16.7** 31.9 7.5 5.2 8.2 0.7 A5 15 100 + pivot 16.5** 35.3 7.5 5 8.1 0.6 A15 16 80 + pivot 17.0 17.5 7.5 22.5 8.4 0.9 A21 17 84 On tunnel lateral + door 9.5 A22 18 85 On tunnel lateral + door 4.5 A23 19 86 On tunnel lateral + door 2.5 A24 20 87 On tunnel lateral + door

A26 21 88 On tunnel top +top


A16 23 91 External box + door



A19 26 108 External box + door ** Measurement in X direction taken from the Teflon plate surface: 1 cm should be added to compare to others


30

Table 4.2 Extensometers numbering

A/A DAS Channel Column in data file Strain gauge F1 27 27 F3.1 F2 28 28 F3.2 F3 29 29 F3.3 F4 31 30 F3.4 F5 32 31 F3.5 F6 49 32 F3.6 F7 50 33 F3.7 F8 51 34 F3.8 F9 52 35 F3.9

F10 53 36 F3.10 D3 54 37 CL5 D4 55 38 CL6 D1 56 39 CL7 D2 57 40 CL8

The accelerometers were installed in vertical arrays (Fig. 4.2). Figs. 4.3-4.6 show filtered

acceleration time histories. Figs. 4.7-4.10 summarize the distribution of the maximum horizontal

accelerations with depth indicating soil amplification effects.

A2A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

A14A15

Array 1

Array 2

Array 3

Array 4

Array 5

A16

A17

A18A19

A1

Fig. 4.2 Accelerometers vertical arrays

Fig. 4.11 presents representative transfer functions computed along the free field, the tunnel and

the reference array (ESB container) for EQ1. The results do not clearly show the predominant

frequencies of the soil-tunnel system.


31

Fig. 4.12 presents vertical acceleration time histories near the soil base and on the tunnel’s roof

slab sides during EQ2 (control points 25 and 26 in Fig. 4.1), indicating a yawing movement of

the ESB container. The in-phase response of the tunnel roof corners denotes a racking-type of

deformation. However, further investigation is needed to comment on a possible mobilization of

a “rocking-motion component”.

Typical stress-strain loops based on Zeghal and Elgamal procedure (Zeghal and Elgamal, 1994)

between sets of accelerometers are presented in Figs. 4.13-4.14. In Fig. 4.15 the shear wave

velocities, estimated according to the mobilized shear moduli, derived from the stress-strain

loops, are compared to the small strain shear wave velocity (Vso). The latter is estimated

according to the Hardin and Drenvich (1976) model. The results indicate reduction of the

velocities with increasing amplitude of the input motion. Moreover, Vs seem to be lower close to

the tunnel section compared to free-field values.

Figs. 4.16-4.17 present filtered deformation time histories recorded on the tunnels wall. In the

third column the recorded at each level signals are compared, inverting the polarity of one of the

compared signals. The results referring to EQ1 and EQ4, indicate an out of phase response for

the sensors located at the same level, while similar results are reported for the other shakes. As

expected the walls deformations are increased towards the roof slab. The maximum wall

deformations, as recorded for both the walls are compared for all the shakes in Fig. 4.18. The

walls deformations are increased with the increase of the amplitude input motion. Moreover, the

results indicated minor differences between the walls distributions, revealing an almost

symmetric response of the walls.

Figs. 4.19-4.20 present typical time histories of the tunnel diagonal deformations recorded by the

diagonal blades, indicating an in plane response of the tunnels.

Similar results were reported using the band pass filter for the tunnel deformation signals (Figs.

4.21 - 4.23). The maximum walls deformations were slightly smaller than the values observed by

the low pass filter results, due to the preclusion of the small residual values in this case.


32

CPT tests results obtained before and after the main test are summarized in Fig. 4.24. The results

indicate soil densification during shaking, as reflected in Fig. 4.25.


33

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26

Fig. 4.3 Processed acceleration time histories – EQ1


34

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26



35

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A2

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A3

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A4

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A5

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A6

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A8

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A9

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A10

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A11

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A12

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A14

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A15

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A16

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A17

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A18

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A20

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A21

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A22

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A23

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A24

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A26



36

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A/4

0g

A1 − Input

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A2

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A3

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A4

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A5

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A6

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A/4

0g

A7

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A8

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A9

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A10

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A11

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A12

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A/4

0g

A13

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A14

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A15

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A16

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A17

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A18

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A/4

0g

A19

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

A20

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A21

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A22

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A23

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A24

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A/4

0g

A25

0 0.16 0.32 0.48 0.64−0.6−0.3

00.30.6

t(s)

A26



37

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.15 0.2 0.250.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)

A/40g @ tunnel depth

Array 1Array 2Array 3Array 4Array 5

Fig. 4.7 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. 4.2) – EQ1

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.2 0.25 0.3 0.35 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





38

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.25 0.3 0.35 0.4 0.45 0.50.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.4 0.45 0.5 0.55 0.60.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





39

0 50 100 150 200 250 300 350 4000

5

10

15

20

f(Hz)

Am

plit

ud

e

Transfer functions

Reference arrayFree Field arrayTunnel array

Fig. 4.11 Typical transfer functions along vertical accelerometers arrays – EQ1

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

A/4

0g

A20

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

A25

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

A26

0.2 0.4 0.6−0.1

−0.05

0

0.05

0.1

t(s)

A/4

0g

A25 vs A26

Fig. 4.12 Vertical accelerations – EQ2


40

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20

stre

ss (

kPa)

A12−A13

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20A13−A14

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20A14−A15

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20

strain (%)

A6−A7

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20

strain (%)

stre

ss (

kPa)

A7−A8

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20

strain (%)

A9−A10

−0.08 −0.04 0 0.04 0.08−20

−10

0

10

20

strain (%)

A10−A11

Fig. 4.13 Stress-strain loops – EQ1

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60

stre

ss (

kPa)

A12−A13

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60A13−A14

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60A14−A15

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60

strain (%)

A6−A7

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60

strain (%)

stre

ss (

kPa)

A7−A8

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60

strain (%)

A9−A10

−0.6 −0.3 0 0.3 0.6−60

−30

0

30

60

strain (%)

A10−A11

Fig. 4.14 Stress-strain loops – EQ4


41

0 100 200 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Dep

th(m

)Vs(m/s)

Array 2Array 4Array 5Hardin & Drenvich, 1972

EQ1

0 100 200 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Dep

th(m

)

Vs(m/s)


EQ2

0 100 200 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Dep

th(m

)

Vs(m/s)


EQ3

0 100 200 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Dep

th(m

)

Vs(m/s)


EQ4

Fig. 4.15 Shear wave velocity profiles computed along vertical accelerometers arrays; comparison with Vso computed according to Hardin and Drenvich (1972) formulation


42

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

D(m

m)

F1

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05F6

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05F1−F6

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

D(m

m)

F2

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05F7

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05F2−F7

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

D(m

m)

F3

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05F8

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05F3−F8

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

D(m

m)

F4

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05F9

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05F4−F9

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

F10

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05

t(s)

F5−F10

Fig. 4.16 Walls deformations obtained using a low pass filter – EQ1


43

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F1

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F6

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F1−F6

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F2

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F7

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F2−F7

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F3

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F8

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F3−F8

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F4

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F9

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F4−F9

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

F5

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

F10

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15

t(s)

F5−F10



44

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)

Left side wallRight side wall

EQ1

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4

Fig. 4.18 Walls maximum deformations obtained using a low pass filter


45

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D2

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D3

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D4

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4

Fig. 4.19 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a low pass filter – EQ1

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

D1

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D2

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D3

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D4

0.2 0.25 0.3−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



46

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F1

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F6

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F1−F6

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F2

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F7

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F2−F7

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F3

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F8

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F3−F8

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

D(m

m)

F4

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15F9

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15F4−F9

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

F5

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

F10

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15

t(s)

F5−F10

Fig. 4.21 Walls deformations obtained using a band pass filter – EQ4


47

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4

Fig. 4.22 Walls maximum deformations obtained using a band pass filter


48

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

D2

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

D3

0 0.25 0.5 0.75 1−0.1

−0.05

0

0.05

0.1

t(s)

D4

0.25 0.3 0.35−0.1

−0.05

0

0.05

0.1

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4

Fig. 4.23 Diagonal tunnel deformations obtained along several locations of the tunnel axis using a band pass filter – EQ3

0 100 200 3000

50

100

150

200

250

300

350

Dep

th(m

m)

Force (daN)

Before testAfter test

Fig. 4.24 CPT test results


49

0 100 200 300 400 500 600 700 800 900 1000 11000

1

2

3

4

5

6

Sampling point

Set

tlem

ent(

mm

)

S1S2

Fig. 4.25 Soil surface settlements

Stabilization circles

Northridge 0.1g to 0.3g

Sine wavelet


50


Fig 4.26 presents the model set up along with instrumentation scheme. Tables 4.3 and 4.4

summarize channels and sensors locations before and after the main test. The coordinates refer to

the reference system presented in Fig. 2.21. The settlements estimated for each instrument by the

direct measurements are also reported.

DRESBUS2_2_1: Flexible tunnel ‐ Smooth surface ‐ Dry Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

A23

A24

A21

A22

A25A26F5

F1F5

F10

D1 D2D3

D4

S1 S3

800mm


50mm

47mm

Model

14mm

y

x

z

S2

Accelerometer Laser displacementssensor


1.5mm6.0mm

A16

A17

A18A19



51




DAS Channel

Sensor #


cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

cm A1 1 68 End table + pivot A2 2 69 Bottom plate + pivot A20 3 77 Bottom plate +top A3 4 95 Above plate + pivot 16.3** 39 39.2 34.2 39.2 0 A4 5 96 +13 cm/bottom + pivot 17.5** 40.3 27.8 22.8 28 0.2 A12 6 74 +13 cm/bottom + pivot 17.5 17.7 27.6 22.6 27.7 0.1 A9 7 100 + pivot 17.5 48.5** 14.5 9.5 14.9 0.4 A6 8 97 + pivot 17.5 44.5** 14.5 9.5 14.85 0.35 A13 9 75 + pivot 17.2 18 14.5 9.5 14.9 0.4 A7 10 98 + pivot 17.2 44.5** 12.2 7.2 12.35 0.15 A10 11 102 + pivot 17 47.7** 9.5 4.5 9.85 0.35 A8 12 99 + pivot 17 44.5** 9.5 4.5 9.85 0.35 A14 13 76 + pivot 17.3 17.3 9.5 4.5 10 0.5 A11 14 93 + pivot 17.8 48 6.8 1.8 6.9 0.1 A5 15 101 + pivot 17.5** 40 6.8 1.8 7.3 0.5 A15 16 80 + pivot 17.8 17.4 6.5 1.5 7.1 0.6 A23 17 84 On tunnel lateral + door A24 18 85 On tunnel lateral + door A22 19 86 On tunnel lateral + door A21 20 87 On tunnel lateral + door


A16 22 90 External box +door





** Measurement in X direction taken from the Teflon plate surface: 1 cm should be added to compare to others


52


A/A DAS Channel Column in data file Strain gauge F5 27 27 F3.1 F4 28 28 F3.2 F3 29 29 F3.3 F2 30 30 F3.4 F1 31 31 F3.5 F10 32 32 F3.6 F9 33 33 F3.7 F8 34 34 F3.8 F7 35 35 F3.9 F6 36 36 F3.10 D3 37 37 CL5 D4 38 38 CL6 D1 39 39 CL7 D2 40 40 CL8

Figs. 4.27-4.30 show filtered acceleration time histories, while in the Figs. 4.31-4.34 the

maximum horizontal accelerations, obtained along the vertical accelerometer arrays for all

shakes are summarized.

Similar to the first test case, the computed transfer functions did not clearly show the

predominant frequencies of the soil-tunnel system. Moreover, the yawing movement of the ESB

container on the shaking table and the in phase response of the vertical acceleration records on

the tunnel’s roof slab edges were also observed. Similar conclusions are also drawn regarding the

computed shear wave velocity profiles, estimated based to the Zeghal and Elgamal procedure

(Fig. 4.35). Finally, the tunnel deformed in a similar manner with the previous test (Figs. 4.36-

4.40).


indicate soil densification during shaking, as reflected in Fig. 4.42. The settlements above the

tunnel were slightly larger compared to the free field, during the stabilization circles, while the

opposite observed during shaking.


53

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26



54

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26



55

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A2

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A3

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A4

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A5

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A6

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A8

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A9

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A10

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A11

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A12

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A14

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A15

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A16

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A17

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A18

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A20

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A21

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A22

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A23

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A24

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A26



56

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A1 − Input

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A2

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A3

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A4

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A5

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A6

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A7

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A8

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A9

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A10

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A11

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A12

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A13

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A14

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A15

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A16

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A17

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A18

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A19

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A20

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A21

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A22

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A23

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A24

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A/4

0g

A25

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A26



57

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.05 0.1 0.15 0.2 0.30.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.15 0.2 0.25 0.3 0.35 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





58

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.25 0.3 0.35 0.4 0.45 0.50.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)



Fig. 4.33 Maximum horizontal acceleration along the vertical accelerometer arrays (arrays according to Fig. – EQ3

0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.3 0.4 0.5 0.6 0.7 0.80.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





59

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)Vs(m/s)


EQ1

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ2

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ3

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ4



60

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

D(m

m)

F1

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08F6

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08F1−F6

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

D(m

m)

F2

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08F7

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08F2−F7

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

D(m

m)

F3

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08F8

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08F3−F8

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

D(m

m)

F4

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08F9

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08F4−F9

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.08

−0.04

0

0.04

0.08

t(s)

F10

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08

t(s)

F5−F10



61

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ4



62

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D2

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D3

0 0.25 0.5 0.75 1−0.03

−0.015

0

0.015

0.03

t(s)

D4

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4


0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

D1

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D2

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D3

0 0.16 0.32 0.48 0.64−0.15

−0.075

0

0.075

0.15

t(s)

D4

0.25 0.3 0.35−0.15

−0.075

0

0.075

0.15

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



63

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.075 0.150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ4



64

0 100 200 3000

50

100

150

200

250

300

350

Dep

th(m

m)

Force (daN)

Before test


0 100 200 300 400 500 600 700 800 9000

1

2

3

4

5

6

7

8

Sampling point

Set

tlem

ent(

mm

)

S1S2S3




Sine wavelet


65


Fig 4.43 presents the model set up along with instrumentation scheme, while Tables 4.5 and 4.6

summarize channels and sensors locations before and after the main test.

DRESBUS2_3_1: Rigid tunnel ‐Rough surface ‐ Dry Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

14mm

y

x

z

S2

Accelerometer Laser displacement sensor


50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19



66




DAS Channel

Sensor #


cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

cm A1 1 68 End table + pivot A2 2 69 Bottom plate + pivot A20 3 79 Bottom plate +top A3 4 95 Above plate + pivot 17.5 40 39.5 34.4 39.7 A4 5 96 +13 cm/bottom + pivot 17 39.5 27.5 22.4 27.7 A12 6 74 +13 cm/bottom + pivot 17 24.5 27.5 22.4 27.7 A9 7 101 + pivot 17 32.3 15 9.9 15 A6 8 91 + pivot 17 35.2 15 9.9 15.1 A13 9 75 + pivot 17.3 24.2 15 9.9 15.2 A7 10 99 + pivot 17.5 35.5 12.5 7.4 12.5 A10 11 102 + pivot 17.1 32.3 10 4.9 10.3 A8 12 93 + pivot 17.2 35 10 4.9 10.2 A14 13 76 + pivot 17.5 24.1 10 4.9 10.55 A11 14 97 + pivot 17.5 32 7.8** 7.8 A5 15 100 + pivot 17 40 7.8** 7.8 A15 16 80 + pivot 17.5 24.1 7.8** 7.8 A23 17 84 On tunnel lateral + door A24 18 85 On tunnel lateral + door A22 19 86 On tunnel lateral + door A21 20 87 On tunnel lateral + door







** Erroneous measurements Figs. 4.44-4.47 show filtered acceleration time histories obtained for this test, while in the Figs.

4.48-4.51 the maximum horizontal accelerations, obtained along the vertical accelerometer

arrays for all shakes are summarized. The horizontal acceleration was slightly amplified towards

the soil surface. The acceleration recorded at the invert slab was found to be larger than the

acceleration on the roof. It is noted that the maximum acceleration is estimated as the absolute

maximum value of the time history. To this end, the values may biased by signal spikes that are

not eliminated by the filter. Further study, using also the numerical simulation results is needed

to better understand this behavior.


67


A/A DAS

Channel Column in data file Strain gauge

D1 27 37 CL5 D2 28 38 CL6 D4 29 39 CL7 D3 30 40 CL8 F10 31 27 F3.1 F9 32 28 F3.2 F8 33 29 F3.3 F7 34 30 F3.4 F6 35 31 F3.5 F5 36 32 F3.6 F4 37 33 F3.7 F3 38 34 F3.8 F2 39 35 F3.9 F1 40 36 F3.10

Similar observations with the previous tests are made regarding the transfer functions, the

vertical acceleration and the Vs profiles. Although the rigid tunnel deformed less than the flexible

tunnels, similar observations were made for the tunnel deformations, namely: increase of the

walls deformations reaching the roof slab, increase of the tunnel deformations with the increase

of the input motion amplitude and in phase response of the diagonal deformations (Figs. 4.53-

4.58).


indicate soil densification during shaking, as reflected in Fig. 4.60.


68

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26



69

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26



70

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A2

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A3

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A4

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A5

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A6

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A8

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A9

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A10

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A11

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A12

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A14

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A15

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A16

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A17

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A18

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A20

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A21

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A22

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A23

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A24

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A26



71

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A1 − Input

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A2

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A3

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A4

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A5

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A6

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A7

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A8

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A9

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A10

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A11

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A12

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A13

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A14

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A15

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A16

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A17

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A18

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A19

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A20

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A21

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A22

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A23

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A24

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A/4

0g

A25

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A26



72

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.15 0.25 0.35 0.450.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





73

0 0.125 0.25 0.375 0.50

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.125 0.25 0.375 0.50

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.125 0.25 0.375 0.5

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.125 0.25 0.375 0.5

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.125 0.25 0.375 0.50

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.25 0.35 0.45 0.550.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.35 0.45 0.55 0.650.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





74

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)Vs(m/s)


EQ1

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ2

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ3

0 100 200 300 4000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Dep

th(m

)

Vs(m/s)


EQ4



75

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F6

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F1−F6

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F7

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F2−F7

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F8

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F3−F8

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F4

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F9

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F4−F9

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

F10

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

F5−F10



76

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

D(m

m)

F1

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03F6

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03F1−F6

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

D(m

m)

F2

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03F7

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03F2−F7

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

D(m

m)

F3

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03F8

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03F3−F8

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

D(m

m)

F4

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03F9

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03F4−F9

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

t(s)

D(m

m)

F5

0 0.16 0.32 0.48 0.64−0.03

−0.015

0

0.015

0.03

t(s)

F10

0.25 0.3 0.35−0.03

−0.015

0

0.015

0.03

t(s)

F5−F10



77

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ1

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



78

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

D2

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

D3

0 0.25 0.5 0.75 1−0.05

−0.025

0

0.025

0.05

t(s)

D4

0.25 0.3 0.35−0.05

−0.025

0

0.025

0.05

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4


0 0.16 0.32 0.48 0.64−0.08

−0.04

0

0.04

0.08

t(s)

D(m

m)

D1

0 0.16 0.32 0.48 0.64−0.08

−0.04

0

0.04

0.08

t(s)

D2

0 0.16 0.32 0.48 0.64−0.08

−0.04

0

0.04

0.08

t(s)

D3

0 0.16 0.32 0.48 0.64−0.08

−0.04

0

0.04

0.08

t(s)

D4

0.25 0.3 0.35−0.08

−0.04

0

0.04

0.08

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



79

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.025 0.050

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



80

0 100 200 3000

50

100

150

200

250

300

350

Dep

th(m

m)

Force (daN)

Before test


0 200 400 600 800 1000 12000

1

2

3

4

5

6

7

8

Sampling point

Set

tlem

ent(

mm

)

S1S2S3



This test was the first in saturated sand. The tunnel ends were formed following the configuration

presented in Fig 2.12b. This configuration did not manage to withstand the water pressures

during the tests, leading to water leakage inside the tunnel and subsequently to problems to the

extensometers that did not work properly.



Sine wavelet


81


This test was a repetition of the test DRESBUS_2_4_1. Fig 4.61 presents the model set up along

with instrumentation scheme. The viscosity of the saturation fluid was formulated for a

temperature of 14°C which was verified to be consistent with the temperature in the centrifuge

room. The resulting viscosity was controlled just before the test to be between 39 and 40 cSt.

DRESBUS2_4_2: Rigid tunnel ‐ Rough surface ‐ Saturated Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

14mm

y

x

z

S2

Accelerometer Displacementsensor


Transversal "fork"extensiometers

50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19

Pore pressuresensors

A27

P3P1

P2 P4 P5

P6


Tables 4.7 and 4.8 summarize channels and sensors locations before and after the main test. The

coordinates refer to the reference system presented in Fig. 2.21. The settlements estimated for

each instrument by the direct measurements are also reported.


82




DAS Channel

Sensor #

Positive Direct X

cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

mm A1 1 68 + pivot A2 2 109 + pivot 17 41 46.6 36 A20 3 111 + top 17 34 46.6 36 A3 4 106 + pivot 16** 39 44.8 34.2 40.8 0 A27 5 97 +top 14.5 39 33.6 22.7 29.5 2 A4 6 99 + pivot 15.5 42 33.3 22.7 29.5 2 A12 7 98 + pivot 16 18 33.4 22.82 30 6 A9 8 101 + pivot 16 49 24 13.4 17.4 26*** A6 9 95 + pivot 15.8** 44.5 24.5 13.9 17.0 35*** A13 10 103 + pivot 16.6 19 27 16.4 18.2 48*** A7 11 96 + pivot 14.2** 55.5 18 7.4 14.6 6 A14 12 92 + pivot 17.7 18.4 15.1 4.5 13.1 20 A8 13 108 + pivot 15.6** 45.1 15.4 4.9 12.3 9 A10 14 102 + pivot 17 50 15.4 4.9 12.9 15 A15 15 104 + pivot 17 19 12.9 2.3 10.7 6 A5 16 105 + pivot 16** 38 13 2.4 9.6 6 A11 17 100 + pivot 17 46 13 2.4 10.4 14 A16 18 85 + door A17 19 86 + door A18 20 87 + door A19 21 88 + door A25 22 125 + top A26 23 126 + top A21 24 127 + door A22 25 128 + door A24 26 129 + door A23 27 130 + door P1 28 5798 15** 39 -21.5 -10.9 -17.7 2 P3 29 5796 17 56 -21 -10.4 -17.5 5 P5 30 5799 13.4** 36 -18.4 -7.8 -15.0 6

P2 31 5805 17 59 -14.9 -4.3 Non

Measured

P4 32 5801 18.5 41.5 -13 -2.4 -10.6 16

P6 33 5803 Non

Measured

** Measurement in X direction taken from the Teflon plate surface: 1 cm should be added to compare to others *** Erroneous measurements


83


A/A DAS

Channel Strain gauge

F6 34 F2.1 F7 35 F2.2 F8 36 F2.3 F9 37 F2.4 F10 38 F2.5 F5 39 F2.6 F4 40 F2.7 F3 41 F2.8 F2 42 F2.9 F1 43 F2.10 D4 44 CL9 D3 45 CL10 D2 46 CL11 D1 47 CL12

Due to a problem with the acquisition system, the tunnel deformations were not recorded during

shaking. Upon repairing of the problem the shaking program renewed. To this end, the shakes

were re-fired in an already modified soil-tunnel system.

Figs. 4.62-4.65 present the obtained filtered acceleration time histories for this test, while in the

Figs. 4.66-4.69 the maximum horizontal accelerations, obtained along the vertical accelerometer

arrays for all shakes, are summarized. Some of the acceleration time histories were highly

"decreased" during shaking. This observation explains the de-amplification of the maximum

horizontal acceleration from the soil base to the soil surface, as presented along the vertical

accelerometers arrays. This response is also observed to the tunnel distortion time histories.

Further investigation of the data in needed to conclude on whether this response is attributed to

recording issues or liquefaction of the sand deposit.

To capture the water pore pressures during and after shaking, pore pressure cells were used

(Figs. 4.76-4.79). The specific sensors were used for first time by the facility. Although the

sensors seemed to worked properly, a problem with their calibration exists. Table 4.9

summarizes the calibration procedure for the pore pressure cell P1 (left side), while the expected

initial pore pressure at the specific location is also presented for comparison (right side). The

differences are significant even if the settlement of the sensor is accounted. To this end the pore


84

pressure signals may have a consistent shape but their actual values are not reasonably

exploitable. Further investigation regarding this aspect is needed.

Table 4.9 Measured vs. theoretical water pore pressure at P1

Computation of the initial (static) pore pressures at the beginning of the test

Calculation of the hydrostatic Pore Pressure

Calibration coefficients Model sensor depth -10.9 cm Slope -4.3507 kPa/mV Water table (over sand

surface) 1.5 cm

Offset 191.11 kPa Prototype depth 4.36 m Measurement 14.66 mV Prototype Water table 0.60 m Computed absolute pore pressure

127.33 kPa Total water height 4.96 m

Atmospheric pressure 101.20 kPa Water density 1000 kg/m3 Computed relative pore pressure

26.13 kPa Static Theoretical Pore Pressure

48.7 kPa

Generally, the pore pressures were increased during shaking. After shaking pore pressures

recorded at P1, P3 and P5 continue to increase, while at P2 and P4 the pore pressures tend to

decrease indicating a possible flow from higher levels to the tunnel foundation level.

Fig. 4.80 presents the results of the CPT test performed prior the main test. The curve appears to

be concave rather than convex toward the top and not completely monotonous, meaning

probably a default of regularity in the pluvation. However, this default is of reduced amplitude.


85

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A27



86

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A27



87

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A27



88

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A2

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A3

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A4

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A5

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A6

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A/4

0g

A7

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A8

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A9

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A10

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A11

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A12

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A/4

0g

A13

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A14

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A15

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A16

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A17

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A18

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A/4

0g

A19

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

A20

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A21

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A22

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A23

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A24

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A26

0 0.16 0.32 0.48 0.64−0.4−0.2

00.20.4

t(s)

A27



89

0 0.05 0.1 0.15 0.20

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.05 0.1 0.15 0.20

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.05 0.1 0.15 0.2

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.05 0.1 0.15 0.2

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.05 0.1 0.15 0.20

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.05 0.1 0.15 0.20.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





90

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.4 0.50.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.4 0.50.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





91

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F6

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F1−F6

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F7

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F2−F7

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F8

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F3−F8

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F4

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F9

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F4−F9

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

F10

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

F5−F10



92

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

D(m

m)

F1

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01F6

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F1−F6

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

D(m

m)

F2

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01F7

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F2−F7

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

D(m

m)

F3

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01F8

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F3−F8

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

D(m

m)

F4

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01F9

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F4−F9

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

F5

0 0.16 0.32 0.48 0.64−0.01

−0.005

0

0.005

0.01

t(s)

F10

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

F5−F10



93

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ1

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



94

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D2

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D3

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D4

0.25 0.3 0.35−1

−0.5

0

0.5

1x 10

−5

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4


0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D2

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D3

0 0.25 0.5 0.75 1−1

−0.5

0

0.5

1x 10

−5

t(s)

D4

0.25 0.3 0.35−1

−0.5

0

0.5

1x 10

−5

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



95

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.005 0.010

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4

Fig. 4.75 Walls maximum deformations recorded by fork extensometers; low pass filter


96

0 0.75 1.5 2.25 3127.3

127.4

127.5

127.6

t(s)

Po

re p

ress

ure

s(kP

a)P1

0 0.75 1.5 2.25 3113.5

114

114.5

115

t(s)

P2

0 0.75 1.5 2.25 3129.4

129.6

129.8

130

t(s)

P3

0 0.75 1.5 2.25 3253.3

253.35

253.4

253.45

253.5

t(s)

P4

0 0.75 1.5 2.25 3103.3

103.4

103.5

103.6

t(s)

Po

re p

ress

ure

s(kP

a)

P5

0 0.75 1.5 2.25 3112.9

113

113.1

113.2

t(s)

P6

Fig. 4.76 Water pore pressures during and after shaking – EQ1

0 0.75 1.5 2.25 3127.8

128

128.2

128.4

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.75 1.5 2.25 3113.5

114

114.5

115

t(s)

P2

0 0.75 1.5 2.25 3130

130.2

130.4

130.6

t(s)

P3

0 0.75 1.5 2.25 3253.1

253.2

253.3

253.4

253.5

t(s)

P4

0 0.75 1.5 2.25 3103.6

103.8

104

104.2

t(s)

Po

re p

ress

ure

s(kP

a)

P5

0 0.75 1.5 2.25 3113

113.1

113.2

113.3

t(s)

P6



97

0 0.75 1.5 2.25 3128.8

128.9

129

129.1

129.2

t(s)

Po

re p

ress

ure

s(kP

a)P1

0 0.75 1.5 2.25 3114

114.5

115

115.5

116

t(s)

P2

0 0.75 1.5 2.25 3130.8

131

131.2

131.4

t(s)

P3

0 0.75 1.5 2.25 3252.9

252.95

253

253.05

253.1

t(s)

P4

0 0.75 1.5 2.25 3104.3

104.4

104.5

104.6

t(s)

Po

re p

ress

ure

s(kP

a)

P5

0 0.75 1.5 2.25 3113.2

113.3

113.4

113.5

t(s)

P6


0 0.75 1.5 2.25 3129.7

129.8

129.9

130

130.1

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.75 1.5 2.25 3114.5

115

115.5

116

116.5

t(s)

P2

0 0.75 1.5 2.25 3131.4

131.6

131.8

132

t(s)

P3

0 0.75 1.5 2.25 3252.7

252.75

252.8

252.85

252.9

t(s)

P4

0 0.75 1.5 2.25 3104.9

105

105.1

105.2

t(s)

Po

re p

ress

ure

s(kP

a)

P5

0 0.75 1.5 2.25 3113.4

113.5

113.6

113.7

t(s)

P6



98

0 100 200 3000

50

100

150

200

250

300

350

Dep

th(m

m)

Force (daN)

Before test



99


Fig 4.81 presents the model set up along with instrumentation scheme. Tables 4.10 and 4.11


DRESBUS2_5_1: Rigid tunnel ‐ Smooth surface ‐ Dry Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

19mm

y

x

z

S2

Accelerometer Laser displacementssensors

Diagonal extensiometers Transversal "fork"extensiometers

50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19



100




DAS Channel

Sensor #


cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

cm A1 1 68 + pivot A2 2 69 + pivot 16* 40 41.2 41.2 0 A20 3 79 +top 16* 41 41.2 41.2 0 A3 4 97 + pivot 16.5* 40 39.3 39.2 0.1 A4 5 98 + pivot 16.5* 39.7 27.7 27.8 0.1 A12 6 99 + pivot 17 19 27.8 27.8 0.1 A13 7 91 + pivot 17.5 16.5 14.9 15.1 0.2

8 No sensor – clear

channel + pivot

A14 9 100 + pivot 18.5 15 9.5 9.9 0.4 A6 10 80 + pivot 16* 43.7 15 15.4 0.4 A9 11 82 + pivot 16* 46.5 15.3 15.6 0.3 A7 12 93 + pivot 16.5* 44 11.8 12.1 0.3 A10 13 76 + pivot 16.5* 47.4 9.85 10.1 0.2 A8 14 101 + pivot 16* 44.2 9.6 9.8 0.2 A15 15 75 + pivot 17 17.5 6.7 7.1 0.3 A5 16 74 + pivot 16.5* 39.8 6.8 7.1 0.3 A16 17 84 + door A17 18 85 + door A18 19 86 + door A19 20 87 + door

A24 21 102 + door

A21 22 103 + door

A23 23 104 + door

A22 24 105 + door

A25 25 106 +top

A26 26 108 +top

* Measurement in X direction taken from the Teflon plate surface: 1 cm should be added to compare to others


101


A/A DAS



Figs. 4.82-4.85 summarize filtered acceleration time histories obtained for this test, while in the

Figs. 4.86-4.89 the maximum horizontal accelerations are summarized. The horizontal

acceleration was generally amplified towards the soil surface.

The recorded tunnel deformations (Figs. 4.90- 4.93) indicated unrealistically large deformations

for the tunnel (deformations larger than for the flexible tunnels), probably due to a recoding

problem.

CPT test results, obtained before the main test, are summarized in Fig. 4.94, while Fig. 4.95

summarizes the recorded soil surface settlements.


102

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26



103

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26



104

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A2

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A3

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A4

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A5

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A6

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A/4

0g

A7

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A8

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A9

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A10

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A11

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A12

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A/4

0g

A13

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A14

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A15

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A16

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A17

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A18

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A/4

0g

A19

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

A20

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A21

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A22

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A23

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A24

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.6−0.3

00.30.6

t(s)

A26



105

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A1 − Input

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A2

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A3

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A4

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A5

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A6

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A7

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A8

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A9

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A10

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A11

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A12

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A13

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A14

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A15

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A16

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A17

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A18

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A/4

0g

A19

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

A20

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A21

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A22

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A23

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A24

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A/4

0g

A25

0 0.16 0.32 0.48 0.64−0.8−0.4

00.40.8

t(s)

A26



106

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.07 0.14 0.21 0.28

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.07 0.14 0.21 0.280

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.30.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.15 0.25 0.35 0.450.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





107

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.25 0.35 0.45 0.550.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.2 0.4 0.6 0.8

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.2 0.4 0.6 0.80

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.35 0.45 0.55 0.650.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





108

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

D(m

m)

F1

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2F6

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2F1−F6

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

D(m

m)

F2

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2F7

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2F2−F7

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

D(m

m)

F3

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2F8

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2F3−F8

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

D(m

m)

F4

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2F9

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2F4−F9

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

F10

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2

t(s)

F5−F10



109

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

D2

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

D3

0 0.25 0.5 0.75 1−0.2

−0.1

0

0.1

0.2

t(s)

D4

0.25 0.3 0.35−0.2

−0.1

0

0.1

0.2

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



110

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ1

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.4 0.80

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



111

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.3 0.60

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.4 0.80

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



112

0 100 200 3000

50

100

150

200

250

300

350

Dep

th(m

m)

Force (daN)

Before test


0 100 200 300 400 500 600 7000

1

2

3

4

5

6

Sampling point

Set

tlem

ent(

mm

)

S1S2S3


Stabilization circles Northridge

0.1g to 0.3g

Sine wavelet


113


Fig 4.96 presents the model setup along with instrumentation scheme. Tables 4.12 and 4.13


DRESBUS2_6_1: Rigid tunnel ‐ Smooth surface ‐ Saturated Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10 A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

14mm

y

x

z

S2




50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19


A27

P1

P2 P4 P3

A28 A29


The viscosity of the saturation fluid was formulated for a temperature of 18°C which was

verified to be consistent with the temperature in the centrifuge room. The resulted viscosity was

checked one day before the test to be around 32 cSt.


114




DAS Channel

Sensor #

Positive Direct X

cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

mm A1 1 68 + pivot A2 2 90 + pivot 16 39 46.2 36 A20 3 108 + top 16 41 46.2 36 A3 4 91 + pivot 16.5 40.5 44.7 34.5 40.8 3.9 A4 5 101 + pivot 16 39.5 32.7 22.5 29.1 3.6 A27 6 96 +top 16* 42.5 32.6 22.4 29.1 3.5 A12 7 104 + pivot 16.5 19 32.7 22.5 29.1 3.6 A6 8 103 + pivot 14.5* 43.5 20.4 10.2 16.5 3.9 A9 9 106 + pivot 14* 47 20.1 9.9 16.4 3.7 A13 10 105 + pivot 16 18 20.3 10.1 17.2 3.1 A7 11 95 + pivot 16* 44.5 17.4 7.2 A10 12 100 + pivot 16.2 48 15.1 4.9 11.6 3.5 A8 13 99 + pivot 15.6* 44.3 15.3 5.1 11.5 3.8 A14 14 98 + pivot 17.7 18.3 14.6 4.4 11.6 3 A5 15 97 + pivot 14.5* 43.5 12.2 2 8.6 3.6 A15 16 102 + pivot 15.7 21.4 11.5 1.3 8.6 2.9 A28 17 124 + top 15.7* 40.2 11.9 1.7 A29 18 92 + top 15.5 18.5 11.3 1.1 8.05 3.25 A26 19 125 + top A25 20 126 + top A21 21 127 + door A22 22 128 + door A24 23 129 + door A23 24 130 + door A16 25 83 + door A17 26 84 + door A18 27 85 + door A17 86 + door P1 28 5802 18.5 59 20.5 10.3 17.2 3.3 P3 29 5805 17* 35 17.4 7.2 14.4 3 P2 30 5804 17.8 55.2 14.4 4.2 11.3 3.1 P4 31 5796 16.5 40 14.5 4.3



115


A/A DAS



Figs. 4.97-4.100 show filtered acceleration time histories, while in the Figs. 4.101-4.104 the

maximum horizontal accelerations, obtained along the vertical accelerometer arrays for all

shakes are summarized. The maximum horizontal acceleration recorded on the tunnel was

generally found to be larger than the free field.

Similar to the dry tests observations were made from the tunnel deformations, namely: increase

of the walls deformations reaching the roof slab, increase of the tunnel deformations with the

increase of the input motion amplitude and in phase response of the diagonal deformations (Figs.

4.105-4.108).

The pore pressures were generally increased during shaking (except P3, middle of tunnel's wall).

After shaking pore pressures recorded at P1, P3 continue to increase, while at P2 the pore

pressure tend to decrease indicating a possible flow from higher levels to the tunnel foundation

level.

Fig. 4.113 presents the soil surface settlements, as recorded at three locations by the

displacement sensors. The sensor above the tunnel was probably shifted during EQ4 (reduction

of the settlement).


116

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A27

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A28

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A29

Fig. 4.97 Maximum Processed acceleration time histories – EQ1


117

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A27

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A28

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A29



118

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A27

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A28

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A29



119

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.160.320.480.64−0.5

−0.250

0.250.5

A2

0 0.160.320.480.64−0.5

−0.250

0.250.5

A3

0 0.160.320.480.64−0.5

−0.250

0.250.5

A4

0 0.160.320.480.64−0.5

−0.250

0.250.5

A5

0 0.160.320.480.64−0.5

−0.250

0.250.5

A6

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.160.320.480.64−0.5

−0.250

0.250.5

A8

0 0.160.320.480.64−0.5

−0.250

0.250.5

A9

0 0.160.320.480.64−0.5

−0.250

0.250.5

A10

0 0.160.320.480.64−0.5

−0.250

0.250.5

A11

0 0.160.320.480.64−0.5

−0.250

0.250.5

A12

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.160.320.480.64−0.5

−0.250

0.250.5

A14

0 0.160.320.480.64−0.5

−0.250

0.250.5

A15

0 0.160.320.480.64−0.5

−0.250

0.250.5

A16

0 0.160.320.480.64−0.5

−0.250

0.250.5

A17

0 0.160.320.480.64−0.5

−0.250

0.250.5

A18

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.160.320.480.64−0.5

−0.250

0.250.5

A20

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A21

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A22

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A23

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A24

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A26

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A27

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A28

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A29



120

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.30.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





121

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.125 0.25 0.375 0.50

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.125 0.25 0.375 0.5

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.125 0.25 0.375 0.5

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.125 0.25 0.375 0.5

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.125 0.25 0.375 0.50

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.30.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





122

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F6

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F1−F6

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F7

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F2−F7

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F8

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F3−F8

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F4

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F9

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F4−F9

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

F10

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

F5−F10



123

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



124

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D4

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4



125

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



126

0 0.5 1 1.5 2120.36

120.38

120.4

120.42

120.44

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.5 1 1.5 2111.1

111.15

111.2

111.25

111.3

111.35

t(s)

P2

0 0.5 1 1.5 2117.2

117.3

117.4

117.5

117.6

117.7

t(s)

Po

re p

ress

ure

s(kP

a)

P3

0 0.5 1 1.5 2130.38

130.4

130.42

130.44

130.46

130.48

t(s)

P4


0 0.5 1 1.5 2109.8

109.85

109.9

109.95

110

110.05

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.5 1 1.5 2100.1

100.2

100.3

100.4

t(s)

P2

0 0.5 1 1.5 2109.2

109.4

109.6

109.8

110

t(s)

Po

re p

ress

ure

s(kP

a)

P3

0 0.5 1 1.5 2117.65

117.7

117.75

117.8

117.85

117.9

t(s)

P4



127

0 0.5 1 1.5 2111.35

111.4

111.45

111.5

111.55

111.6

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.5 1 1.5 2102.1

102.2

102.3

102.4

102.5

102.6

t(s)

P2

0 0.5 1 1.5 2110.95

111

111.05

111.1

111.15

111.2

t(s)

Po

re p

ress

ure

s(kP

a)

P3

0 0.5 1 1.5 2120.2

120.25

120.3

120.35

120.4

120.45

t(s)

P4


0 0.5 1 1.5 2117.6

117.65

117.7

117.75

117.8

117.85

t(s)

Po

re p

ress

ure

s(kP

a)

P1

0 0.5 1 1.5 2107.4

107.6

107.8

108

108.2

t(s)

P2

0 0.5 1 1.5 2115.2

115.4

115.6

115.8

116

t(s)

Po

re p

ress

ure

s(kP

a)

P3

0 0.5 1 1.5 2126.45

126.5

126.55

126.6

126.65

126.7

t(s)

P4



128

0 100 200 300 400 500 600 700 800 9000

2

4

6

8

10

12

14

Sampling point

Set

tlem

ent(

mm

)

S1S2S3


Stabilization circles Northridge

0.1g to 0.3g

Sine wavelet


129


Fig 4.114 presents the model set up along with instrumentation scheme. The saturation was

scheduled to be performed the week before the test for an anticipated temperature of 16°C in the

centrifuge room. The real temperature in the command room during the test was 18°C leading to

a viscosity between 35 and 39 cSt. The level of the water table was 2 cm over the sand level.

DRESBUS2_7_1: Rigid tunnel ‐Rough surface ‐ Saturated Sand

250mm

400mm240mm

360mm

180mm326mm

360mm

A2

A1

A3

A4

A20

A12

A9 A6 A13A7

A10A11

A8 A5

130mm

130mm

A14A15

20mm

100mm

F5

F1F6

F10

D1 D2D3

D4

S1 S3

800mm


Model

14mm

y

x

z

S2




50mm

5.0mm6.0mm54mm

A23

A24

A21

A22

A25A26

A16

A17

A18A19


A27

P1

P2 P4 P3

A28 A29


The test was interrupted by a centrifuge shut down due to a default of the cooling system. The

test stopped before the main shakings.


130

Tables 4.12 and 4.13 summarize channels and sensors locations before and after the main test.

The coordinates refer to the reference system presented in Fig. 2.21.




DAS Channel

Sensor #

Positive Direct X

cm Y

cm Z / top box

cm Z / surface

cm Z / top box

cm Settlement

mm A1 1 68 + pivot A2 2 122 + pivot 17 39 46.2 36 A20 3 123 + top 17 41 46.6 36 A3 4 108 + pivot 16* 40 44.6 34.4 A12 5 104 + pivot 16.5 18.2 32.9 22.7 A4 6 101 + pivot 16* 40.5 33.4 23.2 A27 7 96 + top 16.5* 43.4 33.2 23 A6 8 103 + pivot 16* 45 20.2 10 A9 9 106 + pivot 17 48.5 20 9.8 A13 10 105 + pivot 16.5 19 20.1 9.9 A7 11 95 + pivot 16* 44.5 17.4 7.2 A11 12 100 + pivot 16.8 47.5 12.2 2 A5 13 99 + pivot 16 41 12.4 2.2 A15 14 98 + pivot 16.8 17 12.3 2.1 A8 15 97 + pivot 16 44 14.9 4.7 A14 16 102 + pivot 17 17.5 14.8 4.6 A28 17 124 + top 17* 38.3 12.2 2 A29 18 92 + top 17.5 20.5 12.3 2.1 A26 19 125 + top A25 20 126 + top A21 21 127 + door A22 22 128 + door A24 23 129 + door A23 24 130 + door A16 25 83 + door A17 26 84 + door A18 27 85 + door A19 28 86 + door P1 29 5799 17 52.5 19.1 8.9 P3 30 5798 16* 35.5 17.4 7.2 P2 31 5797 16.5 50 14.5 4.3 P4 32 5801 17.5 40 12.2 2 P5 33 5802 In the air

A10 34 119 + pivot 17 47.2 14.8 4.6



131


A/A DAS



Figs. 4.115-4.118 present the obtained filtered acceleration time histories, while in the Figs.

4.119-4.122 the maximum horizontal accelerations are summarized. Some of the acceleration

time histories were “decreasing” during shaking. This observation explains the de-amplification

of the maximum horizontal acceleration from the soil base to the soil surface, as presented along

the vertical accelerometers arrays. Similar with the previous tests observations were made from

the tunnel deformations records, namely: increase of the walls deformations reaching the roof

slab, increase of the tunnel deformations with the increase of the input motion amplitude and in

plane response of the diagonal deformations (Figs. 4.123-4.126).

Figs. 4.127-4.130 summarize the pore pressures records, while Fig. 4.131-4.132 summarize the

recorded soil surface settlements.


132

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A2

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A3

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A4

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A5

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A6

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A7

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A8

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A9

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A10

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A11

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A12

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A13

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A14

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A15

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A16

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A17

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A18

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A/4

0g

A19

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

A20

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A21

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A22

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A23

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A24

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A26

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A27

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A28

0 0.25 0.5 0.75 1−0.3

−0.150

0.150.3

t(s)

A29



133

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A2

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A3

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A4

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A5

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A6

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A7

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A8

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A9

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A10

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A11

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A12

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A13

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A14

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A15

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A16

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A17

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A18

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A/4

0g

A19

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

A20

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A21

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A22

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A23

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A24

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A26

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A27

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A28

0 0.25 0.5 0.75 1−0.4−0.2

00.20.4

t(s)

A29



134

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A2

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A3

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A4

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A5

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A6

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A8

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A9

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A10

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A11

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A12

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A14

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A15

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A16

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A17

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A18

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

A20

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A21

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A22

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A23

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A24

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A26

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A27

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A28

0 0.25 0.5 0.75 1−0.5

−0.250

0.250.5

t(s)

A29



135

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A1 − Input

0 0.160.320.480.64−0.5

−0.250

0.250.5

A2

0 0.160.320.480.64−0.5

−0.250

0.250.5

A3

0 0.160.320.480.64−0.5

−0.250

0.250.5

A4

0 0.160.320.480.64−0.5

−0.250

0.250.5

A5

0 0.160.320.480.64−0.5

−0.250

0.250.5

A6

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A7

0 0.160.320.480.64−0.5

−0.250

0.250.5

A8

0 0.160.320.480.64−0.5

−0.250

0.250.5

A9

0 0.160.320.480.64−0.5

−0.250

0.250.5

A10

0 0.160.320.480.64−0.5

−0.250

0.250.5

A11

0 0.160.320.480.64−0.5

−0.250

0.250.5

A12

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A13

0 0.160.320.480.64−0.5

−0.250

0.250.5

A14

0 0.160.320.480.64−0.5

−0.250

0.250.5

A15

0 0.160.320.480.64−0.5

−0.250

0.250.5

A16

0 0.160.320.480.64−0.5

−0.250

0.250.5

A17

0 0.160.320.480.64−0.5

−0.250

0.250.5

A18

0 0.160.320.480.64−0.5

−0.250

0.250.5

A/4

0g

A19

0 0.160.320.480.64−0.5

−0.250

0.250.5

A20

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A21

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A22

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A23

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A24

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A/4

0g

A25

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A26

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A27

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A28

0 0.160.320.480.64−0.5

−0.250

0.250.5

t(s)

A29



136

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.30.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.075 0.15 0.225 0.3

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.075 0.15 0.225 0.30

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





137

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)Array 1 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.1 0.2 0.3 0.4

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.1 0.2 0.3 0.40

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.2 0.3 0.4 0.50.05

0.06

0.07

0.08

0.09

0.1D

epth

(m)




0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 1 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 2 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 3 − A/40g0 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Array 4 − A/40g

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

Array 5 − A/40g 0.1 0.2 0.3 0.40.05

0.06

0.07

0.08

0.09

0.1

Dep

th(m

)





138

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F6

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F1−F6

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F7

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F2−F7

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F8

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F3−F8

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

D(m

m)

F4

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01F9

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01F4−F9

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

F5

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

F10

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

F5−F10



139

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ1

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ3

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4



140

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

D1

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D2

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D3

0 0.25 0.5 0.75 1−0.01

−0.005

0

0.005

0.01

t(s)

D4

0.25 0.3 0.35−0.01

−0.005

0

0.005

0.01

t(s)

D(m

m)

Comparisons

D1 D2 D3 D4


0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ1

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ2


141

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)D

epth

(mm

)


EQ3

0 0.0075 0.0150

9.5

19

28.5

38

Deformation (mm)

Dep

th(m

m)


EQ4


0 0.5 1 1.5 2110.6

110.8

111

t(s)

Po

re p

ress

ure

s(kP

a) P1

0 0.5 1 1.5 2117.2

117.4

117.6

t(s)

P2

0 0.5 1 1.5 297.1

97.15

t(s)

P3

0 0.5 1 1.5 2258.2

258.3

258.4

t(s)

Po

re p

ress

ure

s(kP

a) P4

0 0.5 1 1.5 2104.5

105

105.5

t(s)

P5



142

0 0.5 1 1.5 2112.6

112.8

113

t(s)

Po

re p

ress

ure

s(kP

a) P1

0 0.5 1 1.5 2117

117.5

118

t(s)

P2

0 0.5 1 1.5 297.6

97.8

98

t(s)

P3

0 0.5 1 1.5 2257.3

257.4

257.5

t(s)

Po

re p

ress

ure

s(kP

a) P4

0 0.5 1 1.5 2104

105

106

t(s)

P5


0 0.5 1 1.5 2115.5

116

116.5

t(s)

Po

re p

ress

ure

s(kP

a) P1

0 0.5 1 1.5 2117.5

118

118.5

t(s)

P2

0 0.5 1 1.5 298.6

98.8

99

t(s)

P3

0 0.5 1 1.5 2256

256.1

256.2

t(s)

Po

re p

ress

ure

s(kP

a) P4

0 0.5 1 1.5 2104

105

106

t(s)

P5



143

0 0.5 1 1.5 2117.5

118

118.5

t(s)

Po

re p

ress

ure

s(kP

a) P1

0 0.5 1 1.5 2118

118.5

119

t(s)

P2

0 0.5 1 1.5 299.2

99.4

99.6

t(s)

P3

0 0.5 1 1.5 2255.3

255.4

255.5

t(s)

Po

re p

ress

ure

s(kP

a) P4

0 0.5 1 1.5 2104

105

106

t(s)

P5


0 50 100 150 200 2500

0.5

1

1.5

2

2.5

3

3.5

4

Sampling point

Set

tlem

ent(

mm

)

S1S2S3

Fig. 4.131 Soil surface settlements during swing up


144

0 20 40 60 80 100 120 140 160 180 2000

2

4

6

8

10

Sampling point

Set

tlem

ent(

mm

)

S1S2S3

Fig. 4.132 Soil surface settlements during shaking


145

5 Interpretation of experimental data

Representative comparisons of recorded soil-tunnel system response are reported in this section.

To this end, soil response is compared in terms of horizontal acceleration amplification, whereas

tunnels response is compared in terms of walls racking deformations.

5.1 CPT DATA DURING TEST SEQUENCE

The results of the CPT tests performed before shaking for all the dry tests are compared in Fig.

5.1. The results variation is within 10% with respect to the mean value, indicating the

repeatability of the soil deposits properties.

0 100 200 3000

50

100

150

200

250

300

Dep

th(m

m)

Force (daN)

DRESBUS2 1 1DRESBUS2 2 1DRESBUS2 3 1DRESBUS2 5 1

Fig. 5.1 CPT test results for the dry sand tests

5.2 RECORDED SOIL AMPLIFICATION

Fig. 5.2 depicts maximum horizontal acceleration, recorded along the free field Array 2 for the

dry test cases, denoting a slight amplification within the soil deposit.


146

The corresponding results for the saturated sand are given in Fig. 5.3 showing a considerably

higher scatter with respect to the dry cases.

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ10 0.15 0.3 0.45 0.6

0

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ2

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ3

0 0.15 0.3 0.45 0.60

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ4

DRESBUS 2 1 1DRESBUS 2 2 1DRESBUS 2 3 1DRESBUS 2 5 1

Fig. 5.2 Maximum horizontal acceleration at the soil free field (Array 2) for the dry tests


147

0 0.1125 0.225 0.3375 0.450

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ10 0.1125 0.225 0.3375 0.45

0

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ2

0 0.1125 0.225 0.3375 0.450

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ3

0 0.1125 0.225 0.3375 0.450

0.09

0.18

0.27

0.36

Dep

th(m

)

A/40g − EQ4

DRESBUS 2 4 2DRESBUS 2 6 1DRESBUS 2 7 1

Fig. 5.3 Maximum horizontal acceleration at the soil free field (Array 2) for the saturated tests

5.3 TUNNELS RACKING DEFORMATIONS

The following paragraphs present comparisons of the maximum deformations recorded on the

tunnels walls as affected by (i) the input motion amplitude, (ii) the rigidity of the tunnel and (iii)

the roughness of the tunnel’s external face.

5.3.1 Input motion amplitude effect

Figs. 5.4-5.10 show maximum racking deformations imposed on the tunnels side walls (lsw: left

side wall, rsw: right side wall) for each test case. EQ1, EQ2 and EQ3 refer to the Northridge

record scaled to 0.1 g, 0.2 g and 0.3 g, respectively, whereas EQ4 refers to the sine wavelet (0.3

g, 85 Hz). Generally, the racking deformations are increased with increasing amplitude of the

base excitation in a symmetrical manner between the two side walls of the tunnel section. It is


148

noted that the tunnel response recorded during tests DRESBUS_4_2_2 and DRESBUS_2_5_1

was partially corrupted.

0 0.05 0.1 0.150

9.5

19

28.5

38

Dep

th(m

m)

0 0.05 0.1 0.15 0.2

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.4 Maximum racking deformations for different input motion amplitudes – rough flexible tunnel in dry sand (DRESBUS2_1_1)

0 0.05 0.1 0.150

9.5

19

28.5

38

Dep

th(m

m)

0 0.05 0.1 0.15 0.2

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.5 Maximum racking deformations for different input motion amplitudes – smooth flexible tunnel in dry sand (DRESBUS2_2_1)


149

0 0.0063 0.0125 0.01880

9.5

19

28.5

38

Dep

th(m

m)

0 0.0063 0.0125 0.0188 0.025

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.6 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in dry sand (DRESBUS2_3_1)

0 0.0063 0.0125 0.01880

9.5

19

28.5

38

Dep

th(m

m)

0 0.0063 0.0125 0.0188 0.025

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.7 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in saturated sand (DRESBUS2_4_2)


150

0 0.15 0.3 0.450

9.5

19

28.5

38

Dep

th(m

m)

0 0.15 0.3 0.45 0.6

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.8 Maximum racking deformations for different input motion amplitudes – smooth rigid tunnel in dry sand (DRESBUS2_5_1)

0 0.0063 0.0125 0.01880

9.5

19

28.5

38

Dep

th(m

m)

0 0.0063 0.0125 0.0188 0.025

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.9 Maximum racking deformations for different input motion amplitudes – smooth rigid tunnel in saturated sand (DRESBUS2_6_1)


151

0 0.0063 0.0125 0.01880

9.5

19

28.5

38

Dep

th(m

m)

0 0.0063 0.0125 0.0188 0.025

EQ1EQ2EQ3EQ4

D(mm)

lsw rsw

Fig. 5.10 Maximum racking deformations for different input motion amplitudes – rough rigid tunnel in saturated sand (DRESBUS2_7_1)

5.3.2 Tunnel stiffness effect

Notwithstanding the similar deformation pattern, the flexible tunnel sections showed higher

deformation amplitudes compared to the rigid ones.

5.3.3 Soil‐tunnel interface effect

Fig 5.11 compares wall deformations for smooth and rough soil-tunnel interface. The results

refer to the flexible tunnel case embedded in dry sand (tests DRESBUS2_1_1,

DRESBUS2_2_1). A similar deformation pattern is revealed, while larger deformation amplitude

is observed for the smooth surface tunnel under the low-amplitude base excitations (EQ1 and

EQ2). The opposite trend is observed for the high-amplitude motions (EQ3 and EQ4) were the

deformations of the rough surface tunnel are generally larger than the smooth interface tunnel.


152

0 0.0375 0.075 0.11250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0375 0.075 0.1125 0.15

0 0.0375 0.075 0.11250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0375 0.075 0.1125 0.15

0 0.0375 0.075 0.11250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0375 0.075 0.1125 0.15

0 0.0375 0.075 0.11250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0375 0.075 0.1125 0.15

RoughSmooth

EQ1 − D(mm)

EQ2 − D(mm)

EQ3 − D(mm)

EQ4 − D(mm)

lsw rsw

Fig. 5.11 Maximum racking deformations for different input motion amplitudes – rough vs. smooth flexible tunnel in dry sand (DRESBUS2_1_1 vs. DRESBUS2_2_1)


153

Comparisons of the walls deformations as recorded for the rigid tunnels embedded in saturated

sands are summarized in Fig. 5.12 (test case DRESBUS_2_6_1: smooth tunnel,

DRESBUS_2_7_1: rough tunnel). The wall deformations were generally larger for the rough

tunnel, with the difference being increased with the increase of the input motion amplitude.

0 0.005 0.01 0.0150

9.5

19

28.5

38

Dep

th(m

m)

0 0.005 0.01 0.015 0.02

0 0.005 0.01 0.0150

9.5

19

28.5

38

Dep

th(m

m)

0 0.005 0.01 0.015 0.02

0 0.005 0.01 0.0150

9.5

19

28.5

38

Dep

th(m

m)

0 0.005 0.01 0.015 0.02

0 0.005 0.01 0.0150

9.5

19

28.5

38

Dep

th(m

m)

0 0.005 0.01 0.015 0.02

RoughSmooth

EQ1 − D(mm)

EQ2 − D(mm)

EQ3 − D(mm)

EQ4 − D(mm)

lsw rsw

Fig. 5.12 Maximum racking deformations for different input motion amplitudes – rough vs. smooth rigid tunnel in saturated sand (DRESBUS2_6_1 vs. DRESBUS2_7_1)


154

5.3.4 Soil saturation effect

Fig 5.13 presents the effect of the sand saturation on the wall deformations as recorded for the

rigid tunnel having a rough external face (tests DRESBUS2_3_1: dry sand, DRESBUS2_2_1:

saturated sand). The walls deformations found to be systematically larger for the dry sand case.

This observation may be attributed to some extend to the higher sand stiffness of the dry sand

compared to the saturated case.

0 0.0075 0.015 0.02250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0075 0.015 0.0225 0.03

0 0.0075 0.015 0.02250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0075 0.015 0.0225 0.03

0 0.0075 0.015 0.02250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0075 0.015 0.0225 0.03

0 0.0075 0.015 0.02250

9.5

19

28.5

38

Dep

th(m

m)

0 0.0075 0.015 0.0225 0.03

DrySaturated

EQ1 − D(mm)

EQ2 − D(mm)

EQ3 − D(mm)

EQ4 − D(mm)

lsw rsw

Fig. 5.13 Maximum racking deformations for different input motion amplitudes – effect of sand saturation (DRESBUS2_3_1 vs. DRESBUS2_7_1)


155

6 Conclusions

This report included a detailed description of the centrifuge tests performed within the SERIES

TA Project: DRESBUS II: Investigation of the seismic behaviour of shallow rectangular

underground structures in soft soils using centrifuge experiments. Experimental procedures and

data processing methods were described followed by a detailed presentation of the complete set

of the recorded data. The preliminary interpretation of the results revealed the following issues:

Maximum soil horizontal accelerations were increased within the soil deposit indicating

base-to-surface soil amplification effects.

In some test cases, maximum tunnel acceleration recorded on the base slab was larger

than the corresponding value recorded on the roof slab. This counterintuitive behavior

may be associated with recording spikes that were observed after filtering.

The horizontal deformations along the tunnels side walls developed in a symmetrical

manner proving the theoretical assumption of racking distortion mode.

The diagonal extensometers recordings showed in-phase diagonal deformations along the

longitudinal axis of the tunnel denoting the plane strain behavior of the model sections.

Rigid tunnels were understandably less deformed during shaking compared to the flexible

sections.

For the specific soil-tunnel systems under investigation, the external face rugosity seems

to have a minor effect on the tunnels deformation, probably due to the small dimensions

of the test models.

Tunnel walls deformations were generally larger for the dry test case compared to the

saturated case. This observation may be attributed to some extend to the higher sand

stiffness of the dry sand compared to the saturated case.


156

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series dresbus ii final report · a low pass filter – eq4..... 45 fig. 4.21 walls deformations...

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