| Today, along with the upper part coal resources dried up gradually in our country, it is most necessary to mine deep coal seam. With gradually deepening coal mining depth, seam roof disasters are increasing, so how to accurately evaluate the stability of the deep coal seam roof will be much to ponder. The No.13-lmajor coal roof of Zhuji mine are chosen to be the research objects in this paper. Based on a large number of detailed survey data by drilling and the experimental data from laboratory, the effect of depth on mechanical parameters of deep rock is discussed and 12 factors, such as combination strength of rock stratum, characteristics of the thickness of sandstone and mudstone ratio and development of bedding, affecting coal roof stability are analyzed synthetically from three major aspects, namely is the characteristics of the immediate roof, the sedimentary characteristics of roof and the the structure character of rock mass.Grey variable weight clustering is adopted in zoning and evaluation of stability of No.13-1 coal seam roof of Zhuji mine based on 12 evaluation indicators. First of all, the real value of each index and 4 gray classes of dimensionless processing, according to whitenization weight functions is calculated for the clustering weights of all indicators, and then the clustering coefficient of each evaluation unit is calculated by the formula operation. According to different clustering coefficient, the No.13-1 coal seam roof in the study area is divided into four different types of area based on the stability of seam roof.The results showed that the main distribution type of the No.13-1 coal seam roof in the study area is medium stable roof, which accounts for about 40% in the study area, mainly distributed in central and eastern regions. Stable roof and unstable roof occupy about 25% of the area respectively. Very stable roof occupies the smallest, about 10%. |
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