岩石冻融循环及抗拉特性试验研究

Research on rock freeze-thaw cycle and anti-tensile characteristics test

通过开放饱水状态下的冻融循环试验研究了红砂岩和页岩2种岩石的冻融损伤劣化及破坏行为,将经历不同冻融次数后的岩样进行抗拉试验,分析了冻融循环作用对岩石损伤及抗拉特性的影响。研究表明:由于岩性及初始损伤状态不同,红砂岩的冻融损伤劣化模式为剥落模式和断裂模式,而页岩为裂纹模式;岩石抗拉压特性的冻融效应具有相同的规律性,2种岩石的劈裂抗拉强度均随冻融循环次数的增大而减小,但其抗拉特性对冻融循环反映更敏感,损伤劣化更显著;红砂岩受冻融循环次数影响引起的损伤较页岩大;寒区岩体工程稳定性评价中必须考虑应力状态对岩石冻融损伤的影响。

The freeze-thaw damage deterioration and breaking behavior were investigated for red sandstone and shale by freeze-thaw cycle test on open and saturated states. The tensile test for the rock on different freeze-thaw cycles was conducted, and the influence of freeze-thaw cycle on rock damage and anti-tensile characteristics were studied. It is shown that the freeze-thaw damage deterioration modes of red sandstone are spalling mode and fracture mode, but it is crack mode for shale due to the difference of lithology and initial damage state between the two types of rock. The regularities of freeze-thaw effects of compression and tensile characteristics for the two types of rock are ＇identical, the splitting, tensile strength of rock decreases significantly with the increasing of the number of freeze-thaw cycle, but the tensile characteristic is more sensitive to freeze-thaw cycle, and the rock damage deterioration is more significant. The damage of red sandstone is more serious than that of shale by the number of freeze-thaw cycles. The influence of stress state on freeze-thaw damage for rock must be considered in the stability assessment of rock engineering in cold regions.