Study On Rock-burst Prediction Of A Deep Buried Extra Long Tunnel

The tunnel in the study area possesses the regional characteristics of high in-situ stress and the engineering characteristics of large buried depth.During construction process of the tunnel,rockburst is one of the main engineering geological problems and safety hazards.Based on the engineering geological environment and initial in-situ stress field of the study area,we take the rockburst prediction research as the main line of this article,and conduct a case study on the rockburst problem of the deep and super long tunnel in the study area.The research contents and conclusions of this paper mainly include the following aspects:?1?Based on the regional geological environment,especially the geotectonic framework,geological structure and seismic activity,combined with the existing research results of regional in-situ stress field,the general situation of initial in-situ stress field of tunnel area was analyzed.On this basis,taking the engineering geological characteristics and topography of the tunnel area as the basic conditions,and the in-situ stress measurement as the basic test basis,the initial in-situ stress field characteristics of the tunnel area were analyzed by numerical fitting,which provided the initial conditions and boundary conditions for the rock burst prediction of surrounding rock.?2?Based on the Tao Zhenyu criterion modified by Zhang Jingjian and the R_b/?₁ criterion in the code for geological investigation of water conservancy and Hydropower Engineering,the occurrence of rock burst in the surrounding rock of each tunnel section in the study area was predicted,and the rock burst intensity was obtained through comprehensive analysis.It was found that serious rock burst may occur in the tunnel section with hard rock lithology and good integrity,while the tunnel section with soft surrounding rock lithology and poor integrity is less likely to have rock burst.?3?The rock burst prediction results calculated by numerical simulation were compared with the actual situation of rock burst during the construction process,and the results were close to the occurrence of rock burst during construction,which shows that the finite element numerical simulation method has a certain practical value.