Achieving crack propagation and rapid deterioration of high-temperature rock masses by using cooling shocks is important for improving the efficiency of low-permeability oil and gas production, geothermal well pumping, and other engineering facilities. In this study, the temperatures of four groups of granite samples with holes were set as 150, 350, 550, and 750 °C. To study the crack propagation in high-temperature granite suffering from different cooling shocks, the cooling shock temperatures were set as −20, 0, 20, and 25 °C in experiments and an RFPA^2D-Thermal numerical simulation. The results indicated that in the range of 350–550 °C, there is a critical temperature for the sudden change of the crack macroscopic shape. Numerous open cracks appeared on the rock surface, and the thermal damage caused by the cooling shocks was significantly enhanced within the temperature range. Additionally, under the action of the cooling shocks, cracks were initiated in the high-temperature granite at the boundary of the cooling shock hole and the sample and extended radially to the interior of the sample. Moreover, in the process of crack propagation, there was always an annular heat-balance zone inside the rock. Thus, the cracks generated at the boundary of the cube are not connected to the cracks formed at the center hole. A larger temperature gradient in the rock led to a higher crack propagation rate, larger penetration depth, and higher density of cooling-induced cracks. The results of this study can not only improve the permeability of reservoir rocks but also have important reference value for rock engineering in high-temperature environments.

通过使用冷却冲击来实现高温岩体的裂纹扩展和快速劣化，对于提高低渗透油气生产，地热井抽水和其他工程设施的效率非常重要。在这项研究中，将四组带孔的花岗岩样品的温度设置为150、350、550和750°C。为了研究遭受不同冷却冲击的高温花岗岩中的裂纹扩展，在实验和RFPA ^2D中将冷却冲击温度设置为-20、0、20和25°C-热数值模拟。结果表明，在350–550°C的范围内，裂纹宏观形状的突然变化存在临界温度。在岩石表面上出现了许多开放裂缝，并且在该温度范围内，由冷却冲击引起的热损伤显着增强。另外，在冷却冲击的作用下，在冷却冲击孔和样品的边界处的高温花岗岩中产生了裂纹，并在径向上延伸到样品的内部。而且，在裂纹扩展的过程中，岩石内部始终有一个环形的热平衡区。因此，在立方体的边界处产生的裂纹不与在中心孔处形成的裂纹连接。岩石中较大的温度梯度导致较高的裂纹扩展速率，更大的穿透深度，以及更高的冷却诱导裂纹密度。研究结果不仅可以提高储集层岩石的渗透率，而且对高温环境下的岩石工程具有重要的参考价值。