Aiming at the difficult problems of the large deformation in deep and soft rock roadways

the reasons of large deformation are first analyzed for roadways in Panshan coal mine

Huainan

China. On this basis

step by step and combined supporting technique with steel grid frame for soft and fractured rock roadway

including steel grid + primary bolt and cable

initial shotcrete

shallow grouting

pre-stressed bolts

further shotcrete with thickness of 150 mm

deep grouting

and pre-stressed cables

was proposed for deep weak and fractured rock roadway. Furthermore

the control principle of grid arch support is analyzed

and the optimal support parameters (diameter of steel is 20 mm and space between frames is 700 mm) are determined by FLAC3D. The comparative analysis shows that both of the initial deformation rate and final convergence deformation of the steel grid technique are larger than that of the steel support

however

the roadway deformation can quickly converge after the addition of the secondary support was applied. The monitoring results showed that the reasonable period for applying pre-stressed bolt/cable is after about 10 days of shallow/deep grouting. The time between pre-stressed bolt and deep grouting that is set as 2 weeks will be better. Therefore

step by step and combined supporting technique with steel grid frame proposed here can provide an effective method for the soft rock roadway control in deep and soft coal mines.