Water Inflow Calculating Method and Grouting Parameters Analysis after Considering the Velocity of Groundwater

Tunnel is buried under the ground and surrounded by groundwater in general, to grantee the safety of tunnel during construction and operation phase, it is essential to deal with the groundwater effectively. However, how to calculating the water inflow exactly and design the reasonable grouting parameters are the main factor to influence the water plugging effectiveness. Based on the theory of well flow and dynamic of groundwater, the formulas for calculating water inflow considering flow velocity was deduced. Meanwhile, the formulas for counting water inflow and groundwater pressure after grouting and lining was obtained. Due to the analysis, there is an optimal scope for selecting grouting parameters. When the permeability coefficient of grouting circle larger than 1/100 of permeability coefficient of surrounding rock, and the thickness of grouting circle is smaller than 6 m, water inflow decreases with the thickness of the grouting circle increasing, and diminishes with permeability coefficient of grouting circle decreasing. While the permeability coefficient and the thickness of grouting circle exceeds the optical scope, it is poor to diminish the water inflow by reducing the permeability coefficient and raising the thickness of grouting circle continually.