与地热场相关的高温显著影响地下岩石节理的力学性质，因此，高温循环热处理后节理力学性质研究成为亟待解决的重要课题之一。对粗糙度大致相同的花岗岩节理进行400 ℃高温下不同次数的循环加热-自然冷却处理，并在不同法向应力下开展了直剪试验，分析了花岗岩节理剪切力学性质随循环热处理次数的变化特性，并基于电镜扫描技术（scanning electron microscope, SEM）从细观角度解释其高温力学机理。试验结果表明，随着循环热处理次数的增加，节理的峰值剪切强度和剪切前后粗糙度系数（joint roughness coefficient, JRC）的变化（ΔJRC）总体上呈现先增后减变化趋势，剪切刚度呈减小趋势，而残余剪切强度和峰值剪切位移呈增大趋势。随着循环热处理次数的增加，矿物颗粒出现热膨胀并产生热硬化现象；而当循环热处理次数进一步增加（超过5次）时，矿物内的微裂纹不断发育与扩展。这导致了花岗岩节理力学性质的变化。研究成果可为变温环境下围岩稳定性分析提供参考。

The mechanical properties of underground rock joints are significantly affected by high temperatures associated with geothermal fields. Consequently, investigating the mechanical properties of joints subjected to high-temperature cyclic heat treatment has become a crucial research focus. Granite joints with similar roughness were exposed to cyclic heating and air-cooling treatment at 400℃ for varying cycles. Direct shear tests were subsequently conducted under different normal stresses to explore the change of shear mechanical properties with increasing heat treatment cycles. Additionally, scanning electron microscopy (SEM) was utilized to elucidate the micro-mechanisms underlying the high-temperature effects. The experimental results indicate that as the heat treatment cycles increases, the peak shear strength and the variation in the joint roughness coefficient (JRC) before and after shearing (ΔJRC) initially increase and then decrease. In contrast, shear stiffness generally exhibits a decreasing trend, while both residual shear strength and peak shear displacement tend to increase. With prolonged heat treatment, mineral particles undergo thermal expansion and hardening. However, when the number of cycles exceeds five, microcracks within the minerals continue to develop and propagate, leading to further modifications in the mechanical properties of the granite joints. These findings provide valuable insights for assessing the stability of surrounding rock in environments experiencing temperature variations.