砂土堆积试验的组合Clump颗粒离散元模拟

Discrete element simulation of accumulation test for sand with multi-sphericity Clump particles

为研究颗粒形状对砂土力学性质的影响,以室内试验结果为基础,采用离散元软件PFC3D模拟了颗粒堆积试验。选取球形度为颗粒形状特征系数,生成一系列球形度为0.33~1.0的Clump颗粒,用PFC软件对颗粒之间分别赋予不同的摩擦系数共模拟了81种试样。通过将模拟结果与室内试验结果对比以验证采用球形度模拟砂土的可行性,探讨了颗粒球形度及摩擦系数对颗粒堆积体宏观响应和细观组构变化的影响。结果表明：组合Clump颗粒试样的最大孔隙比与最小孔隙比与室内实测结果基本一致,验证了该方法的可行性;试样的自然休止角及孔隙率均与颗粒摩擦系数存在正相关关系,平均接触数则随摩擦系数增大而减小;根据颗粒球形度统计结果在离散元中模拟砂土颗粒可直接采用实际颗粒的摩擦系数;该方法对传统散体颗粒的细观模拟研究方法进行了改进,能够弥补离散元中用圆球颗粒模拟不规则颗粒的不足。

In order to study the influence of sand particle shape on the mechanical properties of soil,several accumulation tests were established by PFC3D based on indoor test data. The particle sphericity was taken as the key shape parameters to create multiple Clump particles,and the sphericity of the Clump particle ranged from 0. 33 to 1. 0. Using PFC software,81 accumulation test samples were established under different particle friction coefficients. The proposed method was confirmed to be feasible by the comparison between simulation results and lab results. The results indicate that the maximum void ratio and the minimal void ratio of the multi-sphericity Clump particle sample basically agree with the indoor test results. There is a positive relationship between natural repose angle,porosity and particle friction coefficient. The average contact number increases with the increaseof friction coefficient. It can be found from the simulation results that sphericity and friction coefficient both affect the relationship between macroscopic response and microscopic evolution. Using multiple Clump particles to simulate irregular sand could be directly given real friction coefficient.The results show that this new simulation method can improve the traditional method,and it can make up the demerits of the traditional ones.