Mechanism analysis and type determination of the rockburst of the Gaoloushan tunnel based on a study of rockburst fragments

The Gaoloushan Tunnel is a control project for Longnan city and Jiuzhaigou, Sichuan Province. With the characteristics of "three high and one large," this project is a typical representative of a deeply buried, long highway tunnel under complex geological conditions. In this dissertation, two types of rockburst in the field are taken as the research objects. By impacting a rockburst experimental system and setting different stress paths, an image acquisition system recorded the entire process of impact rockburst and slab buckling rockburst in real time to analyze the characteristics of spalling and ejection. Rockburst due to static loading was performed and compared with rockburst caused by static loading + dynamic loading. Then, the quality, scale distribution, shape, and fractal dimension of slab buckling rockburst test fragments (rockburst fragments 1), impact rockburst test fragments (rockburst fragments 2), and unknown types of rockburst fragments (rockburst fragments 3) collected in the field were compa