土石混合体材料大型三轴试验及PFC-FLAC耦合仿真研究  

Triaxial test and PFC-FLAC coupling simulation study on material parameters and deformation characteristics of soil-rock mixture

作　　者：胡世兴 靳晓光[1] 孙国栋 李翰林 聂紫珩 HU Shixing;JIN Xiaoguang;SUN Guodong;LI Hanlin;NIE Ziheng(School of Civil Engineering,Chongqing University,Chongqing 400041,China;China Railway ErYuan Engineering Group Co.,Ltd.,Chengdu,Sichuan 610031,China)

机构地区：[1]重庆大学土木工程学院,重庆400041 [2]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《岩石力学与工程学报》2021年第S02期3344-3356,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51578091)。

摘　　要：基于室内大型三轴试验与PFC^(3D)-FLAC^(3D)耦合分析方法,建立还原部分大尺寸块石实际形状的柔性伺服三轴加载模型,分析土石混合体试样变形破坏特征以及剪切面、接触力链发展规律。数值试验结果表明:土石混合体三轴剪切过程分为轴向压密、侧向鼓出2个阶段,轴向压密阶段随围压的增大而缩短,径向变形量随围压的增大而增大;土石混合体摩擦角随着含石量的增大而增大,黏聚力的变化趋势相反,含石量对摩擦角与黏聚力的影响约为10%,块石主要增强土石混合体的结构性:三轴试样破坏时试样中部形成X形剪切带,且主,要发生侧向位移,试样上下端有锥形弹性区,主要发生竖向位移;当轴向应变小于5%时,配位数随轴向应变的增大而增大,孔隙率随轴向应变的增大而减小,当轴向应变大于5%时变化规律相反:随着轴向应变的增加,接触力链逐渐向块石较多的区域集中,轴向力主要由块石间的接触提供;轴向力主要由颗粒法向接触力组成,水平方向的力主要由切向黏结以及摩擦提供。Based on large-scale triaxial test and PFC^(3D)-FLAC^(3D)coupling analysis method,flexible servo triaxial loading models,which restore the actual shape of some large-size stones are established.The deformation and failure characteristics of soil-rock mixture(SRM)specimens and the development law of shear plane and contact force chain are studied.The numerical simulation results show that the triaxial shear process of SRM can be divided into two stages:axial compaction and lateral bulging.The axial compaction stage decreases with the increase of confining pressure,while the radial deformation increases with the increase of confining pressure.The friction angle of SRM increases with the increase of the gravel content,while the change trend of the cohesion is opposite.The impact of rock content on the friction angle and cohesion is about 10%,and rocks mainly enhance the structural of the SRM.X-shaped shear bands are formed in the middle of the sample during failure and lateral displacement mainly occurs in the middle,while the upper and lower ends have tapered elastic areas and vertical displacement mainly occurs.When the axial strain is less than 5%,the coordination number increases with the increase of the axial strain,and the porosity decreases with the increase of the axial strain while the change low is opposite when the axial strain is greater than 5%.With the increase of axial strain,the force chain gradually concentrates to the area with more rocks,and the axial force is mainly provided by the contact between rocks.The normal contact force of particles mainly provides the axial force,while the horizontal force is mainly composed of tangential bonding and friction.

关 键 词：土力学 土石混合体 大型三轴试验 PFC-FLAC耦合 变形破坏 力学特征 

分 类 号：TU43[建筑科学—岩土工程]