Meso-scale study of effects of stress path on deformation behaviors of sand

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.