Abstract: To probe into the influence of super long connecting passage on shield tunnel and surrounding strata in active freezing process, we examined the temperature field and displacement field of the 65.8 meters long cross passage, the shield tunnel and surrounding soil layer by using ANSYS with the frozen connecting channel between Ziyang station and Wuliting station of Fuzhou Metro Line 2 as engineering background. Results suggest that in the first 21 days of the active freezing, the average rate of frozen wall diffusion at the cross section of freezing pipe amounted to 57 mm/d, while in the last 29 days the average rate was only 27.6 mm/d; in the active freezing period, we observed a deformation concentration area of 10 meters in width and 2.5 meters in height near the bell mouth, which had a greatest impact on ground deformation. Freezing had a significant impact on the horizontal displacement of the arch shoulder and the vertical deformation of the arch foot. In the end of the active freezing period, the horizontal displacement of the arch shoulder was 85% larger than that of the right wall of the shield tunnel, and the vertical displacement of the arch foot was 45% larger than that of the arch crown. In addition, the structural deformation value and deformation growth rate both increased with the elongation of freezing time. Therefore, we suggested controlling the active freezing time and method reasonably to ensure the safety of buildings (structures).

Key words: shield tunnel, extra-long contact aisle, numerical calculation, displacement field, freezing temperature field