A Singapore case history of temporary removable ground anchor design to TR26: 2010

摘要

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.