Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group

Engineering, Singapore

Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group

Engineering, Singapore
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Low Y.H.S.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | David Ng C.C.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | Chin Y.P.Y.,Engineering Diversion | Ting S.K.E.,Engineering Diversion
IES Journal Part A: Civil and Structural Engineering | Year: 2012

Contract 937B, design and construction of Tai Seng Facility Building (TSFB), is part of Downtown Line Stage 3 (DTL3) of the Singapore mass rapid transit (MRT) System. The proposed TSFB will provide maintenance, operation and staff facilities for DTL3. It is a 52 m wide and 295 m long underground building which consists of two basement levels and entrance structure at ground level. The depth of excavation for the construction of basement is approximately 20 m. The schedule for completion of this project is very tight and it is critical to optimise the design of earth retaining and support system (ERSS). Contiguous bored pile (CBP) wall retaining system supported by temporary removable ground anchorage and a top-down roof slab is proposed as the ERSS for the excavation and construction of the underground TSFB. Partial top-down construction method is adopted, where the roof slab with large access opening will be cast first. Excavation will proceed and ground anchors will be installed as excavation progress downward. The use of partial top-down construction method and incorporating the roof slab as part of the support system to the excavation help to reduce one layer of temporary support system and cut down construction time. This paper presents the design approach and consideration for the temporary removable ground anchor using TR26: 2010. Some site-monitoring data compared against design prediction will be discussed in this paper. © 2012 Copyright Taylor and Francis Group, LLC.


Pong K.F.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | Foo S.L.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | Chinnaswamy C.G.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | Ng C.C.D.,Meinhardt Infrastructure Pte Ltd Member of Meinhardt Group | Chow W.L.,Formerly of Geotechnical Amberg and TTI Engineering Pte Ltd
IES Journal Part A: Civil and Structural Engineering | Year: 2012

Technical Reference 26: 2010 (TR26: 2010) requires the design of an earth retaining and stabilising system (ERSS) to be structurally safe, robust and has sufficient redundancy to avoid catastrophic collapse of the ERSS system resulting from an isolated case of overloading or failure of any particular member which may lead to the failure of adjacent members thus leading to progressive failure. One such redundancy check is the condition, where failure of a single strut, anchor or tie-rod occurs or more commonly known as one-strut failure (OSF) stated in Clause 3.7.4 of TR26: 2010 at each stage of the construction works. Analysis for OSF is actually a three-dimensional (3D) problem and carrying out such 3D analyses covering all the cases of wall stiffness, properties of the soil layers, friction between retaining wall panels in the case of diaphragm wall, soil arching effect due to the deflection of the retaining wall, etc. is very time consuming. In the conventional approach for OSF using two-dimensional (2D) plane strain analysis, the whole layer of failing strut is removed and thus provides paths to distribute the forces in the vertical direction only. This usually leads to more conservative design with heavier struts sections. In this paper, a procedure to rationally idealise OSF from a 3D analysis to a 2D plane strain analysis is presented. This simplified approach will be more practical for practising engineers to arrive at a more efficient design without the need for rigorous 3D analysis. The results of this simplified approach are compared with the conventional approach and results incorporating appropriate strut stiffness from 3D analysis. The comparison showed that the approach is reasonable. © 2012 Copyright Taylor and Francis Group, LLC.

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