Effect of a two-tiered configuration on the seismic behaviour of reinforced soil walls

Abstract

Shaking table tests were performed on reduced-scale models of integrated and two-tiered mechanically stabilised earth (MSE) walls to evaluate the effect of a tiered configuration on the seismic behaviour of metal-strip and geogrid reinforced soil walls. The results showed that, although inextensible reinforcements could reduce the fundamental period, acceleration amplification and lateral deflection and improve wall stability, these benefits declined with the use of a tiered configuration and gradually faded with an increase in the offset distance. This made changing the degree of extensibility a low-impact factor in two-tiered MSE walls with a sufficiently large offset distance (D > (0.4–0.5)H). In order to benefit from the advantage of a tiered configuration, it was found that 0.22H should be considered as the minimum offset distance. The findings indicated that preventing the development of a slip surface in the lower half of the wall, improving the seismic stability by increasing the failure threshold acceleration, mitigating acceleration amplification and decreasing the reinforcement load were the main advantages of a tiered configuration. Moreover, it was concluded that the Mononobe–Okabe method could be used to find the upper bound for estimating the reinforcement forces in two-tiered MSE walls.