This study aims to establish a simulation method reflecting the initial macroscopic deformation of rock and propose a determining method for internal micro-cracks closure stress. Firstly

a deformation analysis model was established between rock matrix and micro-cracks

based on the stress and deformation characteristics of rock and its internal micro-cracks. Then deformation analysis methods were put forward for rock matrix and internal micro-cracks

respectively

according to the analysis of material deformation mechanics. Thus

an initially macroscopic constitutive model was deduced for rock

and its determining methods for the model parameters were also given. Secondly

a new method was proposed to obtain the closure stress of micro-cracks

due to the defects and deficiencies of those existing methods. Lastly

this study investigated the effect of confining pressure on the nonlinear concave degree of initially macro deformation of rock by using the established model. The theoretical result indicated that there was a negative correlation between them. Research results show that this established model can not only simulate the full deformation procedure of rock before failure

but also explain the deformation relationship between rock and their components. The new method can not only satisfy the theoretical significance of micro-cracks closure stress

but also avoid the interference of human factors. Moreover

this new method is easy to operate. Therefore

the above results verify the rationality and feasibility of the proposed model and method in this study.