Numerical analysis on the flying of highspeed and long runout landslide

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.