Limit Analysis Optimization of Design Factors for Mechanically Stabilized Earth Wall-Supported Footings

Abstract

Increasingly in the past few decades, mechanically stabilized earth (MSE) walls have been a common choice for earth retention solutions due to their ease of construction, cost-effective design, and flexibility. However, limit state capacity of footings atop a MSE structure, such as a bridge abutment, is a complex and non-intuitive stability problem dependent on factors like reinforcement layout and strength, location of footing, and failure mechanism. In order to evaluate the effects of these factors, a parametric study was performed utilizing a robust tool in the framework of limit analysis of plasticity. It demonstrates the effect of the parameters on bearing capacity and optimized reinforcement efficiency, all in context of an existing MSE wall-supported bridge abutment. It is shown that closely spaced reinforcement layouts allow for more efficient reinforcement behavior and improved bearing capacity nearer to the wall facing, while inverse, detrimental trends were observed for wider reinforcement spacing. The implications of this analysis illustrate that an optimized approach involving footing location, reinforcement strength, and reinforcement spacing allow for reduced bridge deck length requirements. This clearly has economic consequences. The optimization of these design factors is especially applicable to MSE wall-supported bridge abutments since the location of the footing affects expensive elements such as length of girders. Fundamentally, this work adds to the limited existing knowledge of bearing capacity of footings on top of MSE walls.