Abstract: Gushing water causes many geological disasters in tunnel. High viscosity grout plays a positive role in water controlling under complex geological conditions. In this paper, time-varying viscosity of common cement grout and high viscosity grout are measured and analyzed with experiments. The principle of effective stress for porous medium is applied to analysis the fluid-structure coupling in grouting. Considering coupling physical variables, dynamic models of porosity and permeability are contained. The diffusion radius of grout thus can be defined by porosity and pressure gradient. By filling the shallow rock and compacting deep rock, holes are designed in the grout experiment to reduce static water pressure. The distance between grout holes is arranged referring to the calculation results. Then, rationality of the mathematical model and grout scheme is verified by water monitoring and strength testing. According to the results, gushing water reduces by 97%, and strength of rock increases by 200% to 400%, indicating that gushing water is stopped and the tunnel foundation enhanced.

Key words: coupling, grouting, porosity, pressure gradient, viscosity