Numerical analysis of influence of large-diameter shield tunneling on underground ventilation adit of metro station

With the speedy development of metro construction in China, more and more attention has been paid to shield directly crossing underground ventilation adit of metro station. By taking Gaojiayuan Station of the experimental project of Beijing Metro Line No. 14 as an engineering background, a large-size earth pressure balanced (EPB) shield with an outer diameter of 10 m directly crossing an underground ventilation adit is simulated by means of three-dimensional finite element method based on the soil-structure interaction theory. The total displacement and stress of the ventilation adit is obtained, and the influence of the large-diameter EPB shield tunneling on the deformation and stress characteristics of the ventilation adit is analyzed. The numerical results show that the deformation of the ventilation adit mainly focuses on the ring beams, and the maximum deformation occurs at the top of the ring beams. Moreover, the deformations of the left and right ring beams increase dramatically before and after shield crossing the ventilation adit. The maximum stress of the ventilation adit also appears on the ring beams, and the stresses on the left and right ring beams vary largely during the shield crossing the ventilation adit. With the increase of the supporting pressure on the excavation face, the left ring beam is subjected to greater deformation and stress during the construction, compared with other structures. It is therefore suggested that the ring beams of the ventilation adit should be reinforced in the design and the supporting pressure on the excavation face should be adjusted at an appropriate level to ensure the safety of the ventilation adit.