Study On Excavation Scheme Of Large Span And Small Spacing Tunnel Group At Badaling Station Of Beijing-Zhangjiakou High-speed Railway

With the rapid development of China's economy,the transportation industry has entered a period of high-speed development,and more requirements have been placed on the construction of tunnels.The construction of tunnels with large cross-sections and small net distances will be more and more.However,due to the large cross-section and small-distance group tunnel tunnel construction,the mutual influence is large and the structure form is complex and diverse,which will inevitably bring great problems to the design and construction of the tunnel.Therefore,the research on the group tunnel tunnel excavation technology is very useful.necessary.This article relies on the three-segment separation section of the Beijing-Zhanghai high-speed railway large-span and small-spacing railway tunnel,and uses a combination of theoretical analysis,numerical simulation and field test to study its different construction sequences and methods.The main research contents and results are as follows:(1)Collect on-site monitoring data.In the three-segment separation section of the Badaling Group Tunnel Tunnel of Beijing-Zhanghai High-speed Railway,the construction sequence of excavating the left and right two holes and then excavating the middle hole is adopted,and the upper and lower steps are used for construction.The reliability of the numerical simulation is verified by comparing the results of on-site monitoring data with numerical analysis.(2)Using theoretical analysis,the influence of the group tunnel construction was studied.Based on this,numerical simulation was used to study the influence of different construction sequences on the blasting vibration speed and settlement of the middle rock wall.The principle of mutual influence was explored.The group cave tunnel must ensure the conclusion of the stability of the middle rock wall.(3)Relying on the Badaling section of the Beijing-Zhanghai high-speed railway project,using numerical simulation to analyze the factors affecting the blasting vibration,and comparing the vibration speed of the middle rock wall and the previous tunnel lining under different blasting construction methods and different construction sequences,The vibration intensity rankings of different blasting construction methods and different construction sequences were obtained;and according to the blasting vibration safety standards,the construction sequence of excavating the left and righttwo holes and then the middle hole was determined,and the up and down blasting construction was adopted to suit the large span and small spacing group The blasting construction plan of the tunnel.(4)Relying on the Beijing-Zhanghai high-speed railway Badaling section tunnel project,using numerical simulation,the factors affecting the vault are analyzed,and the settlement and stress values of the vault settlement under different blasting construction methods and different construction sequences are compared respectively to obtain Based on different blasting construction methods and settlement and stress sequence of different construction sequences,the construction sequence of excavating the left and right holes first and then excavating the middle hole,as well as the use of upper and lower bench blasting construction are suitable for the blasting construction scheme of large-span and small-distance group tunnels.(5)Relying on the Badaling section tunnel project of the Beijing-Zhangjiazhuang High-speed Railway,the vibration speed of the surrounding rock in the middle rock wall under the synchronous blasting construction of the upper and lower steps is monitored.The on-site monitoring results are basically consistent with the numerical simulation results;this guarantees the reliability of this study The quality and authenticity will be of reference significance for the similar large-span and small-spacing group-cavity tunnel projects in the future.