13/04/2015

1

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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25

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:

26

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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29

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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49

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