摘要
2004年4月20日下午3:30,新加坡地铁环线C824标段的一段明挖区间隧道发生严重的坍塌事故[1],事故发生后调查工作随即展开。通过为期一年的全面深入调查,最终形成了各方认可的一致意见和权威的调查分析报告。调查结果表明,围护体系设计中的两方面的错误是导致基坑围护体系失事的诸多原因之一:①在土-结构相互作用的有限元模拟分析中,对饱和软土采用排水条件下的参数,使得水土荷载较实际情况偏小,进而低估了围护体系的变形和内力,使围护体系设计偏于不安全;②支撑与围檩的连接细部设计中错误地选用了局部屈曲失稳的悬伸长度,导致结构偏于不安全,以及后来又用槽钢代替胫板在极限承载力增加不大的情况下,体系的延性却大大降低,短短数小时内体系彻底崩溃,应急预案来不及反应。
The causation investigation was carried out immediately after Singapore MRT circle line C824 Nicoll highway collapse occurred at approximately 3：30pro 20th April 2004. A comprehensive and authoritative report was provided by expert panel after one year investigation. It has been inferred from the investigation report that the collapse was rooted in two critical design errors in temporary retaining system： 1. the method used to model the undrain behavior of soft clay was wrong which over-predicted the undrained shear strength of it and under- estimated wall bending moments and deflections and therefore resulted in the under design of diaphragm wall; 2. under design of the waler-strut connection in two respects which include i） a wrong value 400mm for stiff bearing length was adopted instead of 69mm according to BS5950 resulting in over-estimating buckling load of connection, ii） using C-channel as stiffener caused the connection buckled in brittle way.
出处
《现代隧道技术》
EI
北大核心
2009年第6期28-34,共7页
Modern Tunnelling Technology
