砂土单调剪切力学性状的颗粒流模拟

利用离散单元法中的二维颗粒流方法(PFC2D),采用了两种不同接触刚度模型对福建标准砂常规三轴试验结果进行了细观数值模拟,并探讨了不同围压水平下两种接触刚度模型的适用性.研究结果表明:对于Hertz-Mindlin接触模型,细观剪切模量影响数值试样的宏观变形模量,颗粒摩擦系数影响试样的峰值强度,细观泊松比变化对试样宏观响应影响不大.当考虑一个确定围压水平下的三轴试验模拟时,两种接触刚度模型均能得到较理想的结果;而当考虑不同围压条件时,由Hertz-Mindlin接触模型得到的结果要比线性接触模型更加符合实际砂土的性质.

Numerical Simulation of Mechanical Response on Sand Under Monotonic Loading by Particle Flow Code

The paper presents a discrete element method named particle flow code in 2-dimension(PFC2D).Two different contact stiffness models were used to simulate the behavior of Fujian standard sand under conventional triaxial compression condition.The validity of these two contact models in different confining stress level was also studied by comparison with the results of laboratory test.The study result shows that as for Hertz-Mindlin contact model(abbreviated to H-M contact model),the micro shear modulus and the friction coefficient affect the macro modulus and the macro strength of numerical sample respectively,and the micro Poisson's ratio has little effect on macro response.The behavior of standard sand under triaxial monotonic loading in a certain stress level can be sucessfully modelled by either liner contact model or H-M contact model.However when a wide confining stress range is considered,the H-M contact model is more suitable than the liner model.