Three-Dimensional Finite Element Analysis of Deep Excavations

A nonlinear, three-dimensional finite element technique for deep excavation analysis is proposed in this paper. The technique as well as the analytical procedures for modeling the excavation processes were coded into a computer program, and the accuracy of the program was assessed. In order to minimize the number of elements and nodes without sacrificing the accuracy of analysis, a series of convergence studies were performed, which makes three-dimensional analysis computationally and economically feasible. The effect of the existence of the corner on the deflection behavior of an excavation was studied in detail by analyzing a typical excavation with soft to medium clayey subsoil stratum. By performing a series of parametric studies, a tentative relationship is developed for estimating three-dimensional maximum wall deflection of an excavation based on two-dimensional finite element results. Finally, the case of an irregularly-shaped excavation with field measurements of wall deflection was studied. The results of analyses show close agreement with field measurements.