Comparative Study between Two-and Three-Dimensional Analyses of a Deep Excavation

Abstract

—The subsoil stratigraphy, the excavation geometry, and the temporary supporting system are significant factors that affect the design and construction of a deep excavation. This paper presents the findings of a numerical simulation of an anchored pile-supported 36m deep excavation with a length to width ratio of L/B=2.2. The significance of 3D geometry and excavation stages in the out of plane direction on the pile wall’s performance is highlighted. The analysis is carried out with PLAXIS FE code and the effective stress approach. The following critical parameters are used for the results’ comparison: (a) wall lateral displacement, (b) ground settlement, and (c) internal structural forces. The impact of wall structural anisotropy and construction sequence on the soil-structure system's performance is also investigated. The unrealistic 2D boundary conditions considerably overestimate results in terms of both displacements and stresses of the wall, which may lead to an overconservative design.