Design of Temporary Excavation and Lateral Support System for the DSD Sheung Wan Stormwater Pumping...
Transcript of Design of Temporary Excavation and Lateral Support System for the DSD Sheung Wan Stormwater Pumping...
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8/10/2019 Design of Temporary Excavation and Lateral Support System for the DSD Sheung Wan Stormwater Pumping Station
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Design of Temporary Excavation
and Lateral Support System
for the DSD Sheung Wan
Stormwater Pumping Station
By Eric Li - GCG (Asia)
Presented to the HKIE Geotechnical Division
18th June 2008
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Sheung Wan StormwaterPumping Station (SWSPS)
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Project Set Up
DSD Contract DC/2006/10
Contract Sum : HK$ 78 million (approx)
Designer : Drainage Services Department
(with GEO as in-house geotechnical consultant)
Site Supervision : DSD Drainage Project Division
(with the engagement of an IGE)
Contractor : China National Chemical Engineering Group
ELS Designer : Geotechnical Consultant Group (Asia) Ltd.
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
43m
57m
Pile Cap Layout Plan
~ -5.9mPD
~ -7.1mPD
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
43m
Retaining Wall
Pile Cap / Base Slab
Typical North-South Section
~ +4.0mPD
~ -5.9mPD~ -7.1mPD
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Selection of Retaining Wall Type
Wall Types Considered:
Diaphragm Wall
Bored Pile Wall
Pipe Pile Wall
Sheet Pile Wall No wall (open cut)
Design Objectives:
Approximate max. 10m deep excavation
Effective control of settlement due to excavationand groundwater drawdown
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Reclamation and Seawall Dredging Plan
Approx. Location of Site
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Typical Cross Section
Vertical Seawall (Indicative)Approx. Extent of SWSPS
Victoria Harbour
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Pre-Contract Borehole Location Plan
Pre-Contract Ground investigation
2 series in 2002 & 2006 (32 holes) Common sampling, field and laboratory tests In situ vane & pressuremeter tests
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
North-South Geological Section
Sand Fill
Rock Fill
CDG
Marine Deposits
Alluvium
Fill
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
East-West Geological Section(away from Seawall)
Marine Deposits
Fill
CDG
Alluvium
Existing SaltWater PS
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Isopach of Soft Marine Clays
Seawall Cope Line
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Seawall Cope Line
Small sink hole at sea wall
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
5m3 sink hole
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
15m3 sink hole
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
-0.300
-0.200
-0.100
0.00021/8/06
31/8/06
10/9/06
20/9/06
30/9/06
10/10/06
Se
ttlemen
t(m
)
SS1
SS2
SS3
SS4
Settlement near Seawall-0.300
-0.200
-0.100
0.00021/8/06
31/8/06
10/9/06
20/9/06
30/9/06
10/10/06
Se
ttlemen
t(m)
GS20
GS21
GS24
GS25
SS Markers on Seawall
GS Markers on Ground Adjacent to Seawall
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Design Considerations Reclamation Site
Sensitive Structures nearby, i.e. WSD Pumping Station
High water table, i.e. 1.2m below existing ground level
(+3.0mPD)
Presence of thick layer of variable FILL
& soft MARINE DEPOSITS
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Design Methodology
Drained and Undrained Conditions
Lateral Stability
Global Slope Stability
Base Stability
Hydraulic Stability
Dewatering
Ground Deformation / Settlement
Structural Capacities
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Plot of SPT-N against Elevation
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Plot of Undrained Shear Strength (Cu) against Elevation
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Adopted Shoring Layout Plan
FSP IV Sheet PileWalings & Struts(3 levels)
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Longitudinal Cross Section further from Seawall
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Longitudinal Cross Section nearest Seawall
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Transverse Cross Section
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Elevation of Wall D(Showing Grouting Ground Improvement)
Penetration(T.A.M.) Grout Jet Grout
Sheetpile(not shown for clarity)
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Fill
Marine DepositAlluvium
CDG
EastWestCulvert
Grout A
Grout B
Finite Element Analysis(East-West Section)
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Wall Deflection (East-West Section)
East WallWest Wall
max = 60mm
max = 115mm
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Ground Settlement (East-West Section)
West WallEast Wall
max = 18mm
max = 82mm
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Wall Deflection (North-South Section)
South Wall North Wall
max = 102mm
max = 88mm
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Ground Settlement (North-South Section)
North WallSouth Wall
max = 53mm
max = 75mm
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Settlement against Time
-0.350
-0.300
-0.250
-0.200
-0.150
-0.100
-0.050
0.000
0.050
01-Aug-06
01-Sep-06
01-Oct-06
01-Nov-06
01-Dec-06
01-Jan-07
01-Feb-07
01-Mar-07
01-Apr-07
01-May-07
01-Jun-07
01-Jul-07
01-Aug-07
01-Sep-07
01-Oct-07
01-Nov-07
01-Dec-07
01-Jan-08
Date
Settlement(m)
SS3 SS2 SS1 SS4
Settlement against Time
-0.600
-0.500
-0.400
-0.300
-0.200
-0.100
0.000
01-Aug-06
01-Sep-06
01-Oct-06
01-Nov-06
01-Dec-06
01-Jan-07
01-Feb-07
01-Mar-07
01-Apr-07
01-May-07
01-Jun-07
01-Jul-07
01-Aug-07
01-Sep-07
01-Oct-07
01-Nov-07
01-Dec-07
01-Jan-08
Date
Settlement(m)
GS23 GS24 GS20
Ground Settlement Time Plot behind North Wall (Seawall)
SS Markers on Seawall
GS Markers on Ground Adjacent to Seawall
ExcavationH-Piling, Sheetpiling, Ground Improvement Grouting
Pile Cap
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Settlement against Time
-0.500
-0.450
-0.400
-0.350
-0.300
-0.250
-0.200
-0.150
-0.100
-0.050
0.000
01-Aug-0
6
01-Sep-0
6
01-Oc
t-06
01-Nov-0
6
01-Dec-0
6
01-Jan-0
7
01-Fe
b-0
7
01-Mar-
07
01-Apr-
07
01-May-0
7
01-Jun-0
7
01-Ju
l-07
01-Aug-0
7
01-Sep-0
7
01-Oc
t-07
01-Nov-0
7
01-Dec-0
7
01-Jan-0
8
Date
Se
ttlemen
t(m)
GS31 GS34 GS28
Ground Settlement Time Plot behind East Wall
Excavation
H-Piling, Sheetpiling, Ground Improvement Grouting
Pile Cap
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Ground Deformation behind East Wall(due to excavation only)
GS28 (6.2m) GS31 (9.6m) GS34 (15.6m)
Inclinometer IN2 (1m)
Predicted max = 115mm
Predicted max = 82mm
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Settlement against Time
-0.070
-0.060
-0.050
-0.040
-0.030
-0.020
-0.010
0.000
0.010
01-Aug-0
6
15-Aug-0
6
29-Aug-0
6
12-
Sep-
06
26-
Sep-
06
10-Oc
t-06
24-Oc
t-06
07-
Nov-0
6
21-
Nov-0
6
05-
Dec-0
6
19-
Dec-0
6
02-Jan-0
7
16-Jan-0
7
30-Jan-0
7
13-Fe
b-0
7
27-Fe
b-0
7
13-Mar-
07
27-Mar-
07
10-Apr-
07
24-Apr-
07
08-May-0
7
22-May-0
7
05-Jun-0
7
19-Jun-0
7
03-Ju
l-07
17-Ju
l-07
31-Ju
l-07
14-Aug-0
7
28-Aug-0
7
11-
Sep-
07
25-
Sep-
07
09-Oc
t-07
23-Oc
t-07
06-
Nov-0
7
20-
Nov-0
7
04-
Dec-0
7
18-
Dec-0
7
01-Jan-0
8
Date
Se
ttlemen
t(m
)
SS13 SS9 SS10 SS14
Ground Settlement Time Plot behind West Wall
Predicted max = 18mm
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
-18.0
-16.0
-14.0
-12.0
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
0 5 10 15Displacement (mm)
Eleva
tion
(mPD)
"+" toward excavation
Ground Deformation behind West Wall(due to excavation only)
Inclinometer IN5 (1m)
Predicted max = 60mm
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Jet grouting
Jet grout cuts insitu soft clay and mixes that withinjected cement
Disturbed clay is displaced to surface in slurryform
Jet nozzle is typically 1.4mm to 3mm dia.
Applicable to more cohesive soils where T.A.M.grouting may not work
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Typical Set up of Jet Grouting
(Double Tube Method)
Temporary casing fordrilling through fill.Withdrawn prior to jetting.(optional)
Jet Grout Zone
Soil Overburden
PVC tubing to assist spoilreturn. (optional)
Ref. : CNCEC
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
1. Set up rig 2. Drill to toe level 3. Test jetting
6. Jet grout completed.Withdraw grout string
5. Simultaneously withdrawal androtation of grout string to next level4. Commence Jetting
Sequence of Jet GroutingRef. : CNCEC
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Jet grout parameters Jet grout parameters adopted at SWSPS
Target grouted dia. = 1500 2000 mm
Grout pressure = 300 400 bars
Air pressure = 8 - 12 bars
Withdraw rate = 13 to 15 min/m
Rotation rate = 6 7 rev/step
Target strength & stiffnessUCS = 600 kPa
Elastic modulus = 150 MPa
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Hole S2Hole S5
Jet Grout Core Sample
(UCS: typically 7-10 MPa, sometimes >40 MPa)
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
T.A.M. Grout Core Sample
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
T.A.M. Grout Core Sample
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Sheetpiling (by push-in method)
Suitable in area where vibration is undesirable
With limited penetration depth
Difficult to overcome obstruction
Tend to be more costly
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Augering to assist penetration
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Alignment out-of-line whenencountering obstructions
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Groundwater leaking throughretaining wall
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Excavation in progress
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Disposal by barge
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Installing waling and strut
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Excavation completed
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Concreting in progress
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Concreting in progress(3 concrete pumps & 13 concrete trucks)
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Foundation Completed
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Ref. : DSD
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Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Before Commencement After Completion
Ref. : DSD
Asia HKIE Technical Talk ELS Design for SWSPS 18 June 2008
Summary
Issues to be considered in ELS design
Site history
Site characterization
Design parameters (drained or undrained)
Design objective and constraints
Retaining wall installation effects
Economy and construction programme
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