Numerical study on seismic performance of tiered reinforced soil retaining walls

Tiered reinforced soil retaining walls (TRS-RWs) are increasingly prevalent in mountainous terrains. Although TRS-RWs have been extensively studied in recent years, a large knowledge gap still exists regarding their seismic behavior. This study addresses this gap by investigating the deformation and failure characteristics of TRS-RWs under seismic conditions based on a rigorously validated dynamic numerical model. The dynamic numerical model incorporates a sophisticated cyclic mobility model to replicate the backfill behavior. In addition, more realistic ground conditions were considered by implementing equal-displacement boundaries at both sides and setting a specific thickness of the foundation. On this basis, eight different TRS-RW configurations were established to comparatively analyze the effects of tier-offset, soil compactness, and reinforcement layout on the seismic response of TRS-RWs. The results show that TRS-RWs exhibit good stability under seismic loading. The increase in tier-offset and the optimization of reinforcement layouts significantly enhance the seismic performance of TRS-RWs. For practical engineering applications, it is recommended to adopt the reinforcement layout in Case 45°@RE. Furthermore, it is worth emphasizing that increasing the soil compaction at the end of the reinforced area while meeting the reinforcement length requirements is crucial to ensure the robustness of TRS-RWs under seismic conditions. This research can provide some insights into the seismic design and optimization of TRS-RWs.