Prediction Of Water Abundance Of Sandstone Aquifer In 2^-2 Coal Seam Roof And Risk Assessment Of Water Inrush In 22 Mining Area Of Yingpanhao Coal Mine

The 2-2 coal of the main coal seam in the 22nd mining area of Yingpanhao Coalmine is buried deep and the mining thickness is large.After the coal seam is exploited,the water flowing fractured zone communicates the upper Yan’an Formation sandstone aquifer and the Zhiluo Formation sandstone aquifer.The sandstone aquifer of Zhidan Group is large and medium rich in water,but it is far from the coal seam and is an-indirect water bearing strata.This paper takes YCM No.22 mining area as the research object.Based on the systematic analysis of geological and hydrogeological conditions in the study area,the spatial development characteristics of the roof structure of coal seam are studied,and the aquifer and water-resisting layer of coal seam roof are classified in detail,and the water rich characteristics of the direct water filled aquifers and the indirect water filled aquifers of Zhidan group are predicted,and the water hazard of coal seam roofs is evaluated.First of all,this paper analyzes horizontally and longitudinally the stratigraphic structure characteristics of the roof of the 22 mining area,and the aquifer and water-resisting layer of coal seam roof are classified in detail;FLAC3D numerical simulation software was used to establish the model to study the failure of overburden of 3m,6m,9m and the development law of the water flowing fractured zone under different conditions.When the mining height is certain,with the increase of the driving distance,the height of the water flowing fractured zone also increases,and it does not increase after reaching a certain height.At this time,the advancing distance is approximately equal to the oblique length of the working face;under different conditions,with the increase of the mining height,the height of the water flowing fractured zone increases,but the ratio of the height of the fractured zone to the mining height decreases.According to the empirical formula method,numerical simulation method and analogy method,the development height of the water flowing fractured zone in this research area is synthetic determined.In this paper,five factors affecting the water-richness of aquifers are selected:the equivalent thickness of sandstone,the sandstone lithology coefficient,the number of sand-mud interbedded,the core rate,and the interbedded coefficient of sand and mud.Using the method combining entropy weight coefficient and principal component analysis to determine the combination weights,build a prediction model of aquifer water-richness,the water rich classification of the direct water filling aquifer and indirect water filling aquifer of Zhidan group is evaluated.By superimposing the information on the water-rich information of the water-filled aquifer within the water flowing fractured zone and the information on the cracking degree of the roof,the risk of water inrush from 2-2 coal roof in the study area was evaluated.