CHEN Zuyu, XIANG Yuanhong

Abstract: 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.

Keywords: deep excavation; reliability index; coefficient of variability

(Journal of China Institute of Water Resources and Hydropower Research, Vol. 16, No. 2, 2018)