Impact of anchor failure for deep excavation in soft clay based on 3D FEM analyses

摘要

The paper investigates 3D effects related to a deep excavation in soft clay supported by sheet pile walls and three levels of tieback anchors using a 3D finite-element program. The focus is on the impact of failure of an anchor and shows how earth pressures and structural forces are redistributed as a result of that. In Norwegian design practice anchor failure is commonly considered as an accidental limit state (ALS) case, but accounts for some redistribution of loads as a result of the failure. The numerical 3D analyses were performed with the Plaxis 3D finite element program. The NGI-ADP constitutive model, which is an elasto-plastic total stress based material model with anisotropic shear strengths and hardening functions, is used to describe the clay behaviour. The results of the analyses are presented in terms of soil and wall deformations, lateral earth pressure and loads in the supporting structure. The results shows that for the considered example, the load redistribution effects assumed in current design are considerably on the conservative side.