The soft rock roadway in deep high‐stress environment has the problems of strong rheology and large deformation. Based on the analysis of the stress distribution of the surrounding rock of the roadway in a kilometer‐deep mine, rheological tests under different stress paths are carried out for mudstone in a kilometer‐deep mine. The rheological deformation curve, damage characteristics, and change rule of the main mechanical parameters of mudstone under different stress conditions are studied. The results show the following: (1) the peak strength of the triaxial compression of mudstone is closely related to confining pressure, and, with increasing confining pressure, the confining pressure effect decreases gradually; (2) the strain increases slowly under uniaxial loading, and, with increasing axial pressure, the velocity of rheological deformation increases nonlinearly, and the amount of mudstone deformation increases with time; (3) under the condition of unloading confining pressure with constant axial pressure, with decreasing confining pressure, the instantaneous axial and radial strains of mudstone specimen increase nonlinearly, the rheological strain and velocity of mudstone increase gradually, and the lateral rheological strain is close to the axial rheological strain; and, (4) in the unloading confining pressure with axial compression triaxial test, with increasing deviating stress, the axial and radial instantaneous strain increments of mudstone decrease gradually, the lateral strain and rheological velocity of mudstone increase gradually, and the lateral strain is approximately 2.05 times the axial strain. These conclusions reveal the rheological characteristics of the mudstone under different surrounding rock conditions and provide a theoretical basis for the excavation deformation and support control of roadways.

To explore the causes of mine tremors in coal mines with sandstone roofs, a three-point bending loading experiment was designed for composite sandstone layers, and the fracture and interlayer shear slip characteristics of the composite sandstone layers were studied using optical measurement and acoustic emission techniques. The results show that the bending of the rock layers led to interlayer sliding deformation, while the fracturing greatly promoted interlayer sliding. The maximum interlayer slip accelerations during bending deformation and fracturing were 0.6 mm/s² and 3.8 mm/s², respectively. During the fracturing of the rock layers, the proportion of acoustic emission shear fracture events increased with the continuous occurrence of long-lasting and high-amplitude acoustic emission events. The mechanism of mine tremors in thick sandstone roofs is as follows: the increase in the area of the goaf causes rock bending deformation and fracturing, accompanied by interlayer shear slip, fracturing of the sandstone layer, and friction dislocation at the cementation surface of the adjacent sandstone layers, which jointly cause vibration of the roof.

Rockburst is a dynamic disaster characterized by the sudden instability and violent fracturing of chambers under high-stress conditions, with the critical stress serving as the most pivotal indicator. In this study, the maximum load criterion and the maximum potential energy criterion for the occurrence of rockbursts in chambers were proposed, and the theoretical critical stress formulas for rockbursts in circular chambers under hydrostatic pressure were derived. The discrepancy in critical stress derived from the two discrimination criteria is less than 2%. This study indicated that the critical stress was mainly influenced by uniaxial compressive strength, rockburst energy index, internal friction angle, and support stress. The biaxial isobaric loading experiments were conducted on circular chamber specimens of granite gneiss and basalt with dimensions of 150 mm× 150 mm× 50 mm. The average error between the experimental and theoretical values of the critical stress was 2.53%. Comparative analysis with field cases revealed an average ratio of 0.55 between actual stress and critical stress, prompting subsequent refinement of the formula. The application of the critical stress formula was discussed from the aspects of hazard assessment, prevention design, and safety evaluation of chamber rockbursts.