A Case Study on Development of Water-flow Fractured Zone During Close-Distance Repeated Coal Mining

Le résumé fourni par la source

Abstract The upper and lower seam of seam No.3 of some coal mines in Shandong Province are in close proximity which can be regards as close-distance coal seam mining.This paper takes the close-distance working face of Fucun coal mine as engineering background and mainly focuses on the investigation and research on inaccuracy of the forecasting and incompetence of the developing principles of water-flow fractured zone(WFFZ)during close-distance coal seam group mining.First,calculations on the height of WEEZ by adopting empirical formula.And FLAC3D software was established to calculate the height of the overburden WFFZ after repeated mining of the upper and lower seam of seam No.3.At the same time,using the double-ended water plugging observation technology of downhole drilling and upward hole drilling by analyzing the water injection loss ratio of the reference hole and the post-mining hole,the accurate numerical values of the WFFZ and the ratio of WFFZ height to mining height(W-M ratio)are obtained.The comparative analysis shows that the numerical simulation results are close to the measured ones,and the empirical formula is not applicable to the near-distance repeated mining.Finally,the prediction model is established based on the measured height of the WFFZ of multiple working faces,which provides a scientific basis for further exploring the development law of the overlying rock in underwater coal mining and ensuring the safe mining of coal seams at close distances.

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