53 / 2025-07-29 12:40:27

Granular flow impact on shed tunnels and the buffering effect of cushion layers: Insights from model tests and EDEM simulations

granular flow; shed tunnel; impact dynamics; buffer layer; physical model testing; EDEM

Granular flows rank among the most devastating geological hazards in mountainous areas, exerting severe threats to transportation infrastructure and human safety ^[1]. Shed tunnels have emerged as a widely employed key engineering measure for mitigating granular flow risks along mountain roads. Consequently, investigating the impact mechanisms of granular flows on shed tunnels holds significant implications for disaster prevention and mitigation efforts. This study integrates physical model experiments with discrete element method (EDEM) simulations to examine how buffer layers influence the dynamic characteristics of granular flow impacts on shed tunnels. Special emphasis is placed on analyzing the force-reducing effects of buffer layers with varying thicknesses on the structural components of shed tunnels, particularly the frontal and top regions. The findings demonstrate good consistency between the physical model experiments and numerical simulations, leading to the following conclusions: 1) Increasing the buffer layer thickness effectively dissipates impact energy and markedly reduces the peak impact force on the frontal structure of shed tunnels. A significant reduction in the maximum impact force is observed when the buffer layer thickness increases from 0 mm to 200 mm. 2) The protective effect of the buffer layer on the tunnel top is directly linked to its thickness and full coverage of the top surface. Only when the buffer layer is sufficiently thick to fully cover the tunnel top does its impact force reduction effect on the top become particularly pronounced.