Numerical investigation of the interaction of back-to-back MSE walls

This paper presents a numerical investigation of the interaction of back-to-back mechanically stabilized earth (MSE) walls under static loading. The numerical model was validated using measurements from instrumented field back-to-back MSE walls. A parametric study was then conducted to investigate the effects of horizontal distance between the MSE walls, soil friction angle, and wall height on the interaction of back-to-back MSE walls. Maximum facing displacement, lateral soil thrust behind reinforced soil zone, and required reinforcement tensile force generally increase nonlinearly with increasing horizontal distance up to a certain critical value, and the effects of interaction between back-to-back MSE walls are stronger for lower friction angle and higher wall. The critical horizontal distances for different soil friction angles and wall heights are generally close to the theoretical Federal Highway Administration (FHWA) values for the full active failure wedge to be developed and could be approximated as 0.5. The FHWA method significantly underestimates the lateral soil thrusts for the range of horizontal distances involving interaction between back-to-back MSE walls but significantly overestimates the required reinforcement tensile strengths. Design recommendations on lateral soil thrust and required reinforcement tensile strength calculations that account for the interaction between back-to-back MSE walls are provided.