Evaluating the Necessity of Sliding Mechanisms in Trapezoidal MSE Wall Design

To optimise constructability and achieve a cost-effective solution, in the design case of this paper, traditional rectangular Mechanically Stabilised Earth (MSE) reinforcement lengths, which require vertical excavation into the existing abutment slope, were replaced with trapezoidal-shaped reinforcement lengths. However, the design methodology for trapezoidal MSE retaining structures located in front of slopes or walls lacks clarity. Specifically, it remains uncertain whether sliding mechanisms should be incorporated into the design of trapezoidal MSW walls. In this paper, a case study was conducted using the finite element method to investigate the lateral earth pressure exerted on trapezoidal walls. The inquiry into the necessity of the sliding mechanism in a trapezoidal MSW has been analysed. Design charts for the sliding mechanism were developed for specific conditions to assist geotechnical designers in making preliminary assessments regarding the necessity of sliding mechanisms for a given design scenario. Based on the thorough analysis conducted on Trapezoidal MSE walls, it is established that the consideration of the sliding mechanism may not be universally necessary in the design approach. In the meantime, a composite trapezoidal MSE-embankment system was designed and implemented to support the embankment widening project at a Highway Bridge. The successful application of this wall is substantiated by stability observations and monitoring conducted during and after construction.