2-D and 3-D FEM idealisation of soil nailed walls

Abstract

Recently, soil nails are finding extensive application in the slope stabilization problem mainly due to the relatively low cost and easy installation process. The increasing importance of soil nails necessitates the need for an effective design of the soil nailed walls. The soil nailed wall is a three dimensional (3-D) problem that is controlled by factors like nail cross section, overburden pressure and shear resistance of the soil nails. The present study emphasizes that the 3-D soil nailed wall can be designed using a two dimensional (2-D) analysis taking into account the stiffness parameters of the nail. The 2-D FEM analysis of soil nailed walls considers the soil nails as a plate element which in reality is usually circular in cross section. Proper optimization of the real 3-D nail to a 2-D plate element will simulate the real behavior of the wall. This project deals with a comparative study between 2-D and 3-D analysis of two cases, the first is the laboratory set up of soil nailed walls at Nanyang Technological University by Dr. Raju and the second is soil nailed wall at the PGPR residences at National University of Singapore. The study revealed that the 2-D idealization of 3-D nails works well for the soil nailed wall excavation. The nail forces and horizontal wall deflection produced by both the 2-D and 3-D analysis reasonably match the exact profile in the field.