Numerical Simulation Of Piping Erosion Mechanism Based On Fluid-solid Coupling Theory

Piping refers to the phenomenon that,under a certain hydraulic gradient,fine particles of soil are gradually taken away along the pores by seepage and form a leakage channel.After the formation of the leakage channel,the diameter varies from a few centimeters to a few meters.The leakage channel will cause the soil to be continuously eroded by water flow,and the soil structure will be destroyed,which will eventually lead to catastrophic consequences.Piping is the main cause of destruction of earth-rock dams and dikes.Piping often occurs inside the dam,which is difficult to observe and measure.And piping is a multi-phase coupled nonlinear dynamic process,the influencing factors are complex.It has always been the focus of water conservancy research.(1)Pipe erosion is a process that gradually develops from the surface to the deep layer.In this process,the loss of filler particles has little effect on the soil structure,and the loosening of the skeleton particles marks the beginning of structural instability.Hydraulic gradient is an important cause of loosening of skeleton particles and instability of soil structure.By analyzing the change of particle velocity,the hydraulic gradient of particle starting and the hydraulic gradient of skeleton deformation are obtained.They are used to judge the stability of soil structure.(2)Through the change process of flow field velocity vector from stable to turbulent,as well as the distribution map of permeability coefficient,combined with the change rule of particle loss and porosity,the mechanism of the interaction of pipe water and soil is analyzed.The loss of particles affects the distribution of pores and permeability coefficients,and the distribution of pores and permeability coefficients affects changes in flow velocity,and changes in flow velocity accelerate the loss of particles.(3)Through the analysis of this numerical model,it is feasible to use discrete element software to study the mechanism of pipe erosion.Discrete element software can intuitively reflect the changes of soil mechanical structure,and is an advanced simulation technology.