Thermal damage analysis based on physical and mechanical indices of granodiorite

This paper proposes the development of indices that describe the extent of damage to granodiorite caused by thermal shock. Samples were exposed to repeated high-temperature heating cycles and various physical and mechanical parameters of the samples, including the P-wave velocity, thermal conductivity, compressive strength, tensile strength, elastic modulus and peak strain, were evaluated. The main conclusions were as follows: the internal structure of granodiorite was altered by exposure to high temperatures, as reflected by a decrease in the wave velocity, thermal conductivity, compressive strength, elastic modulus and tensile strength as well as an increase of peak strain with increases in temperature. The thermal damage indices for the six parameters showed that the thermal damage of granodiorite increased with increasing temperature. For the range of 1–7 thermal cycles, the number of cycles had little effect on the physical and mechanical parameters of granodiorite, and the thermal damage indices calculated by these parameters showed almost no change. Through comparison and analysis of the relationships between the thermal damage indices calculated by the six parameters, the damage indices gave excellent correlation with each other, especially so for the damage indices calculated by the P-wave velocity and the other five parameters.