Study on advance treatment technology and engineering practice of faults in coal mining face

Huainan Mining Area has complex geological conditions and many fault structures. In order to solve the problems of advanced mining of large-scale roof rock blocks, coal wall slabs, support instability, difficulties in protecting the roof and supporting during the coal mining face passing through the fault, an advanced pre-reinforced inorganic composite grouting material was developed for the working face to cross the fault. The sealing method of “two plugs and one injection”high pressure resistant bag and grouting machine were optimized, combined with long-distance drilling and inclination measurement verification, this paper put forward the technology of pre-grouting treatment technology for faults in coal working face. According to the occurrence characteristics and occurrence conditions of the fault layer in the coal mining face, the principle of full coverage of grouting borehole in fault reinforcement area and the improvement of utilization rate of grouting borehole are adopted, the layout of pre-grouting boreholes for advanced treatment of fault in the working face is divided into the following three ways:①for a single fault structural zone with a small angle （less than 45°）between fault strike and mining roadway strike, parallel progressive pre-grouting drilling holes can be arranged vertically in the mining roadway; ②for a single fault structural belt with larger angle （more than 45°）between the fault strike and mining roadway strike, it can be concentrated in the roadway side drilling field of working face. The fan-shaped pre-grouting boreholes can be centrally arranged in the drilling yard of the mining roadway at the working face; ③for the fault structural zone with thick coal seam and large drop, the combination of roadway excavation and drilling can be used to arrange pre-grouting boreholes. Engineering practice shows that the use of advanced pre-grouting treatment technology for faults in coal mining face can improve the strength and stability of the roof during the fault crossing period, and effectively avoid the problems such as advanced roof caving, rib spalling and support instability, which is conducive to the working face passing through the fault quickly and provides technical support for the safety production of the coal mining face.