不同应力路径下颗粒材料细观结构分析

Analysis on microstructure of granular materials under different stress paths

用离散单元法对颗粒材料的双轴压缩试验进行了模拟,分析了不同应力状态时颗粒材料细观结构的发展规律。由经典土力学中土体骨架的细观表达出发,延伸出一种表述结构力链的数学统计参数。研究了该参数在不同应力路径下的变化趋势,验证了该参数对于描述颗粒材料细观结构的合理性,并从细观结构的角度解释了破坏滑动面产生的原理。通过定量描述加载过程中土体内部力链结构的变化,建立细观与宏观之间的关系,从细观机理上解释了宏观试验中破坏滑动面一般呈现45°+φ/2左右的事实,为今后从细观结构角度研究土体宏观特性提供了一个新的思路。

A biaxial compression test on granular materials is numerically simulated by DEM. The evolution of the microstructures of granular materials under different stress states is analyzed. A statistical parameter which characterizes the force chain structures is extended based on the microscopic expression of the soil skeleton in the soil mechanics. The evolutions of the proposed parameter under different stress paths are studied, and the rationality of the parameter to characterize the microstructure of the granular materials is verified. From which the mechanism of generation of sliding surface is explicated. Through describing the revolution of the force chain structures, the relationship between the microscopic and macroscopic views is set up, which explains the facts that the destroied sliding surface generally present around 45°＋/2 in mac roscopic trial from the mesoscopic mechanism, leading to a new idea to study the soil properties from the microscopic view.