American Society of Civil Engineers

Performance Monitoring of Deep Excavation at Changi WRP Project, Singapore

by Suresh Parashar, Ph.D., Aff.M.ASCE, (Senior Geotechnical Engineer, CH2M HILL Inc., 15010 Conference Center Drive, Suite 200, Chantilly, VA 20151 E-mail:, Roger Mitchell, (Manager, Construction Engineering, CH2M HILL International Ltd, 21st Floor, One Churchill Place, Canary Wharf, London, E14 5LN, UK E-mail:, Moh Wung Hee, (Director, Best Sourcing Department, Public Utilities Board, 40 Scotts Road, #18-01 Environment Building Singapore 228231 E-mail:, Devaraj Sanmugnathan, (Deputy Director, Best Sourcing Department, Public Utilities Board, 40 Scotts Road, #18-01 Environment Building Singapore 228231 E-mail:, Ed Sloan, (Construction Operations Manager, CH2M HILL Inc., 322 East Front Street, Suite 200, Boise, ID 83702 E-mail:, and Gordon Nicholson, P.E., (Global Program Manager, CH2M HILL International Ltd, Level 34 Gateway West, 150 Beach Road, Singapore 189720 E-mail:
Section: Walls and Excavation Support, pp. 1-12, (doi:

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Document type: Conference Proceeding Paper
Part of: 7th FMGM 2007: Field Measurements in Geomechanics
Abstract: This paper describes the monitoring of cut-slopes and the retaining wall that was adopted at CWRP site. During construction, thick deposits of soft marine clay, not discovered during previous site investigations, were encountered at the northern and eastern project boundaries. A high quality supplementary site investigation combined with the performance monitoring of slopes allowed the risk of instability in these areas to be effectively managed with the result that the use of relatively lower safety factors than traditionally adopted could be accepted. In addition, a detailed re-evaluation of the anticipated behavior of the CBP retaining wall combined with performance monitoring of the retaining wall and cut slopes allowed the originally planned jet grout ground improvement works at the location of EJC to be omitted. The use of pro-active construction management and resident engineering during construction, together with comprehensive instrumentation, robust data acquisition and continuous data review ensured that the risk of slope and retaining wall instability was well managed. This approach resulted in significant direct and indirect cost and time savings to the project and all project stakeholders were satisfied. The slopes and retaining wall at CWRP performed satisfactorily without failure and the excavation has since been backfilled.

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