Experimental study of shaking table for reinforced soil retaining walls: Analysis of tiered configuration effects

Deciding on the inclusion of tiers and determining the optimal number of tiers are critical considerations in the design of reinforced soil retaining walls (RSRWs). In this study, the mechanical properties of RSRWs under seismic loading are discussed in depth, with special attention paid to the influence of tiered configuration effects on the seismic performance of RSRWs. The response characteristics of these structures under seismic loading were comparatively analyzed by conducting shaking table tests of single-tiered, two-tiered, and three-tiered modular geogrid RSRWs. The results show that localized modular misalignment mainly occurs at the top of the retaining walls of all tiers, and reasonable tiered design can enhance the stability, but too many tiers may instead reduce the structural stability. The tiered reinforced soil retaining walls (TRSRWs) exhibit higher natural frequencies and damping ratios, which increase with more tiers, and the natural frequencies and damping ratios of the upper-tiered walls are always higher than those of the lower-tiered walls. The acceleration amplification effect is more significant in the upper part of the retaining wall structure, and the tiered design can reduce the acceleration amplification effect to a certain extent, but the increase in the number of tiers does not have much effect on this. The horizontal displacement of the TRSRWs shows the distribution of “upper large and lower small”, and the two-tiered retaining wall effectively reduces the horizontal displacement of the wall facing, whereas the three-tiered retaining wall does not have a significant improvement effect. The tiered design significantly optimizes the settlement of the retaining walls, and the number of tiers has little effect on the settlement improvement. The seismic active soil pressure increased with the peak ground acceleration and loading frequency, and the tiered design changed its distribution, and the increase in the number of tiers helped to further reduce the soil pressure. The increment of reinforcement strain in TRSRWs was lower than that in single-tiered retaining walls, and the tiered design effectively reduced the reinforcement stress, but the number of tiers had a limited effect on the improvement of this effect. The upper part of the wall in the un-tiered design is prone to overall tilt and horizontal expansion, and the deformation of the upper-tiered walls of the TRSRWs is all in a composite deformation mode, while the lowest-tiered walls are in a single deformation mode. The tiered design has a positive effect in limiting the development of potential failure surfaces in the substructure, resulting in improved stability of the substructure. The results of the study can provide a reference for the design selection of RSRWs.