循环荷载下砂土变形的细观数值模拟I松砂试验结果 Micro-numerical simulation of cyclic biaxial test I results of loose sand.pdfVIP

第29卷 第7期 岩 土 工 程 学 报 Vol.29 No.7 2007年 7 月 Chinese Journal of Geotechnical Engineering July, 2007 循环荷载下砂土变形的细观数值模拟 I ：松砂试验结果 1 2 1 刘 洋 ，周 健 ，吴顺川 （1.北京科技大学土木与环境工程学院土木系，北京 100083；2.同济大学地下建筑与工程系，上海 200092） 摘 要：采用颗粒流方法模拟不同排水条件下砂土的双轴试验，研究了循环荷载作用下松砂渐进破坏过程中配位数、 接触方向、粒间接触力的演化规律，应用表征上述量的组构参数研究了砂土的诱发各向异性，探讨了饱和砂土液化、 状态转换面产生的微细观机理。研究表明：宏观的液化对应于细观组构上配位数的连续累积丧失和粒间接触力的不断 减小，其根本原因在于循环荷载往返过程中，组构各向异性与应力各向异性发展的不匹配。研究成果对于揭示砂土变 形的细观机理以及建立砂土的细观力学模型都具有意义。 关键词：砂土液化；细观组构；循环荷载；诱发各向异性 中图分类号：TU432 文献标识码：A 文章编号：1000 –4548(2007)07 –1035 –07 作者简介：刘 洋(1979 – ),男，江苏徐州人，博士，讲师，主要从事岩土工程的教学与科研工作。E-mail: ly-ocean @ 。 Micro-numerical simulation of cyclic biaxial test I: results of loose sand 1 2 1 LIU Yang , ZHOU Jian , WU Shun-chuan （1. Department of Civil Engineering, University of Science and Technology, Beijing 100083, China; 2. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China ） Abstract: A series of cyclic biaxial tests on loose sand sunder both drained and undrained conditions with constant amplitudes of strain and stress were performed. The evaluation of micro fabric parameters such as coordinate number, contact orientation and contact forces were studied during the process of failure under cyclic loading. The mechanism of liquefaction and phase transformation was discussed from the viewpoint of micro-mechanism. It was indicated that macroscopic liquefaction was induced due to the cumulative loss of co-ordination number and continuous reduction of contact forces in microscop