1 g Shaking table model tests on seismic active earth pressure acting on retaining wall with cohesive backfill soil

The effects of backfill cohesion on the seismic behavior of a retaining wall are discussed on the basis of a series of 1 g shaking table model tests. The model test results show that a retaining wall having cohesive backfill soil is more stable than a wall without it. The following aspects are observed in the cases of cohesive backfill soil from a detailed analysis using the measured seismic active earth pressure acting on the retaining wall: 1) the existence of a stable region at the top part of the backfill soil, 2) the increase in shear force acting on the boundary between the back face of the wall and the backfill soil, and 3) the mobilization of cohesion along the failure plane in the backfill soil. The existence of a stable region results in reductions in both the driving force and the overturning moment, while it tends to disappear under a high seismic load. The increase in shear force acting on the back face of the wall contributes to an increase in the resistant moment against the overturning of the wall with respect to the base of the footing, and it mobilizes even under a high seismic load. Mobilized cohesion along the failure plane contributes to the support of the soil wedge, resulting in a decrease in the seismic active earth pressure. It also continuously mobilizes even under a high seismic load. These observations indicate that giving consideration to the backfill cohesion when calculating the seismic active earth pressure leads to the rationalization of the evaluation of the seismic performance of the retaining wall even though further study is required, namely, carrying out the validation in the prototype scale and setting the applicable conditions for the seismic design.