Investigation of Limit Equilibrium Method and Finite Element Analyses for Ground Anchored Slopes-Paper

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The study compares the Limit Equilibrium Method (LEM), using Carpenter’s Load Distribution Method, with the Strength Reduction Finite Element Method (SRFEM) for a hypothetical slope stabilized by one row of ground anchors. The Load Distribution Method spreads concentrated anchor forces along a potential slip surface using an elastic stress-distribution model, avoiding numerical difficulties that concentrated loads can cause in LEM.<br /><br />In general, SRFEM and LEM produced similar safety factors when a well-developed slip surface formed in the soil. This supports using the Load Distribution Method as a reasonable approximation under those conditions. However, SRFEM results were sensitive to modeling choices such as soil stiffness, anchor diameter, and flow rule; non-associated flow rules sometimes caused convergence problems.<br /><br />The methods diverged when soil–structure interaction controlled failure. SRFEM showed that larger anchors could carry more load and identified a failure surface between the soil and facing wall at high anchor forces. LEM cannot represent this interaction or determine the maximum usable anchor force from such a mechanism; its predictions beyond the identified failure limit may therefore be unreliable. SRFEM can also calculate structural demands, including facing-wall moments and shear.<br /><br />The authors caution that even the more rigorous Spencer LEM method may fail to converge for some trial slip surfaces, so results should be checked using multiple methods. Because the analysis considered only a hypothetical slope with uniform soil, further work is needed to verify the findings for other geometries and soil conditions.

Keywords

Limit Equilibrium Method

Strength Reduction Finite Element Method

ground anchors

slope stability

Carpenter's Load Distribution Method

safety factor

soil-structure interaction

slip surface

Spencer method

finite element analysis