Abstract: In order to solve the problem of how to construct a new shield tunnel under the condition of waterrich
sand layer and pass through the underground obstacles of an existing operating station, this article relies
on the construction of a new section of Wuhan Metro Line 12, which passes through an existing operating
station, and proposes a plan of providing a working surface by open excavation of a clearing shaft, breaking
through the underground obstacles by longitudinal freezing and manual excavation in the clearing shaft, and
shield tunneling after backfilling with plain concrete.Firstly, by referring to industry standards and similar cases,
the corresponding allowable deformation control indicators for the existing operating station are
given.Secondly, using finite element numerical analysis method, the mechanical analysis of each process of
freezing excavation, clearing shaft excavation, and shield tunneling is carried out, and the key technical points
of design and construction of each process are proposed.Finally, through the analysis of the measured
deformation data on site, the deformation of the existing station floor is within the range of the calculated value
of finite element.This plan not only ensures the controllability of the deformation of the existing operating
station, but also overcomes the problems of water inrush and collapse during manual breaking of the
underground obstacles under the condition of water-rich sand layer, and improves the safety of the new tunnel
passing through the underground structural obstacles.