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为研究含孔洞的岩石在动静载荷作用下的细观结构损伤破坏规律,对含圆形和方形孔洞的花岗岩试样分别进行不同轴向预静载、相同冲击动载下的霍普金森压杆试验,并对动静加载前后的试样进行核磁共振(NMR)测试,得到花岗岩试样的弛豫时间T2谱曲线、核磁孔隙度和核磁共振图像等特性参数。试验结果表明,随着轴向预静载的增大,花岗岩受动力扰动作用后的T2谱峰值、谱面积以及核磁孔隙度均逐渐增大,岩石内部的损伤程度不断加剧,且当预静载大于10 MPa时,动力作用下岩石的损伤劣化特性表现得越来越敏感。对比分析含圆形和方形孔洞试样的核磁共振特性试验结果,发现相同荷载条件下方形孔洞试样的损伤程度均大于圆形孔洞试样,这一规律在预静载大于10 MPa时表现得更突出。核磁共振图像直观反映出孔洞花岗岩在动静载荷作用下岩石内部的孔隙结构和损伤劣化的演变规律,为揭示深部硬岩巷道的动力破坏机制提供有意义的试验指导。
In order to study the damage and destruction of meso-structure of rock with holes under static and dynamic loads, the granite samples with round and square holes were prestressed in different axial directions respectively. The Hopkinson pressure bar under the same impact load The magnetic resonance (NMR) tests were performed on the samples before and after the static and dynamic loading. The T2 relaxation time curves, nuclear magnetic porosimetry and NMR images of the granite samples were obtained. The experimental results show that with the increase of the axial pre-static load, the peak value of T2 spectrum, the spectral area and the nuclear magnetic porosity of granite are gradually increased after the disturbance of dynamic force, and the damage degree inside the rock is increasing. When it is more than 10 MPa, the damage characteristics of rocks under dynamic action are more and more sensitive. Comparing and analyzing the results of the test of the nuclear magnetic resonance with circular and square holes, it is found that the damage of the square holes is greater than that of the circular holes under the same load. This law shows when the pre-static load is more than 10 MPa More prominent. Nuclear magnetic resonance images intuitively reflect the evolution of pore structure and damage deterioration of porous granite under dynamic and static loads and provide meaningful experimental guidance for revealing the dynamic failure mechanism of deep hard rock roadway.