苏北粉土非线性特性离散元模拟与参数分析

DEM Simulation and Parameter Analysis of Nonlinear Characteristics of Northern Jiangsu Silt

离散元法对颗粒系统进行动态分析,在离散颗粒单元接触分析与宏观响应间建立联系,使其成为试验手段分析细观特性的有益补充.采用三维颗粒离散元程序YADE进行了颗粒细观参数的参数分析,分析细观参数对三轴试验宏观响应的影响.研究表明:弹性模量和泊松比不仅与接触法向刚度和刚度比有关,同时随粒间摩擦角变化;而固结和剪切两个阶段粒间摩擦角控制了试样的剪胀水平和孔隙率向临界孔隙率的发展趋势.根据参数分析结果,提出了改进的三轴试验细观参数的标定步骤,并对室内试验进行模拟.模拟结果与室内试验结果较为吻合,表明该数值方法应用于三轴非线性变形特性研究具有可行性.

Discrete element method is used to do dynamic research into particulate systems, aimed at establishing a correlation between discrete particulate element contact analysis and macroscopic response. This method is thus made a helpful supplement to the conventional experimental techniques of analyzing microscopic properties. Parameter analysis of particulate micro parameters is carried out using a three-dimensional discrete element method （YADE）, in order to study the influence of micro parameters on macroscopic response of triaxial tests. The results show that elastic modulus and Poisson Ratio are related to normal contact stiffness and the contact stiffness ratio, and they also change when the friction angle varies. The dilatancy level and porosity＇ s development tendency to critical porosity are dominated by inter-particle friction angles at the consolidation stage and shear stage. Based on these results, a modified calibration procedure of particulate micro parameters for triaxial shear test is proposed, and then a numerical simulation is also carried out. The numerical results are quantitatively in agreement with the laboratory results, and the feasibility of the numerical method is validated to study the nonlinear deformation characteristics of triaxial shear test.