Research On The Working Face Of Broken Roof Control Technology Under The Gob In Splitting And Merging Coal Seams

For the splitting and merging coal seams,when the roof broken underlying seam mining after overlying coal gob,the lower part coal seam of working face are easily advance roof fall,serious rib spall ing,support sinking and so on.It will be resulted in constrainting work-face advancing speed and even be forced stop production and difficult to achieve safe and efficient mining.This thesis based on71and72coal seams of Huaibei coal group Xutuan mine,according to it appearing splitting and merging,great changes of spacing,roof breakage under the goaf,this paper adopting such methods as laboratory mechanic experiment,theoretical analysis,numerical stimulation and field investigation,does some research and comes up with the effective control mode of broken roofs in working face,the floor destruction depth in71seam,the roof breakage mechanism in lower seam. This paper calculates the supports selection about the working face of72seam, and designs broken roof grouting parameters combining theory and practice. The roof control effect is concluded and the effective control mode of broken roofs in72seam,by comparing strata behavior in working face,the surface displacement of gateway,the adaptability of ZZ7600/20/40hydraulic support parameters. The research achievements are as follows.(1) Optimization of a four-post support to adapt to the splitting and merging coal seams with standing shield hydraulic support structure,rationally designed support parameters,developed ZZ7600/20/40hydraulic support,resolved technical problems such as serious rib spalling,advance roof fall,to ensure the work-face recovery efficient and security.(2) Optimized grouting material and grouting parameters,innovativing to design the new way of" drill bit replacement" and "following tube drilling", forming a broken roof grouting reinforcement technology which is economically viable to control roof falling.(3) Revealling the splitting and merging coal seams mine pressure behavior and surrounding rock control under the roof broken condition of overlying coal gob,and giving theoretical direction to the breaking roof control technique and roof management. Application of the results of this study has achieved safe and efficient mining for splitting and merging coal seams under the condition of broken roof.The application of the results has gained a significant economical benefit and a broad application prospects.Figure [59] table [16] reference [60]...