复杂三维地形条件下滑坡–碎屑流运动与堆积特征物理模拟实验研究

Experimental study on the propagation and deposit features of rock avalanche along 3D complex topography

为定量化揭示真实复杂三维地形条件对滑坡–碎屑流运动与堆积特征的影响,基于谢家店子滑坡真实三维地形空间分布形态,设计并建立滑坡–碎屑流三维物理模型实验装置,开展相关物理模拟实验研究,获取复杂三维地形条件下,滑坡–碎屑流运动与堆积特征的图像和定量化数据,并依此观察和分析其流态化运动与堆积特征。主要得出以下结论:(1)滑坡运动路径上沟谷转折段等复杂地形的展布,可引起碎屑流动能的快速耗散,运动速度陡降,从而减小碎屑流的运动距离;(2)碎屑流运动过程中,颗粒之间的动量传递作用,可明显促进碎屑流的远程运动;(3)运动路径上沟谷两侧缓坡平台的展布,可导致碎屑流的"分流–汇流"运动,并最终在碎屑流表面形成纵向沟状槽;(4)当碎屑流流动至运动路径的开阔地段时,碎屑流进入一种以碰撞为主的无侧限扩离运动状态,在粒间碰撞–推挤力、重力和地形的共同作用下,形成"X"型共轭堆积脊。

To study the propagation behaviours of rock avalanche along 3D complex topography quantitatively, a 3D analogue model was built based on the true topography of the Xiejiadianzi rock avalanche. A series of experimental tests were conducted to document the propagation and deposit features of rock avalanche under the effect of 3D complex topography. Along the travelling path, the layout of complex terrains such as the twisted spots generated the rapid dissipation of the kinetic energy of rock avalanche, and reduced the travel distance finally. In the motion of rock avalanche, the existence of momentum transfer among particles played an important role in the long runout of the debris. The extension of small ramps along the both sides of the traveling path induced the shunting-converging movement of the debris, with longitudinal groove-like troughs formed finally. When the debris reached the open area of the travelling path, it transferred into an unconfined spreading movement with particle collisions occurred frequently. Under the co-work of the pushing force, gravity and topography, squeezing effect occurred in the motion of particles with stress ridges generated.