挡墙后铺设柔性垫层或回填轻量土，对其优化设计和降低成本有着重要的工程意义。通过开展不同级别荷载下的挡土墙物理模型试验，分析墙后铺设EPS柔性垫层、回填泡沫轻量土及二者同时施加时的墙后土压力大小及分布特征，并探讨相应的减载效应。结果表明：挡土墙铺设柔性垫层、回填轻量土或二者同时施加时，墙后土压力均随埋深呈先增大后减小的“鼓肚”状非线性特征，土压力最大值多出现在1/2墙高处；同等荷载作用下，仅回填轻量土的减载效果相对较弱，减载率为10%~25%，而铺设柔性垫层的最大减载率较之提高了1.5倍，当二者同时施加时，减载效果最佳，最大减载率相应提高了近3倍；柔性垫层减载效果随着厚度的增加逐渐降低，但泡沫掺量对墙后回填轻量土的减载率影响更为敏感。工程中可考虑采用中等厚度的垫层，若墙后填土附加荷载较大，可适当提高回填泡沫轻量土的掺量。

Laying a flexible cushion or backfilling lightweight soil behind the retaining wall has important engineering significance for its optimized design and cost reduction. By carrying out model tests of retaining walls under different level of loads, the magnitude and distribution characteristics of the lateral earth pressure when laying EPS flexible cushion, backfilling lightweight soil and applying it simultaneously are analyzed, and the load-reducing effect is discussed. The result shows: when the retaining wall is paved with flexible cushion, backfilled with lightweight soil, or both applied, the lateral earth pressure exhibits a “bulging” nonlinear feature that increases first and then decreases with the burial depth, and the maximum value of earth pressure generally appears at half of the wall height; under the same loading, the load-reducing effect of backfilling lightweight soil is relatively weak, achieving a reduction rate of 10%-25%, the maximum load-reducing rate of laying a flexible cushion is increased by 1.5 times compared with lightweight soil, when both are applied, the load-reducing effect is the most significant, and the maximum load-reducing rate is increased by nearly 3 times; the load-reducing effect of the flexible cushion decreases with the variation of thickness, the foam content is more sensitive to the load-reducing rate of the backfill lightweight soil. In the engineering project, a medium-thickness cushion is an optimal choice, if the applied load of the backfill is large, the content of the backfill lightweight soil can be appropriately increased.

TU432

湖北省自然科学基金创新群体项目（2020CFA049）；湖北省交通运输厅科研项目（2022-11-6-4）