Thermal-Dependent Dynamic Compressive Behavior and Damage Mechanism of Granite

In numerous underground engineering endeavors, rock often face the dual challenges of elevated temperatures and dynamic disruptions concurrently. This study involved conducting dynamic compressive experiments on heat-treated granite specimens. The aim was to analyze the thermal influences on the dynamic behavior of rock. Furthermore, the internal structure and composition of the specimens are analyzed using SEM and X-ray diffraction, respectively, to uncover the mechanisms of damage induced by thermal effects. The apparent morphology, P-wave velocity and density were also analyzed. The results indicate that as the temperature increases, the P-wave velocity, density, dynamic compressive strength, and elastic modulus of the granite specimen decrease. Due to chemical reactions, the quartz content increases, while the contents of feldspar, mica, and montmorillonite decrease with rising temperature. The total crack length and the width of the widest crack also increase as the temperature rises. The main causes of granite degradation following heat treatment include chemical reactions among its components and changes in its internal structure, such as the proliferation and enlargement of cracks due to thermal stress, as well as the evaporation of both free and bound water. Temperature affects both the chemical and physical properties of the specimens, ultimately influencing their dynamic compressive behavior.