基于上海市11个工程的地勘报告共111组实验数据,提出了上海市4类土变异系数的建议值;回顾了国内现行的规范,以并《工程结构可靠性设计统一标准》(GB50153-2008)为依据,建议一个目标可靠指标3.7来对应《建筑基坑支护技术规程》(JGJ120-2012)中规定的安全系数1.35;基于总应力法,采用简化毕肖普法计算安全系数,采用Rosenbleuth法计算可靠指标,并采用由第一作者开发的STAB程序搜索临界滑裂面;对上海市3个深基坑工程进行了复核分析,发现在可靠指标3.7时安全系数均在1.35左右,从而验证了规范规定的安全系数的允许值和可靠指标有较好的对应关系.%This paper is aimed at validating the acceptable factor of safety specified in the code JGJ120-2012.The authors proposed the recommended values of the coefficients of variability for 4 types of Shanghai soils based on 111 groups of soil testing data from 11 geological survey reports.The paper reviews the currently applied Chinese codes and proposed a reliability index β of 3.7 on the basis of the code GB50153-2008 as a target to calibrate the allowable factors of safety.The corresponding criterion specified in the code JGJ120-2012 is 1.35.Deterministic stability analysis was performed based on the total stress method using Bishop's simplified method.Rosenblueth method was used to find the reliability index.Search for critical slip surface is realized using the computer program STAB which is developed by the first author.The study investigated 3 large scale deep excavation projects in Shanghai and came to a conclusion that the criterion of 1.35 based on the allowable factor of safety specified in the code is generally in compliance with 3.7 for the target reliability index.This finding provides a theoretical support to the currently available codes in our profession.
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