| TBM construction technology is widely used in the construction of tunnel engineering due to its advantages such as fast driving speed,high degree of mechanization,and low labor intensity.However,the poor adaptability of TBM to bad geology has greatly restricted the further development of TBM construction technology.Based on the ABH project and the Yinhanjiwei project,this paper is aimed at the rockbursts encountered in the construction of TBM and the risk analysis and prevention and control technology of rockbursts in TBM construction are studied.In this thesis,the characteristics of different types of rockbursts and their impact on construction are obtained by analyzing the conditions of rockbursts at the site.The accuracy of rockbursts predicting by microseismic monitoring system is counted.The improved operating conditions-management factor risk assessment method is used to carry out TBM construction rockbursts risk assessment on the ABH project and the Yinhanjiwei project,and the rockburst risk level of construction under different rockburst prediction results is obtained.Finally,combined with the characteristics of rock burst prevention and control in TBM construction,the classified prevention and control technology of rock burst in TBM construction is proposed.The main research results of this paper are as follows:(1)The impact of rockbursts of medium and below grades on construction is not significant,mainly manifested in the decrease in construction speed,while the impact of a single rockburst on the construction speed is not obvious.Usually,a large number of rockbursts may have a significant impact on construction.Moderate to intense rock bursts will accelerate equipment wear or damage,threaten personnel safety,and greatly reduce construction speed.Strong rock bursts can damage equipment and hurt personnel.A single strong rock burst can cause large-scale shutdowns and pose a huge threat to construction.(2)The impact of rockburst on construction speed mainly depends on the excavating speed and pure excavating time.From the perspective of excavating speed,the more suitable the rock’s compressive strength is for TBM excavating,the more obvious the impact of rockburst on excavating speed.From the perspective of pure excavation time,the type I and II surrounding rocks are greatly affected by rock bursts,and the type III and IV surrounding rocks are relatively less affected by rock bursts.(3)In the Yinhanjiwei project,the lag time of rockbursts is mostly within 24 hours,and the distance from the tunnel face is generally within 15 meters.The length range of a single rock burst is usually less than 5 meters,and it is located 120 degrees above the tunnel.When the rockburst level is high,reducing daily advance will not change the lag time and range of impact of the rockburst,but it can reduce the distance from the rockburst to the tunnel face.(4)When the project has moderate to strong rockburst hazards and strong rockburst hazards,it is necessary to use a microseismic monitoring system to provide early warning of rockburst hazards.When the project does not have medium to strong rockburst and strong rockburst risks,you can decide whether to introduce a microseismic monitoring system based on the actual situation of the project.(5)When a microseismic monitoring system predicts no rockburst,it is a generally low level danger.When the microseismic monitoring system predicts a slight rockburst,a mild to moderate rockburst,or a moderate rockburst,that is a major danger.This is very dangerous when the microseismic monitoring system predicts a moderate to strong rockburst or a strong rockburst.(6)The classified prevention and control technology of rock burst in TBM construction is put forward and the construction effect is verified.From the perspective of equipment optimization and flexible support,a powerful optimization scheme for rockburst prevention technology was proposed.The research of this paper has certain guiding significance for the evaluation of TBM construction safety risk,construction schedule impact,and what kind of rock burst prevention and control strategy and technology to be adopted. |
