Abstract：The failure of rock bridge in rock slopes is an important factor for the instability of a slope. The triaxial loading，triaxial loading-unloading and triaxial unloading tests of different length of rock bridges were carried out. Acoustic emission(AE) characteristics of rock bridge during failure process under different stress paths was described，and the influence of confining pressure and rock bridge length on the AE characteristics was analyzed. The results showed that AE events are low during the compression and elastic deformation phase. AE events increased significantly during the plastic phase，and AE counts，the accumulated energy and amplitude reached their peak during failure phase. Significant changes in AE characteristics can be used as early warning for failure of rock sample， the variation of amplitude is more sensitive than other AE indicators. Therefore the monitoring of the amplitude is more effective for the failure warning. In this experiment the rock bridge is not immediately dropped to the residual strength after the peak strength，but two stress drop occurred after peak stress，each sudden drop of stress corresponds to the AE signal peaks. The phenomenon of“quiet period”or“post-peak rebound”occurred in the two stress drop，and AE characteristics of the“post-peak rebound”and“quiet period”is similar to the plastic phase. However，its amplitude，count rate and the accumulated energy are greater than plastic deformation stage which indicates the rock crack is still in a relatively rapid rate expansion，and resulting in the failure of rock bridge. Accumulated energy from the large to small are triaxial loading-unloading，triaxial unloading and triaxial loading under different stress paths. With the increase of length of rock bridges and confining pressure AE count rate peak and cumulative energy increased，and meaning more severe failure of rock bridge.
2016, Vol. 35 
