采用环向周期边界的静力触探三维离散元模拟  

Three-dimensional DEM simulation of cone penetration test by using circumferential periodic boundary

作　　者：杨彦骋 邓益兵[1] 史旦达[1] 薛剑峰 

机构地区：[1]上海海事大学海洋科学与工程学院,上海201306 [2]澳大利亚联邦大学工程与信息科技学院

出　　处：《岩石力学与工程学报》2016年第A01期3372-3384,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金青年基金项目(51208294);上海市研究生教育创新计划项目(20131129);上海市教委科研创新项目(15ZZ081)~~

摘　　要：为探寻静力触探的细观机制,采用自主开发的环向周期边界,将轴对称问题转换为1/4模型,对静力触探进行了三维离散元模拟。基于排水三轴试验模拟,通过与全模型模拟结果的对比,验证模型边界的有效性。进一步将环向周期边界用于砂土中的静力触探贯入模拟,在宏观上,深入分析探头贯入过程中土体位移场、应力场、孔隙率分布等特征,数值模拟得到的探头径向应力和端阻应力变化规律与实际Fontainebleau砂模型试验结果较为一致;在细观上,着重探讨了探头端部及杆侧土体的组构各向异性演化规律,并应用组构张量对组构与应力关系进行定量分析,从细观层面揭示了探头承载方式的影响机制。研究结果对提高三维离散元模拟效率和揭示静力触探细观机制具有重要意义。In order to explore the micro-mechanism of CPT, a new circumferential periodic boundary was developed to consider the three-dimensional axisymmetric problem with 1/4 of the cylinder. To validate the method, a drained triaxial test was modeled with the proposed method and the traditional full model. The results are comparable and the proposed method is very effective. The method was further used to simulate a cone penetration test in dry Fontainebleau sand. It was found that, the variation of cone radial stress and tip resistance during penetration from the model are in good agreement with the reported test results. The micromechanical responses, such as the distributions of particle displacement, internal stress and local porosity to cone penetration are extensively studied. The evolutions of fabric anisotropy during penetration are also discussed. The relationship between stress and fabric is quantitatively described using fabric tensor, which reveals the mechanism of cone penetration capacity microscopically. The results of the work not only improve the efficiency of three-dimensional discrete element method（DEM） simulation, but also promote better understanding of CPT mechanism.

关 键 词：数值模拟 离散元 环向周期边界 静力触探 组构各向异性 模型试验 

分 类 号：O242[理学—计算数学]