Evaluation of seepage failure by heave in homogeneous cohesionless soils using finite element method

ABSTRACT Commonly, the base stability of sheeted excavation pits against seepage failure by heave is evaluated by using Terzaghi’s failure plane, which is based on the results of the two-dimensional model tests. However, seepage flows in excavation pits are three-dimensional, and stress levels are relatively high compared to those existing in the model tests. In this study, hydraulically-mechanically coupled, axisymmetric finite element (FE) analyses are performed to investigate the seepage failure by heave in circular-shaped sheeted excavation pits constructed in homogeneous cohesionless soils. The results of FE analyses are compared with those obtained from the well-known failure approach of Terzaghi. The FE analyses show relatively different failure zones compared to Terzaghi’s failure plane. However, the difference between the critical potential differences obtained from the FE analyses ΔH failure(FEM) and Terzaghi’s approach ΔH failure(Terzaghi) is negligible. The maximum and minimum ratios of ΔH failure(FEM)/ΔH failure(Terzaghi) are 1.07 and 0.96, respectively.