Study on stability and control of retracement channel with thin bedrock and broken roof

Abstract

In order to reduce the risk of roof falling and the accident of removing the supports during equipment withdrawal in the working face with thin bedrock and broken roof, the 11271 working face of Zhaogu No.1 Mine is used as the engineering background, and the theoretical analysis, numerical simulation and field test are used. The loads on the hydraulic support with the different spatial locations of the retracement channel and the basic top fracture line location are quantitatively analyzed, and the reasonable location of the retracement channel is determined. The technology of step expansion is proposed, which uses manpower in the upper part and shearer in the lower part, and the combined support technology of anchor cable supporting roof and bolt supporting coal rib is proposed. The result shows that the maximum cumulative shrinkage of the hydraulic support is 221 mm, the maximum shrinkage rate of the hydraulic support is 4.2 mm/h, the maximum variation of the hydraulic support working resistance is 11.2 MPa, and the maximum displacement of roof and floor is 305 mm, the requirements of safe mining is met, and the surrounding rock control effect of the retracement channel is well.

Keywords

• thin bedrock
• broken roof
• retracement channel
• key block
• reasonable location
• technology of step expansion