Study on Advance Pre-Grouting Overlong Chemical Grout Bolt Technology Applied to Prevent and Control Spalling of Coal Wall

The spalling of the coal wall is often occurred in the fully mechanized coal mining face and is a not effectively solved problem.The seam in the fully mechanized coal mining face in Zhaogu No.1 Mine had well developed vertical cracks.The top of the seam was soft and the bottom of the seam was hard.There was a parting in the middle of the seam.The fault with small angle was well developed.All above could make the coal wall to have spalling easily.The conventional treatment method of the spalling would affect the normal advancing forward of the coal mining face.According to the site observation and analysis,the spalling mechanism of the coal mining face could be divided into two types and they were a tension type and a shear type.In order to reinforce the coal wall not affected to the normal mining operation of the coal mining face,poly-resin was applied to the grouting of the two gateways and to form the advance pre-grouting overlong chemical grout bolt for the spalling prevention and control technology.The chemical grout bolt would have the easy cutting,easy separation and no pollution features,have excellent physical mechanics performances would not affect to the normal production of the coal mining face and could ensure the high production and high efficient mining and obvious economic benefits.