The Study Of Large Section And Super-closely-spaced Subway Subsurface Excavation Tunnel Construction Technology

Along with our country urbanization process accelerating, urban transportation is being more and more crowded, which seriously restricts the further development of economy and society. Urban rail transit, especially the underground railroad, as a new means of transportation provides an effective method to relieve the crowded urban transportation.The tunnel station of Ying-Wan Town in Changsha metro line.2, which is so big underground construction using the mining method ever built in Changsha, is of big tunnel profile, small distance rock wall and so on. Combined with the actual construction situation, This thesis carries out the research mainly on the aspects of field monitoring and finite element numerical calculation. The main work of this thesis is dealt with three following respects:(1) Site monitoring and analysis of the displacement of the small distance rock wall in parallel tunnel and the tress of the steel arch frame in bi-directional tunnelSite monitoring of displacement of small distance rock wall is made at the typical sectional and the tress monitoring of the steel arch frame is made in the bi-directional tunnel constructed by the double drift method. Further more, some analysis and conclusion is made based on this Site monitoring.(2)Numerical simulation of mined tunnel excavationExcavation on both sides drift first, and then excavation on the middle pilot drift is the traditional six steps of the double-side-wall heading constructing method. Heading method, namely the excavation on the first part elaborated on both sides, then the middle pilot drift excavation on the parts, and then the excavation under part elaborated on both sides, the last part of the middle pilot drift excavation. Establish Finite element model for simulating optimization of double wall heading construction method, and analysis of the results of numerical calculation, the conclusion will be getting:that Changsha regional geological conditions underground cut tunnel section super small clear distance using optimized double wall heading construction method is feasible.(3)Stability analysis of the small distance rock pillars 2-D model of parallel tunnel is built. With respect to the complex situation in the neighborhood tunnel, the main factors such as excavating sequence, construction method of the double line tunnel and so on are also taken into account.