Analysis of soil nailing using finite element method

Abstract

Soil nailing system is always well known preventive method in slope improvement. Soil nailing is a complex system that requires detailed analysis to ensure stability. In the past, slope stability has always been limited in using limit equilibrium (LE) method. LE method developed based on slices concept along the potentially sliding block. Due to certain complications, finite element (FE) method is slowly replacing LEM in geotechnical application. The advantage of using FEM over LEM because FEM is able to provide nearactual results through model simulations. PLAXIS 2D software based FEM is selected to perform analysis for this research project. PLAXIS 2D, provides simulation of interaction between soil and nails, construction stages and installation processes which in turns demonstrate the deformation of soil nail system, failure planes identification compared to LEM. In addition, PLAXIS 2D is also able to provide safety factors using phi-c reduction calculation. Soil nailing relatively give satisfactory response under seismism, so pseudostatic method is applied for seismic loading study. Pseudo-static force is an equivalent static force acting on center of gravity of sliding block during earthquake ignoring the earthquake-induced, time varying inertia force. Lastly, parametric study is conducted focusing on different soil nail spacing and their effects on soil nail displacements. Soil nail spacing varies from 1.5 m, 2.0 m, 2.5 m and 3.0 m. Results on deformations and force distribution along nail body are discussed, together with factor of safety to access the global stability of soil nail system.