Optimizeresearchon Constructiontechnology For Vriable Large Cross-sectiontunnel Of Urban Metrocrossover Area

The construction of large cross-section subway tunnel with complex structure and varied section in the weak stratum with abundant water,poor stability of the formation and rich groundwater lead to great difficulties in construction;Due to the large number of buildings and underground pipelines in the urban area,the construction of deformation control standards are very strict,it is put forward higher requirements on the construction of large cross-section tunnel.In order to ensure the safe and rapid construction of the tunnel,it is necessary to optimize the existing construction technology.Based on the Beijing metro line 14 Ping LeYuan Station-JiuLongShan Railway Station crossing line project,mainly introduces the construction method and key technology of the large span tunnel with complex section in the weak stratum with abundant water,and puts forward optimized construction schemes.Through the analysis and calculation to the construction process by using numerical simulation software and compared with the measured data,verify the rationality of the optimization schemes.Firstly,the transition between different sections of the tunnel and the construction of the initial support to the secondary lining is the key to the construction of large cross-section tunnel.In order to achieve the construction of transition area quickly and securely,this paper puts forward the construction method of adding horizontal channel,and the scheme of temporary support removal of large cross-section tunnel is optimized.The finite element software Midas/GTS is used to simulate and calculate the stratum deformation and stress of the structure during construction,and find out the key link of construction control.Secondly,numerical study on the two kinds of construction method of the side drift method and center diagram method on triple arch tunnel with large cross-section,and carries on the calculation and comparison to these two kinds of constructions method from the aspects of surrounding rock deformation and stress,the stress of the supporting structure and the safe and rapid construction.Through the study on the numerical results and the measured data,the side drift method is selected as the construction scheme of the triple arch tunnel in this project.The research and optimizationin this paper to the construction technology provide guidance for practical project,ensure the safe and efficient construction of the project,and also provides theoretical basis and engineering experience for similar projects.