Study On The Type Selection Of Shield And Tunneling Parameters Of Shield Method In The Composite Stratigraphy Of The Changsha Metro

As the widely adaptable in defferent soil stratum and the high safety factors in the construction of cevel,Shield method is now playing an increasingly important role in the construction of metro tunnels.There was few experience of shield construction in the composite stratum of Changsha area.Based on the subway tunnel engineering of Jintai sqware station to Wanjiali Road station, it has been Systemly studied and summaried on the control of shield tunneling, parameter management, field monitoring to get the result of the shield method construction in complex strata of tunnel construction control technology. Main content:(1) In the concrete condition of10construction shuttle of Changsha Metro Line2, the influencing factors of the shield machine selection has been discussed on the stratum penetration coefficient, the pellet gradation number, the stratum category, soil residue processing and the economic efficiency. The type of the shield was chosed by anlysing the defferent tunnulling method in soild between the earth pressure balance shield and Slurry balance shield.(2) Construction parameters has been analysed by mathematical statistic method under complex formation including driving speeds, total thrust and torque of cutterhead, cutterhead speed, explored the relationship between driving parameters in different formations, analysis of the factors affecting parameters of, and gives the empirical formula.(3) Through the rational selection of shield tunneling parameters, data normalization and curve fitting treatment, a summary analysis of the interaction between the thrust, torque, and formation, draw the vertical variation of the tunneling parameters along the interval and with the correlation between the strata(4) According to gather the statistics of the surface deformation, it is concluded that the the regular pattern of the lateral surface and the longitudinal surface.And also discussed the main causes of the surface deformation.(5) By numerical simulation of shield tunneling, combined with the comparison of monitoring results, confirms reliability of the results. According to different stratigraphic model, on surface subsidence, formation and segment of the stress change rule summary and further analysis of the effect of different load on the ground and thrust in different formations of a proposed value.