云南头寨滑坡全程流体动力学机理分析

云南昭通头寨沟于1991年9月23日突然发生大型高速滑坡,总方量约1 800×104 m3的滑体高速下滑,在2～3 min的时间内冲入盘河.文中用流体动力学理论分析了头寨滑坡全程各个活动阶段的动力学机理,并得出了几点结论.启程阶段由于孔隙水压力及水汽垫层的共同作用,使作用在滑动面上的有效应力显著降低,从而导致滑带土抗剪强度减小;近程阶段高速飞行的滑坡体会产生机翼效应,使滑体势能更多地转化为动能,高速滑体可越过小山包且凌空飞行时间更长,飞行距离更远;远程阶段高速运动的碎屑体与周围空气之间产生复杂的空气动力学现象.产生的高速运动的垂直向上的气流和旋转向前的高速涡流的共同作用是碎屑流高速远程运动的根本原因.

Whole Course Analysis on Hydrokinetics Mechanism of Touzhai Gully Landslide

A giant high speed landslide occurred in the Touzhai Gully of Yunnan province on September 23rd,1991.From the points of view of hydrokinetics,this paper presents an analysis of the mechanism of high speed and long run out all over the course and several conclusions are drawn.In the set out stage,the coupling of pore water pressure and vapor pressure resulted in substantial reduction of the effective normal pressure at the slipped surface.In the short range stage,the high speed sliding mass formed the aerofoil like aerodynamics effect.The high perceentage of the potential energy of the sliding mass was transferred into the kinetic energy.Consequently,the sliding mass flew over the small hill on the slope.In the long run out stage,due to the action of air vortex,the sliding mass changed the style of motion from flying to fragment flow,which was similar to the kinematic characteristics of debris flow at high speed.