Abstract：Based on effective stress analysis method，the elasto-plastic model of seepage and stress coupling analysis is established，and the dynamic water table is followed by means of VOF(Volume of Fluid). The computing program of numerical simulation is developed and the dynamic process of dewatering and construction of a subway tunnel engineering are simulated with the settlement of ground surface being analyzed in details and the dynamic variation curves of ground settlement are acquired. The results by numerical simulation and in-situ measurement are coincident well. These results indicates that the influence radius by dewatering is 30 m or so，the maximum ground surface settlement induced by dewatering is about 23 mm，and the total settlement by dewatering and excavation is 43 mm. Generally the settlement criterion is 30 mm，the engineering practice that buildings and pipelines adjacent to the engineering are safe during whole construction. It shows that ground settlement control criterion on city metro engineering construction should be determined according to specific environmental conditions. The result offers theoretical basis and reference for this and similar engineering.
