滑坡-碎屑流冲击导引结构的离散元模拟

滑坡碎屑流对拦挡结构的直接冲击常产生较高的峰值冲击力和冲击能量,导致结构发生破坏而失效;而导引结构通过改变碎屑流的运动路径,可减缓其冲击效应,提高结构抗冲击能力。文章运用三维离散元模拟软件,结合室内休止角试验的结果,校准数值模拟参数,以三种不同导引结构(凹型圆弧、直线型、凸型圆弧)为变量进行数值模拟分析。研究结果表明:凹型圆弧结构B1可以有效地将碎屑流颗粒的冲击力进行转化,结构所受的法向力最小,切向力最大,对颗粒的导引作用最大。经过三种不同导引结构后,颗粒与滑槽之间的碰撞和摩擦是导致颗粒动能减小的主要原因;而三种不同导引结构对颗粒动能的耗散效果无显著差异。导引结构的作用对于颗粒堆积体积分布有显著的影响,主要影响区是靠近坡脚处,对导引结构之后的堆积区域的颗粒体积分布影响不显著。通过对冲击效应和堆积特性的研究,得到凹型圆弧结构形式最优,可以为碎屑流的防护工程抗冲击设计提供参考。

Discrete element simulation of the landslide-debris flow impact guiding structure

The direct impact of the landslide debris flow on the resistive structure often produces higher peak impact and impact energy is often generated, which may result in easy failure and losing effectiveness. However, the guiding structure can slow down the impact effect and improve the structural impact resistance by changing the path of motion of the debris flows. Therefore, we used 3-D discrete element simulation software, whose parameters are calibrated by comparing the results of the rest angle of repose test and the numerical simulations. Numerical simulation analysis was studied with three different guiding structures (concave arc, straight line, convex arc) as variables. The results indicate that the impact force of debris flow is effectively transformed by concave circular arc structure B1, in which the structure receives the least normal force and the largest tangential force. The guiding effect of the concave circular arc structure B1 is the most obvious. After three different guiding structures, the collision and friction between the particles and the chute are the main reasons for the decrease in the kinetic energy of the particles, and the effect of the three different guiding structures on the dynamic energy dissipation of the particles is not significant. The guiding structure has a significant effect on the particle volume distribution. The main affected area is near the foot of the slope, and the accumulation area after the guiding structure and the particle volume distribution are not significant. The study of the impact effect and the accumulation characteristics shows that the concave arc structure is optimal, and can provide the reference for the design of shock resistance engineering protection of debris flow.