Saturated water-weakening effects on the compressive behavior of thermally damaged granite

A detailed understanding of the compressive behavior of granite under environments of high temperature and water is critical for deep resource exploitation. In this study, uniaxial compressive strength tests were conducted on dry and water-saturated granite with thermal damage at room temperature. A new phenomenon was discovered: With the increase of thermal damage degree of granite at different heat-treatment temperatures, the saturated water-induced weakening effects on the stress thresholds representing each crack development stage of granite present an obvious non-monotonic trend. Of the saturated water-induced weakening effects, 500 degrees C is the key point, where the abrupt change occurs and the attenuation of compressive strength (peak stress) attains the maximum, reaching 41.77%. Further, the corresponding phenomenon was attributed to the form transformation of microcracks near 500 degrees C based on the microstructural analysis. This study enriches the understanding of rock behavior deep underground and can provide a guide for more efficient hydraulic fracturing in deep resource exploitation, as well as the long-term safe and stable use of nuclear waste disposal projects within the granite.