Study Of The Motion Mechanism And Accumulation Characteristics Of Non-Cohesive Particles Based On Model Experiment And Numerical Simulation

In recent years,influenced by strong earthquakes and extreme meteorological events,landslide-debris flow occurs frequently in China,causing heavy losses of lives and property.The movement mechanism and damage scope of landslide-debris flow have been the focus of domestic and foreign scholars.However,up to now,there is no generally accepted movement mechanism of landslide-debris flow,so the mechanism of movement and accumulation of debris granular remains to be studied.In this paper,the movement and accumulation process of landslide-debris flow under specific conditions are simulated by means of indoor model test and numerical simulation.Firstly,the spherical particle accumulation is selected as the research object,indoor model tests are carried out to explore the influence of the volume and the content of small particles on the movement and accumulation of granular particles,and the movement and accumulation of granular particles are analyzed combined with numerical simulation.The results are as follows:(1)The sliding accumulation of spherical granules has the reverse order phenomenon,which is more obvious with the increase of volume;the spherical granules have obvious lateral expansion phenomenon in the acceleration stage,which is greatly affected by the content of large particle.(2)The distance between the end of the particle accumulation body and the bottom of the slope largely depends on the stopping distance of the particles arriving at the bottom of the slope first.For the particles arriving at the bottom of the slope later,some of the large particles can jump over the small particles previously stopped and move forward,stopping in front or above the small particles,while the small particles are more blocked at the end of the accumulation.(3)The particle distribution at the end of accumulated body is mainly influenced by volume;the stopping distance of the front-end particles is seldom affected by volume and particle grading.At the same time,the square particle accumulation is selected as the research object,and the trajectories of the particles in different positions on the initial accumulation are analyzed.The accumulation distribution of the particles under different working conditions is simulated and analyzed briefly.The results show that:(1)The movement modes of particles in different positions are different in square particle accumulation.The particles in the upper part are mainly jumping and rolling.The main movement modes of intermediate particles are sliding,accompanied by a little rolling of particles,while the lower particles are mostly sliding on the slide surface.(2)The movement mode of particles is not fixed,and the movement mode of particles alternates with each other in the course of movement.(3)In the acceleration stage,the particles at the edge of the front row stop expanding horizontally and keep the vertical foot line moving downward after the maximum lateral expansion is reached,while the particles at the back edge keep expanding horizontally until the bottom of the slope.Based on the model tests and numerical simulations,the motion process of non-cohesive granular particles during start-up and acceleration process and the influence of different factors on the accumulation distribution are analyzed.The results can be used as a reference for the further study on the movement and accumulation of landslide-debris flow.