滑坡碎屑流冲击刚性挡墙动力响应的数值模拟分析

Numerical simulation of dynamic response of dry granular flow impacting rigid retaining wall

【目的】刚性拦挡结构是一种被用于减弱滑坡碎屑流致灾强度的工程措施。为研究碎屑流运动路径的坡度与碎屑流体积对于碎屑流冲击刚性拦挡结构的动响应的影响,【方法】利用Fish语言开发不同形状的块体簇颗粒,并基于室内滑槽试验结果,开展三维离散元数值模拟研究(PFC^(3D)),探究滑坡冲击动力特性、冲击力、堆积形态与能量演变过程。【结果】能量演化过程和冲击力时程曲线结果显示:在整个滑坡过程中,摩擦耗能占总能量消耗的约80%;对于坡度为35°、40°、45°(H=15 cm)的碎屑流,峰值冲击力与残余堆积力的比值随着坡度的增大而不断增大(1.064,1.380,1.538)。【结论】模拟结果表明:块体(clump)簇颗粒能够较好地被用于模拟颗粒的形状作用,为碎屑流冲击动力学的离散元模拟提供一定的参考;摩擦耗能是碎屑流发生时主要的能量耗散形式;坡度的增大会加快滑坡滑动进程,增大峰值动能,形成更大的峰值冲击力与残余堆积力;碎屑流体积的增大会增加坡度对于碎屑流运动能力的影响,使得堆积体在坡体与拦挡结构上的长度显著增加。

[Objective]Rigid barrier structures are an engineering measure used to reduce the disaster intensity of landslide dry debris flows.In order to investigate the dynamic response of dry debris flow impact on rigid barrier structures under different inclination angles of flow path and volumes of dry debris flow,[Methods]this study developed clump particles using the Fish language and conducted a three-dimensional discrete element numerical simulation study(PFC^(3D))based on indoor flume test result to explore the dynamic characteristics of landslide impact,impact force,accumulation morphology,and energy evolution process.[Results]The energy evolution process and impact force-time curve result show that throughout the entire landslide process,frictional energy accounts for approximately 80%of the total energy consumption;for slope angles of 35°,40°,45°(H=15 cm),the ratio of peak impact force to accumulation force increases(1.064,1.380,1.538)with the increase of slope angle.[Conclusion]The simulation result indicate that clump-shaped particles can effectively simulate the shape effect of particles,providing a reference for the discrete element simulation of dry debris flow impact dynamics.Frictional energy dissipation is the main form of energy consumption,when dry debris flow occurs,Increasing slope angle accelerates the landslide sliding process,increases peak kinetic energy,and forms larger peak impact force and accumulation force;increasing the volume of dry debris flow increases the effect of slope angle on the movement capability of dry debris flow,Resulting in a significant increase in the length of accumulation on the slope and barrier structure.