Dynamic fatigue properties of the cracked sandstone samples under freezing and cyclic loading

Based on the idea of using the prefabricated cracks in the sandstone samples to simulate the actual rock mass, the mechanic properties of rock samples with the intermittent cracks are studied by means of dynamic cyclic loading (2.0 Hz, 20.0 Hz). Moreover, the dynamic fatigue properties of the cracked samples in the frozen state (-15 ℃) are also studied via the contrast of their deformation and strength with those of the saturated samples.The test results indicate that (1)fatigue effect: the cracked samples have more obvious fatigue effects than the non cracked samples under frozen condition;(2)freezing effect: the freezing lightens the fatigue effect much more for non cracked samples than for cracked samples;(3)loading frequency (rate) effect: freezing also reduces the loading rate effect for cracked samples, which means that the strength increasing with loading frequency (rate) for saturated rock samples is more obvious than that for frozen rock samples.