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13/04/2015
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16th Mar 2015
Jack Pappin
The design and construction of the
16 hectare basement at Marina Bay Sands,
Singapore
2
Marina Bay Sands Integrated Resort
3
600m
Overall Development at Marina Bay Sands Integrated Resort 4
• Ground conditions
• Excavation sequence (area by area)
• Issues (area by area)
Overview of presentation
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5 Plan of 16 hectare excavation 6 Geological sections
7
Thick deposit of soft clay.
Severe time constraints
- More than 40% of concrete construction works for substructure
- Minimise inter-dependency between different contracts.
Movement control for existing structures (ECP and BSB).
Very limited site access.
Challenges for Excavation Works 8 Layout of excavationsSite
access
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9
Jul 2007
View of site access 10 Minimum use of strutting
Circular Cofferdams
Site
access
11
Jan 2008
MICE & Hotel Donuts & Hotel Peanut 12
Design
Effective Wall Thickness
To take into account:
• Plan offset at commencement level
• Verticality tolerance
Design wall
alignment
tt
teff
PLANt = Wall thickness
teff = Effective wall thickness
Maximum Hoop stress ~ K0 insitu stress * R / teff
Design of Circular walls
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13
3-D Analysis for Peanut Cofferdam
1. Obtain different earth pressures from
OASYS FREW to account for
variation in geology.
2. Set up 3-D Finite Element Model
SAP2000 to assess stresses and
deformation shape of the cofferdam
3. Structural design of diaphragm wall
panels, cross wall and fin wall.
Cross wall
Design of Circular walls
8m wide 15m deep
cantilever fin walls
14
As shear stress and in plane
compression stress are
mutually dependant the
BS8110 friction coefficient for a
plain concrete joint was used
iteratively in the SAP analysis.
Design for shear in peanut cross wall
Location of peak
inter panel shear
15 Construction sequence – South Podium 16
MICE Casino
Theatre
Retail
MuseumPromenade
Crystal pavilions
Hotel
Tower 1
Hotel
Tower 2
Hotel
Tower 3
Construction sequence – South Podium
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17
RL(m)
110
100
90
80
70
60
50
40
Fill
Old Alluvium
Sea
Sand
Soft clay
Retail MICE
Proposed excavation level
MICE
Retail
Construction sequence – South Podium 18
STAGE 1:
RL(m)
110
100
90
80
70
60
50
40
Sand
Retail MICEDiaphragm
wall
Bored piles
Diaphragm
wall
6m
thk.
Jet
grout
4m
thk.
Jet
grout
Existing
Ground Level
Existing
Ground Level
Existing
Ground
Level
Existing
Ground
Level
99.5
mRL
Capping beam Capping beam
1. Install diaphragm wall, jet grout and bored
piles.
2. Excavate along perimeter of circular
cofferdam to construct capping beam.
Construction sequence – South Podium
19
RL(m)
110
100
90
80
70
60
50
40
Sand
Retail MICE
B2 FEL
(~+90.5)B4 FEL
(~ +86.0)
Top down column
1. Excavate to final excavation level inside
cofferdams.
2. Install top down columns.
FEL
Construction sequence – South Podium
STAGE 2:
20
RL(m)
110
100
90
80
70
60
50
40
Sand
Retail MICE L1 slab for construction access
B2 slab B4 slab
B2 slab
Steel trussSteel truss
1. Install steel truss at +100mRL using trench
method.
2. Construct part of L1 slab as construction
access.
3. Cast base slab in cofferdams.
Construction sequence – South Podium
STAGE 3:
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21
RL(m)
110
100
90
80
70
60
50
40
Sand
Retail MICE
+91mRL
Construct
basement
slabs
above B4
B4 FEL
(~ +86.0)
Construct
L1 slab
+91mRLB2 FEL (~ +90.5)
B2 FEL
(~ +92.5)
Sand
L1 slab
1. Excavate to final excavation level in MICE
and +91mRL in the remaining areas outside
cofferdams.
2. Construct basement structure inside
cofferdams.
FEL
Construction sequence – South Podium
STAGE 4:
22
RL(m)
110
100
70
60
50
40
Retail MICE
90
80
Sand
B2
Slab B4 FEL (~ +86.0)
B4 FEL
(~ +86.0)1. Cast B2 slab in MICE.
2. Install struts in the remaining area below B2
soffit.
3. Excavate to final excavation level in the
remaining areas.
Strut below B2
FEL
B2 slab
Construction sequence – South Podium
STAGE 5:
23
RL(m)
110
100
70
60
50
40
Retail MICE
90
80
Sand
B4 slab
B4 slab
B4 slab1. Cast B4 slab.
B4 slab
Construction sequence – South Podium
STAGE 6:
24
RL(m)
110
100
70
60
50
40
Retail MICE
90
80
Sand
G/F slab to
be cast
L1 slab previously cast
L1 slab
previously castL1 slab
previously cast
1. Complete L1 slab.
2. Install struts across the openings of L1 in
Retail.
3. Remove steel truss.
L1 slab
Strut at L1
Construction sequence – South Podium
STAGE 7:
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RL(m)
110
100
70
60
50
40
Retail MICE
90
80
Sand
B2 slab to
be cast
Hack Dwall to
below B2 slab
B2 slab
previously cast
B2 slab
previously cast
1. Demolish cofferdam diaphragm wall to
below B2.
2. Construct and connect B2.
3. Remove struts below B2.
B2 slab
Construction sequence – South Podium
STAGE 8:
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RL(m)
110
100
70
60
50
40
Retail MICE
90
80
Sand
Hack Dwall to
below B4 slab
Hack Dwall to
below B4 slab
B4 slab
previously cast
1. Demolish cofferdam diaphragm wall to
below B4 slab.
2. Complete basement structure.
Construction sequence – South Podium
STAGE 9:
27 View of central 120m donut 28
Recorder
Winch UnitKoden Test Results
Koden Test on every panel to check Verticality
Construction of cofferdams
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Inclinometer readings
B180 (-) B0 (+)
A0 (+)
A180 (-)
Excavation
Construction of cofferdams 30
GSA Analysis
Steel Truss Layout
Design of cofferdams
Steel truss against top of donuts to retain stability of donuts
when excavating outside
31
Steel truss against top of donuts to retain stability of donuts
when excavating outside
Design of cofferdams 32
30,000 m3
8,000 trucks
Removal of cofferdams above excavation level
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33 Sequence for North Podium (a) (Casino – Retail)
Oct 2008
34 Semi Top Down Excavation (Casino Area)
35 Semi Top Down Excavation (Casino Area) 36
South Podium
3D analysis carried out to investigate stability of north donut
Initial excavation
Excavate North
Excavate South
OR
17.5m
8m
Struts
along
Dwall
17.5m11m
Steel
Truss
North Podium
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37 Museum C Wall 38
100
90
80
70
60
50
RL(m)
Sand
Museum Retail Theatre
Shear support to museum from the curved wall supported at ends
Museum C Wall
39
SAP model of circular
with loads being
transferred in shear to
Old Alluvium at the
ends.
Lateral support at the
ends provided by
anchors on the north
side and adjacent bored
pile perimeter wall at
south hear support to
museum form the
curved wall supported at
the south side.
Museum C Wall 40 Excavation at DTE – DCS - Theatre
Oct 2008
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41 DTE – DCS – Theatre Area : Issues
Theatres DTEDCS BSB
84.5
78
67
CT
Horizontal Displacement Contour
110.00
100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
mm
40.00
30.00
20.00
10.00
00.00
-10.00
-20.00
-30.00
-40.00
-50.00
-60.00
-70.00
-80.00
-90.00
-100.00
200.00 210.00 220.00 230.00 240.00 250.00 260.00 270.00 280.00 290.00 300.00 310.00 320.00 330.00 340.00 350.00
DCS box needs to resist large lateral earth pressure from the East of DTE
Lateral Force from the East of DTE
DTE movement needs to be controlled to minimise impact onto BSB
Benjamin Sheares Bridge
movement control
42
Lateral Force from East of DTE
DTE – DCS – Theatre Area : Issues
Continuously Reinforced
Wall (Shear Wall)
Large lateral soil load to be carried in shear to the DCS
requires continuously reinforced shear cross walls to
transfer load to Old Alluvium
26m
43
Continuously reinforced Shear Wall
Extent of trench
for female panels
Female panel
(only the
middle
portion is
concreted)
Male panel
(excavated after
adjacent female
panels are
concreted)
6400 3000
DTE – DCS – Theatre Area : Issues 44 Regular review of DCS performance
Theatres
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45 Regular review of DCS performance 46 Regular review of DCS performance
Theatres
47 Benjamin Sheares Bridge 4848
Benjamin Sheares Bridge - Elevation
Pier 22 South Abutment
MBS Site
Pier 21
Pier 21Pier 20Pier 19
N
Benjamin Sheares Bridge
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DCS
DTE
Theatre
TBM
Shaft
Benjamin Sheares Bridge 50
DCS
DTE
Theatre
TBM
Shaft
Benjamin Sheares Bridge
Inevitable movement
to the bridge abutment
Dowell pins
overstressed
51 Benjamin Sheares Bridge
DCS
DTE
Theatre
TBM
Shaft
Inevitable movement
to the bridge abutment
Allow articulation
between the Pier
and the Deck
52
View looking up from underneath
Section on Plan
Pier crosshead
Underside of deck
Deck crossbeam
BSB Adjustable Shear Pins
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53
0
10
20
30
40
50
mm
Adjustment dates
Adjustment schedule 54 Permanent underslab drainage
55
The end