Segment Floating Control Technology by Cooperating Water-stop Ring Hoops with Shield Parameters in Water-rich and Unevenly Fractured Strata with Large Longitudinal Slope

To address the problems of significant soil disturbance, severe segment floating, and excessive building settlement when a double-line shield tunnel passes beneath a cluster of exisyed buildings, this study was based on the Haiyun'an-Hudao Station section project of Qingdao Metro Line 5. The combined technologies of real-time tunnelling monitoring, shield parameter optimization, and interval water-stop ring hoops were adopted, and field tests were conducted from aspects including regulating shield tunnelling parameters, improving the synchronous grouting process, and setting water-stop ring hoops. The results showed that the tunnel's elevation deviation and the horizontal deviationis were controlled within 25 ± 20 mm by controlling cutterhead torque (2 250~2 750 kN·m), tunnelling speed (15~20 mm/min) and matching segment assembly, and shield segment floating was avoided effectively. By regulating synchronous grout, water-based epoxy resin, water-stop ring hoops caused by secondary grouting, the vertical displacement of segments is controlled within ±3.0 mm, and the maximum difference in building settlement is less than 0.1%.