Analysis of Incremental Excavation Based on Critical State Theory

Abstract

Earth structures such as embankments and excavations are constructed sequentially, and for realistic modeling of these structures the construction sequences should be simulated as accurately as possible. This paper addresses the problems associated with accurate incremental excavation modeling using an efficient finite element‐based excavation analysis algorithm that satisfies the uniqueness principle for cutting in an elastic material and a new stress‐point integration algorithm for the modified Cam‐Clay model that is both accurate and stable. The combined excavation and stress‐point algorithm is unconditionally convergent at subfailure condition and is shown to perform extremely well on an intensive accuracy analysis designed to model the process of sequential excavation in a modified Cam‐Clay soil under plane strain, axisymmetric, and three‐dimensional configurations. Both drained and undrained conditions are considered in the analyses. The paper ends with an example of braced wall movement prediction in a soft bay mud deposit near San Francisco Bay to demonstrate the practical application of the proposed solution.