Research on grades identification and prevention of rockburst in deep and long buried tunnels of Dadu River to Minjiang River Water Diversion Project

To address the high risks of rockburst caused by deep burial, high crustal stress, and numerous brittle and hard rock masses in the diversion tunnel groups of Dadu River to Minjiang River Water Diversion Project, research was conducted on rockburst assessment and prevention measures for the project.This paper reviewed typical characteristics of rockburst in domestic tunnels, summarized experiences in recent years regarding tunnel excavation and construction management measures.Based on geological mapping and test results from the feasibility study phase, the project s rockburst classification was evaluated by using rock strength and crustal stress two core indicators to predict rockburst length and severity levels.The results showed that rockburst occured in Erlang Mountain, Laojun Mountain, Qianchi Mountain, and Lianhua Mountain four tunnels, with mild, moderate, and severe rockburst proportions of 4.80%, 6.88% and 2.39%, respectively.It is recommended to adopt prevention measures such as "optimized techniques, new materials, and stress relief" for drilling and blasting methods, as well as "equipment upgrades, graded control, and strong management" for TBM methods.The research results provided a systematic prevention plan for rockburst hazards in the Dadu River to Minjiang River Water Diversion Project, and could be a reference for similar projects.