application of micropiles for uplift control and foundation of ... application of...gl=1,5 asl...
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Deep Experience Local Focus
Widest Range of Technologies Broad Customer Base Growth Platform
Global Scale
Application of Micropiles for Uplift Control and Foundation of Large Access Ramps of an Underwater Road Tunnel in Gdańsk
MSc. Civ. Eng. Oskar Mitrosz Keller Polska Sp. z o.o.
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June
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014,
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Scope of presentation
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General Project overview
Geotechnical conditions
„WET” vs. „DRY” excavation pit protection
Design aspects of anchoring systems
Quality control and monitoring
Conclusions
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General Project overview - Gdańsk (North Poland)
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Inte
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General Project overview - main information
First Road Tunnel ever done by TBM in Poland
Polish record TBM shield Ø 12,6 m (2 tubes)
H=1
,8 m
7 x
Total volume of exctracted spoil (~1,0 mln m3) big enough to fill up the Wembley Stadium full
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Over 3,300 micropiles installed (ca. 38.5 km)
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June
11-
14 2
014,
Kra
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(Pol
and)
General Project overview - Gdańsk (North Poland)
ww
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r.com
.pl
Inte
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l Wor
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June
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14 2
014,
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and)
General Project overview - longitudinal cross section
EAST WEST TBM LAUNCHING CHAMBER
RIVER
3 1
2 4 5
TBM RECEIVING CHAMBER
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Inte
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June
11-
14 2
014,
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(Pol
and)
Geotechnical conditions – TBM launching chamber
Fine Sand qC=10MPa, φ=33º, γ=20kN/m3
Organic cu=20kPa, φ=10º, γ=14kN/m3
DEA
D V
ISTU
LA R
IVER
Medium Sand qC=15MPa, φ=34º, γ=20,5kN/m3
Silty clay cu=150kPa, φ=15º, γ=21,5kN/m3
Coarse Sand qC≥15MPa, φ=40º, γ=21kN/m3
GW=0,5 ASL GL=1,5 ASL
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Inte
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l Wor
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June
11-
14 2
014,
Kra
kow
(Pol
and)
Construction phases – Primary solution („WET”)
Sand
Organic
Sand
Clay
Sand
GW=+0,5m ASL GL=+1,5m ASL
Sand
-52,0m ASL
-33,5m ASL
-19,0m ASL
-20,5m ASL
Sand
Organic
Sand
Sand
Anch
orin
g el
emen
ts
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Inte
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June
11-
14 2
014,
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kow
(Pol
and)
Construction phases – Adopted solution („DRY”)
Sand
Organic
Sand
Clay
Sand
GW=+0,5m ASL GL=+1,5m ASL
Sand
-19,0m ASL
-22,5m ASL
-32,5m ASL
-29,5m ASL
-3,0m ASL
-10,5m ASL
Anch
orin
g el
emen
ts
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Inte
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l Wor
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June
11-
14 2
014,
Kra
kow
(Pol
and)
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w.k
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Construction phases – Adopted solution („DRY”)
Inte
rnat
iona
l Wor
ksho
p on
Mic
ropi
les
June
11-
14 2
014,
Kra
kow
(Pol
and)
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w.k
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r.com
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Construction phases – Adopted solution („DRY”)
Inte
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l Wor
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p on
Mic
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June
11-
14 2
014,
Kra
kow
(Pol
and)
Design aspects of anchoring systems
1. Structural capacity of an anchoring element
DYWI-Drill hollow bar T76 (steel class 28 Mn 6)
Steel deduction due to corrosion (3.25 mm / 100 years)
Anom = 24.68 cm2 Acorr = 17.57 cm2
Allowable tensile capacity
Pallow = fyd ⋅ Anom = 968 kN (temporary stages)
Pallow = fyd ⋅ Acorr = 689 kN (permanent stage)
> Rmax = 791 kN
> Rmax = 589 kN
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Inte
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June
11-
14 2
014,
Kra
kow
(Pol
and)
Design aspects of anchoring systems
2. Bond capacity
Ultimate bond stress tested on trial elements on site
f1 = 1.05 MPa f2 = 0.63 Mpa
Length and circumference of hallow bar / encapsulated part
Lpile = 10.0 m Cpile = 0.239 m
Lencap = 3.5 m Cencap = 0.503 m
Allowable pull-out capacity
Pallow = f1 ⋅ Cpile ⋅ Lpile = 2509 kN
Pallow = f2 ⋅ Cencap ⋅ Lencap = 1109 kN
> Rmax = 791 kN
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f2
f1 jet grouting plug
Grout (factory applied)
Corrugated Sheathing
T76 bar
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June
11-
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Design aspects of anchoring systems
3. External capacity of an anchoring element (jet grouting column)
Ultimate bearing capacity
Rsk = Ʃ(qci/ksi ⋅ ti) ⋅ πD
Rsk = (2.5/40⋅4+20/150⋅6)⋅π1.0 = 3297 kN
Allowable bearing capacity
Pallow = 3,297/2.0 = 1640 kN
> Rmax = 791 kN
Dep
th b
elow
gro
und
leve
l [m
] -22,5m ASL
-32,5m ASL
Clay
Sand
2.5MPa
20MPa
4. Bearing plate capacity
Allowable loading (max. contact pressure)
Pallow = fcd⋅Asp,eff = 20000⋅0.058 = 1160 kN
Allowable loading (punching)
Pallow = fctd⋅Cm⋅h = 1330⋅2.2⋅0.4 = 1170 kN
> Rmax = 791 kN
> Rmax = 791 kN
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Inte
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June
11-
14 2
014,
Kra
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(Pol
and)
Design aspects of anchoring systems
5. Global stability against uplift (UPL) Temporary stage 1a (decisive)
Ve ⋅ γdst ≤ (Ge + 2Te + G’b + 2Tb) ⋅ γstb
where: Ve – uplift forces (destabilising actions) Ge, G’
b, Te, Tb – dead weights and friction forces (stabilising actions) γdst/stb – partial safety factors (acc. to EC7 γdst=1.0, γstb=0.9)
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Inte
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l Wor
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p on
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June
11-
14 2
014,
Kra
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(Pol
and)
Quality control and monitoring
QC prior to production on site: Trial jet grouted columns (diameter) Tests of strength and permeability (samples) Pull-out tests of anchoring elements (hollow bars)
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QC while production on site: Positioning control system utilising local GPS Inclinometer measurements of every jet grouting column Automatic printouts Constant verification (3D visualizations) Lab tests of used materials (cement grout, steel)
Monitoring: Precise geodesic monitoring of jet grouting plug Measurements of GW (in / out of excavation)
Inte
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June
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014,
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Conclusions
Main challenges: High GW levels Poor ground conditions Very deep excavations Extreme drilling depths Decoupling hollow bars Complex geotechnical solutions demanding 7 technologies
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Are there any limits for geotechnique?
Benefits of „DRY” method: Safe Cost effective Time efficient
Thank You…
www.keller.com.pl
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