Abstract:Acoustic emission(AE),which is produced by the microcracks occurrence or growth,is an ubiguitous phenomenon associated with brittle fracture in many materials such as rock and concrete. AE technique,which is better than other methods,can monitor the real-time microfractures developed in the rock sample continuously. In this paper,AE technique was employed to study rock failure process. The rock failure process was investigated by using 10 granite specimens(70 mm×70 mm×150 mm),and AE sensors were surface mounted. A simplex location algorithm allows event location of first arrival times to be determined by AE sensors that are applied to crack initiation and propagation process. Also,the crack spatial evolution mode with loading time and stress changing during the total loading process was analyzed. The experimental results are displayed as follows:(1) AE activity represents different characteristics with the loading time and stress changing during the total loading process;(2) the quantity of AE events was few in the initial loading up to crack initiation when initial crack generated by AE events apparently increased;and (3) AE events were in quiet period after crack appears before crack propagation,and AE activity sharply increased from crack stable propagation up to crack unstable propagation,especially in crack unstable propagation step,thus AE events reach to the most quantity in the division strain. For the “quiet period”,when appeared after initial cracks are generated,cracks have no direct propagation with stress(strain) changing,and when loading energy accumulates to some extent,initial crack started to propagate. That is to say,after initial cracks are generated,the inner stress field needs to seek new stress equilibrium in the rock samples. After stress field reaches to a new stress equilibrium,initial crack propagation continues. Meanwhile,when rock fails,stress is no completely released. After stress arrives to a new stress equilibrium strength,rock will fail. The AE location results will also directly reflect the spatial position,direction and spatial curved face of crack propagation in the rock sample,which is very significant to the mechanism of rock failure.