基于3维离散元颗粒流的土石混合体大型直剪试验模拟分析

Simulation Analysis of Large Direct Shear Test of Soil and Rock Mixture Based on PFC3D

为能更好的揭示土石混合体的剪切特性与力学行为,以新疆博乐地区某土石坝坝料为研究对象,选取了3种不同含石量的室内混合料试样,通过导入随机多面体模板建立真实块体颗粒模型,并进行了不同含石量在不同围压下的3维离散元颗粒流(PFC3D)土石混合体室内大型直剪试验模拟,研究了含石量对试样抗剪强度的影响,分析了土石混合体在剪切过程中的体积变化以及不同含石量下土石混合体的力链网络分布。结果表明:模拟结果与室内试验的拟合度较好,二者具有良好的一致性;含石量对土石混合体的剪切特性有显著影响,含石量越高,土石混合体的抗剪强度越大;在相同法向应力下,试样的剪胀量随着含石量的增加而增大,低含石量试样表现出一定的“软化特性”,高含石量试样表现出“硬化特性”;不同含石量的土石混合体力链网络分布表现为各向异性,随着含石量的增加,强力链数目增多,分布更加集中,试样整体较为稳定,土石混合体在宏观上表现出更高的剪切强度。该研究可以更好的理解土石混合体的细观力学机理,可为相关岩土力学模拟提供参考依据。

In order to better revealed the shear characteristics and mechanical behavior of soil-rock mixture,three samples of indoor mixtures with different rock contents were selected for the studied of the core wall material of a soil-rock dam in Bole District,Xinjiang,by importing the random polyhedron templates to build real block particles,and the different content of rock under different confining pressure of large direct shear test simulation of soil-rock-mixture PFC3D stone content in the sample shear strength was studied,the influence of soil-rock-mixture was analyzed in the process of shearing force of soil-rock-mixture volume change and chain distribution network.The results show that the fitting degree between simulation results and laboratory tests was good,they had good consistency.The higher content of rock,the greater the shear strength of soil-rock mixture.Under the same normal stress,the dilatancy of the sample increases with the increase of the rock content,the low rock content is the softening characteristic,and the high rock content is the hardening characteristic.With the increase of rock content,the number of strong chains increases,the distribution becomed more concentrated,and the overall stability is relatively stable.The soil-rock mixture shows higher shear strength macroscopically.This studied could better understand the micromechanical mechanism of soil-rock mixture and provided reference for the relevant rock-soil mechanical simulation.