Frost heave and thawing settlement of the ground after using a freeze-sealing pipe-roof method in the construction of the Gongbei Tunnel

The port section of the Gongbei Tunnel of the Hong Kong Zhuhai Macao Bridge is constructed by the freeze-sealing pipe-roof method, a new construction method that combines the pipe-roof and artificial ground freezing techniques. If the frost heave and thaw settlement of the ground are not effectively predicted and controlled during tunnel construction, then the surrounding environment of the tunnel will be adversely affected. In this study, thermophysical and mechanical parameters such as frost heave ratio and thawing settlement coefficient are obtained by the laboratory test of frozen-thawed soil. Then, the frost heave and thawing settlement laws of the ground are simulated by the full-coupled analysis method of transient temperature and displacement according to the secondary development technology of the ABAQUS finite element software considering the orthotropic deformation characteristics of frozen soil during the construction of the Gongbei Tunnel. The numerical simulation results show that the maximum vertical frost heave displacement of the stratum is 164.47 mm and the maximum horizontal frost heave displacement of the stratum is 53.80 mm, while the maximum vertical thawing settlement displacement of the stratum is −69.45 mm and the maximum horizontal thawing settlement displacement the stratum is −43.89 mm. Moreover, the error of the maximum vertical frost heave displacement between numerical simulation and field measurement is only 5.89 mm, which shows that the numerical simulation method proposed in this paper has high prediction accuracy.