Dynamic evaluation of tiered geogrid mechanically stabilized earth (MSE) walls using shake table test

Shaking table tests were performed on reduced-scale models of integrated and two-tiered mechanically stabilized earth walls (TMSEWs) to evaluate the effect of a tiered configuration on the dynamic behavior of geogrid-reinforced soil walls. The results of particle image velocimetry and instrumentation indicate 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. It was found that the use of an insufficient offset distance in TMSEWs not only eliminated the advantage of the tiered configuration for reducing wall deformations, but also increased the lateral displacement at the wall crest. In this regard, 0.22H was identified as the minimum offset distance required when constructing MSE walls in a tiered configuration. Moreover, comparison of integrated and tiered MSE walls showed that the effect of a tiered configuration on reducing the force of the reinforcements in the lower tier was approximately 2.2 times that for the upper tier reinforcements. It was also found that Mononobe-Okabe method can be used to find the upper bound for estimating the load of reinforcements in TMSEWs.