Deformation analysis of shield undercrossing and vertical paralleling excavation with existing tunnel in composite stratum

Abstract

A deformation of an existing tunnel is complicated when a shield tunnel undercrossing and vertical paralleling excavates with existing tunnel in composite stratum. Therefore, a novel deformation calculation method is proposed for the existing tunnel considering slurry consolidation and shield undercrossing and vertical paralleling excavation. First, the equivalent layer method is used to simplify the composite stratum, the deformation caused by different factors is analyzed, and the slurry consolidation equation is introduced to correct it. Then, according to the subsection calculation idea, the calculation formula of shield undercrossing and vertical paralleling with the existing tunnel is established. Finally, considering an actual engineering case, a finite element model is established to analyze the deformation of the existing tunnel. Results show that before the shield construction section overlaps with the existing tunnel, the deformation curve of the existing tunnel generally exhibits an “M” form; After the overlap, the deformation curve of the existing tunnel gradually becomes “U” shape, and the maximum deformation point moves from the overlapping point to the shield tunneling direction; The settlement deformation range of the existing line gradually expands, and the maximum deformation increment gradually decreases and tends to stabilize.

Keywords

shield tunnel / existing tunnel / undercrossing and vertical paralleling

References

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