土体颗粒物流动物质点法模拟的弹塑性和非牛顿流体本构模型比较研究

土体颗粒物流动是一种典型的大变形破坏,具有非牛顿流体的流动特征。准确模拟土体颗粒物的流动及冲击过程,对滑坡和泥石流等地质灾害的防治具有重要意义。物质点法是一种无网格粒子类方法,已在各类大变形问题中得到了广泛应用。以往土体颗粒物流动的模拟,通常采用弹塑性本构模型,但缺乏对非牛顿本构模型的模拟分析。本文引入非牛顿本构模型的模拟分析,旨在为土体颗粒物流动模拟提供一种新的方法与思路。非牛顿本构模型的模拟分析是将非牛顿广义Cross模型引入三维物质点法,通过人工阻尼力模拟颗粒间的摩擦力,对土体颗粒物的坍塌、沿斜面滑动以及冲击障碍物等问题进行了动态模拟,研究了其运动全过程,并与弹塑性本构模型的模拟结果进行了对比验证。结果表明,基于非牛顿流体本构模型的物质点法可以较好地模拟土体颗粒物加速、减速到再次稳定的流动全过程及其对障碍物的冲击效应。

A comparative study of elastoplasticity and non-Newtonian fluid constitutive models simulated by the material point method for soil granular flow problems

The flow of soil particles is a typical large deformation failure and has the flow characteristics of a non-Newtonian fluid.Accurately simulating the flow and impact process of soil particles is of great significance to the prevention and control of geological disasters such as landslide and debris flow.Material point method (MPM) is a kind of meshless particle method which has been widely used in various large deformation problems.In the past,the elastoplastic constitutive model is usually used to simulate the flow of soil particles,but there is not much analysis of the non-Newtonian constitutive model.In this paper,the non-Newtonian constitutive model is introduced to provide a new method and idea for soil particle flow simulation.In the simulation,generalized Cross non-Newtonian model 3 d material point method is used,with an artificial damping force representing the friction between the particles,to simulate the collapse of the soil particles,sliding along the slope,and hitting obstacles,and to study its movement process.The simulation results of the elastic-plastic constitutive model are compared for verification.The results show that the material point method based on the non-Newtonian fluid constitutive model can well simulate the whole process of soil particles acceleration,deceleration and stabilization and their impact on obstacles.