Relationships between rock ultrasonic properties with loading stresses and challenges in deep mining

In-situ stress measurement is a key task in deep underground mining activities. An efficient stress measurement technique is important for determining the safety of the surrounding rock mass. Rock acoustic characteristics can comprehensively reflect rock physical and mechanical properties, structures, and in-situ stresses. Acoustic information, with the wave velocity as a key parameter, is significantly correlated with factors such as stress, deformation, microstructure, and environmental conditions. Recent studies and developments regarding rock acoustic properties were summarized based on numerous research results in regard to four aspects: the wave velocity–stress–strain correlation, the influence of intrinsic factors such as lithology and pore structure, the influence of external factors such as confining pressure and temperature, and theoretical wave velocity models. Equations for the coupled stress–temperature–wave velocity relationship considering the effect of temperature under stress were presented. Finally, suggested research directions for future advances in rock acoustics and in-situ stress measurement for the development of deep mining engineering were described.