Experimental Study on Long-Term Performance of Tiered Geogrid-Reinforced Soil Walls under Sustained Loading

Abstract

In a tiered configuration, a geogrid-reinforced soil (GRS) wall is an acceptable alternative to a traditionally high gravity retaining wall. However, limited studies have been conducted so far to study the long-term performance of tiered GRS walls under working load conditions. In this study, four well-instrumented model tests were carried out to investigate the long-term performance of the two-tiered GRS walls subjected to the sustained loading of 30 kPa. The test results demonstrated that the additional vertical stress at the wall base for the single GRS wall increased over time but generally decreased for the two-tiered GRS walls. Overall, the reinforcement strains increased with the sustained time increasing at the initial loading stage, then decreased to some extent due to wall deformation and stress redistribution, and finally tended to be a slight increase due to the rate-dependent properties of the reinforcement. Moreover, the offset distance has a remarkable effect on the reinforcement layers adjacent to the location of the presence of offset distance. Besides, the lateral wall facing deformations and the settlement at the top surface increased at the initial loading stage and then tended to be relatively stable. A larger offset distance of the adjacent tiers caused a significant reduction in the lateral wall facing deformations and settlements. Finally, a modified analytical method for predicting the lateral wall facing deformation, accounting for the variation of the reinforcement secant stiffness with time, was presented in this study. The predicted lateral wall facing deformations agreed well with the experimentally measured ones in the lower portion of the single-tiered GRS wall and the lower wall of the two-tiered GRS walls.