Analysis of Rock Mass Mechanical Response and Rockburst Tendency During Excavation of Deep Buried Chamber in High Ground Stress Area
In order to explore the rock burst problem induced by the unloading process of deep buried tunnel excavation in high stress areas,taking the cavernous spillway of Shuangjiangkou Hydropower Station as the engineering background,the spatiotemporal distribution characteristics of rock burst microseismic events during the tunnel excavation process were analyzed based on microseismic monitoring technology,and the risk location of rock burst disasters in the tunnel was determined.The initial stress field of the tunnel was constructed using finite element software,and the cloud map of the tunnel damage area obtained from the finite element method was compared and analyzed with the on-site microseismic monitoring results.On this basis,the deformation and stress changes of the spillway in the tunnel were analyzed,the deformation mechanism of the tunnel was revealed,and the level of rock burst in the tunnel was discussed.The research results indicate that in the early stage of tunnel excavation,the left arch shoulder position undergoes deformation first;with the large-scale excavation and unloading of the tunnel,the sudden release of stress on the left side wall is prone to brittle failure;In the later stage of tunnel excavation,the intersection of the left side wall and the bottom plate resulted in stress concentration leading to the failure of the surrounding rock to split.Meanwhile,according to Barton's criterion and Rb/σ1 criterion and Tao Zhenyu's criterion,rock burst analysis is conducted on the positions of the arch foot,arch shoulder,and arch crown of the tunnel.The arch foot position is prone to serious rock burst phenomena during the excavation process,and the arch shoulder and arch crown positions may experience slight or moderate rock bursts.
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