Comparison of Factor of Safety Between LEM and FEM for Geotextile Reinforced Embankment on Difficult Foundation

Abstract

AbstractGeotextile Reinforced Embankment (GRE) stability analysis by software is widely accepted practice when slope configuration and soil parameters are known. Stability and deformation are the two main concerns for Reinforced Soil Structures (RSS). Stability is evaluated by the limit equilibrium method (LEM), locating the critical slip surface that produces the minimum factor of safety (FS) and assessment of deformation (stress–strain relationships for given tensile load in reinforcement layers) through finite element method (FEM). The application of FEM to RSS is relatively recent, but it renders additional information compared to traditional LEM and has gained attention in understanding the performance of these structures. In the present study, an attempt has been made to understand the difference, study the similarities and compare the results of FS calculated between these two analysis methods. An analytical GRE on difficult foundation was designed and modeled in GEO5 software. The stability analysis on the model was performed using the GEO5-LEM. Critical slip surface with FS of 1.5 for normal condition and FS of 1.0 for the flooded condition was set acceptable. The same model was reanalyzed with GEO5-FEM software for deformation study. With the understanding of analysis approach between LEM and FEM, conclusions were drawn for the modeled slope geometry, soil properties, geotextile reinforcement tensile strength/stiffness properties and it’s spacing. This study attempts to guide the development of more accurate LEM analysis or arrive at a suitable LEM procedure to be adopted in given boundary conditions based on the results obtained from FEM analysis or vice versa.KeywordsGeotextileFactor of safetyEmbankmentLEMFEM