The present study investigated the dynamic fatigue damage of thermally shocked granite with cyclic impact load. Firstly, cyclic impact tests were performed with a split Hopkinson pressure bar (SHPB) device to study the dynamic stress–strain relationship of water-cooled granite at various temperatures and cyclic numbers. Subsequently, the dynamic stress, elastic modulus, maximum strain and strain rate affected by temperature and cyclic number were further discussed, the energy evolution and cumulative damage during cyclic impact were revealed. Finally, the crack propagation, failure mode and fatigue life (the maximum impact number) of granite were analyzed, a fatigue life prediction model was proposed. The results show that the dynamic stress, elastic modulus and transmitted energy of granite exponentially decrease, while the maximum strain, strain rate, reflection energy, absorption energy and cumulative damage exponentially increase as the cycle number increases with a fixed thermal treatment temperature. In addition, microcracks first appear in the longitudinal section, then develop into macrocracks and penetrate to cause granite failure as the impact number increases. Granite exhibits different failure modes after cyclic impact. Split tensile single fracture surface failure before 600 °C and multiple fracture surface failure at 800 °C. The fatigue life decreases as the temperature and impact pressure increase.

本研究研究了循环冲击载荷下热冲击花岗岩的动态疲劳损伤。首先，利用分体式霍普金森压力棒（SHPB）装置进行循环冲击试验，研究水冷花岗岩在不同温度和循环次数下的动态应力应变关系。随后，进一步讨论了温度和循环次数对动应力、弹性模量、最大应变和应变率的影响，揭示了循环冲击过程中的能量演化和累积损伤。最后，对花岗岩的裂纹扩展、失效模式和疲劳寿命（最大冲击次数）进行了分析，提出了疲劳寿命预测模型。结果表明，在固定的热处理温度下，随着循环次数的增加，花岗岩的动应力、弹性模量和传递能呈指数下降，而最大应变、应变率、反射能、吸收能和累积损伤呈指数增加。另外，随着冲击次数的增加，微裂纹首先出现在纵向截面，然后发展为宏观裂纹并穿透导致花岗岩破坏。花岗岩在循环冲击后表现出不同的破坏模式。600 °C 之前的分裂拉伸单断裂面失效和 800 °C 时的多断裂面失效。疲劳寿命随着温度和冲击压力的增加而降低。