中文摘要：

以成都至兰州铁路某隧道洞口落石防护工程为背景,提出采用聚苯乙烯泡沫（EPS）轻质混合土代替砂垫层作为明洞回填材料。为研究EPS轻质土的耗能减振效果,采用动力有限元方法对落石冲击过程进行数值模拟。结果表明：与传统的砂垫层相比,EPS轻质土能够有效减少明洞上方填土压力,显著降低落石冲击力和衬砌动应力;采用较小的垫层厚度即可取得很好的消能效果,是一种优良的落石防护垫层材料。

英文摘要：

Taking a tunnel entrance rockfall protection project of Chengdu--Lanzhou railway as background, expanded polystyrene （EPS） fight-weight mixed soil is presented to be used as the backfill material instead of sand cushion for open cut tunnel. In order to study the energy dissipation and vibration damping effects of EPS light-weight soil, the rockfall impact process is simulated by using dynamic FEM method. The research result shows that （1） compared with traditional sand cushion, EPS light-weight soil could effectively reduce earth pressure on top of open cut tunnel, and significantly decrease rockfall impact force and dynamic stress of lining caused by the impact; （2） a smaller cushion thickness of EPS light-weight soil could achieve very good energy dissipation effect; （3） IT is an excellent cushion material for rockfall protection.