Wall and ground responses in a braced excavation considering spatial variability

A framework for evaluating the probability of exceeding the specified limiting wall and ground responses in a braced excavation is presented in this paper. In this framework, the wall and ground responses in a braced excavation are computed with finite element method (FEM). To model uncertainty with limited data, fuzzy numbers are used to characterize the uncertainty, and the spatial variability of soil properties are incorporated into fuzzy parameters using spatial averaging technique. The FEM analysis of braced excavations with fuzzy parameters is carried out using the vertex method, in which "sampling" of uncertain soil parameters is by means of α-cut intervals, rather than the Monte Carlo technique. The output (the maximum wall deflection and ground settlement) of the FEM analysis in this case are fuzzy numbers, and a technique called fuzzy point estimate method (FPEM) is used to interpret the resulting fuzzy numbers. A well-documented excavation case history is analyzed to demonstrate the proposed framework. The results show that the proposed framework is effective for assessing the probability of exceeding the specified limiting wall and ground response in a braced excavation.