Evolution characteristics of rock fracture under uniaxial loading by combining acoustic emission and CT imaging
WANG Changbin1，2，CAO Anye1，3，JING Guangcheng1，2，CAI Wu2，ZHU Guang?an1，2，LI Jing1，2，CHEN Tian1，2
(1. School of Mines，，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；2. State Key Laboratory of Coal Resources and Safe Mining，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；3. Key Laboratory of Deep Coal Resource Mining，Ministry of Education of China，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China)
Abstract：Characteristics of fracture evolution inner loaded rock are significant for understanding rock failure mechanism. In this paper，acoustic emission(AE) and CT imaging techniques were combined to perform CT inversing calculation for mudstone samples in different loading speeds， the characteristics of velocity distribution in rocks in different loading phases were analyzed，and relations between velocity evolution and macro- and micro-fractures of rocks were studied. The results show that：(1) In initial loading phase，the variation of velocity scale in rock samples is minor，and the velocity anomalies regions are small and distributed scatteredly. When loading increases，the velocity scale grows and the velocity anomalies regions are enlarging continuously. Before failure，the velocity scale further increases and large areas of low velocity regions connect mutually. (2) The macrofractures position in rock samples after failure has a positive corresponding relation with the region of low wave velocity and affluent wave velocity anomalies，indicating that when approaching failure，numbers of sprouting and growing microfractures lead to rapid expansion and connection of low velocity regions，and the regions of particles around microfractures represent high velocity status caused by compression；(3) In initial loading phases，locations of the emerging micro-fractures correlate well with low velocity regions. When loading increases，numbers of microfractures sprout in the regions of low velocities and affluent velocity anomalies. Before failure，dense areas of microfractures expand and connect，which correspond with the macrofracutres of rock samples. (4) There is a similar AE events distribution before and after inversing calculation，which proves the accuracy of the initial AE locations and the reliability of CT imaging results.
2016, Vol. 35 
