摘要
颗粒材料在土木工程中应用广泛,明确颗粒材料系统变形演化状态十分关键。采用离散元方法(DEM)对颗粒材料的直剪试验进行数值模拟,假定剪应变由颗粒自身旋转和滑移共同组成,并结合颗粒材料率态剪切强度理论,研究了颗粒材料系统在剪切过程中的变形状态演化。为研究颗粒旋转对颗粒材料系统抗剪强度的影响,使用PFC3D对球形玻璃珠颗粒系统进行了等速率直剪试验的三维离散元数值模拟,得到了系统中颗粒自身旋转引起的滑移占总滑移的比例参数。结果表明,颗粒旋转是颗粒材料系统在剪切作用下,其内部结构演化的重要部分,由颗粒自身旋转引起的滑移占比不可忽略。通过监测剪切带内颗粒绕Y轴旋转的角度,获得了颗粒旋转的变化规律。在本研究所施加竖向应力范围内,随着竖向应力的增大,颗粒旋转引起的滑移占总滑移的比例减小;随着剪切位移的增大,旋转比例逐渐减小并趋于某一不受竖向应力影响的定值。通过对颗粒材料系统内部旋转演化的数值分析,进一步验证了颗粒材料系统率态剪切强度模型,并给出了确定理论模型关键参数的方法,为分析和确定颗粒材料系统强度提供依据。
Granular materials are widely used in civil engineering and it is crucial to clarify the deformation evolution of granular material systems.The Discrete Element Method(DEM)is used to simulate the direct shear test of granular materials.The shear strain is assumed to be a combination of the particles’rotation and slip.The deformation evolution of the granular material system during shearing process is investigated with the rate-state shear strength theory for granular material.To study the effect of particle rotation on the shear strength of granular material system,a 3D discrete element simulation of a constant-shear-rate direct shear test using spherical glass bead system is carried out by PFC3D.The ratio of the slip caused by the particles rotation to the total slip in the system is obtained.The results show that the particle rotation has a significant contribution to the internal structure evolution of the granular material system,and the slip caused by the particle rotation cannot be ignored.The evolution of particle rotation is obtained by monitoring the particle rotation angle around Y-axis in the shear band.For the vertical stresses applied in this study,the slip caused by particle rotation decreases as the vertical stress increases.With the increase of shear displacement,the slip caused by particle rotation decreases gradually and tends to be a constant.Based on the numerical analysis on rotation evolution of the granular material system,the rate-state shear strength model of the granular material system is further verified and the corresponding method for determining the key model parameters is also given,providing a basis for analyzing and determining the strength of the granular material system.
作者
童立红
傅力
徐长节
TONG Li-hong;FU Li;XU Chang-jie(State Key Laboratory of Performance Monitoring and Protecting of Rail Transportation Infrastructure,East China Jiaotong University,Nanchang 330013,China;School of Civil Engineering and Architecture,East China Jiaotong University,Nanchang 330013,China;Research center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China)
出处
《工程力学》
EI
CSCD
北大核心
2024年第11期125-133,共9页
Engineering Mechanics
基金
国家自然科学基金项目(52278350,52168049)
国家自然科学基金高铁联合基金项目(U1934208)
江西省科技合作专项项目(20212BDH81034)
江西省教育厅课题项目(GJJ210618)
江西省交通运输厅科技项目(2021H0004)。
关键词
岩土工程
剪切强度理论
离散元数值模拟
颗粒旋转
直剪试验
geotechnical engineering
shear strength theory
discrete element numerical simulation
particle rotation
direct shear test
