Modifying rock burst criteria based on observations in a division tunnel

Rock burst is a geological hazard that occurs when hard and brittle rock mass is excavated under high in situ geo-stress or in the presence of high-stress concentration. This paper presents a case study of rock bursts that occurred in the Qirehataer Diversion Tunnel excavation project in gneissic granite. The tunnel is 15.66 km long at a maximum depth of 1720 m below the ground surface, many rock bursts occurred over the total length of 4071.5 m. Detailed geological settings, in situ and laboratory test data, as well as the method that is used to interpret the test data to obtain the threshold parameters used for classification criteria, are introduced. A database consisting of 29 rock bursts and classifications using the three criteria is compiled. Based on the database, the criteria are modified to obtain consistent classifications. Evaluation of the modifications and application of the modified criteria to rock bursts in a case study indicate that the consistency of classifications is greatly enhanced.