Numerical Simulation Study Of Avalanche Formation And Release Mechanics Based On Discrete Element Method

With the increasing global climate change,various natural disasters have been occurring frequently recently,especially in the snow-covered highland mountains,the probability of avalanches is growing exponentially,and it is urgent to establish an avalanche disaster warning mechanism.Among them,dry snow slab avalanche is one of the main forms of avalanche occurrence,and is also the most common type of avalanche.Dry snow slab avalanche refers to the process of releasing the snow layer with low humidity along the slope under the action of internal and external forces,which divides the snow layer into the upper layer with high cohesion and the lower layer with poor mechanical properties of the weak layer,both of which are deposited on the basal surface,and the destruction of weak layer is the direct cause of avalanche occurrence.Snow is regarded as an elastic-brittle material,deformable and its mechanical properties are influenced by environmental factors,and it is important to study the formation and release of avalanches under different snow layer parameters.In this paper,a three-dimensional avalanche dynamics model is developed using the discrete element method,and the spherical particles and viscous units are used to replace the slab layer and the base layer as well as the weak layer bonded to each other,and the crack propagation properties of the weak layer after damage are studied,including the crack propagation velocity,critical crack length,interface fracture characteristics,and the instability of the snow slab layer due to crack propagation,including the collapse instability of the upper slab layer,and the gravity-induced snowboard tension fracture release from slope terrain.The factor of temperature has not been considered in previous studies,but temperature has an important influence on avalanche formation and release by altering the cohesion within the snowpack.Avalanche occurrence is also accompanied by a reciprocal exchange of mass and momentum,enhancing the destructive forces on the surrounding environment.By analyzing the mechanical mechanism of avalanches,we also gain a more comprehensive understanding of the process of avalanche formation and release,and will eventually establish an early warning mechanism for avalanches from a micromechanical perspective and apply the parametric scheme to snow-covered mountainous areas.The damage and crack propagation model of the weak layer at the rock-snow layer interface was developed.As the ambient temperature increases,the mechanical properties of the snow layer change and its cohesive strength improve substantially,increasing the avalanche formation and release conditions compared to the loose snow layer.Weak layer cracks can propagate several meters to several kilometers and induce avalanches remotely.The propagation speed of crack in the weak layer decreases with the increase of cohesive strength,and the critical length of crack increases with the increase of cohesive strength.As the cohesion strength decreases,the tensile fracture of the slab layer that avalanche finally released along the slope.