粗粒土力学特性的大型三轴试验及离散元—有限元耦合模拟  

Large scale triaxial test and discrete element-finite element coupling simulation of mechanical properties of coarse-grained soil

作　　者：刘重宏 巨能攀[1] 周新[1] 许烈 LIU Zhonghong;JU Nengpan;ZHOU Xin;XU Lie(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]地质灾害防治与地质环境保护国家重点实验室(成都理工大学),成都610059

出　　处：《成都理工大学学报（自然科学版）》2024年第2期291-302,共12页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：四川省科技计划资助项目(2022YFG0183);地质灾害防治与地质环境保护国家重点实验室自主研究课题项目(SKLGP2020Z006)。

摘　　要：本文旨在探究粗粒土的力学特性,并揭示细观力学组构与宏观变形特征之间的内在关系。综合室内大型三轴试验及离散元—有限元耦合技术,建立还原大粒径块石含量及形状的粗粒土三维数值模型,基于柔性围压加载,考虑Rigid Block刚性块优化块石的细观模型,采用PFC程序对粗粒土试样开展了大型三轴试验数值模拟研究,分析粗粒土试样的宏观变形特征及细观力学组构特性。试验研究表明:该试样呈现出应变强化效应,在围压柔性加载下,试样侧向鼓胀变形,试样中部发育“X”形剪切带,竖直方向接触力链逐渐加强,呈现贯通趋势。结合宏观变形特征和细观力学组构综合分析,发现试样在竖直方向由压缩引发的变形程度较试样径向方向由剪切破坏所引发的变形程度更为显著,且竖直各向异性变化程度大于水平各向异性变化程度,这表明细观力学组构与宏观变形特征的变化趋势具有明显的一致性。This article investigated the mechanical properties of coarse-grained soil to identify the internal relationship between its micromechanical fabric and the characteristics of its macroscopic deformation.By integrating laboratory-scale triaxial tests and discrete element-finite element coupling-based simulations,we established a three-dimensional numerical model of coarse-grained soil to replicate the content and shapes of large stone blocks.We used flexible confining pressure-induced loading and rigid block technology to optimize the microscopic models of the stone blocks,and conducted comprehensive numerical simulations of coarse-grained soil specimens by using the PFC(Partical Flow Code)program.The findings showed that the specimens exhibited a strain-hardening effect.Under a flexible confining pressure-induced loading,the specimens exhibited lateral bulging-induced deformation and developed“X”-shaped shear bands in the central region.The chains of the vertical contact force gradually intensified,and exhibited a trend of interconnection.Our comprehensive analysis of the macroscopic deformation and micromechanical fabric of the soil showed that the degree of deformation caused by its compression along the vertical direction was more significant than that caused by its shear failure along the radial direction,and the degree of change in its vertical anisotropy was greater than that in its horizontal anisotropy.This indicates that the trend of changes in its micromechanical fabric and the characteristics of its macroscopic deformation were clearly consistent.

关 键 词：三轴试验 粗粒土 离散元—有限元耦合 细观组构 

分 类 号：TU43[建筑科学—岩土工程]