Water Resources and Power

Aiming at the failure mechanism of rockburst during the excavation process of deep buried underground tunnel,this paper takes the rockburst phenomenon occurring in the diversion tunnel of Qizhalhaal Hydropower Station as the research object.Based on the laboratory test,a two-dimensional discrete element model of two different cross-sectional caverns with circular and gate hole types is established.The occurrence of rockburst phenomenon under different crosssection shapes is analyzed,and the failure mechanism of rockburst is explored.The results show that there are some differences in the form and location of rockburst failure in different excavation-shaped caverns;The lateral pressure coefficient has a great impact on the stress concentration area after excavation of the cavern;The rockburst failure shows a gradual serious trend with the increase of the lateral pressure coefficient;The stress required for rockburst failure in a circular cavern is relatively small,and it is more stable than the city gate cave type cavern;The city gate cave type cavern has a relatively weak area where rockburst is likely to occur at the intersection of the side wall and the floor,and it should be reinforced during construction.