Mechanical response and failure behavior of granite under confining pressure and strain rate

Grasping the dynamic behavior of rocks subjected to confining conditions plays a vital role in elucidating the failure mechanisms of deep rock masses. This research conducted triaxial compression tests on granite at intermediate strain rates to systematically investigate how confining pressure and strain rate affect rock strength and deformation behavior. The energy dissipation and damage evolution characteristics were analyzed, and the regulatory roles of confining pressure and strain rate in energy dissipation mechanisms were clarified. The results indicate that both confining pressure and strain rate significantly enhance the rock strength and deformation resistance, with the effect of confining pressure being more pronounced. The evolution curves of energy dissipation and damage exhibit an overall trend of initial decrease followed by subsequent increase. Confining pressure primarily promotes energy dissipation by enhancing plastic deformation, while its influence on internal damage remains limited. In contrast, strain rate not only enhances plastic dissipation but also markedly accelerates damage evolution. Moreover, a higher frequency of transgranular cracking is observed under elevated confining pressure and strain rate, revealing the underlying mechanisms behind improved energy dissipation and the formation of smoother fracture surfaces. These findings provide theoretical insights for stability analysis and hazard mitigation in deep rock engineering.