基于SPH-DEM的泥石流冲击刚性防护结构的动力过程研究

Research on the dynamic process of debris flow impacting rigidbarrier based on SPH-DEM

泥石流为含有大量泥沙与石块的固液两相混合物,对于山区基础设施安全威胁巨大。在当前的防灾工程中,防护结构常被用于拦截泥石流。然而,目前对泥石流与防护结构的相互作用机理仍缺乏认识。为此,采用耦合的光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)和离散单元法(discrete element method,DEM)数值模型模拟了水槽试验中含有石块的泥石流运动,其中SPH模拟泥石流中的黏性流体,DEM模拟泥石流中的石块,分析了泥石流对刚性防护结构的冲击过程及冲击力。模拟结果表明,随着水槽倾角由0°依次增长为8°、15°、24°、30°,峰值冲击力增长倍数依次为2.59、4.75、8.88、11.45,倾角越大其峰值冲击力的增长率越大;而随着流体体积的增大,其峰值冲击力增长率也逐渐变大,相较V=0.024 m 3分别增长了0.79倍、1.64倍、3.20倍和4.56倍,但是稳定下来的静态冲击力基本与体积的变化成正比,而石块粒径对峰值水面高程的影响更显著。研究成果为泥石流防护结构的强度设计提供了理论支撑。

Debris flows are solid-liquid two-phase mixtures containing large amounts of debris and rocks,which pose a great threat to the safety of mountainous infrastructure.Rigid barriers are often used to intercept debris flows in current disaster prevention engineerings.However,the interaction mechanism between debris flow and rigid barrier is still poorly understood.Therefore,the coupled smooth particle hydrodynamics(SPH)and discrete element method(DEM)numerical models are used to simulate the movement of debris flow containing rocks in the flume experiments,where SPH simulates the viscous fluid in debris flow and DEM simulates rocks in debris flow,and the impact process and impact force of the debris flow on the rigid barriers are analyzed.Simulation results show that as the inclination of the flume from 0°to 8°,15°,24°,30°,the peak impact force growth multiplier is 2.59,4.75,8.88,11.45,the larger the inclination angle,the greater the growth rate of the peak impact force.As the fluid volume increases,the growth rate of its peak impact force becomes gradually larger,compared to V=0.024 m 3 respectively,0.79 times,1.64 times,3.20 times and 4.56 times,but the stabilized static impact force is basically proportional to the change in volume,while the effect of rock size on the peak water surface elevation is more significant.The research results provide theoretical support for the strength design of debris flow barriers.