Abstract: For the deficiencies of common grouting technology in deep soft rock roadways, three-step grouting technology is proposed to reinforce the surrounding rock to get better results. The three-step grouting diffusion mechanism is explored in this paper, and the technique is applied to field engineering. Step one is to grout with low grouting pressure to fill the gravel pack interval and blocked the channels which relieves the grouting pressure in the shallow surrounding rock. Step two is mainly for the filling of the fractures space in the surrounding fractured rock to improve the bearing capacity of the surrounding rock through the effect of grout cementation and filling with grout solidifying. In step three grouting is prepared to further reinforce the strong deformation sections of the roadway. Although increasing the working procedures of grouting, the three-step grouting technology ensures the radius of grouting diffusion. The inspection holes monitoring shows that grouting diffusion depth is generally more than 3 m, and that the three-step grouting technology has achieved the expected effective range of grouting reinforcement. The roadway deformation monitoring datum of grouting before and after indicates that three-step grouting technology has greatly improved the effect of grouting reinforcement of surrounding rock and effectively improved the bearing capacity of rock mass，and thus the overall stability of surrounding rock of roadway is effectively controlled.

Key words: deep roadway, grouting reinforcement, diffusion mechanism