Study of Freezing Scheme in Freeze-Sealing Pipe Roof Method Based on Numerical Simulation of Temperature Field

Though application of pipe-roofing and artificial ground freezing are becoming increasingly common, there are few published papers or practical projects concerning combined application of Pipe-Roofing Method and Artificial Ground Freezing Method (AGF), which can be named as Freeze-Sealing Pipe Roof Method (FSPR). In this paper, Gongbei Tunnel project of Zhuhai Link Road, Hong Kong-Zhuhai- Macao Bridge, which is proposed to be constructed by FSPR, is taken as the study object. Taking the development of temperature field, the resisting ability of the frozen ground curtain to thermal disturbance resulted from excavation, and the control of frost heave as criteria, analysis of different freezing schemes by numerical simulation is carried out for active and maintaining freezing stages, so that some guidance could be given for the final selection of freezing scheme. The results show that FSPR is capable to form a sustainable and stable waterproof curtain, and has good construction maneuverability. With the arrangement of enhancing pipes and limiting pipes, the freezing scheme can effectively resist the impact of thermal disturbance of excavation and limit the development area of frozen soil curtain to control the frost heave amount. The recommended freezing scheme of FSPR is reasonably practicable.