我国西部地区受冻融循环作用的影响较大，岩石在经历冻融循环作用后其内部温度应力造成岩石结构性损伤，岩石物理力学性质产生显著的变化，进而会影响岩石工程的安全性和可靠性。为研究冻融循环对岩石动态拉伸力学性能的影响，选用新疆典型寒冻地区砂岩，利用分离式霍普金森压杆(SHPB)试验系统，对不同冻融循环次数（0、5、10、15、20和25次）后的试样进行动态巴西圆盘试验；并利用SEM电镜扫描和高速摄像机分析冻融循环对试样宏细观破碎特征的影响，在此基础上对冻融循环作用机制进行讨论。结果表明：冻融循环对砂岩动态抗拉强度有很大影响，冻融循环后试样结构损伤，力学性能劣化。随着冻融循环次数的增加，试样结构损伤和力学性能劣化加剧。动态抗拉强度随冻融循环次数的增加逐渐降低，循环25次之后，降低幅度约为50%。同一冻融循环次数下，动态抗拉强度具有明显的应变率增强效应。不同冻融循环次数后砂岩破碎特征差异明显，低应变率和高应变率下分别出现剥落式破坏和颗粒状粉碎破坏。从微观角度，冻融循环主要对岩石矿物颗粒、胶结物质、孔隙面积产生影响，削弱了岩石颗粒间的黏结力，同时在岩石内部产生不同形式的断裂裂纹；冻融循环作用产生的冻胀力与孔隙间水压力导致岩石内部出现损伤，使得宏观上表现出强度的下降。

The western region of China is greatly affected by the freezing-thaw cycle. After experiencing the freezing-thawing cycle, the internal temperature stress of rocks will cause structural damage of rocks, and the physical and mechanical properties of rocks will change significantly, which will further affect the safety and reliability of rock engineering. In order to study the effect of freezing-thaw cycles on dynamic tensile mechanical properties of rocks, sandstones in typical cold and frozen regions of Xinjiang were selected and dynamic Brazil disk test was carried out on samples with different freezing-thaw cycles (0, 5, 10, 15, 20 and 25 times) using SHPB test system. The fragmenting characteristics of macro and micro of samples were analyzed by SEM scanning and high-speed camera, and the mechanism of freezing-thawing cycle was discussed. The results show that the freeze-thaw cycle has a great influence on dynamic tensile strength of sandstone, and the sample structure is damaged and the mechanical properties are deteriorated after the freeze-thaw cycle. With the increase of freezing-thawing cycle times, the structural damage and mechanical properties of the samples deteriorate. The dynamic tensile strength gradually decreased with the increase of the number of freeze-thaw cycles, and the decrease range was about 50% after 25 cycles. Under the same number of freeze-thaw cycles, the dynamic tensile strength has obvious strain rate enhancement effect. The fracture characteristics of sandstone after different freeze-thaw cycles are obviously different, and exfoliation failure and granular crushing failure occur〖LM〗at low strain rate and high strain rate, respectively. From a microscopic point of view, freeze-thaw cycle mainly affects rock mineral particles, cementing materials and pore area, and weakens the bonding force between rock particles. At the same time, different forms of fracture cracks are generated inside the rock. The frost heaving force and pore water pressure caused by freezing-thawing cycle lead to damage inside the rock, resulting in a decrease in strength on a macroscopic scale.