A novel obtaining method and mesoscopic mechanism of pseudo-shear strength parameter evolution of sandstone

The pre-peak microstructure evolution of the material is crucial in determining strength and failure scheme material, but not captured by existing shear parameters models which focus on post-peak stage information. Novel concepts pseudo-cohesion pseudo-internal friction angle that account for both information were proposed this study, based experimentally observed response rock mechanics to an external load (the maximum principal stress). These two analytically derived as functions strain, with coefficients be determined (i.e., applying Mohr–Coulomb criterion these experimental data). dependence axial strain confining pressure was investigated. found relate propagation micro-crack developed loading process, revealed PFC2D simulations reproducing experiments. results show (1) analytical model characterizing internal quadratic function accurately reflects mechanical characteristics specimen; (2) before residual stage, first increases then decreases increasing while continuously; (3) sandstone specimens studied, at peak stress a gradually decreasing rate pressure, pressure; (4) CPM well characterized properties under multiple pressures, total stress–strain curves modes numerical reproduced results. pseudo-shear closely related generation, propagation, penetration process cracks. are mobilized load, propagating cracks owing decrease mobilizable cohesion increase angle.