High temperatures can cause deterioration of the physical–mechanical properties of rocks. In this study, the triaxial cyclic loading and unloading of rock specimens under different temperature conditions were investigated to reveal stress–strain curves, strength and deformation characteristics, failure forms, and peak stress dropping of the rock specimens at high temperatures. The deformation of treated rocks has an elastic after-effect, and the stress–strain curves formed a hysteresis loop. Under increasing confining pressures and temperatures, the increase in plastic deformation exacerbated the degree of damage in the rock specimens, and the stress–strain curves gradually transformed from brittle to ductile failure, thereby reducing its severity. With the rise of σ₃, the bearing capacity, strength and deformation of the rock specimens increased, showing an enhancement effect of the confining pressure. With the rise of T, the effect of deterioration due to temperature was apparent. The brittleness index (B_s) of the stress rock specimens was established to quantitatively express the rules of influence from σ₃ and T on the state of post-peak stress drop. Specifically, B_s increased with the rise of σ₃, whilst the post-peak stress drop (N_s) decreased, then increased with the rise of T. These findings provide a theoretical basis for the analysis of surrounding rock stability, restoration and reinforcement, and the shoring design of underground works following exposure to high temperature such as those occurring after a fire.

高温会导致岩石的物理力学性能恶化。在本研究中，研究了不同温度条件下岩石试样的三轴循环加载和卸载，以揭示岩石试样在高温下的应力-应变曲线、强度和变形特征、破坏形式和峰值应力下降。处理后岩石的变形具有弹性后效，应力-应变曲线形成滞后回线。在围压和温度升高的情况下，塑性变形的增加加剧了岩石试样的破坏程度，应力应变曲线逐渐由脆性破坏转变为韧性破坏，从而降低了其严重程度。随着σ ₃的上升, 岩石试样的承载力、强度和变形量增加，显示出围压增强作用。随着T的升高，由于温度引起的劣化效果明显。建立应力岩试样的脆性指数（B _s），定量表达σ ₃和T对峰后应力降状态的影响规律。具体而言，B _s随着σ _3的增加而增加，而峰后应力降（N _s）随着T的增加而减少，然后增加。 研究结果为火灾等高温环境下地下工程的围岩稳定性分析、修复与加固、支护设计等提供了理论依据。