论崩塌滑坡—碎屑流高速远程问题

Research on High Speed and Long-Distance of the Avalanches or Landslide——Debris Streams

高速远程崩塌滑坡—碎屑流具有规模大、速度快、滑程远、多态化、常转向、冲程多、冲击性和摧毁性等特征。崩塌或滑坡高速远程实质上是其解体后的碎屑流运动形式。碎屑流高速远程与崩塌滑坡规模、物质成分结构、地形高差、沟道形态和引发因素及运动路经的环境等因素密切相关。崩塌滑坡变形破坏形式一般显示为蠕动—拉裂—剪断—滑移—冲出—解体—碎屑流化的过程。崩塌滑坡形成机理主要基于残余强度、蠕变作用和孔隙水压力等理论认识进行解释。碎屑流运动机理主要立足于势能动能转化传递、气体浮托和颗粒流运动理论予以解释。动势能转化、气体浮托作用和颗粒流运动三种解释是层次不同、相互补充的关系,不是彼此独立的。基于成年人在复杂地形下能够奔跑逃生,崩塌滑坡—碎屑流前锋的运动速度5m/s作为高速运动的下限值是比较合理的。崩塌滑坡—碎屑流区域的前后缘高差(H)与前后缘水平距离(L)的比值小于0.4或L/H值大于2.5可作为其远程运动的判据。崩塌滑坡—碎屑流成灾模式包括直接压覆、解体推挤、碰撞冲击、气浪吹袭、激流涌浪、堰塞湖淹没与滑坡坝溃决—洪水泥石流等多种形式。

Objectives： Some avalanches or landslide—debris streams are of many characteristics, such as large volume, high speed, long distance of movement, polymorphic existing, changes in direction, many motion stages, impact force and mega destroying energy. In fact, the high speed and long distance of the movement occur primarily in the stage of debris streams after rock or soil mass broken up. Methods： The rapid and long distance of the movement are related with the scale, component and structure of substance, difference of landform in elevation, valley features, induced factors and environmental condition which passed by avalanches or landslide. The deforming and breaking down types of rock or soil mass slopes are often being a chain of action process which includes creeping, fissuring, shearing off, sliding, rushing out, breaking up and eventually to be debris stream. Mechanism of the avalanches or landslide can be explained through the existing theories such as residual strength of soil or rock mass, creep action principle and effective stress or porous water press effect. At present, mechanism of the debris stream is complex that it is interpreted through transformation of potential to kinetic energy, buoyant force of gaseous fluid and motion of pellet flow. The understanding from actual examples of avalanches or landslide—debris stream is, the above three recognitions are not independent each other, but different gradation from macroscopic view to microcosmic grain action and mutual complementary in different measurements. Results： Author suggests that the value of the speed of avalanches or landslide—debris stream vanguard is arriving 5m/s to be as lower limit of rapid movement based on the adult to flee for one’s life. The ratio of H/L is less than 0.4 can be as criterion of long distance of avalanches or landslide—debris stream in which H is difference of landform in elevation and L is horizontal distance from beginning to end of the motion. Basic disaster models of the avalanches or landslide—debris stream include direct pushing down, breaking up destruction, colliding and pounding, air wave blowing, turbulent current and tornado, blocking dam to be lake and bursting floods, etc.