基于颗粒离散元法的连接键应变软化模型及其应用

发布时间：2018-07-10 19:45

本文选题：颗粒流 + 连接键　；参考：《力学学报》2016年01期

【摘要】：基于颗粒间的有限接触假设,提出了可表述颗粒间力、力矩传递的连接键模型.为了表征连接键的塑性、损伤及断裂过程,在连接键中引入了考虑应变软化效应的Mohr--Coulomb准则及最大拉应力准则.单一连接键的单向拉伸测试及直剪测试表明了上述连接键应变软化模型的计算精度.研究了颗粒体系的宏观应变能与颗粒平均配位数的对应关系.通过计算发现,对于二维颗粒体系,当平均配位数为5时,颗粒体系的宏观应变能与相同参数下连续介质方法 (如有限元等)计算获得的应变能基本一致.利用上述连接键应变软化模型对岩石的单轴压缩过程进行了模拟,计算结果表明:岩石单轴压缩的应力应变曲线经历了线性上升段、非线性上升段、非线性下降段及缓变段等4个阶段,并给出了上述4个阶段与岩石内部损伤破裂状态的内在联系.计算结果还表明,随着断裂应变的增大,岩石的破裂模式逐渐由拉剪复合型破裂向单一压剪型破裂转化;随着断裂应变的增大,峰值应力及达到峰值应力时的应变均逐渐增大,但峰值时的破裂度及终态时的破裂度将逐渐减小.
[Abstract]:Based on the assumption of finite contact between particles, a joint bond model is proposed to describe the force and torque transfer between particles. In order to characterize the plasticity, damage and fracture process of bond, Mohr-Coulomb criterion and maximum tensile stress criterion considering strain softening effect are introduced. Uniaxial tensile test and direct shear test of single bond show the accuracy of the strain softening model. The relationship between the macroscopic strain energy and the average coordination number of particles was studied. It is found that when the average coordination number is 5, the macroscopic strain energy of the particle system is basically consistent with that obtained by the continuum method (such as finite element method) with the same parameters. The uniaxial compression process of rock is simulated by using the above bond strain softening model. The calculation results show that the stress-strain curve of rock under uniaxial compression has experienced a linear ascending phase and a nonlinear ascending phase. The four stages of nonlinear descent and slow variation are given, and the internal relations between the four stages and the damage and fracture state of rock are given. The results also show that with the increase of fracture strain, the fracture mode of rock transforms from tension-shear composite fracture to single compressive shear fracture, and with the increase of fracture strain, the peak stress and the strain at peak stress increase gradually. However, the rupture degree at the peak and the final state will gradually decrease.
【作者单位】：中国科学院力学研究所流固耦合系统力学重点实验室;
【基金】：国家科技支撑计划(2012BAK10B00) 国家自然科学基金青年基金(11302230,11302229)资助项目
【分类号】：O347.7

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