Acoustic emission features of granite from different rockburst areas in Sangzhuling Railway Tunnel.

In order to investigate the acoustic emission (AE) features of rocks in different (medium and strong) rockburst areas, the Sangzhuling Railway Tunnel granite in China was taken as an example, the mineral composition of rocks in different rockburst areas was analyzed by using XRD (X-ray diffraction) method. The Original rock cores of different rockburst areas were processed into standard rock specimens (diameter 50 mm, height 100 mm) in different directions (transverse, oblique and longitudinal). AE feature parameters (event number, ringing count and energy) of standard rock specimens during indoor uniaxial compression test were obtained by using AE technique. The variation law of AE feature parameters of rocks in different rockburst grade areas was then analyzed. The AE features of failure precursor of rocks in different rockburst areas were therefore discussed. It shows that compared with rocks in medium rockburst area, the content of quartz and feldspar of rocks in strong rockburst area is high, while the content of biotite is low; the rock in the strong rock burst area released more energy during the failure process with about 2-3 times that of the rock in the medium rock burst area; the cumulative ringing curve of rock in medium burst area is a stepped type, while the cumulative ringing curve of rock in strong burst area is the smoothed type; the end of the second and first AE quiet period may be regarded as the failure precursor of rocks in medium and strong rockburst area, respectively. The results presented herein are important for understanding the mechanisms of rockburst.