Abstract: Guanjiao tunnel is the key works of the Second XiningGeermu Railway. The control and discharging of the groundwater is modeled and the sandy waterrich ground section is simulated by means of finite element method, so as solve the waterproofing and drainage problem of the waterrich section of Guanjiao tunnel. The relationship among the permeability coefficient of the waterstop circle, the thickness and the node flow amount is analyzed. Conclusions drawn are as follows: the parameters of the grouting circle in the waterrich section should be controlled in a certain range; the situation of the groundwater is verified by the node flow variation process; in the construction of tunnel in waterrich section, the thickness of the grouting circle should be 3 m and the permeability coefficient should be 2.1×10-3 m/d. The paper can provide reference for the control and release of the groundwater in tunneling so as to minimize the impact on the water resource environment.

Key words: Guanjiao tunnel\waterrich section, grouting circle parameter, controlled discharge, waterproofing and drainage