Assessment of Fault Influence on Slope Stability Using Finite Element Limit Analysis

Abstract

Geological discontinuities such as faults and shear joints present significant challenges in slope stability assessments, often altering failure mechanisms and reducing safety margins. This study explores the influence of fault geometry on slope stability through a comprehensive numerical investigation using finite element limit analysis with upper and lower bound formulations. A series of parametric simulations were conducted on a 17-meter-high slope model, incorporating faults of varying lengths (3.75 to 21.5 meters) positioned at different distances from the slope face. The fault-free slope exhibited stable conditions, with safety factors ranging from 1.889 to 1.923 and circular failure surfaces. In contrast, the introduction of faults in close proximity to the slope resulted in marked reductions in stability. The most critical scenario, involving a 21.5-meter fault located 1 meter from the slope, yielded safety factors as low as 0.675–0.693 and a transition in failure mode from circular to planar sliding. Results reveal that fault proximity has a more pronounced impact on slope behavior than fault length. Faults situated beyond 4 meters from the slope face exhibited negligible influence on stability, whereas those within the near-field zone induced safety factor reductions exceeding 60%. These findings provide actionable insights for geotechnical design, emphasizing the necessity of detailed fault mapping within critical slope zones. The study contributes to the development of more reliable, risk-informed approaches to slope stability analysis in structurally complex terrains.