Numerical Simulation Of Viscous Debris Flow Based On CBOS Finite Element Method

Debris flow is a common sudden geological disaster in mountainous areas.Among them,viscous debris flow is the most typical and harmful,which seriously threatens people's lives and property.In recent years,with the continuous development of science and technology and theoretical models,numerical simulation has gradually become an effective means to study the dynamic characteristics of viscous debris flow.In this paper,a finite element model for viscous debris flow is established by combining the characteristic operator splitting finite element method with the structural two-phase flow single-fluid model.Based on the physical accumulation experiments of Liu Xilin and Tangchuan,the dynamic process of viscous debris flow is simulated,and the model is applied to study the debris flow disaster in a mountain area.The details are as follows:Operator splitting method is used to divide the equation into diffusion term,convection term,mud depth correction term and average flow correction term.Convection term is discretized in explicit time by characteristic line method.The model overcomes the problem that the traditional Galerkin method is superior to the single-fluid model for structural two-phase flow,and improves the computational efficiency.The model is applied to simulate the dynamic process of viscous debris flow,and the calculated results are in good agreement with the existing research data.Under the condition of continuous inflow,with the increase of debris flow recharge,the length,width and area of debris flow increase linearly,and the shape of the deposit body changes from sector to ellipse gradually;the slope of the deposit area is proportional to the length of the deposit body,and inversely proportional to the width;when the volume weight of debris flow decreases,the internal resistance decreases gradually,and the deposit shape changes from semi-circular to ellipse;The area and final location of debris flow fan are greatly affected,and the non-uniform bottom resistance may cause fluctuations in the movement process.In the study of different orientation settings of obstacles,it is found that when the height of obstacles is much higher than the depth of mud,a "safe area" will be formed between the stacking fans.When the obstacle is downhill,a part of debris fluid is intercepted,which reduces the area of accumulation fan formed in the accumulation area and enlarges the scope of "safe area".Therefore,the reasonable setting of obstacles is helpful to reduce the losses caused by debris flow disasters.The simplified model is used to calculate the debris flow disaster in a mountainous area.The results are approximately the same as the actual disaster range.It shows that the finite element model proposed in this paper has high reliability and good application prospects in the study of debris flow disaster.