Coupled CFD-DEM Simulation Of Submarine Landslide Movement Behavior

Submarine landslide is a common disaster geological phenomenon in the ocean.Once it happens,it will destroy the underwater infrastructure,not only seriously affect the progress of ocean development,but even cause great economic loss and casualties.At present,there are few studies on the movement simulation of submarine landslides,especially viscous landslides.In this paper,a fluid-structure coupling model describing the interaction between water and particles is established by using computational fluid dynamics(CFD)and discrete element method(DEM).By introducing the JKR cohesive force model between particles,the viscous properties inside the landslide are described,and then the CFD-DEM coupling analysis method is developed to simulate the movement behavior of the viscous landslides.Several typical examples are verified and analyzed.On this basis,the kinematic characteristics(velocity and distance)and morphological characteristics(length,width,shape,etc.)of the submarine landslides are systematically simulated by considering the viscosity,initial velocity and slope gradient of the landslide,and the force mechanism of the landslide in the process of movement is deeply explored.The specific research work is as follows:(1)The fluid-structure coupling model of water-particle interaction is established by introducing the model of cohesive force between particles.The rationality and correctness of the fluid-structure coupling model established in this paper are illustrated by three typical validation cases of single particle settlement in still water,underwater collapse of particle accumulation body,and movement process of viscous particle flow.(2)The numerical simulation of particle accumulation Angle of repose test and triaxial compression test are carried out to provide parameter guidance for the simulation of specific working conditions of submarine landslide movement behavior.(3)The movement process of submarine landslide under different conditions was simulated respectively,including different viscosity,initial velocity,slope angle and other factors.And the morphological characteristics of sliding mass under various working conditions were explored in depth,and the relevant change rules were proposed.(4)By setting movement monitoring points inside the sliding mass,the variation characteristics of movement velocity and displacement at each point of each section of the sliding mass are deeply explored,and the variation rules of movement at each point of the sliding mass are proposed.(5)The kinematic and force characteristics of viscous sliding mass are studied,and the influence of water resistance and cohesive force on the shape and kinematic characteristics of sliding mass is explored.The results show that the coupling method can well simulate the small-scale movement behavior of the submarine landslide,and the viscous action of the landslide has a significant influence on its kinematic and morphological characteristics,as well as the variation and distribution characteristics of the particle flow field in each part of the landslide.The results can provide an important scientific basis for simulating and predicting the movement behavior of real submarine landslides.