Deformation behavior and damage-induced permeability evolution of sandy mudstone under triaxial stress

The mechanic and permeability behavior in sandy mudstone is crucial to hazard prevention safety mining. In this study, investigate the evolution characteristic of mechanical properties subjected loading in-site stress, a series triaxial compression–seepage experiments are performed. increase decrease strength gradually transformed responding confining stress from 5 15 MPa, which corresponds transformation brittleness ductility mudstone, threshold 10 MPa was determined. penetration shear fracture generated at brittle regime, while plastic flow presented semibrittle ductile state. critical value yielding stage axial strain increases with stress. relatively higher pore pressure during promoted volumetric strain, increased reduced lower occurred strain. addition, an improved model developed describe loading-based considering Klinkenberg effect.