-- http://www.thesail.com.sg/video.htmlhttp://www.thesail.com.sg/video.html

Innovative Diaphragm Wall SystemInnovative Diaphragm Wall Systemat at ““The Sail @ Marina BayThe Sail @ Marina Bay””

Background of The Sail

• New Downtown at Marina Bay development

• Tallest private residential development

• Two towers – 70 storey (245m), – 65 storey (215m)

• Basement (9m) at Tower 1 – Retail spaces

New Downtown @ Marina Bay development in 10-15years time

New Downtown @ Marina Bay development New Downtown @ Marina Bay development in 10in 10--15years time15years time

Constraints

• Tight working schedule– 40mths of construction

• Restricted site– 140,000 m sq of working area

• Soil Condition– 40m of marine clay, away from the competent soil layer

• Proximity to CST & RTS– Less than 15mm of deflection – Code of Practise

– CST under-construction

Project Timing

• Time for construction: 40months

– Soil Investigation

– Structural modelling

– Construction

Restricted SiteRestricted Site

Geology•• Made of Kallang Formation Made of Kallang Formation

(up to 36m)(up to 36m)

-- Soft Marine Clay Soft Marine Clay

-- Fluvial Sand (F1)Fluvial Sand (F1)

-- Fluvial Clay (F2)Fluvial Clay (F2)

-- Old Alluvium and Fort Canning Old Alluvium and Fort Canning

Boulder ClayBoulder Clay

•• Reclaimed Fill Reclaimed Fill –– Sand Fill (6.5 Sand Fill (6.5 --9m)9m)

GeologyGeology

Justification Justification ““The Sail @ Marina BayThe Sail @ Marina Bay””

Choice of Retaining Wall

Sheet Piles? Contiguous Bored Pile?

Diaphragm Wall?Diaphragm Wall? Secant Pile Wall?

Choice of Retaining Wall

LowLowLowHighVibration

HighMediumMediumLowCost

HighestHigherMediumLowWater-tightness

HighMediumMediumLowStiffness

Diaphragm wall

Secant PileCBPSheet piles

Choice of Diaphragm Wall

Cellular diaphragm wall

vs.

Rectangular diaphragm wall

Choice of Diaphragm Wall

• Why not choosing Rectangular Diaphragm Wall?

– The base stability in soft clay excavations is expected to be better using circular walls compared to a rectangular excavation due to shape effect

– Propose a cellular wall and due to geometry constraints

Choice of Diaphragm Wall

Advantages of the cellular wall system:

• Self-supported walls

1. Strut-free

2. Subject to pure compression

3. Jet-Grout-Slabs-free

Cellular Diaphragm Wall

1. Strut-free excavation

– Shorter construction time

• excavation

• steel placement and concrete pouring

• avoids installing and removing steel struts

Cellular Diaphragm Wall

2. Pure compression

Cellular Diaphragm Wall

2. Pure compression

• Reduced toe depth –Need to reach firm soil

• Small deflection –close proximity to CST & RTS

Cellular Diaphragm Wall

3. Jet-Grout-Slab-free

– What jet-grout-slab?

• Control lateral deflection of the walls and against basal heave stability along with piles to anchor the forces imposed on them in deep excavations

– Problem:

• not easy to ensure the column diameter or the position

• pressure used to cut the soil is huge, damaging to adjacent structures as it heaves the soil behind the wall

• Environmental problems for disposal

Cellular Diaphragm Wall

3. Jet-Grout-Slab-free

Innovative Diaphragm Wall SystemInnovative Diaphragm Wall SystemTriple Cellular Diaphragm WallTriple Cellular Diaphragm Wall

Evolution of Diaphragm Wall

2nd Generation

Manjung, MalaysiaManjung, Malaysia

3rd Generation

StormStorm--water water

decontamination decontamination

control basin @ Lievin, control basin @ Lievin,

France France

1st Generation

19971997--2B Complex, 2B Complex,

Robertson QuayRobertson Quay

Evolution of Diaphragm Wall

Innovative Diaphragm Wall SystemInnovative Diaphragm Wall SystemConstruction SequenceConstruction Sequence

Construction Sequences

73mRL73mRL

94mRL94mRL

97mRL97mRL

102mRL102mRL

Shaping into peanut-shaped Diaphragm Wall

Circular Diaphragm Wall with Flying Beam (in Red)

Cut-off Cross Wall

Completion of Peanut Diaphragm Wall

Site Overview

Batching PlantBatching Plant

Mobile CraneMobile Crane

BFCBFC

CSTCSTRTSRTS

1. Building the guide wall

2. Diaphragm wall excavation 2. Diaphragm wall excavation

adjacent to the CST ventilation shaft adjacent to the CST ventilation shaft

3. Installation of reinforcement 3. Installation of reinforcement

cages into the diaphragm wall cages into the diaphragm wall

Bentonite Bentonite

Tremie Pipes Position

Excavating

BackactorBackactor

LorryLorry

Flying Beams Flying Beams

4. Excavation for the basement & foundation cap under way4. Excavation for the basement & foundation cap under way

King Posts King Posts

5. Excavation complete and the barrette pile cap 5. Excavation complete and the barrette pile cap

reinforcement being laid reinforcement being laid

6. Casting of floor slab with the protection of the tents 6. Casting of floor slab with the protection of the tents

Base of Base of Towner CraneTowner Crane

Tarpaulin Tarpaulin

6. Casting of floor slab with the protection of the tents 6. Casting of floor slab with the protection of the tents

7. Removal of Flying Beam for the Construction of Basement7. Removal of Flying Beam for the Construction of Basement

Construction Sequences

• HK Central Station

– Circular diaphragm wall

– Barrettes piles

– Near CBD area – restricted site

– On reclaimed land and with marine clay

– Tight schedule

Innovative Diaphragm Wall SystemInnovative Diaphragm Wall SystemAnalysis of the system & Analysis of the system &

InstrumentationInstrumentation

Equilibrium of Forces

• Software developed by SOLETANCHE-BACHY:

– PAROI 2

– PARIS

•• Horizontal EquilibriumHorizontal Equilibrium

– New equilibrium achieved after the removal of flying beam.

Equilibrium of Forces

• The Plan View Equilibrium

• Non-symmetrical pressure due to geology, excavation and water table variation

• Non-symmetrical pressure due to the pier

• Basal Heave and Water Uplift

• Higher toe level

Moment Moment ∞∞ StiffnessStiffness

Instrumentation

• Issues:

– Next to the MRT safety zones,

– The excavation was monitored for settlement, basal heave, deflection of the wall and change in pore pressures.

– New system to Singapore

– Hence,

• place instruments in the wall, barrettes and the surrounding areas

Instruments

• Monitoring during the excavation:

– Strain gauges

– Inclinometers

– Piezometers

– Settlement and Heave Markers

Figure 2:Instrumentation Plan

Monitored Results of Strain gauges

Monitored Results of Inclinometers

Innovative Diaphragm Wall SystemInnovative Diaphragm Wall SystemConclusion & SignificanceConclusion & Significance

Conclusion & Significance• Innovative and creative idea is a crucial in today’s

construction industry

• No single construction project is identical, we should be flexible and open to the new ideas

• Concept of triple circular diaphragm wall is the evolution of the conventional rectangular one.

• Technology makes a challenging design into a reality

• The buildability and constructablity of an building - the optimum use of construction knowledge and experience in planning, design, procurement, and field operations to achieve overall project objectives

Conclusion & Significance• Cellular diaphragm walls are viable, efficient and robust

structures that can be designed carefully to bring saving, safety and efficiency

• Paves the way for extending the idea to further find solutions for future projects in this area of Singapore and elsewhere.

• Construction industry is changing all the time, we have to keep ourselves on the track.

Current updates on The Sail

Thank you!

AZLIFAH BINTI SARMIDI U054907EDIANA LAI NGIIK CHUI U054840LHO BEE LAN U055009NJIANG PING PING U054867PLEE SING YEE U054857MLI SAI TING WAYNE U054863MNUR ALIYAH BINTE KHAMIS U054909A

Special Thanks To

• Bachy Soletanche Singapore Pte. Ltd. For the provision of information on the innovative diaphragm wall system which is employed in the project, “The Sail @ Marina Bay”.

• Mr. PEREZ, Frederic, the Project Director from Dragages Singapore Pte Ltd for giving us a wonderful presentation on the project, “The Sail @ Marina Bay” as well as giving us the eye-opening experiences during the site visit.

References*

• S. Chandrasegaran, C. Gilbert, T. Jeanmaire, Bachy Soletanche Singapore Pte. Ltd, S. Nasim, J.Quereshi., Meinhardt (Singapore) Pte. Ltd, Lauw S.W, LSW Consulting Engineers, Tan S.A., Harry,National University of Singapore, F. Perez, F. Calimag, R. Furio, DragagesSingapore (2006). Triple Cellular Diaphragm Wall in Singapore Marine Clay, International Conference on Deep Excavations 28-30 June 2006, (pp. 2-5, 8-14, 16, 18 -20).Singapore: Bachy Soletanche Singapore Pte. Ltd.

• Bachy Soletanche, Liesse Communication. (2004). MTRC 501 Hong Kong Central Station [Motion Pictures]. Hong Kong: LiesseCommunication

• Bachy Soletanche. (2005). Bachy Soletanche Singapore – 2005 – The Sail @ Marina Bay, Retrieved March 8, 2007 from http://www.bachy-soletanche.com.sg/BSSworks.htm

• Dragages Singapore Pte Ltd (2007, March). The Sail @ Marina Bay. Slides presented at the site visit.

• City Development Limited. (2004). The Sail @ Marina Bay. Retrieved March 26, 2007 from http://www.thesail.com.sg/video.html

• The Sail @ Marina Bay (245 + 215m/70 + 63 floors, due 2009) #2 - Skyscraper City. Retrieved March 2, 2007 from http://www.skyscrapercity.com/showthread.php?t=168683&page=2

• Skycrapers.cn (2007). The Sail @ Marina Bay. Retrieved March 24, 2007 from http://www.skyscrapers.cn/data/skyplan/si_The_Sail_@_Marina_Bay.htm

• Green Mark 2006 (2006 March - April). The Building And Construction Authority, p.5.

• Urban Redevelopment Authority. (2005). Marina Bay – Explore Marina Bay. Retrieved March 22, 2007 from http://www.marina-bay.sg/explore.htm#

• Raymond Wong Wai Man (2003 First Phrase). International Finance Centre Phrase II. Construction & Contract News 2003, 1, p3-4

• S.K. Kong (2004). Safety Control For Development Adjacent To Existing MRT Structure And Observed Field Performance, p3

* For more references, please kindly refer to the project report