滑坡-碎屑流物理模型试验及运动机制探讨

Physical modeling and movement mechanism of landslide-debris avalanches

滑坡-碎屑流由于高速、远程的特点常常引发灾难性事故,其复杂的运动机制导致预测致灾范围非常困难。通过开展室内模型试验,研究了碎屑粒径、滑床糙率和挑坎对运动特性的影响。试验结果发现,滑坡碎屑运动距离受控于前端碎屑,且随着碎屑的粒径增大而增加,增加滑床糙率、挑坎均可使碎屑的运动距离减小。在前人研究成果的基础上结合碎屑材料的力学特性探讨了滑坡-碎屑流出现流态化的原因和高速远程机制,即高速运动中颗粒间的作用力远小于完整岩体,因此颗粒间的"黏聚力"不能维持滑坡体的整体性,同时致使滑坡体与滑床接触的过程中传递至滑坡体内部的摩阻力减少,从而导致碎屑滑坡的远程结果。

Landslide-debris avalanches always cause disastrous catastrophes because their high speed and long runout. Their complex movement mechanisms make the prediction of runout very difficult. Laboratory experiments are used to investigate some factors influencing the movement of rock fragments, including size of fragments, bed roughness and scrap. Flume tests show that the runout of rock fragments is decided by front part and increased with the increasing size of rock fragments. The runout becomes smaller when the bed roughness increasing or scrap is added. The movement mechanism of landslide-debris avalanche is also discussed based the physical properties of granular material and previous studies: the force between particles is much smaller than intact rock in high speed, so the 'cohesion' of particles can not ensure the landslide maintain an fixed shape, and the friction reduces when transferred by the particles at bottom, making the result of long run out.