砂卵石土直剪试验颗粒离散元细观力学模拟

砂卵石土作为一种特殊的岩土材料越来越受到研究者的重视。以三维颗粒流程序(PFC3D)为工具,建立砂卵石土直剪试验数值模型,并与试验结果进行对比分析,由于砂卵石土是一种三维不连续介质,并具有任意的形状,数值模拟结果相对于试验数据偏低。为更好地研究其抗剪特性,采用多面体颗粒近似模拟砂卵石土,并将其结果与以传统的球形颗粒模拟砂卵石土的结果进行对比分析。结果表明:多面体颗粒相对于球形颗粒而言,能较好地反映砂卵石土直剪试验的剪切破坏现象,与试验数据更加吻合。细观参数敏感性分析表明:抗剪曲线的峰值段主要受接触刚度和摩擦系数的影响,剪切曲线的上升段主要受接触刚度的影响。

MICROMECHANICS SIMULATION OF DIRECT SHEAR TEST OF SANDY PEBBLE SOIL WITH DISCRETE ELEMENT METHOD

As a special geotechnical material,sandy pebble soil was studied by more and more researchers. Direct shear test numerical models of sandy pebble soil were built with the help of discrete element method in threedimension,and the numerical results were compared with the experimental data. As sandy pebble soil was not continuous medium in three-dimension with arbitrary shapes,in order to study its shear characteristics better, polyhedral particles were created to simulate sandy pebble soil approximately. The results were compared with the results came from traditional spherical particles simulation. The results showed that polyhedral particles overcame the defect of spherical particles,the simulation with polyhedral particles could reflect the direct shear phenomenon better and be more consistent with the experimental data. Analysis of microparameter sensitivity showed that the peak segment of shear curve was mainly affected by the contact stiffness and the friction coefficient,while the rising speed of shear curve was mainly affected by the contact stiffness.