Behavior of Two-Tiered MSE Walls Under Static and Seismic Loading

This paper presents a study on the behavior of two-tiered Mechanically Stabilized Earth walls (MSEW) with varying offset distances under static and seismic loading. From the literature, it is observed that the interaction mechanism between the two tiers and the behavior of tiered retaining walls under static and seismic loading are not addressed adequately. A validated numerical model of a two-tiered wall of individual heights of lower and upper tiers (H₁ and H₂) of 5 m each was analyzed using the finite element software, PLAXIS 2D V20, and the performance was studied by varying offsets from 0 to 2.2H₁ where H₁ is the height of the lower tier. The first ten seconds of the Kobe earthquake with a Peak Ground Acceleration (PGA) of 0.29 g was considered for the seismic analysis. The interaction mechanism is responsible for higher values of lateral stresses, lateral displacements, settlements, and reinforcement forces in the bottom 1/3rd of the upper tier and upper half of the lower tier. The critical offsets predicted in the study are less than those given by the current design guidelines, such as National Concrete Masonry Association (NCMA) and Federal Highway Administration (FHWA). This study recommends an offset between 0.4 and 1.2H₁ by considering economy and space constraints.