冲击载荷作用下砂岩的动力学特性及能耗规律

采用分离式霍普金森(SHPB)压杆装置对砂岩进行动态冲击压缩试验,通过不同的加载气压实现不同应变率条件下对煤矿区的砂岩进行冲击压缩,以此来分析煤矿区砂岩的动力学特性以及能量损耗规律。根据试验结果分析可得,应力-应变曲线反映出砂岩的动态弹性模量及峰值应力都表现出明显的应变率效应,动态压缩强度表现出很强的应变率效应,两者之间呈现线性关系；在动态冲击压缩中,动态抗压强度高于静态抗压强度,通过动态强度增长因子DIF可以反映岩石在动载条件下的强度指标；随着应变率的增大,砂岩试样单位体积吸收破碎耗能增加,试样破坏更严重,破坏程度与单位体积破碎耗能之间形成很好的对应关系。同时借助SEM扫描电镜分析冲击压缩后试样微观条件下的破坏模式,结合宏观上的破坏形态共同分析岩石的损伤特性。

Dynamic characteristics and energy consumption of sandstone under impact loading

The dynamic impact compression test of sandstone was carried out by using a split Hopkinson (SHPB) pressure bar device. The sandstone in the coal mine area is tested by different loading pressures to analyze the dynamic characteristics and energy loss of the sandstone in the coal mine area. According to the test results, The stress-strain curve reflects that the dynamic elastic modulus and peak stress of sandstone show significant strain rate effects,and the dynamic compressive strength of sandstone shows a strong strain rate effect, and there is a linear relationship between them. In dynamic impact compression, the dynamic compressive strength is higher than the static compressive strength, and the dynamic strength is increased. The factor DIF can reflect the strength index of the rock under dynamic load conditions. With the increase of the strain rate, the energy consumption per unit volume of the sandstone sample increases, the damage of the sample is more serious, and a good correspondence between the degree of damage and the energy consumption per unit volume. At the same time, the failure mode of the sample under the microscopic condition was analyzed by means of SEM scanning electron microscopy, and the damage characteristics of the rock were analyzed together with the macroscopic failure morphology.