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Abstract The foundational mechanical behavior and acoustic emission(AE) characteristics of intact Beishan granite under different stress conditions are investigated，with the MTS815 Flex Text GT rock mechanics test system and PCI–II AE test system. The obtained direct tensile strength is 9.53 MPa，which is 1/17 of the average uniaxial compressive strength. Under the tensile stress condition，the AE events appear much later and mainly concentrate at the failure stage，since there is not a closing process of original microcracks. At the post-peak strength，the constantly increasing AE events indicate that the granite specimen does not break immediately and still has a certain tensile strength. Under compressive stress condition，AE events appear at initial loading stage，and increase continuously with loading stress，representing the initiation and propagation of the stress-induced microcracks. With the increase of confining pressure，the granite exhibits a more significant ductile at the peak stress，and a nonlinear mechanical behavior at the same time，with a progressive propagation of the microcracks(damage)，which leads to more intensive accumulated AE events. The significant ductile characteristics especially before the failure stage are obviously different from those of other common granite. The achievements of the work about mechanical behavior and AE characteristics of intact Beishan granite under different stress conditions are essential to the further study on the damage evolution mechanism of Beishan granite under different stress conditions.
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Received: 18 April 2012
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2012, Vol. 31 
