辉长岩短棒试件中的断裂过程区(FPZ)

Fracture Process Zone (FPZ) in Short-Rod Specimens of Kallax Gabbro

本实验研究采用国际岩石力学学会建议的V型切口短棒岩石断裂韧度试件,岩石为瑞典的卡莱克思(Kallax)辉长岩,试件直径为71.4mm。把试件加载至不同的载荷水平后,向裂纹注入荧光渗透剂;然后,把试件切成厚度为4～8mm的岩片并测量每一岩片上的裂纹长度,以获得各试件的裂纹前端曲线。结果表明,裂纹前端曲线可以被认为是直线。分析表明,根据卸载切线柔度估计的裂纹长度近似地等于裂纹的无表面力段长度,根据割线柔度估计的裂纹长度等于测量的裂纹长度;两者的差值近似地等于FPZ(Fracture Process Zone)长度,其值约为10mm.

The author used the chevron notched short-rod specimen for fracture toughness test suggested by ISRM in his experiment. The specimen is Kallax gabbro from Sweden with diameter of 71.4mm. Under a certain load level, flourescent penetrant is injected into the crack of specimen. It is then divided into some slices with 4～8mm thick and length of each crack is measured to obtain the crack front in the specimen. It is found that crack fronts can be considered to be straight. Crack length estimated by unloading tangent and secant compliances are approximately equal to the traction-free segment of crack and the measured crack length respectively. The difference between them equals the length of FPZ approximately which is about 10mm.