循环动力扰动下花岗岩细观损伤特性试验研究

为研究循环动力扰动下岩石细观损伤特性,本文选取花岗岩为研究对象,利用分离式霍普金森压杆(SHPB)进行循环冲击试验,并结合核磁共振系统(NMR),得到了循环动力扰动后花岗岩孔隙度、横向弛豫时间T₂谱分布以及核磁共振图像(MRI).试验结果表明:在岩石弹性极限范围内,动力扰动结束后,岩石材料孔隙度降低;初始与最终横向弛豫时间T₂缩短,循环扰动过程促使了小孔隙生成,大孔隙尺寸与数量减小;孔隙度降低不意味着所有类型孔隙的数量均减少,相反小孔隙数量是增加的,大孔隙数量减少是动力扰动后花岗岩孔隙度降低的根本原因. 

Experimental study on microscopic damage characteristics of granite under cyclic dynamic disturbances

To investigate the microscopic damage characteristics of rock materials under cyclic dynamic disturbance, granite was chosen as the research object, and the split Hopkinson pressure bar (SHPB) was used to outperform the cyclic impact test. Besides, with the nuclear magnetic resonance (NMR) technique, the porosity, crosswise relaxation time T₂ distribution and magnetic resonance image (MRI) of the rock sample were obtained. The results show that within the range of the rock's elastic limit, the porosity reduces after the dynamic disturbance. The initial and final transverse relaxation time T₂ shortens, which indicates the process of cyclic disturbance causes the formation of small pores, where the size and number of large pores decrease. The decrease of porosity does not mean that the number of all kinds of pores decreases; on the contrary, the number of small pores increases, and the decreased number of large pores is the root cause which leads to the decrease of porosity after dynamic disturbance.