柔性边界的有限差分法-离散元法模拟及其对砂土三轴固结排水和不排水剪切特性的影响  

Finite difference method-discrete element method simulation of flexible boundary conditions and their influence on the drained and undrained triaxial shear behavior of sands

作　　者：金磊 李晶晶 李新明[2,3] 孙翰卿[4,5] JIN Lei;LI Jing-jing;LI Xin-ming;SUN Han-qing(College of Civil Engineering,Jiangsu Open University,Nanjing,Jiangsu 210036,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;School of Civil Engineering and Architecture,Zhongyuan University of Technology,Zhengzhou,Henan 450007,China;School of Civil Engineering and Transportation,South China University of Technology,Guangzhou,Guangdong 510640,China;Guangzhou Design Institute Group Co.,Ltd.,Guangzhou,Guangdong 510620,China)

机构地区：[1]江苏开放大学建筑工程学院,江苏南京210036 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [3]中原工学院建筑工程学院,河南郑州450007 [4]华南理工大学土木与交通学院,广东广州510640 [5]广州市设计院集团有限公司,广东广州510620

出　　处：《岩土力学》2025年第3期980-990,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.12002121);河南省优秀青年基金(No.242300421153);岩土力学与工程国家重点实验室开放基金(No.SKLGME022027)。

摘　　要：三轴试验离散元模拟是探究砂土等岩土材料变形破坏机制的一种重要手段,合理地模拟侧向边界是三轴试验离散元模拟的一个重要环节。基于有限差分法(finite difference method,简称FDM)-离散元法(discrete element method,简称DEM)FDM-DEM耦合开展了柔性侧向边界条件下砂土三轴固结排水和不排水试验的数值模拟,并与相应的刚性侧向边界三轴数值试验进行了对比分析。结果表明:相比刚性侧向边界,基于FDM-DEM耦合的柔性侧向边界三轴试验能更好地再现室内砂土三轴试样的宏观力学响应和微观颗粒运动学特征;对于所模拟的砂土三轴固结排水试验,柔性侧向边界试样峰值强度后的应变软化和剪胀性明显弱于刚性侧向边界试样;对于所模拟的砂土三轴固结不排水试验,当轴向应变较大时,柔性侧向边界试样的偏应力小于刚性侧向边界试样,且产生绝对值较小的负孔压;三轴固结不排水试验中,当轴向应变较大时,柔性侧向边界对试样的约束和支撑作用弱于刚性侧向边界,其力链的稳定性较低,力链屈曲数较多,剪切带形成较早,故其各向异性和偏应力均较低。Discrete element simulation of triaxial tests is an important tool for exploring the deformation and failure mechanisms of geotechnical materials such as sands.A crucial aspect of this simulation is the accurate representation of lateral boundaries.Using a coupled finite difference method(FDM)-discrete element method(DEM)approach,numerical simulations of consolidated-drained and consolidated-undrained triaxial tests were conducted under flexible lateral boundary conditions.These results were then compared with those of corresponding triaxial tests using rigid lateral boundaries.The results indicate that,compared to the rigid lateral boundary,the triaxial test using the FDM-DEM coupled flexible lateral boundary better captures both the macroscopic mechanical response and the microscopic particle kinematics of laboratory triaxial specimens.In the consolidated-drained triaxial tests,the strain softening and shear dilatancy of the specimen with the flexible lateral boundary are significantly weaker after reaching peak strength than those of the specimen with the rigid lateral boundary.In the consolidated-undrained triaxial tests,when the axial strain is large,the specimen with the flexible lateral boundary exhibits both a lower deviator stress and a smaller absolute value of negative excess pore pressure.Furthermore,in the consolidated-undrained triaxial tests,as the axial strain increases,the flexible lateral boundary provides weaker lateral constraint and support to the specimen compared to the rigid lateral boundary.Consequently,the stability of the force chains in the specimen with the flexible lateral boundary is lower,leading to more buckling events of force chains within the shear band.As a result,both the anisotropy and the deviator stress are reduced.

关 键 词：离散元 砂土 三轴固结不排水试验 柔性侧向边界 FDM-DEM耦合 力链 

分 类 号：TU441[建筑科学—岩土工程]