The Influence of Secondary Supporting Parameters and Secondary Supporting Time on Tunnel Stability in Extremely Soft Rock

In order to solve the supporting problem of surrounding rock in Shaba Coal Mine, the paper presents scheme including secondary supporting parameter and secondary supporting time, considering three factors about the length of anchor cables l_a, intervals of anchor cables e_a×I_a and displacement values of secondary supporting time d_a. It adopts orthogonal tests to design 16 schemes of secondary supporting and analyzes different influence ranges of secondary supporting opportunity on tunnel stability. It has a good effect on application.