冻融循环作用下黄砂岩的动态抗压特性与能量特征试验研究

Experimental Study on Dynamic Compressive and Energy Characteristics of Yellow Sandstone Under Freeze-Thaw Cycles

为了探究冻融循环条件下黄砂岩的动态抗压特性与能量特征,采用分离式霍普金森(SHPB)系统对冻融循环0次、10次、20次、40次的黄砂岩试件进行动态压缩试验,得到黄砂岩在冲击荷载下的动态压缩强度、能量耗散及破坏形态的变化规律。结果表明:随着冻融循环次数的增加,受冲击后的黄砂岩破碎程度提高;相同冻融循环次数的黄砂岩试件,动态抗压强度随应变率的增大而增大,拟合系数接近1,二者近似成线性正相关关系;相同冲击气压的黄砂岩试件,随着冻融循环次数的增加,其动态抗压强度先增大后减小,具有较为明显的冻融循环效应;试件的耗散能量随着应变率的增大而增大,同时耗能提升的速度也加快,两者近似成幂函数关系;随着黄砂岩所经受冻融循环次数的增多,耗散能量出现了先增后减的趋势,整体上呈减少的趋势,两者表现出负相关性。

In order to investigate the dynamic compressive and energy characteristics of yellow sandstone under freeze-thaw cycle,a Split Hopkinson Pressure Bar(SHPB)system was used to conduct dynamic compression tests on yellow sandstone specimens subjected to 0,10,20,and 40 freeze-thaw cycles.The dynamic compressive strength,energy dissipation,and failure mode of yellow sandstone under impact load were obtained.The results show that as the number of freeze-thaw cycles increases,the degree of fragmentation of impacted yellow sandstone increases.The dynamic compressive strength of yellow sandstone specimens under the same number of freeze-thaw cycles increases with increasing strain rate,and the fitting coefficient is close to 1,which has an approximately linear positive correlation.With the increase of freeze-thaw cycles,the dynamic compressive strength of yellow sandstone specimens under the same impact pressure increases first and then decreases,showing an obvious freeze-thaw cycle effect.The dissipated energy of the specimen increases with the increase of strain rate,and at the same time,the speed of energy dissipation improvement also increases,which has an approximately power function relationship.With the increase of freeze-thaw cycles experienced by yellow sandstone,the dissipated energy has a trend of increasing first and then decreasing,and there is an overall trend of decreasing,which shows a negative correlation.