Subway Tunnel Shallow Tunnel Wafa Technology In Collapsible Loess Stratum, The Application Of Research And Practice

Nearly20years, shallow tunneling method has been widely applied successfully in all kinds of underground engineering, urban subway tunnel especially. But the subway tunnel project is less in collapsible loess layer. Based on the subway tunnel engineering from5th FengCheng Road to the municipal library on the first period engineering of Xi’an subway line2, this paper summarizes the application and practice of the shallow tunneling method on the subway tunnel in collapsible loess, on construction methods and processes and the site monitoring and management theoretical analysis system. The main research contents:(1)According to the project features including of the third class (serious level) in the collapsible loess ground, high underground water level, various tunnel sections, strict control requirements for surface and vault subsidence, serious double construction interference, and to follow the basic principles of shallow tunneling method d, this paper discusses the reasonable construction method and process for the different tunnel sections.(2) Because the collapsible loess has the characteristics which is low intensity, big deformation, poor stability and vulnerable to large deformation after tunnel excavation, on use of the site monitoring method, the paper researched tunnel deformation on the surface subsidence, tunnel arch top settlement, horizontal convergence and the characteristics and laws with the tunnel construction process on internal stress of steel support and surrounding rock stress. And according to the test results, through the information feedback, the site construction safety guidance is realized.(3) According to the arch crown cover of collapsible loess tunnel is shallow, located in the city, the traffic is busy, the space of the ground and underground construction is narrow and construction management characteristics on more parallel flow operation working faces arc needed, this paper discusses the mode of the modernization construction organization and management for every key construction process on use of the advanced computer management software system (P3) and controlled comprehensively the construction progress, quality, cost, safety.(4) According to the basic control, production control and overall control, choose the proper quality system factors. Based on the principle of analytic hierarchy process (AHP), this paper studies the mechanism for management level evaluation of project quality on organization management system operation, quality control and construction quality in the collapsible loess tunnel construction process.The practice achievements and experience of the engineering may provide preference for the similar engineering or similar projects, have Experience and promoting significance to the shallow tunnel construction and management in soft soil layer in city.