【摘要】 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。更多还原

【Abstract】 According to the results of previous tests the mesostructure of sand has been analyzed,which could provide theoretical foundation and further understand the mechanism of deformation characters.The relationship between θ and the principal stress ratio and also that of the void ratio were put forward through the analysis of the loading and deflection process of the particle unit.The results show that,there is the corresponding relation between the principal stress ratio and the void ratio,which is in accordance with the test result that the effect of stress path on plastic volumetric strain mainly depends on the stress ratio.And then the meso-scale study of evolution process of the pores of sand was made during the increasing of stress ratio.There are two kinds of pores,macro-pore and structural void of particle unit which are the major factors on deformation characters of sand.The macro-pore is independent of stress path,however,the structural void of particle unit which consists of two kinds of basic states depends on stress path(mainly on stress ratio).Finally,the peak stress ratio and phase transformation stress ratio were analyzed from the viewpoint of mesomechanics,As the results that,the smaller the initial void ratio is,the lower the peak stress ratio is;and however,the higher the phase transformation stress ratio is.It is consistent with the experiment observations of sand.更多还原