Abstract：Water flow in fractured rock mass is commonly cared about in most rock engineering cases. Based on 3D FEM numerical analysis，seepage characteristics in rock and concrete lining of outlet bifurcation in Shanxi Yellow River Diversion Project under high inner water pressure are obtained. Furthermore，via field measurements of pore water pressure by osmotic pressure gauge in concrete lining and displacements in surrounding rocks by multi-point extensometers，it can be concluded that the variation law of water pressures in concrete from field measurements are quite similar with those from numerical results. The research results show that the reinforced concrete lining should be adopted in the case of elastic modulus of rock mass less than that of concrete，even when the hydraulic jacking pressure of rock mass is greater than the inner water pressure. The conclusions from the research work can be adopted in other similar tunnel engineering.
