节理角度对岩石材料的动态响应影响研究

Research on the effect of joint angle on dynamic responses of rock materials

为探究一维动载下节理角度差异对岩石动态响应的影响规律,利用分离式霍普金森压杆(SHPB)对预制完整试件及7组不同节理角度的水泥砂浆试件进行冲击试验;试验前后利用核磁共振成像(NMR)系统对试件的孔隙度及孔径分布进行检测。从动态强度、能量耗散和细观损伤等方面系统地分析节理角度对类岩石材料动态响应特征的影响规律,结果表明:节理角度由0°增加至90°时,试件峰值强度呈先降后升的变化趋势,当节理角度处于45°~60°时,相对于其他节理角度试件更容易发生破坏;试件的能量吸收情况与损伤呈正相关,试件的孔隙变化率与能量吸收情况均随节理角度增加呈倒"U"型变化,节理角度45°~60°范围内试件吸收能量最多,冲击前后孔隙变化率最为突出,可知荷载最有利于破碎的作用方向与节理成角为30°~45°。

To explore the influence of the joint angle on the dynamic responses of rocks under one-dimensional dynamic load,the split Hopkinson pressure bar(SHPB) was used to carry out impact tests on prefabricated complete specimens and 7 groups of cement mortar specimens with different joint angles. Before and after the tests,nuclear magnetic resonance(NMR) imaging system was used to detect the porosity and pore size distribution of the samples. The influence of the joint angle on the dynamic response characteristics of rock-like materials was systematically analyzed from the aspects of dynamic strength,energy dissipation and meso-damage. The results show that the peak strength of the specimens first decreases and then increases when the joint angle increases from 0° to 90°. The specimens with a joint angle ranging between 45° and 60°are more likely to be damaged than those with other joint angles. The damage of the specimens is positively related to energy absorption. Both the porosity rate and the energy absorption of the specimens present an inverted "U" shape with the joint angle. The specimens with a joint angle ranging from 45° to 60° absorb the most energy,and the change rate of the porosity before and after impact is the most significant. It is concluded that the angle between the directions of the load and the joint,most conducive to crushing,is 30°-45°.