Stability Analysis of MSE Walls with Stepped Reinforcement Design

The paper reports stability analysis of a special design of mechanically stabilized earth (MSE) walls with stepped reinforcement arrangement (referred to here as trapezoidal MSE walls), which is suitable for projects that face space limitations. A strength reduction method (SRM) based on limit analysis (LA) was used to investigate the sliding and overturning stability of such MSE walls as a function of reinforcement design (i.e. arrangement, length, vertical spacing, and tensile strength), wall height, and the magnitude of surcharge load applied on the wall. Numerical results indicate that overall, a stepped reinforcement design leading to a trapezoidal reinforced zone geometry could adversely impact wall stability relative to sliding, while it could increase its overturning stability. Therefore, a design approach assuming an equivalent uniform reinforcement length for such walls could overestimate their sliding stability, leading to unsafe design. Results also show that slip planes in a more rigorous stability analysis of MSE walls penetrate the reinforced mass, and typically form a two-part wedge failure geometry. As a result, factors of safety for sliding and overturning are influenced by reinforcement design, including its strength and spacing, which are not accounted for in current design approaches based on the assumption of the reinforced zone behaving as a rigid body. Therefore, the current approach for external and internal stability analysis of MSE walls as separate steps could result in inaccurate predictions of slip planes and the corresponding factors of safety in stability analysis of MSE walls in both uniform and stepped reinforcement design alternatives.