Research on the Effect of Zero Distance Underground Excavation through Existing Stations to Control Settlement
Research purposes:The construction of transfer nodes for new subway stations with zero distance underground excavation and sinking control through existing stations will inevitably have an impact on the operation of existing lines.This paper lists cases of new stations crossing existing lines through zero distance underground excavation,compares the settlement impact analysis under different schemes through numerical simulation,and obtains reliable design and construction plans.Research conclusions:(1)According to the conventional design plan,the main structures on both sides of the existing station structure should be constructed first,and a post cast strip should be reserved at the junction.After the concealed excavation is completed,the post cast strip construction can be carried out.Through numerical analysis,it can be found that during the construction process of the underpass section,the vertical deformation of the existing station structure is relatively significant.The track bed of the existing station is raised,and the station bottom plate undergoes uneven settlement.The maximum settlement value is about 2.1 mm,which exceeds the standard warning value and poses a certain safety risk.(2)In response to the traditional connection method,the construction concept of zero distance underpass through existing station excavation construction lifting method is proposed,which directly connects the new structure with the existing structure as a whole,thus forming a lifting system for the new structure to the existing structure during the excavation section construction process.Through numerical analysis,after the completion of the lifting method construction,the settlement of the existing station track bed can be reduced by 50%,and the settlement control effect is significant.(3)The research results can provide guidance for new construction projects to excavate underground through existing projects.
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