Hot dry rock (HDR) is a kind of clean, renewable energy and has received widespread attention worldwide in recent years. It is significant to explore the dynamic tensile properties of thermal-treated granite using different cooling methods for mining HDR. In the current work, a series of tests were performed containing ultrasonic testing and Split Hopkinson Pressure Bar (SHPB) tests on granite at different temperatures (25, 200, 400, 500, 600, and 800 °C) after different cooling methods (including natural, water, and liquid nitrogen cooling). Then the dynamic tensile properties, thermal shock damage, and energy evolution process of granite using different cooling methods were compared and analyzed. The high-speed camera and Digital Image Correlation (DIC) technology were used to analyze the tensile failure mode and the failure mechanism under different thermal treatment and cooling conditions. According to the experimental results, with the increasing thermal treatment temperature by adopting the three cooling methods, the P-wave velocity, dynamic tensile strength, and final absorbed energy of granite decreased, and thermal shock damage increased. In addition, the effect of liquid nitrogen cooling on thermal-treated granite was the most obvious among the three methods, followed by water cooling and natural cooling. Moreover, with the increasing treatment temperature, the time for the occurrence of central cracks in the specimen after impact was prolonged, and the areas of the shear failure zone and tensile failure zone increased; the influence of different cooling methods was also evident (natural cooling < water cooling < liquid nitrogen cooling). The experimental findings were expected to offer a reference for understanding the dynamic tensile properties and failure mechanism of thermal-treated granite after rapid cooling. By studying the degree of deterioration of rock dynamic properties by different cooling methods, the exploitation efficiency of geothermal wells can be improved.

干热岩（HDR）是一种清洁的可再生能源，近年来在世界范围内受到广泛关注。探索采用不同冷却方法开采 HDR 的热处理花岗岩的动态拉伸性能具有重要意义。在目前的工作中，在不同的冷却方法（包括自然冷却、水冷却和液氮冷却）。对比分析了不同冷却方式下花岗岩的动态拉伸性能、热震损伤和能量演化过程。采用高速相机和数字图像相关（DIC）技术分析了不同热处理和冷却条件下的拉伸失效模式和失效机理。实验结果表明，随着采用三种冷却方式的热处理温度的升高，花岗岩的纵波速度、动态抗拉强度和最终吸收能量降低，热震损伤增加。此外，液氮冷却对热处理花岗岩的效果在三种方法中最为明显，其次是水冷和自然冷却。此外，随着处理温度的升高，冲击后试件中心裂纹产生的时间延长，剪切破坏区和拉伸破坏区面积增加；不同冷却方式的影响也很明显（自然冷却<水冷<液氮冷却）。实验结果有望为理解快速冷却后热处理花岗岩的动态拉伸性能和破坏机制提供参考。通过研究不同冷却方式对岩石动力特性的恶化程度，可以提高地热井的开采效率。