building response to excavation

7/28/2019 Building Response to Excavation

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Examples of building response toxamples of building response toexcavation and tunnelingxcavation and tunnelingBarcelona

December 16, 2008

Edward J . CordingEdward J . Cording

University of Illinois at UrbanaUniversity of Illinois at Urbana--ChampaignChampaign

, . , . , . , ..

In the cases illustrated, the structures themselves served as indicators of the type andcauses of distortions and damage that were imposed on them. The ability to observeand read the building response is aided by an understanding of the chain ofrelationships that extends from the excavation or tunnel and adjacent ground loss orground movement, to the distribution of ground movement and volume change throughthe soil mass, to the interaction of the ground with the building, and then to the buildingdistortion and damage.

To properly assess the building behavior both distortion and damage -- it is necessaryto understand not only the ground movement patterns but also the buildings structuralcharacteristics and finishes: how the building was built, maintained, and repaired.

Often the effects of excavation and tunneling are superposed on pre-existing distortionsand deterioration. In many cases, pre-existing conditions are separate from andunrelated to the excavation- or tunnel-induced damage.

u w u vattribute pre-existing conditions in their building to the effects of the adjacent excavationand tunneling.

Pre-construction photographs and video are important in resolving such issues as wellas early set up of monitoring to obtain a history of building movements due totemperature and seasonal changes. In addition, a logical evaluation and description ofthe limits and magnitude of ground movements and building distortions due toexcavation or tunnelin and earl reco nition and acce tance of res onsibilit for


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1. Structures often serve as indicators of the causes of imposed distortionsand damage

2. Understand the chain of relationships and behavior extending from tunnel orexcavation to buildingGround movement sources and ground loss

roun movemen pa erns an vo ume c angeBuilding structural characteristics and finishes - - - how it was built,

maintained and repaired.

3. Effects of excavation and tunneling may be superposed on pre-existingbuilding distortions and deterioration

4. Effects of excavation and tunnelin ma be se arate from and unrelated to

pre-existing building distortions and damage

It is most common and natural for residents and owners of buildings toobserve and attribute pre-existing conditions in their building to theeffects of the adjacent excavation or tunneling.

Benefits of:

. re-constructon assessments an nspecton, p otograp s an v eo-- Assess condition of buildings, sensitivity to damage, whether due to

tunneling and excavation or other effects.

-- Assess structural characteristics and building finisheslateral and distortional stiffnesses, weak zones.2. A logical evaluation and description of the limits and magnitude of

ground movements and building distortions due to excavation ortunnelin : zone of influence sizeof buildin with res ect to settlementtrough, change in ground slope.

3. Early building monitoring to determine temperature &seasonal effects.4. Community relations efforts by contractor, engineer and owner

throughout design and construction.5. Early recognition and acceptance of responsibility for excavation or

tunneling induced-damage


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Increasing ground loss can result in disproportionateincreases in round movement and buildin dama e

Small ground losses may be absorbed by volume increases insoil.

Building damage increases disproportionately with strains

Objective: control ground losses at the tunnel

Increasingly, with pressurized face tunneling, ground movements

are being controlled at the source, around the tunnel shield tolevels that result in negligible damage at the ground surface

Objective: reduce risk of large ground losses or collapse

Examples of building response toExamples of building response to

excavation and tunnelingexcavation and tunneling

Review of ground movements and buildingReview of ground movements and building

Characteristics of bearing wall structuresCharacteristics of bearing wall structures

Bearing walls parallel to tunnel or excavationsBearing walls parallel to tunnel or excavations Separation of upper wallSeparation of upper wall

Side sway of framesSide sway of frames


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2. REVIEW2. REVIEW

Sources of ground movementSources of ground movement

RiskRisk of large, uncontrolledof large, uncontrolled ground loss in faceground loss in face

Shield, EPB:Shield, EPB:

ControlControl of conditioner and pressure in faceof conditioner and pressure in face

NATM:NATM:

Instability at faceInstability at face

Lining failure during or after excavation sequencesLining failure during or after excavation sequences

Regular ground lossRegular ground loss

Shield: AnnularShield: Annular spacesspaces Overcut at front of shieldOvercut at front of shield

Grout annulus between tail of shield and liningGrout annulus between tail of shield and lining

NATM: Lining deflection and ground displacement during excavationNATM: Lining deflection and ground displacement during excavation

Volume decreaseVolume decrease inin soilsoil DewateringDewatering

Stress increases around tunnelStress increases around tunnel


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Distortion/damageDistortion/damage

Width of settlement trough

Angular distortion andLateral strain

LINKLINKb

Volumechange

Volume ofSettlementtrough

Slope ofsettlement trough

Settlement & Lateral displacement

slope beneathstructure

EstimateEstimate of regularof regulartunnel groundtunnel ground lossloss

Source ofground loss

Soft Clay: Short term: VS ~ VLAfter consolidation: VS > VL

Estimating Volume loss

(2) Surface Volume, VS = VL - VVs

Large depth/diameter,very dense: VS


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(3) Estimating Surface Settlement

w = r + Z tan b

max = Vs/w= Trou h Sha e: Gaussian Distribution

max

w = 2.5 ii

Vs

/w

/max = exp ( (x/i)2)Schmidt, Peck, 1969

b oZ Typical values of Angle b:

Sand: 26o Clay: 40o

(+ ~ 5o)

Cording & Hansmire, 1975

(4) Estimating Lateral Movement

(a) Lateral displacement (b) Lateral strain

w = 2.5 i

Li

V

VS mMaximum lateral displacement,

L@ Inflection point, i :

L = 1/3 m (tan b/ 0.5)

FIGURE 3.7 12

L

r

L = m/ w) tan b~ 1/ 2 to 1 x average

settlement slope


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L L

ANGULAR DISTORTION, LATERAL STRAIN, L(Shear Strain)

ope

L = L / L90

1. Building moves with ground &extends beyond settlement zone:

w

m

Angular Distortion ~

FIGURE 3.6 14

r

Average S ope:

~ m /w


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2. Building moves with ground & is narrow enough to tilt,distortion concentrated in unit 1.

w

Lb

m

Angular Distortion = Slope Tilt

Angular Distortion = Change in

FIGURE 3.6 15

r Angular Distortion conservativelyestimated as:

< (m /w) (Lb/w)groun s ope e ween wo un s

3. Building moves with ground & is narrow enough to tilt,frame is subject to side sway, which increases tilt

w

Lb

m

AngularDistortion = Slope Tilt

FIGURE 3.6 16

r

~ prevous case

Distortion in both sections ofbuilding


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4. Building stiff laterally

Grade beams and structural frames reducelateral strain to less than ground strain

Ground strain is concentrated at edges ofbuilding, construction joints between units,or weaker zones in building.

Angular distortion,


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Strain Determined from state of strain at a point

Average state of strain in structural unit ofbuilding

Lower level

Upper level

by settlement trough

Grade beam/slab stiffnessGrade beam/slab stiffness lateral strainlateral strain

1.0

h / hg

0.5

0

0 2 4 6 8

0.2

0.8

Boscardin and Cording, 1989

Eg A / Es Hexc S


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4. Effect of soil/building shear stiffness and cracking on angular distortion inmasonry walls.

M. Son, 2004





Bearing walls parallel to tunnel or excavationBearing walls parallel to tunnel or excavation Separation of upper wallSeparation of upper wall



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Early 1800 faade: alternating headers and stretchers

LATE 1800s, U.S.


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Savannah: Late 1800s

Interior of bearing wall


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Joist set in seats on

bearing wall, not tied

Wood lintel sags:

cracks in brick

Lateral displacement of joists:

12 to 20 mm

1800s Timber joists in seats on masonry bearing walls


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1870: Philadelphia

Masonry bearing walls,

Floors: cast iron I beams

with jacked brick arches

oo suppor : cas rontruss set on bearing wall


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San Francisco: along proposed tunnelEarly 1900s, industrial, Retrofitted for earthquakes

Openingsenlarged,posted

Retrofitted: diagonal brace behind window


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RETROFITTED:

BEARING WALLS

Reducedlateral strain

Early 1900s: concrete floors reduce lateral strains


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Interior of bearingwall building:

Interior of masonry bearing wall buildingI beams tied to brick bearing wall


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Bearing walls parallel to tunnel or excavationBearing walls parallel to tunnel or excavation

Separation of upper wallSeparation of upper wall


Brick bearing walls parallel to tunnel orBrick bearing walls parallel to tunnel or

excavationexcavation


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BEARINGWALLSPARALLELTOTUNNELOREXCAVATION

CASE1:

Two

buildings:

G

1tunnels:

Washington

Metro.,

6m

dia

Brickbearingwallwithtimberjoists Terracesandandgravelandstiffclay.

CASE2: Apartment,Evanston 4.6mdia.tunnel,SoftChicagoclay

CASE3: Gymnasium Brickbearingwallwithconcretefloors Trenchinstiffclaynexttoandbelowbaseofbuildingfoundation

concentratedsettlement

Case4: Apartmenthouse: Brickbearingwallwithtimberjoists

Concentrateddisplacement

on

bearing

wall.

Lossofbearingoftimberjoistsonseatsinbearingwall

Case5: Brickbearingwallwithtimberjoists Lateraldisplacements20to30mawayfrom12mhighexcavationwall. Crackinginstreet,basementandlowerfloor: Smalllateraldisplacementoftimberjoistsonseatsinbearingwall.

Case 1: Two buildings, G 1 Tunnels


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Brick bearing wall, timber joistsTunnel ~ parallel to bearing wall

Common wall & faade wall

38 mm

Washington Metro: G Tunnel:Digger shield in dense sand and stiff clay


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Tilt and Angular Distortion

Bending: separationadjacent to wall

( x10-3)

= Slope Tilt= 4 -1.9 = 2.1

Tilt = 1.9

Measured = 2

GS = 4 - 0.8 = 3.2 /L = 0.8


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Numericaldistinct

element

analysis

BuildingII

Joistsdidnotdisplaceatwallwithsmall(10psf)livefloorload+weightoffloor.

Reductionoffloorloadtoweightofflooronlyproducedopeningoffloorjoistsatwall,aswas

observedinthefield

Washington DC Metro, G Tunnel

( x 10-3 ) Building 1 Building 2

Ground Slope: 4 0.8G. S. 4 - 0.8 = 3.2 * NA: . .

Slope Tilt: 4 - 1.9 = 2.1 0.8-0.3 = 0.5from extensometers: 1.8 to 2.0 ** 0*Separation between walls of building 1 & 2 reduces below GS

** Sticking door, minor shear cracks

Lateral strain base: < 0.1 *** 0.3

Lateral strain top: < 0.1 0.8 ***

**** 5 mm gap due toseparation of joists atleft bearing wall

*** Building 1 is in zoneof small lateral strain


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Case 2: Evanston: Soft Chicago Clay

Tunnel parallel to bearing wall, concrete floors.

Diagonal Cracks Vertical Crack

Effect of tunnelingTunnel

Cracks and out-of plane brick displacement above lintels-- unrelated to tunneling


Effect of tunneling

Tunnel


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Cracks and out-of- plane displacements above lintels,

unrelated to tunnelingbut no pre-construction video in this area of building

FIGURE 4.10

South Wing, pre-existing cracks on construction video,unrelated to tunneling

FIGURE 4.7


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Figure 5-1

Soft Chicago Clay, Evanston

12-ft-diameter Lovat Shield with Flood Doors (Not EPB)

Figure 6-10

12-ft-diameter articulated shield, LovatMcNally Tunneling: Negotiated 160-ft radius turn


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Pneumatic Piez.Pneumatic Piez.

MultiMulti--pointpoint

WestbayWestbay

PiezometerPiezometer Deep Settlement Pts .Deep Settlement Pts .

Figure 6-5

Inclinometer/Inclinometer/

SondexSondexInclinometers/Inclinometers/

SondexSondex

Tunnel Centerline

Chicago Clay: Test Section 4, near CTA elevated structureA joint effort: McNally Tunneling and University of Illinois

Distance (ft)

-100 -80 -60 -40 -20 0 20

0w =19.2 m

T S 3: SETTLEMENT DUE TO PASSAGE OF SHIELD

Articulated shield, wheel excavator : 3.6 m dia

Depth(ft)

20

40

60

0.80 in.

0.52 in.

Sand

Soft to medium gray silty clay

Very soft to soft clay

Medium to stiff silty clay

Stiff clayey silt

30 mm VS =0.57 cu m/m

b=38o Z = 22m

Figure 1-6

80

100

72 ft

0.82 in.

Stiff to very stiff gray silty clay

Hard gray silty clay

VL =0.44 cu m/m

.

79 mm

r


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Distance (ft)

-100 -80 -60 -40 -20 0 20

0w =23 m

T S 3: LONG TERM SETTLEMENT AFTER PASSAGEOF SHIELD

Depth(ft)

20

40

60

0.80 in.

0.52 in.

Sand

Soft to medium gray silty clay

Very soft to soft clay

Medium to stiff silty clay

Stiff clayey silt

34 mm34 mm

445 days Zone of volume change,V, due to consolidationcaused by:

1. Increase in meanstress during

.

80

100

0.82 in.

Stiff to very stiff gray silty clay

Hard gray sil ty clay

passage of shield,and dissipation ofexcess pore pressure

2. Reduction of porepressures due todrainage into tunnel

20 mm

P3 -1 P 4Passage ofshield

Consolidation

MEMBRANE, TS 4

NO MEMBRANE, TS 3

due to stress

increase

Consolidation due

to drainage intotunnel

Figure 6-17

Days after passage of sh ield

Pore Pressure changes with time, Evanston


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2.5 m

10 m 11m 10 m

StreetStreet

79 mm

30mm

17 m

40 o

18 mCourtyard North WingSouth Wing Central Wing

CHICAGO CLAY

NORTH WING

EY

COURTYARD

ALLEY

N

STREET

CENTRAL WING

SOUTH WING

AL

INTERIOR COURTYARDLATERA

L

EXTENS

ION

3 mm

2mm

Basement floor

;TILT

Tunnel

AB ANGULAR

DISTORTIO


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South Wing Central Wing

Concrete floors reduce lateral strains in upper levels

MeasuredVertical buildingdisplace: 30 mm

12 mm crackextension

Lateral grounddisplace: 29 mm(calculated) 5 mm separation

between Wings

Angular distortion, South Wing: < 30 mm/11.3 m =2.7 x10-3

Calculated lateral strain, South Wing:


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Reducedlateral strain

Concrete floors reduce lateral strainsLateral cracks limited to basement/ground floor level


Effect of tunneling

Tunnel

FIGURE 5.18


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Vertical Crack

E wall

At joint between Southand Central Wings.

Open: 5 mm at base

Reducing to hairlineadjacent to 1st floorwindow.

-3) 3

4

SEVERE TO VERY SEVERE

*The results of two fieldcases andone numerical test

are outof range

( ) - Damage level based on

maximumcrack width

(Burlandetal., 1977)

[ ] - Damage level basedon

fieldobservation

Constant Principal

Extension Strain

Damage Criterionbased on state of strain at a point

LateralS

train,L

(x10

1

2

Col 36 vs Col 37Col 39 vs Col 40

Col 48 vs Col 49SLIGHTDAMAGE

MODERATETO

SEVERE DAMAGE

(BoscardingandCording, 1989)

(N) - Negligible

(VSL) - Veryslight

(SL) - Slight

(M) - Moderate

(SE) - Severe

(VSE) - Verysevere

[N] - Negligible

[VS] - Veryslight

[SL] - Slight

[M] - Moderate

[SE] - Severe

[VSE] - Verysevere

Numerical tests

Field cases

MODERATE DAMAGE

Concrete floors:

Reduced lateral strain

Reduced angular distortion due

Angular Distortion, (x10-3)

0 1 2 3 4 5 6 70

NEGL.

Figure 25 Damage level estimation and observed damage level

FIGURE 4-1

Angular Distortion, ( x 10 - 3 )

1/1000 1/500 1/200 1/100Modified after Boscardin & Cording, 1989

to side sway?


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NORTH WING

EY

COURTYARD

ALLEY

N

STREET

CENTRAL WING

SOUTH WING

AL

INTERIOR COURTYARDLATERAL

EXTENSION

3 mm2mm

Basement floor

;

TILT&

TNAT

Tunnel

AB ANGULAR

DISTORTIO

South Wing

Inner

Courtyard

1.

SECTION B

Street

79 mm 38mm

17m

40o

18 m

Angular distortion reduced by tilt and sidesway No evidence of lateral cracks in basement Hairline crack above door Estimate of angular distortion if structure moves with

ground curvature:


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Concentrated vertical and lateral displacements at bearing wallConcentrated vertical and lateral displacements at bearing wallfooting.footing.

Brick bearing wall parallel to shallow excavationBrick bearing wall parallel to shallow excavation

CASE 3

Vertical displacements of bearing wall at ground level: 22 to 31 mmVertical displacements of bearing wall at ground level: 22 to 31 mm

Bearing wall drags down cross walls and end wallBearing wall drags down cross walls and end wall

Shear strains are concentrated within 3 m of bearing of bearing wall.Shear strains are concentrated within 3 m of bearing of bearing wall.

Lateral extension restrained at floor levelsLateral extension restrained at floor levels

Outward displacement at foundation level produces rotation ofOutward displacement at foundation level produces rotation ofbearing wall about main floor level producing horizontal tensionbearing wall about main floor level producing horizontal tension

crack on inside of wall above upper second floor level. level:crack on inside of wall above upper second floor level. level: 57 mm/ 6m =10 x 1057 mm/ 6m =10 x 10--33

CASE 3: Gymnasium: brick bearing wall structure with concretefloor. Trench excavated adjacent to and below footing base elev.

68

22 to 31 mm settlement of S. bearing wall drags down E side

wall, producing distortion and damage at intersection


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Horizontal tensioncrack on inside

Ground movementsconcentrated within~ 3 m of wall

sur ace o wa

Shear crackson cross walls

ConcreteBrick bearing wall

STIFF CLAY

Crosswall

Damage at crosswalls adjacent toS. Bearing wall:

Angular distor tion:

31 mm/6m ? = 5 x 10-3

31 mm /3m = 10 x 10-3

Severe Damage

70

South bearing

wall

31 mm


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Concentrated vertical and lateral displacements at bearing wallConcentrated vertical and lateral displacements at bearing wall

CASE 4

.. Brick bearing wall parallel to shallow excavationBrick bearing wall parallel to shallow excavation Timber joistsTimber joists Lateral & vertical displacements of wall at ground level: 40 to 75Lateral & vertical displacements of wall at ground level: 40 to 75

mm, shear cracks adjacent to distorting portion of wall.mm, shear cracks adjacent to distorting portion of wall. Displacement of timber joists in seats on bearing wall:Displacement of timber joists in seats on bearing wall:

57 mm.57 mm. Requires evacuation of building,Requires evacuation of building, Tem orar osts to su ort floor oistsTem orar osts to su ortfloor oists

Lateral strains in building at ground level:Lateral strains in building at ground level: 57 mm/ 6m =10 x 1057 mm/ 6m =10 x 10--33

33rdrd Floor: SomeFloor: Some sideswaysideswaycausing pulling of joists on opposite sidecausing pulling of joists on opposite sideof building. Continuous joists across intermediate wall reduces joistof building. Continuous joists across intermediate wall reduces joistbearing as settlement takes place.bearing as settlement takes place.

Adjacent

basement

excavation not

backfilled

before pulling

sheet piles

CASE 4Apartment

72

40 to 75 mm


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Crawl Space Basement

PLAN Bearing wall

PROFILE

SECTION

AAdjacentexcavation

Basement

Base adjacent excavation

Crawl space


PLAN

57 mm separation

of joists from

Bearing wall

AAdjacentexcavation

PROFILE

SECTION

Sidesway &

separation

AAdjacentexcavation

57 mm

separation

BasementCrawl space

Base adjacent excavation


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PLAN 57 mm reductionof joist bearing

x v

PROFILE

SECTION

Sidesway &reduction ofjoist bearing

reduction ofjoist bearing

BasementCrawl space

Base of adjacent excavation

57 mm reduction in joist bearing57mm

L > 57mm/ 6 m = 10 x 10-3

Severe to Very SevereJ oists supported withtemporary posts


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Brick bearing walls and wood joistsBrick bearing walls and wood joists

Parallel bearing walls: Opening of joists in seatsParallel bearing walls: Opening of joists in seats

Apartment buildingApartment building

2 in. lateral displacement at seats2 in. lateral displacement at seats

2 in. settlement2 in. settlement

Lateral displacement away from excavationLateral displacement away from excavation

..

= 20 mm /6 m = 3.3 x 10= 20 mm /6 m = 3.3 x 10 --33

Cracks in side walls: total width of cracks: XXXXCracks in side walls: total width of cracks: XXXX

CASE 5: Brick bearing wall parallel to excavation, timber joists

Lateral cracks in street, 20 to 30 m from 12 m deepexcavation: fine sand over soft clay

30 mm/ (30-20 m) = 3 x 10 -3

, ,in basement & main floor:

Basement moves with ground

Decrease in joist bearing on main floorNo significant extension in upper floors


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Sidewalk crack


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Lateral displacement of joists:12 to 20 mm

Superficial cracking of plaster/stuccoon brick bearing wall

Lateral strain: 12 to 20 mm/ 6 m = 2 to 3 x 10-3 (Slight )

Lateral StrainsLateral Strains

N side building: 6 to 12 mmN side building: 6 to 12 mm

J oist displacement out of seats:J oist displacement out of seats: 12 to 20 mm12 to 20 mm

Separation of W. concrete block infill cross wall:Separation of W. concrete block infill cross wall: 12 to 20 mm12 to 20 mm

Floor cracks, Center:Floor cracks, Center: 13 mm13 mm E Wall: Cracks at floor level:E Wall: Cracks at floor level: 10 mm10 mm

E Wall: Cracks at ceiling level (~E Wall: Cracks at ceiling level (~g.sg.s.).) 18 mm18 mm

..

Lateral strain: 18mm/6m = 3 x 10Lateral strain: 18mm/6m = 3 x 10--33


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Predominantly lateral displacements at distance of 1.2 to 2 HPredominantly lateral displacements at distance of 1.2 to 2 Hbehind excavation wallbehind excavation wall

Brick bearing wall parallel to excavationBrick bearing wall parallel to excavation

Timber joistsTimber joists

Lateral strains in building at ground level:Lateral strains in building at ground level: 18 mm/ 6m =3 x 1018 mm/ 6m =3 x 10--33

Approximately equal to lateral strain in groundApproximately equal to lateral strain in ground

Displacement of timber joists in seats on bearing wall:Displacement of timber joists in seats on bearing wall:..

Summation of cracks in floor and wall: sameSummation of cracks in floor and wall: same

33rdrd floor: reduced lateral strains: hairline cracks.floor: reduced lateral strains: hairline cracks.

Damage level: slightDamage level: slight








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5. Separation in upper floors5. Separation in upper floors 77thth St: Perpendicular bearing wallsSt: Perpendicular bearing walls

Shear cracks at faadeShear cracks at faade

Analysis by SonAnalysis by Son

G tunnel: twin buildin s arallel bearin wallsG tunnel: twin buildin s arallel bearin walls Shear first buildingShear first building

Bending at edge of second building: no load in floor joists.Bending at edge of second building: no load in floor joists.

Analysis by Son:Analysis by Son: LoadedLoaded

UnloadedUnloaded

Club 1? Parallel bearing walls.Club 1? Parallel bearing walls.

2 story open.2 story open.

Masonic Temple, Philadelphia: parallel bearing wall. IMasonic Temple, Philadelphia: parallel bearing wall. Ibeams with jacked brick arch. Shear cracks andbeams with jacked brick arch. Shear cracks andseparation at bearing wall.separation at bearing wall.

Separation of upper wallsSeparation of upper walls


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Distortion patterns in masonryDistortion patterns in masonry walls nextwalls next

to excavationto excavation

87FIGURE 4-4

3. Roof structure and floorjoists perpendicular toexcavation restrain lateraldisplacement & separation in

upper floors.

1. Cracks develop dueto angular distortionand lateral strain

2. Cracks extendupward

Distortion patterns in masonry wallsDistortion patterns in masonry wallsDeep beamDeep beam

88FIGURE 4-3

Extension of shear cracks,or weak connection offaade wall to side walls:

Allows rotation of wall andopening of cracks at top


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Beam: Large L/H Deep beam: LowBeam: Large L/H Deep beam: Low

L/HL/HTypical conditionTypical condition

ShearL

H H

L

89FIGURE 4-3

If continuous crack or weakconnection of faade to sidewalls: Rotation andseparation of faade wall

Bending

Concentration

Shear crackintersectingfaade causes28 mm

Bearing wall perpendicular to tunnelBearing wall perpendicular to tunnel

As shear cracks

of shearcracks near

edge ofbearing walldevelopsbecause of

separa on ofaade wall

90FIGURE 4-7

they reducethe bendingstiffness at theedge of thebearing wall.

downdrag offaade wall

Tunnelbelowstreet


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Crack:28 mm

50 mm

Displacement unit: mm

(Horizontal disp, Vertical disp)

Horizontal disp.: Positive sign leftward disp.

Vertical disp.: Positive sign downward disp.

Opening between bearing wall and faade wall: 10 times magnified

(35.48, 27.69)(32.03, 27.43) (9.14, 5.84) (9.14, 1.52) (9.14, -2.29)

Bearing wallFacade

Crack width = 27 mm

Distinct Element Analysis:Each brick modeled as separate block

Crack width= 27 mm

(8.64, 27.50)(4.91, 26.81) (0.76, 6.25)

(22.33, 27.43)

(0.76, 1.29) (1.02, -1.87)

(17.72, 26.37)

wall

LATERAL (

(mm.)

Settlement: 27 mm.Lateral displacement

NUMERICAL ANALYSIS: DOWNDRAG OF FAADE WALL

VERTICAL (Displacement

(M. Son, 2003)

Settlement


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Damage increases at increasing rate withDamage increases at increasing rate withncrease n se emenncrease n se emen

Bearing Wall Parallel toExcavation

-between joist levels

J oist deterioration at seats

Side wall: water damage,deteriorated mortar

Adjacent Braced Cut:. 18 mm settlement


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Mortar deteriorated due to water from downspouts

75mm

TIESPLACED








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Abaqus FEMwithHypoplasticSoil,ConcreteFrame

Excavation

Depth:

25

mDisplacementmagnificationfactor:100

Soil modeled as

FIGURE 6-11 97B. Ghahreman, 2004

Side sway and tilt causeBay 1 distortions to be similar to Bay 3

Abaqus FEM,Hypoplastic Soilw/concreteframe

Excavationdepth: 25m Magnificationfactor:100

Angulardistortionsimilar foreach story

6-12 98

floor

First floor columns are distorted

by lateral ground strainsB. Ghahreman, 2004


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Beambendingmomentrelatedtoangulardistortion

1 = + 0.002 10-32 = + 0.089 10-33 = - 0.087 10-34 = 0.000

Angular distortion, : 0.248 10-3

Slope: 1.647 10-3- Tilt: 1.399 10-3

4

3.02

3.02

2.64 cm

2nd story Bay 1

omen , xe en s: = M = 6(EI/L)( )

M

FIGURE 6-13 99

12 3.

2.56

3.95

2.562.64

7.7 m

M


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Side sway of hotel with concrete floorsSide sway of hotel with concrete floors

Excavation Hotel with concrete floors Historic Brick Bearing WallStructure


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Stiff clays and medium dense sands

BuildingExcavation

Hotel basement: 1 levelHistoricHouse: 1

level

~ 3 mm


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HOTEL


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Early 1800 faade:Alternating headers andstretchers

No apparent cracks


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ARINGWALL

ALL

SMALLSIDESWAY:

~ 3 mm

(Exaggerated)

SETTLEMENT:

Settlement ofintermediate

EDIATETIMBERB

BRICKBE

ARING12 story

Hotel:

Concretefloors

bearing wallover time

INTERM

~ 50 mm


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ALL

SMALLSIDESWAY

:

~ 3 mm

(Exaggerated) ARINGWA

LL

SETTLEMENT:

Shrinkage ofintermediate

BRICKBEARING12 story

Hotel:Concretefloors

EDIATETIMBERB

bearing wall

INTERM

~ 50 mm.

CONCLUSIONS

1. Structures often serve as indicators of the causes of imposed distortionsand damage

2. Understand the chain of relationships and behavior extending from tunnel orexcavation to building

Ground movement patterns and volume changeBuilding structural characteristics and finishes - - - how it was built,

maintained and repaired.

3. Damage due to excavation and tunneling may be superposed on pre-existing building distortions and deterioration

4. Damage due to excavation and tunneling may be separate from andunrelated to pre-existing building distortions and damage


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CONCLUSIONS

It is most common and natural for residents and owners of buildings to

observe and attribute pre-existing conditions in their building to theeffects of the adjacent excavation or tunneling.Benefits of:

1. Pre-construction assessments and inspection, photographs and video-- ssess con ton o u ngs, sens tv ty to amage, w et er ue to

tunneling and excavation or other effects.-- Assess structural characteristics and building finishes

lateral and distortional stiffnesses, weak zones.2. A logical evaluation and description of the limits and magnitude of

ground movements and building distortions due to excavation ortunneling:

a. zone of influence

b. settlement slope,c. size of building with respect to settlement trough,d. change in ground slope.

3. Early building monitoring to determine temperature & seasonal effects.4. Community relations efforts by contractor, engineer and owner

throughout design and construction.5. Early recognition and acceptance of responsibility for excavation or

Control and reduceControl and reduce

RiskRisk of large, uncontrolledof large, uncontrolled ground loss in faceground loss in face

Shield, EPB:Shield, EPB:

ControlControl of conditioner and pressure in faceof conditioner and pressure in face

NATM:NATM:

Instability at faceInstability at face

Lining failure during or after excavation sequencesLining failure during or after excavation sequences

Regular ground lossRegular ground loss

Shield: AnnularShield: Annular spacesspaces Overcut at front of shieldOvercut at front of shield

Grout annulus between tail of shield and liningGrout annulus between tail of shield and lining

NATM: Lining deflection and ground displacement during excavationNATM: Lining deflection and ground displacement during excavation

Volume decreaseVolume decrease inin soilsoil DewateringDewatering

Stress increases around tunnelStress increases around tunnel


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Allowable lAllowable limit forimit for

distortion/damagedistortion/damage

Observations/ControlObservations/Control

ADDITIONAL MEASURESADDITIONAL MEASURES

If Ground loss causes moreIf Ground loss causes moredistortion than allowabledistortion than allowable

Modify groundModify ground

Compensate groundCompensate ground

Protect structureProtect structureNear tunnel

In soil mass

At surface

At structuresLINK

Estimate tunnelEstimate tunnel

ground lossground loss

on ro unne ngon ro unne ngprocessprocess

Increasing ground loss can result in disproportionateincreases in round movement and buildin dama e

Small ground losses may be absorbed by volume increases insoil.

Building damage increases disproportionately with strains

Objective: control ground losses at the tunnel

Increasingly, with pressurized face tunneling, ground movementsare being controlled at the source, around the tunnel shield tolevels that result in negligible damage at the ground surface

Objective: reduce risk of large ground losses or collapse


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METHOD OF CALCULATING BUILDING DISTORTION

BAY 1 BAY 2 BAY 3

CD

UDEC analysis of full scale brick bearing wall

BAY 1

A B

6100 mm

6100m

38 77 16 54

L

H

8 92 4 83

61000 67 10 3

. ..

AVERAGE SLOPE :

TILT :

ANGULAR DISTORTION :

LATERAL STRAIN (T) :

LATERAL STRAIN (F) :

61003 64 10 3

. ..

14 73 4 83

6100162 10 3

. ..

( . . ) .3 64 162 10 2 02 103 3

30 90 14 73

61002 65 10 3

. ..

FIGURE 4.6


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Physical Model Studies, Test 5E

Schnabel Large Soil Model Test Lab at U. I. U. C.

D. Laefer, 2001

1.2 m high

Weightadded atfront tosimulatedowndrag

fromfaade

.

Model Test 5E: Excavation to 1220 mm


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BAY 1 BAY 2 BAY 3 BAY 1 BAY 2 BAY 3

1.06 1.09 1.02 0.96

2.59 2.65 2.59 2.594.32 2.06 0.65 -0.21

VERTICAL(

LATERAL(

Distance (mm.)

Displacement(mm.)

BAY 1

*

BAY 2

SLOPE 1.93*

BAY 3

SLOPE 1.80*SLOPE 4.59

Distance (mm.)

VERTICAL

SOILBUILDING

4.39 2.07 0.62 -0.19

BAY 1

*

BAY 2

SLOPE 2.38*

BAY 3

SLOPE 1.33*SLOPE 3.80

VERTICAL

BUILDINGSOIL

LATERAL

BUILDING SOIL

(

(

123

.

-0.37

lat(F) 0.16

lat(T) 0.49

.

-0.15

lat(F) 0.03

lat(T) 0.05

.

2.29

lat(F) 1.95

lat(T) 2.25

a. Brick-Bearing Wall (Inelastic Analysis)

* Multiply by 10-3

b. Frame Wall (Elastic Analysis)

* Multiply by 10-3

TIL 2.57

-0.19

lat(F) 0.11

lat(T) 0.10

TIL 2.67

-1.34

lat(F) 0.10

lat(T) 0.00

TILT 2.56

1.24

lat(F) -0.05

lat(T) -0.10

Numerical analyses of 2-story brick-bearing wall (Pit 5E) and elastic frame, 1/10th model scale

1.08 mm

L 1830 mm

/L 6.00E-04

1.08 mm

L 1830 mm

/L 6.00E-04

4/L 2/L

FIGURE 5-5

EXTRAS


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52.5S of backof Soldier pile

Separation: ~1/8? open to N,behind E column (adjacent toChroma W Wall), at crown molding.

South WallExcavation

Congress St

West

Wall

ChromaGallery

Ray EllisGallery

separation betweensidewalk and wall

54.5: 1/8crack

86.5: 1/ 4crack, curb, & crack in W. side pave.

95.5: 1/ 4@ c. j. in sidewalk

cr

75: 3/8separation at c. j. on brick sidewalk,

64: 5/16crack cuts straight across bricks, towardgallery entrance (crack gauge)

Fig 2. South side Ellis Square

97.5: 1/ 8 crack, curb,97.5: separation of construction joint betweenconcrete pavement slab extends across street

BarnardSt

57 mm reduction in joist bearing57mm

L >57mm/ 6 m =10 x 10-3

Severe to Very SevereJ oists supported withtemporary posts


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Masonic

Temple,

Philadelphia


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N

BarnardSt.

Congress St.

blockwall

Old drainpatches

1/8-3/8 top

Joists: - out of seat

Joistorientation

1/8

CG371mm

Floor crack: 3/8 lat, 3/8 vert.

Concrete

-

separation1/8

1/16 -3/8 top

1/16 -3/16 topJoists: 12 19 mm out of seat

1/8CG551mm

CG42 3mmCG38 2mm

Fig 3. Chroma Gallery, NE BasementFig 3. Chroma Gallery, NE Basement

3/8 lat, 3/8 vert. 1 /4 -1/8 top

1/16

Photos IMGP 2447-2471


(Main floor, Chroma Gallery: Photos IMGP 2508-2518)


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N

BarnardSt.

Congress St.

blockwall

Old drainpatches

3 10 mmtop

J oists:12-20 mmout of seat

NS J oistorientation

3 mm

CG371mm

Floor crack:

Concrete

12-20 mmseparation

3 mm

2-10 mm top

2-5 mm top

J oists: 12-20 mmout of seat

1/8CG551mm

CG42 3mmCG38 2mm

,10 mm vertical.

Fig 3. Chroma Gallery, NE BasementFig 3. Chroma Gallery, NE Basement

10 mm lat,10 mm vert

6 3 mmtop

2 mm



(Main floor, Chroma Gallery: Photos IMGP 2508-2518)


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Bearing walls parallel to excavationBearing walls parallel to excavation Contact at party walls a plane of weaknessContact at party walls a plane of weakness

DetermineDetermine G.S. between baysG.S. between bays

Opening at top:Opening at top: G.S x HG.S x H

Strain at top:Strain at top: G.S x H/ 2 LG.S x H/ 2 Lbb = 4 (Defl Ratio) x H/2Lb == 4 (Defl Ratio) x H/2Lb =H/2RH/2R

Distribute:Distribute:

To one side of the wallTo one side of the wall

To both sides of the wallTo both sides of the wall

etween two wa s t tetween two wa s t t Party walls assumed continuousParty walls assumed continuous DetermineDetermine

G.S. between baysG.S. between baysFor bearing walls moving with ground:For bearing walls moving with ground:

G.S.G.S.

-3) 3

4

SEVERE TO VERY SEVERE

*The results of two fieldcases andone numerical test

are outof range

( ) - Damage level based on

maximumcrack width

(Burlandetal., 1977)

[ ] - Damage level basedon

fieldobservation

Constant Principal

Extension Strain

LateralS

train,L

(x10

1

2

Col 36 vs Col 37Col 39 vs Col 40

Col 48 vs Col 49SLIGHTDAMAGE

MODERATETO

SEVERE DAMAGE

(BoscardingandCording, 1989)

(N) - Negligible

(VSL) - Veryslight

(SL) - Slight

(M) - Moderate

(SE) - Severe

(VSE) - Verysevere

[N] - Negligible

[VS] - Veryslight

[SL] - Slight

[M] - Moderate

[SE] - Severe

[VSE] - Verysevere

Numerical tests

Field cases

MODERATE DAMAGE

Angular Distortion, (x10-3)

0 1 2 3 4 5 6 70

NEGL.

Figure 25 Damage level estimation and observed damage level

FIGURE 4-1

Angular Distortion, ( x 10 - 3 )

1/1000 1/500 1/200 1/100

after Boscardin & Cording, 1989


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Physical Model Studies, Test 5E

Schnabel Large Soil Model Test Lab at U. I. U. C.

D. Laefer, 2001

1.2 m high

Weightadded atfront tosimulatedowndrag

fromfaade

.

Model Test 5E: Excavation to 1220 mm


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South Wing Central Wing

Concrete floors reduce lateral strains in upper levels

37 32

Vert.

1.2

0.5

Lat. 0.9(calc)

0.2 separation

Angular distortion across South Wing = 0.1/37 = 1/370Angular distortion across South Wing = 0.1/37 = 1/370 Lateral strain across South Wing =Lateral strain across South Wing = 0.08/37 = 1/4700.08/37 = 1/470 Lateral strain largely confined to basement levelLateral strain largely confined to basement level

extens on

of cracksbetween Wings


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Crosswall

Angular distortion:

31 mm6m? =5x 10-3

31 mm /3m ? =10 x 10-3

Severe Damage

145

South bearing wall

31 mm

Max. Lat.

SECTION A

34 37 32

2.5 1.4

56w =

i

.

34

40 o

Z=60 Average Slope = 1/300

Maximum lateral displacement (calculated):

L = 1/3 M (tan b/ 0.5) = 1.4


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Evaluate strains and displacements across bay:

37 bay 32

StreetStreet Vert.1.2

34

Lat. 0.9(calc)

Angular distortion across 37 bay = 0.1/ 37 = 1/370Angular distortion across 37 bay = 0.1/ 37 = 1/370 Lateral strain across 37 bay =Lateral strain across 37 bay = 0.08/ 37 = 1/4670.08/ 37 = 1/467


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building response to excavation

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