Study On Monitoring Measurement And Support Result In Large-span Tunnel

With the rapid development of transportation demands as well as the long and large tunnels constructed both at home and abroad, bell-mouthed road tunnels with large -span appear one after another in the urban transportation. Due to the tunnels' large span, more and more engineering Problems are aroused, such as supporting forms, construetion methods, and stability of surrounding rocks. So far, there has been very little research on large-span tunnels, let alone the related engineering experience on bell-mouthed road tunnels with large span .As a result, Stress analysis and monitoring measures of surrounding rock on Bell-mouthed section with complex stress state are more important. Combined the Tianhengshan tunnel of Haerbing,the stress and the displacement of the bell-mouth' surrounding rock and the supporting Structures are studied by theories analysis, field measurement andnumerical simulation, and the data of monitoring measures are analysedand feedbacked. The main research is as follows:First, field test was taken to tunnel structure mechnical state and stability. The content of monitoring measurement included surrounding rock pressure, interior displacement of surrounding rock, initial support and clearance convergence, steel arch stress, shotcrete stress, anchor axial force, contact pressure between primary support and secondary lining, secondary lining concrete stress and secondary lining clearance convergence and so on. Meanwhile,some problems coming across during arrangement and implementation of monitoring measurement was also taken for considering and discussion.Secondly, characteristics of deformation and lining's stress on primary support and secondary lining were analyzed by numerical simulation for construction process using finite elements analysis software (MIDAS/GTS).Finally, through the comparative analysis of field monitoring data and finite element numerical simulation results, the evaluation was taken on tunnel surrounding rock's stability and support lining structure's safety.Monitoring data and calculation results show that, in large-spanTunnel, steel arch and shotcrete are the main force structure, especially steel arch , significant role. Second lining of the security, good working conditions, there were enough safety reserves...