Reliability Analysis on Anti-Overturning Stability of Supporting Structure of Excavation Using Monte-Carlo Method

Engineering characteristics of soil are different at dissimilar layers and regions because of the variability of geological origin, earth history, environment condition, etc. Traditional safety factor method, which is usually used in design and calculation of geotechnical engineering, cannot reflect this variability and uncertainty of soil scientifically because characteristics of soil are often influenced by sampling and experimental condition. In this paper, reliability analysis method, based on probability and statistics, was applied to analysis anti-overturning stability of supporting structure of excavation. Anti-overturning limit status function, in which layered soil was considered, is derived using equivalent beam method. In the process of computation, geometric dimension of supporting structure was deemed as constant such as excavation depth, anchored depth of pile, pile spacing and so on. Soil parameters, gravity, cohesive force, and internal friction angle of soil were regarded as random variables. At last, the open excavated tunnel of Chengdu-Dujiangyan railway was taken for example to discuss anti-overturning stability of supporting structure influenced by loads nearby excavation.