Study On Prediction By Stages And Control Technology Of Rock Burst Hazard Of Daxiangling Highway Tunnel

These years as the development of China's economic, the needs for infrastructures, especially for transportation are in great demand which result in traffic engineering in a fast progressing. Deep-lying tunnel with large section and long length appears widely. These kinds of tunnels are often difficulty to build, so they are tend to become a control works of the highway road. The most unique feature of the deep-lying tunnel in the condition of high geo-stresses is rock burst while excavating in hard rock. With the progress of engineering construction, the forecasting of rock burst and the safety of construction becomes an outstanding problem in tunnel engineering.This paper takes Da Xiangling tunnel in YaLu expressway as engineering background to research the prediction methods for rock bursting and the controling of rockburst during constructing. And the follow achievements are obtained:First, rock burst prediction in Da Xiangling tunnel design stage:Through studying on regional initial in-situ stress field by FEM numerical simulation and multiple regression analysis, it's distribution law is obtained from the site measured in-situstress data.According to the segments with rock bursts of different grade, predicted by the maximum principal stress along with tunnel axis, various three-dimensional numerical models are respectively established,In order to predict the Level and Position of rock burst from the perspectives of stress and energy.Secondary, rock burst prediction in Da Xiangling tunnel design construction stage:Based on the compressive strength and secondary stress of surrounding rock obtained by field surveing, rock burst in unexcavated sections is predicted by several criteria. It is found that Turchaninov criterion is more suitable for tunnels in strong horizontal tectonic stress field in contrast with other criteria.More samples of rock burst turn up in database that invole levels of rock burst and the values of its correlative factors along with the excavation being driven forward, the prediction for 20m unexcavated Segment is more accurate by BP artificial neural network.Third, the construction control methed for rock burst segment of Da Xiangling tunnel: Applying the numerical simulation method, optimized cyclical footages are obtained for various levels of rock burst, by means of the comparative analysis of tunnel inner perimeter stress and high energy density or stress concentration zone. The weakening effect of stress or energe releasing holes to high energy density or stress concentration zone is analyzed and simulated in order to determine parameters of releasing holes on the condition of optimized cyclical footages.