砂土直剪试验离散元数值模拟与细观变形机理研究

发布时间：2018-04-13 11:19

本文选题：砂土 + 离散元法　；参考：《长江科学院院报》2017年04期

【摘要】：基于离散元法进行砂土直剪试验模拟与剪切宏细观响应研究。采用试样分条带法研究砂土剪切过程中的变形发育情况;记录应力-位移关系,分析砂土剪切应力、应变特性与剪胀特性。通过分析接触力链、接触组构分布、配位数及滑动接触百分比等细观行为演化研究颗粒细观接触状态演变;基于局部孔隙率变化分析颗粒细观分布状态演变;采用颗粒累积转动量和速度场分析颗粒细观运动状态及剪切带发育的细观机制;对离散元软件PFC2D进行二次开发,实现主应力的可视化。研究表明:应变局部化集中于颗粒转动、接触滑动、体胀明显的剪切带内,剪切带内外颗粒不同的运动状态导致细观参量的变化,剪切带厚度为(10~15)d_(50);力链网络、接触组构和主应力场本质上是一致的,三者主方向在剪切过程中发生了近似一致的偏转。
[Abstract]:Based on the discrete element method (DEM), the direct shear test of sand and the meso-shear response of sand are studied.The deformation and development of sand during shear are studied by strip method, the stress-displacement relationship is recorded, and the shear stress, strain characteristics and shear expansion characteristics of sand are analyzed.The evolution of particle meso contact state is studied by analyzing contact force chain, contact fabric distribution, coordination number and sliding contact percentage, and the evolution of particle meso distribution state is analyzed based on local porosity change.The mesoscopic mechanism of particle motion state and shear band development is analyzed by particle cumulative rotation and velocity field, and the discrete element software PFC2D is developed to realize the visualization of principal stress.The results show that the strain localization is concentrated in the shear band where the particles rotate, contact and slide, and bulge obviously. Different motion states of particles inside and outside the shear band lead to the change of the mesoscopic parameters. The thickness of the shear band is 101015d / d, and the force chain network is obtained.The contact fabric is essentially consistent with the principal stress field, and the three principal directions deflect approximately in the shear process.
【作者单位】：北京科技大学土木与资源工程学院;
【基金】：国家自然科学基金项目(51178044) 北京高校青年英才计划资助项目(YETP0340)
【分类号】：TU411.7

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