Study On The Prediction And Prevention Of Rock Burst In Highway Tunnel

Egan tunnel of Daguangnan highway is an extremely long tunnel and has the characteristics of extreme length, deep carving and high strength of surrounding rock. The geological environment is quite complicated in this region. Therefore, the prediction and prevention of rock burst become the most important problem when the tunnel being excavated.The rock burst is fairly complicated and it depends on many factors. The timely prediction of rock burst is especially difficult in the process of construction. Until now, there has no set of mature method all around the world which could make timely and accurate prediction of rock burst.Study on a more convenient and efficient method for the timely and accurate prediction of rock burst. During the tunnel constructing, combined with the numerical simulation analysis, this method is also for the effective comparison of the preventive measures of rock burst.Firstly, the experiments have been carried out at the different mileage of the tunnel using the selected method. The experiments analysis is taken, the probability of the rock burst can be obtained and the preventive measures of rock burst are suggested. Secondly, the frequency and intensity of rock burst can be obtained through the statistics at the construction site. Finally, according to the geological environment and physical mechanical properties of the surrounding rocks, a three-dimensional model is proposed to simulate the change of the crustal stress by using FLAC. The effectiveness of the methods for anti-rock burst has been analyzed. And the relationships among experiments, statistics and numerical analysis are also analyzed.Through the above analysis for the Egan extremely long highway tunnel by using the above method, it is found that: the crustal stress distribution after the excavation of the tunnel obtained from the numerical analysis agrees with the actual situation. Rock burst is the result of integrated crustal stress from three directions, among themσx (direction x is along the axis of the tunnel) plays the main role. Finally, a conclusion can be drawn that it is convenient to use the method provided in this thesis in the timely and accurate prediction of rock burst during tunnel construction. The on-site prediction spot should be the rock located near the tunnel heading at the arch springing.