Deformation analysis on underground ventilation adit of metro station due to large diameter shield tunneling

With the rapid development of metro engineering construction in China, shield directly crossing underground ventilation adit of metro station has been paid more and more attention in recent years. In Beijing, a large diameter earth pressure balanced (EPB) shield with an outer diameter of 10 m is designed to construct the experimental project of metro line 14. During shield tunneling, it will cross several underground ventilation adits. It is therefore urgent to study the influence of large diameter EPB shield tunneling on ventilation adits. To take Gaojiayuan station as an engineering background, large diameter EPB shield crossing an underground ventilation adit is simulated using the three-dimensional finite element method. The displacement of the ventilation adit is obtained, and the deformation characteristics of the ventilation adit during the shield tunneling construction are analyzed. The numerical results show that the ring beams of the ventilation adit are mainly subjected to the deformation during the shield tunneling. Before and after shield crossing the ventilation adit, the deformation of the ventilation adit increases dramatically and the maximum value of the deformation can reach up to 10.66 mm. With the increase of the supporting pressure in a pressure chamber, the deformation of the ventilation adit rises before shield crossing the ventilation adit, however, after that, the growth rate of the deformation is quite small.