Abstract: Setting a flexible cushion behind the rigid retaining wall can increase the actual lateral displacement of the backfill and effectively reduce the earth pressure acting on the wall. A self-made model box was used to conduct laboratory tests to simulate the working conditions of the retaining wall with EPS cushion behind the wall in the static state and the translation mode, and to explore the distribution of the static earth pressure and active earth pressure of the retaining wall under different backfill widths, and to study the influence of EPS cushion parameters on its decompression performance. By defining the decompression efficiency of the EPS cushion, the decompression performance of the EPS cushion behind the retaining wall was quantitatively analyzed. The results show that under limited backfill conditions, there is a gap between the maximum decompression efficiency of the EPS cushion and the equivalent decompression efficiency of the active earth pressure. However, under this circumstance, parameters of the EPS cushion have little effect on the decompression efficiency. As the backfill width gradually increases to the semi-infinite soil range, the maximum decompression efficiency of the EPS cushion gradually increases and then keeps stable at the equivalent decompression efficiency of active earth pressure.

Key words: earth pressure, retaining wall, EPS cushion, model test, limited backfill width