Numerical Investigations on the Behavior of Back-to-Back Mechanically Stabilized Earth Walls: Effect of Structural Components

Over the years, the behavior of Mechanically Stabilized Earth Walls (MSEWs) has been intensively studied, where several design guidelines are now available. However, for Back-to-Back Mechanically Stabilized Earth Walls (BBMSEWs), widely encountered in road construction projects, a survey of the literature shows that a little attention has been paid to the behavior of this type of walls. The existing design manuals and the few numerical investigations do not provide a clear answer on the seismic response of BBMSEWs. Given their importance in transportation systems, understanding the dynamic behavior of BBMSEWs becomes a necessity. For this purpose, this paper reports results from numerical analysis that was carried out to evaluate the influence of numerous parameters of structural components, such as backfill type, wall facing type, reinforcement stiffness and distance between opposing walls, on the static response and dynamic response of an idealized 6 m high BBMSEW with 12-m width. The length of reinforcement is 4.2 m, so the distance between opposing walls is 3.6 m. In this study, geotechnical Finite Element software PLAXIS 2D was adopted, while wall displacement and tensile load in reinforcement were selected as criteria of stability. Based on the findings, it was shown that using stiffer reinforcement leads to a significant decrease in horizontal wall displacement and involves a less reduction of maximum tensile loads in reinforcement. When flexible reinforcements were used, the type of facing wall should have a significant effect on the BBMSEW behavior. Under self-weight, the theoretical solutions overestimate tensile load in the reinforcements. By decreasing the distance between opposing walls to zero, the reinforcements from both sides would meet in the middle and the magnitude of the displacement has been significantly reduced. In this case, designers might be tempted to use single layers of reinforcement that are connected to both wall facings. In this special arrangement of reinforcement, it was revealed that connecting two opposing walls reduces only the maximum horizontal displacement, while the effect of axial rigidity of reinforcement was found to be negligible.