Damage Evolution of Rock and Acoustic Emission Study about Deep Diversion Tunnel in the Excavation Process

Abstract

In order to reveal the scale, location and damage mechanism of depth underground tunnel this was excavated. Experimental study in the project scenes where more than 2500 meters underground, makes use of the acoustic emission technology, and monitor the whole process of the Jin ping 2# experiment hole excavated, researches combining the acoustic emission and the surrounding rock damage evolution process. The results indicate that: The acoustic emission event and the energy parameter can reflect rock internal stress field change, according to above can determine the stable degree of rock mass; The emergence, development of rock burst and unstable rock produce mostly occurred in the place where surrounding rock stress was smaller or have been discharged when great depth underground tunnel was excavated, and its direction was along the direction of roadway excavation, from the part where rock stress was smaller develop to tunnel in wall; And main damage or cracking is developed in 7m range: 3m locations the most severe after free face. Relaxation and damage range of surrounding rock are 2m, 2~5m, and 5~12 m far from tunnel wall, Rock mass abscission is caused by the increasing of rock damage vibration amplitude, and the rock mass falls off is also an energy release’s process.