| Coal mining in ecologically fragile areas in the west will aggravate the destruction of water resources,and the existing research on the impact of coal mining on groundwater systems is mainly based on a single working face mining process.Based on the engineering geological background and coal seam occurrence conditions of Yili No.4 Mine,this paper uses FLAC3 D software and GMS software to carry out numerical simulation research,systematically study the height of mining,working face length,working surface propulsion distance,coal pillar width and goaf.The characteristics of overburden mining permeability change under 25 kinds of mining space parameters,such as the number of noodles,and the basic laws of superficial water system migration under different mining spatial parameters,and the spatial parameters of mining space parameters are obtained.The sensitivity of the groundwater system has achieved the following main results:(1)The distribution law of overburden permeability under different mining spatial parameters is obtained.With the increase of mining space,the maximum value of overburden mining permeability is larger than that of pre-production strata.Under the same mining height,the permeability of overburden increases with the increase of the number of goafs;when the number of goafs is greater than 7,the variation of overburden permeability is small;with the increase of mining height,The overburden permeability is increasing.When the mining height is greater than or equal to 12 m,the variation of the permeability of the overburden is extremely small,and the change of the number of the noodle surface no longer affects the change of the overlying rock permeability.(2)The influence of mining space parameters on groundwater flow field is studied.The results show that when the mining height is 3m,the overall water level of the groundwater flow field is decreasing,and the falling funnel appears.When the mining height is greater than or equal to 6m,the groundwater level is increasing.With the passage of time,the vertical deepening has been increasing,reaching the maximum in December,but its increase gradually decreases and tends to a stable value,which varies between 0.8m and 1.9m.(3)The sensitivity of the mining space parameters to the superficial water system is analyzed.With the vertical depth and the lateral influence radius as the dependent variable indicators,the sensitive order of the influence of the mining spatial parameters on the regional groundwater system is obtained.The primary and secondary order of sensitivity of groundwater system influencing factors is mining height > number of goafs > coal pillar width > working face length > working face advancement length.Among them,the sensitivity of mining height to the groundwater system migration law is much greater than the number of noodle surfaces,working face length,propulsion distance and coal pillar width.The paper has 69 pictures,10 tables,and 72 references. |
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