Damaged acoustic-deformation response characteristics of layered soft rock under water-rock coupling

Abstract To explore the damaged acoustic-deformation response characteristics of layered soft rock under water-rock coupling, the structural anisotropy of wave velocity and micro-fracture morphological characteristics were studied. The results show that the wave velocity of soft rock has significant structural anisotropic characteristics. The water-rock process has a significant strengthening effect on the wave transmission of vertical layering. The wave-velocities V c (parallel layering) and V p (vertical layering) of saturated soft-rock increased by 4.52%–35.76% and 52.28%–113.53%. The structural specificity coefficients of saturated soft-rock are significantly weakened, which was 46.02%–78.44% of that of dry soft-rock. The structural anisotropy of soft-rock is significantly weakened by water-rock interaction, the structural heteromorphic coefficient of saturated soft-rock is 46.02%–78.44% of that of dry soft-rock, and its compaction path is prolonged, the elastic deformation is shortened and the average strength decreases by 42.44%. The wave velocity V c of dry soft-rock goes through the stages of steady development, slow decay, and sharp decay. The soft rock is mainly damaged by splitting, the tension cracks increase and the degree of rupture is intensified after the water saturation, and the micro-sections are mainly dissolution fractures. The research can provide a theoretical reference for the stability analysis of hydraulic rock mass.