FINITE ELEMENT STUDY ON THE STABILITY OF HOMOGENEOUS AND LAYERED SOIL SLOPES UNDER STATIC AND SEISMIC LOADING

Abstract

This study investigates the stability of homogeneous and layered soil slopes under static and seismic loading using the strength reduction finite element method in OPTUM G2. Slopes of 6 m height with inclinations of 30°, 45°, and 60° were analysed using Mohr–Coulomb and Drucker–Prager models. For homogeneous slopes, the factor of safety decreased from 1.44 to 0.87 as slope angle increased, with further reductions of 15–20% under seismic loading (Kh = 0.12); differences between constitutive models were negligible for moderate slopes but reached about 5% for steep slopes. In layered slopes, minimum safety factor occurred when the weak layer was located near the lower slope region (h/t ≈ 2), resulting in stability reductions of nearly 30% compared to homogeneous slopes, while seismic loading reduced sensitivity to layer position except near the crest. Soil nailing restored safety values to target of 1.5 (static) and 1.1 (seismic), needing longer nails for multilayer slopes. The uniqueness resides in the integrated evaluation of weak-layer position, constitutive modelling, and soil nailing optimization under combined loading using OPTUM G2.