高速远程滑坡飞行数值分析

Numerical analysis on the flying of highspeed and long runout landslide

许多大型高速远程滑坡在近程活动阶段呈现凌空飞行运动,其飞行过程必须考虑空气动力学效应和地面效应,但是直接求解高速滑体凌空飞行运动的偏微分方程是困难的。因此,以往的研究只给出了定性分析或粗略的计算结果。本文将以头寨沟滑坡为例,使用数值模拟方法研究高速滑体凌空飞行的运动规律。结果表明,高速滑体凌空飞行时空气动力效应更多地表现为对滑体的抬升作用;高速滑体因空气动力效应的影响而产生不断增大的水平推力和竖向抬升力,使得水平加速度不断增大,竖向加速度不断减小,导致滑体的水平速度不断增大,而竖向速度则趋于稳定值,当水平速度远超过竖向速度时,滑体的飞行姿态将接近于平行于地面。因此,与不考虑空气动力学效应的情况相比,高速滑体凌空飞行时间更长,飞行距离更远,更加符合滑坡的实际情况。

Many large highspeed and long runout landslides could fly in the air at the short-range stage. It is necessary to consider the areodynamics effect and ground effect at the short-range stage of landslide where it starts to fly. However, it is difficult to solve the differential equation with analytical solutions. So the previous study only gave the qualitative analysis or some simple results. Taking example for the Touzhai landslide of Zhaotong County of Yunnan Province in China, this paper applied the numerical analysis method to study the flying rules of highspeed sliding mass. The calculated results illustrate that the aerodynamics effect mostly behaves as the lifting action to the sliding mass, and the horizontal thrust force and vertical lift force are increased resulting in the horizontal acceleration increasing and the vertical acceleration decreasing. The horizontal speed is increased while the vertical speed tending to remain stable. The flying pose of the sliding mass is almost horizontal when the horizontal speed is far greater than the vertical speed. Therefore, the flying time is longer and the distance is farther than those without the consideration of aerodynamics effect. The result is more reasonable by the comparison with the field observation.