基于颗粒流的大理岩三轴循环加卸载细观损伤特性分析  

Analysis on meso-damage characteristics of marble under triaxial cyclic loading and unloading based on particle flow simulation

作　　者：刘静 李江腾[1] LIU Jing;LI Jiangteng(School of Resources and Safety Engineering,Central South University,Changsha 410083,China)

机构地区：[1]中南大学资源与安全工程学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2018年第11期2797-2803,共7页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51374246);湖南省水利厅科技项目(2015131-5);中南大学研究生创新项目(502211848)~~

摘　　要：利用颗粒流程序(PFC)并基于大理岩常规三轴压缩室内试验结果得到一组能够真实反映大理岩宏观力学特性的细观参数,在此基础上进行大理岩三轴循环加卸载试验模拟,研究岩样在循环加卸载作用下的细观损伤特性。研究结果表明:试样内部接触力和平行黏结力在损伤部位产生应力集中,当接触力增大到平行黏结力承载极限时,颗粒间黏结断裂,产生微裂纹;微裂纹数目随应变发展呈阶梯状增加,且在加载初期有良好的"记忆"行为,然后逐渐削弱;微裂纹在加载初期随机分布,然后有序聚集并扩展贯通,加载至峰值附近时形成剪切带;在应变软化阶段反复加载使剪切带扩展贯通形成宏观破裂面,残余强度阶段的裂隙主要由宏观破裂面间的摩擦、滑移产生。A set of microscopic parameters in particle flow code(PFC)reflecting the macroscopic mechanical characteristics of marble were obtained based on the laboratory experimental results of marble under conventional triaxial compression,and the particle flow simulation was carried out for the marble under triaxial cyclic loading-unloading to investigate the meso-damage characteristics of rock sample.The results show that the internal contact force and parallel cohesion of the sample lead to the stress concentration in the damaged parts,while the contact force increases to the bearing limit of the parallel cohesion,the bonds among grains begin to break and the micro-cracks appear.The number of micro-cracks increases with a ladder-like trend as the strain develops,and has great memorial behavior at the beginning of loading,and then gradually weakens.The micro-cracks are randomly distributed at the intial stage of loading,and then collect in order,propagate and coalesce to form shear bands near the peak-stress.The cyclic loading at the stage of strain softening causes the shear bands propagate and coalesce to form macroscopic fracture planes.The cracks at the stage of residual strength are mainly caused by the friction and slip of the fracture planes.

关 键 词：颗粒流模拟 大理岩 循环加卸载 细观损伤 裂纹扩展 

分 类 号：TU45[建筑科学—岩土工程]