Modification for Mohr-Coulomb Strength Rule by Considering Microscopic Physical Geometric Features of Shear Band

There is intimate relation between destabilization failure and shear localization band in rock under uniaxial compression. Based upon frictional damage localization model, the relationship between shear zone and compressive strength of rock was found on the stress-strain curve, that is, with the increase of shear band width, the peak strength of rock decreased, and the deformation modulus before and after peak decreased correspondingly. It is concluded from previous studies that the loading rate, temperature, adsorption gas, mineral particles and other factors have the same influence on the stress-strain curve as the shear zone. On the basis of the friction damage localization model, the Mohr-Coulomb criterion was amended by introducing the cohesion energy and shear band function, and the influence of complex factors such as loading rate, temperature and adsorption gas was comprehensively considered as the influence of shear band, and the mohr-coulomb strength criterion with shear band function was obtained. After that, the mesoscopic expression of shear zone function is derived by using Zhukov formula. It is pointed out that rock failure is the result of thermal activation of mesoscopic defects in shear zone, and the thermal activation mechanism is directly affected by temperature and strain rate. The quantitative relationship between shear zone and loading rate and temperature was obtained by fitting the experimental data of previous experiments, which was consistent with the result of Zhukov formula. Mohr-Coulomb strength criterion with shear zone can be applied to more complex engineering geological environment.