基于颗粒流模拟的黏性土宏细观参数相关性分析

Analysis of the relevance between macro-micro parameters for clays based on particle flow simulation

利用颗粒流方法(Particle Flow Code,PFC)建立数值模型,对红黏土进行大量三轴不固结不排水数值模拟试验。通过改变摩擦系数、黏结强度、刚度比、孔隙率的取值,分析了细观参数的变化对应力-应变关系曲线的影响。通过记录不同围压下样本的应力峰值,依据摩尔-库伦强度准则对数值试样的剪切强度参数进行标定,探讨并定量分析了黏性土宏观强度指标与其对应的细观参数之间的关系。通过不断反演,选取合适的细观参数的值,并将数值模拟与各级围压下室内试验进行结果对比,得到了较为理想的模拟效果,为完善该地区红黏土强度特性的分析提供了支持。

A numerical model is established based on the Particle Flow Code(PFC3 D),and a number of plane unconsolidated and undrained triaxial simulation tests for clays are carried out.The influences of different values of parameters,including friction coefficient,bonding strength,stiffness ratio and porosity on stress-strain curves are discussed.Shear strength parameters of numerical samples are defined by the Mohr-Coulomb strength criterion according to peak stresses recorded under different confining pressures,and the relationships between the macro-mechanical strength parameters of clays and their corresponding microscopic parameters are investigated and analyzed quantitatively.Through continuous inversion,the appropriate microscopic parameters are selected and the numerical simulation results are compared with the laboratory test results under the confining pressures of 100 kPa,200 kPa,300 kPa and 400 kPa,respectively.The results show that the simulation is effective and can make a certain contribution to better analyze the strength characteristics of clays in the area.