Abstract：Aimming at the construction process of Songhua river tunnel which will be built recently，the finite element numerical model is used to solve the actual problem of tunnel for 40 different cases and various proposed sites. The simulation is conducted repeatedly. On the basis of simulated results，the curves between single factor and safe cover thickness are drawn and the high precision fitting relations are given，so that the laws between single factor and safe cover thickness are studied. The main factors affecting the safe cover thickness are singled out. Stepwise regression analysis method is adopted to obtain the forecasting model on safe cover thickness of tunnel and is capable of synthetic embodying the combination action of all main affecting factors. At last，the reliability and efficiency of the model are verified by a calculation example of underwater tunnel.
