碎屑流冲击棚洞的最大冲击力影响因素研究

棚洞是山区用于保护交通路线免受碎屑流冲击破坏的一种常见防护结构。为了研究碎屑流对棚洞最大冲击力的影响,建立了碎屑流冲击拦挡结构的DEM-FEM耦合数值模型,研究了碎屑流的整个冲击过程,分析了最大冲击力与碎屑流密度、冲击高度、坡度之间的关系,并与室内模型试验结果进行了对比,表明该耦合方法可行。研究结果表明:①耦合模型再现了碎屑流启动加速、冲击、堆积的三阶段过程,摩擦耗能是整个冲击过程中最主要的耗能方式;②最大冲击力与碎屑流密度、冲击高度和坡度依次呈线性、幂函数(指数小于1)和幂函数(指数大于1)正相关;③碎屑流的密度、冲击高度、坡度对最大冲击力的敏感度值分别为1.0,0.63和2.68,在棚洞设计时应优先考虑敏感度值大的影响参数。

Influential factors of the maximum impact force of rock avalanche flow on a shed tunnel

Shed tunnels are often used to protect mountain traffic routes from the impact of rock avalanche flow caused by landslides or collapses.In order to study the influential factors of the maximum impact force of rock avalanche flow on a rock shed tunnel, a coupled numerical model of a barrier structure impacted by rock avalanche flow was established based on the coupled DEM-FEM method.The effectiveness of the coupled method was verified by comparing with test results.The entire impact process was studied, and the relationships between the maximum impact force and the bulk density of rock avalanche flow, the impact height of rock avalanche flow and the slope angle were analyzed respectively.The results show that the coupled model vividly reproduces the three stages of rock avalanche flow, i.e., the initiation acceleration, impact and accumulation stage.Friction energy dissipation is the most important energy dissipation mode in the whole impact process.The maximum impact force increases linearly with the bulk density.The maximum impact force increases in the form of a power function with a power index less than 1 as the impact height increases, and increases in the form of a power function with a power index great than 1 as the slop angle increases.The sensitivity values of the bulk density, impact height, and slope angle of the rock avalanche flow to the maximum impact force are 1.0, 0.63, and 2.68, respectively.The parameters with high sensitivity should be given priority in the design of shed tunnels.