Influence of Temperature on Crack Initiation and Propagation in Granite

High ground temperature plays an important role in stability analysis when dealing with underground projects. To study the influence of ground temperature on the properties of surrounding rock, conventional triaxial compression tests were carried out at different temperatures and confining pressures with acoustic emission (AE) technology for the damage analysis and characteristic stress values. AE refers to the phenomenon that transient elastic waves are generated by a partial sudden release of energy in different materials. The results of this study show that many parameters increased at temperatures below 60°C such as the peak strength, maximum AE energy, and brittleness of granite while they all decreased at temperatures above 60°C. Good correlations were found between the damage analysis and characteristic stress values, which were determined on the basis of the volumetric strain method for high-temperature studies. It was concluded that thermal stress relates to the different thermal expansivity measures of mineral particles and that brittleness of granite is most obvious at 60°C. This finding promotes understanding of the mechanical behavior of underground caverns and the stability analysis of rock masses.