Abstract： The selection for overburden thickness is closely related to the safety and cost of the subsea tunnel, which is one of the main parameters of the design of the longitudinal section of the underwater tunnel. At present, there is no unified criterion for determining the minimum overburden thickness in China. Aiming at the selection of the thickness of the shield soil in the Shizi yang section of the Pearl River Delta's Water Resources Allocation Project, and combined with the relevant engineering cases of subsea tunnels at home and abroad, the value range of the soil thickness is studied through three kinds of theoretical model analysis. Finally, the finite element numerical calculation method is used to verify the results. The research shows that in the theoretical model, it is more reasonable to consider the calculation method of the soil shear force and minimum overburden thickness during grouting calculation method, and the minimum overburden thickness of the underwater tunnel—18 m is obtained.
