Study On Kinematic Characteristics Of Lanshibao Rock Avalanche Based On MatDEM

As a special mountain hazard,rock avalanche has always been one of the focus in the field of engineering geology due to its abnormal kinematic characteristics and huge disaster-causing ability.The alpine valley region in western China has strong endogenic and exogenic geological processes,which provides an excellent disaster-preventing environment for rock avalanche and belongs to the high-risk areas of rock avalanche.The Lanshibao rock avalanche developed in the Maoyaba basin of the Tibetan Plateau,China,and its kinematic characteristics and disaster mechanism are representative.Based on the basic theory of particle discrete element method and MatDEM software,the whole process of Lanshibao rock avalanche is simulated in this paper,with emphasis on the analysis of its kinematic characteristics and dynamic response laws in different destabilization modes.The main research results are as follows:(1)The equivalent friction coefficient of the Lanshibao rock avalanche is 0.22,and its excessive travel distance reaches 2500 m,showing a strong long-distance effect.The source volume of the instability of the Lanshibao rock avalanche is 4.3×10~7 m~3,the accumulation volume of Lanshibao rock avalanche is 6.3×10~7m~3,and the expansion coefficient is 1.46.(2)The barycenter motion parameters of the slip mass under different seismic dynamic loads are very close to the simulation results without seismic load.Only the maximum horizontal movement distance of toe of the rock avalanche deposit increases slightly with the increase of the seismic dynamic load intensity.In all cases,the velocity field of the slip mass is distributed in an inclined layer parallel to the motion path,which reveals that the slip mass has a strong internal shearing effect during the high-speed sliding stage.(3)The horizontal displacement,vertical displacement and average velocity of the mass center of the slip mass have a strong positive correlation with the friction coefficient of the particle,but the movement time of the landslide is basically not affected by the friction coefficient of the particle.When the friction coefficient of the particle is 0.4 times the original friction coefficient of the particle,the simulation result of the Lanshibao rock avalanche is most consistent with the actual situation,and the peak value of the average speed of the slip mass is 33.2 m/s.(4)The landslide has a stratification retention phenomenon.When the particle friction coefficient decreases,the stratification retention phenomenon gradually weakens,and the particle mixing degree between the layers gradually increases.There is severe erosion and entrainment effect between the slip mass and the underlying layer on the moving path,and the intensity of erosion and entrainment effect is significantly attenuated with the increase of the depth and horizontal distance of the underlying layer.The frictional energy consumption of landslides is not only concentrated on the sliding zone.The middle and lower parts of the slip mass are high frictional energy consumption areas.The frictional energy consumption of particles inside the slip mass accounts for an important part of the frictional energy consumption of the entire slip mass.The topography condition controls the frictional energy consumption of the landslide.The highest area of frictional energy consumption of the slip mass is located in the abrupt change of terrain from the slope to the basin,and it is also the place with the strongest erosion and entrainment effect of the landslide...