Damage mechanism of granite under subcritical water-rock interaction

The study of rock property deterioration law following subcritical water-rock interaction is of great importance for improving the efficiency of dry, hot rock development, reducing the usage of fossil energy, and achieving global energy conservation and emission reduction goals. This study examined granite's pore structure and mineral element dissolution properties after sub-critical water-rock interaction at different temperatures using NMR and ICP-MS. The damage evolution behavior of granite under sub-critical water-rock interaction was discussed and explained in conjunction with the microstructure images. The conclusions of the study are as follows. (1) The major pores of granite transition from mesopore to macropore after subcritical water-rock interaction. A few minerals on the surface of granite detach as the temperature rises, and the traces of dissolution and oxidation become more prevalent; (2) The dissolved mineral elements altered the properties of the solution, and Si element concentration was significantly higher than that of other elements; (3) The key temperature affecting the sub-critical water-rock interaction of granite is 300-350 degrees C. In general, the sub-critical water-rock interaction primarily influences the properties of granite in two ways: the oxidation and dissolution of minerals and the thermal stress resulting from thermal expansion.