Strain softening and permeability evolution model based on brittle modulus coefficient

The scientific predictions of the strain softening and permeability evolution behaviors of rock are the basis of the stability and safety analysis in rock engineering. Through the analysis on the tri-axial compression tests data,the laws of the effects of confining pressure on the strain softening mechanical behaviors of rock are presented. To describe the effects of the confinement on the brittleness of peak-post rock,the brittle modulus and the brittle modulus coeffi- cient are proposed. The physical meanings of the brittle modulus and the application scope of the brittle modulus coef- ficient are also described. Adopting the brittle modulus coefficient,combined with the strength degradation index,dilat- ancy index,SS model in FLAC and the method of the enhanced permeability of volumetric strain,a new strain softening and permeability evolution model has been developed. Using FLAC software,the deformation and permeability evolu- tion behaviors under the different confining pressures of Gebdykes dolomite and Balikun sandstone are better numeri- cally modeled,and the model proposed in this paper is proved to be valid. Lastly the model proposed in this paper is used to predict the permeability dynamic evolution of overburden rock due to mining. The results show with the work face advance the deformations and failures of overburden rock appear due to mining disturbance stresses,and correspondingly the permeability of rock dynamically changes. The process is better numerically modeled by the model pro- posed in this paper.