Characterization and Modeling Study on Softening and Seepage Behavior of Weakly Cemented Sandy Mudstone after Water Injection

Water injection-induced rock softening and the associated water seepage characteristics are common basic problems in underground reservoir construction prevention of mine disaster. In this paper, a series experimental studies was carried out to investigate these with weakly cemented sandy mudstone collected from Shendong Buertai coal mine, China. The stress-seepage interactions water-saturated were directly obtained. Then, modification method constitutive model for mass considering effect stress-damage-driven permeability evolution established. Research results show that saturation reduces tensile strength, compressive cohesion by 56% elastic modulus 28%. hydraulic effects on Poisson’s ratio internal friction angle negligible. relationship between complete compaction deformation is be divided into three stages shielding, surge, recovery. Rock each stage has negative exponential effective stress. This research provides theoretical basis researches hydromechanical couplings mudstone, which insightful engineering practice.