Experimental study on acoustic emission characteristics of granite tunnel rock burst under different lateral pressure

An experiment is carried out to simulate granites tunnel rock burst under unloading with biaxial rigid servo-controlled system.The acoustic emission(AE) system produced by American physical acoustics corporation is used to collect data of the AE in the process of rock burst synchronously.The influence of different lateral pressure on tunnel rock burst AE is studied.The result shows that in the conditions of biaxial,axial pressure and lateral pressure difference is large,due to excavation unloading load effect more obvious,the inwall of the hole first ejects rock debris is earlier;The rock burst release of total energy gradually were increased,the cumulative energy of AE into the "steep" stage of time lag;The AE ringing count rate can well reflect the stress adjustment of the hole process of rock burst,the AE ringing count rate fluctuation patterns gradually from "lower level fluctuation and the emergence of a number of jump points" to "high level fluctuation and the emergence of a certain number of drop point" transformation at the later stage of the loading with the increasing lateral pressure;Tunnel rock burst process that produces a tensile rupture and shear rupture combined with the RA and AF values of acoustic emission,with the increase of lateral pressure,shear failure of rock burst in proportion gradually increased.The results provided the experimental basis for the prediction and control of rock burst.