橡胶砂直剪试验的颗粒离散元细观力学模拟

Micromechanics simulation of direct shear test of rubber-sand mixture with discrete element method

文章基于颗粒流理论和PFC2D程序,对橡胶砂颗粒混合物的直剪试验进行了数值模拟,并与室内直剪试验的结果相比较,分析了不同竖向应力下混合物颗粒变形的细观机制,探讨了颗粒接触刚度、摩擦系数、孔隙率、剪切速率等细观参数变化对宏观力学特性的影响;从能量变化、力链变化、颗粒分布、速度场、位移场等细观角度分析数值试验结果,揭示了直剪试验中橡胶砂的细观力学性质和颗粒变形规律。研究结果表明:数值模拟能够较好地反映橡胶砂直剪试验的变形规律,得到的剪应力-剪切位移曲线和竖向位移-剪切位移曲线接近试验曲线;颗粒接触刚度、摩擦系数、孔隙率的改变对橡胶砂数值试验的结果均有不同程度的影响,满足加载条件的剪切速率对试验结果影响不大。

The numerical simulation of direct shear tests on rubber-sand mixtures are successfully per formed using particle flow theory based on PFC2D. By comparing the results of numerical experiments and laboratory tests, micro mechanism of particles mixture at different vertical stress is analyzed. The variation rules of macro properties of rubber-sand mixtures under different micro parameters, such as contact stiffness, friction coefficient, void ratio and shear rate, are studied. By analyzing the results of micro aspects including energy changes, force chain changes, particle distribution, velocity, dis- placement, etc. , micromechanics properties and deformation of the particles are disclosed. The re- sults show that the numerical simulation can reflect the deformation of rubber sand mixtures, at the same time, the shear stress-shear displacement curves and vertical displacement-shear displacement curves are in agreement well with laboratory test results. The changes of particle contact stiffness, friction coefficient and void ratio have varying degrees of impact on the results of numerical experiments, but suitable shear rate has little impact on the experimental results.