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在对已有试验结果进行分析基础上,从细观角度研究了砂土变形机制。通过对简化的颗粒单元体的受力及变形分析,推导了主应力比与θ的关系以及孔隙比与θ的关系。结果表明,颗粒单元体变形过程中主应力比与孔隙比有着对应的关系,这与“应力路径对塑性体应变的影响主要是由应力比引起的”的试验结论是一致的。从细观角度分析了应力路径(主要是主应力比)影响砂土变形的过程。研究表明,砂土体中存在着大孔隙以及两种基本状态的颗粒单元体结构孔隙,它们是控制砂土变形特性的关键因素,大孔隙受应力路径影响不大,而颗粒单元体结构孔隙则与应力路径密切相关,主要表现为主应力比对塑性体应变的影响;从细观角度分析了峰值应力比与相变应力比的关系,即初始孔隙比越小,相变应力比越低,峰值应力比越高,这与宏观试验结果是一致的。
Based on the analysis of the existing test results, the deformation mechanism of sand was studied from a micro perspective. The relationship between principal stress ratio and θ and the relationship between void ratio and θ are deduced by analyzing the stress and deformation of the simplified granular unit. The results show that the principal stress ratio and the void ratio have a corresponding relationship with the deformation process of particle unit, which is in agreement with the experimental conclusion that the influence of stress path on plastic strain is mainly caused by stress ratio. From the microscopic point of view, the stress path (mainly the main stress ratio) affects the process of sand deformation. The results show that there are macropores and two basic states of pore structure in the sand body, which are the key factors to control the deformation characteristics of the sand. Macropores are not affected by the stress path, while the pores of the unit structure It is closely related to the stress path, which mainly shows the effect of principal stress ratio on the strain of plastic body. The relationship between peak stress ratio and phase transformation stress ratio is analyzed from the microscopic point of view. That is, the smaller the initial void ratio, The higher the peak stress ratio, which is consistent with the macro test results.