Abstract： By analyzing the equilibrium states of the tunneling face and the tunnel under water，the formulas about the balance between the water and soil pressure in front of working face and the pressure in the cabin given by shield is obtained. The smallest covering depth required by the safety of tunneling face and tunnel is given. Then，based on the Phrase One Project of Nanjing Metro North-South Line，some main methods dealing with the shallow underwater ground are provided. The effect of the presented methods is introduced. The obtained conclusion in this paper can be used to the tunnels through river bed and those under shallow covering by shield.
