Abstract: 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.

Key words: rock mechanics, deep mining, soft rock roadway, steel grid frame, supporting technique