堆石体三轴剪切试验的三维细观数值模拟

3D mesoscopic numerical simulation of triaxial shear tests for rockfill

从细观角度出发,采用随机模拟技术建立堆石体的三维随机颗粒模型,基于修正的增广Lagrangian算法的非线性接触算法模拟颗粒间的相互接触,采用损伤软化模型描述细观单元的应力应变关系,当细观单元的损伤度超过损伤阀值时删除该单元,采用Weibull概率分布描述堆石体材料物理力学性质的非均匀性。以水布垭面板堆石坝茅口组堆石为研究对象,进行其三轴剪切试验的变形体离散元细观数值模拟,采用应变控制加载,再现了堆石体的颗粒变形和运动规律。数值计算结果表明,数值模拟能够较好地反映堆石体三轴试验的变形规律,得到的轴向应变-偏应力曲线和轴向应变-体积应变曲线接近试验曲线。从能量角度分析了颗粒变形、颗粒间的摩擦、颗粒的损伤破碎、颗粒运动在加载过程中对系统的贡献。

A stochastic granule model is developed at mesomechanical level.A random distribution model for rockfill granule is generated by means of random simulation technique.In addition,the nonlinear contact algorithm is presented based on modified augmented Lagrangian algorithm.A simple linear softening damage model is employed to describe the stress and strain relationship of mesoscopic element,and the mechanical properties are distributed with a certain statistical function.The stochastic granule model of Maokou rockfill of Shuibuya rockfill dam is established.The simulated results show that the movement and deformation processes of rockfill granule agree well with the present experiments.