水下隧道最小覆盖层分析是设计过程中关系安全和经济的重要因素。以青岛胶州湾海底隧道工程为背景，建立不同覆盖层厚度的海底隧道渗流有限元计算模型，分别就隧道穿越f3-1破碎带时的涌水量、渗流速度、孔隙水压力以及注浆圈参数选取开展研究和讨论。研究表明： Park公式与有限元涌水量计算结果较为吻合；覆盖层厚度较大时，渗流最快区域出现在拱脚；覆盖层厚度较小时，拱脚和拱顶中心均渗流较快；边墙和底板的孔隙水压力变化梯度随覆盖层厚度的增加而增大，拱顶规律相反，并且覆盖层厚度超过22 m后孔隙水压力变化梯度基本保持不变；从可靠性和经济性两方面综合考虑注浆圈厚度和渗透系数参数选取，本文给出了注浆圈参数建议取值范围为： 注浆圈厚度为4～6 m，渗透系数为1×10-7～2×10-7 m/s。

The analysis of the overburden thickness of subsea tunnels is closely related to the safety and economy in the design process. Taking Jiaozhou Bay Subsea Tunnel in Qingdao as background project, the authors establish finite element seepage models for this drill and blast tunnel with 4 different overburden thicknesses. The authors focus on the inflow water volume, seepage velocity, pore water pressure and grouting zone parameters during the excavating process in the f3-1 fault fracture zone. Conclusions drawn are as follows: 1) Park formula coincides with FEM inflow results; 2) The most serious seepage area will occur at the arch springing if the overburden is thick; serious seepage will occur at both arch springing and crown if the overburden is thin; 3) The pore water pressure gradient of the wall and the floor increases as the overburden thickness increases, while the pore water pressure gradient of the crown is just on the contrary, and the pore water pressure gradient will remain almost stable when the overburden thickness is over 22 m; 4) Both reliability and economy should be taken into consideration when appropriate thickness and permeability value are selected, and the grouting zone thickness of 4～6 m and the permeability of 1×10-7～2×10-7 m/s are proposed for the project.