Abstract:
Large deformation often occurs in the coal wall with weak interlayer, which affects the normal use of the roadway. Based on the research background of the track channel of 3308 working face in Dongtan Coal Mine, the large deformation characteristics of the side of the roadway with weak interlayer are analyzed by means of field measurement, numerical simulation and theoretical analysis, and its instability mechanism is studied. The criterion expression of the shear failure of the coal pillar is obtained, and the influence law of the surrounding rock mechanical parameters on the large deformation is discussed. The results show that the peak value of the horizontal displacement of the two sides is at the weak interlayer, which is the key factor for the large deformation of the coal side; the axial tension produced by the large deformation of the coal wall with weak interlayer on the anchor rod is insufficient to destroy the anchor rod (cable) body. The loss of the bearing capacity of the anchor rod (cable) may be due to the low cohesion of the anchorage zone or the tail detachment of the anchor; by increasing the internal friction angle and cohesion of surrounding rock, the range of shear band can be reduced and even the specific plane can be sheared. Based on the research results, the supporting principles of grouting modification of anchor cable, adaptation of pressure bolt by friction to large deformation, adding anchor at the end of bolt, and reinforcement of shear bolt with limited position are proposed and verified by engineering.