Evaluation Of Conditions Under The Lower Coal Seam During Mining With Pressure In Xinglongzhuang Mine

Along with the depth of coal mining increasing, water inrushing from coal seam floor has been one of main mine geological disasters threaten the safety production of mine.Research on water-resisting property of strata on Lower Coal Group Floor in effect of mining has great significance for the evaluation and prevention of water inrush.Therefore, risk of water inrush in deep lower group of Coal Seams mining had been comprehensive studied,under engineering background of mining with pressure on Lower Coal Group Floor in Xinglongzhuang coal mine of Yanzhou mining area, on this paper.According to the hydrological geological datas and datas of mining with pressure on Lower Coal Group Floor in next neighboring mine, conditions of mining with pressure on Lower Coal Group Floor in Xinglongzhuang coal mine had been analysised. Aquifers had effect of Safety mining on Lower Coal Seam are NO.13 limestone、NO.14 limestone and Ordovician limestone. NO.13 limestone and NO.14 limestone had been mergered the same layer because most areas of Mine had no NO.14 limestone, and thickness between NO.13 limestone and NO.14 limestone was small. Water abundance of Ordovician limestone was medium and water of it flow into other aquifers throw fault zone. Sandstone、thin limestone and argillaceous rock were favorable aquifuge. The lithology、structure and development of thickness between NO.17 coal seam and NO.13 limestone、NO.13 limestone and Ordovician limestone had important affect on safety of mining with pressure on Lower Coal Group Floor.Through the in-situ seepage tests, contrast test datas of water-resisting property about different lithology and structure Lower Coal Seam Floor in Yanzhou mining area had been Obtained. In addition, recommended value of average water-resisting strength about different lithology and structure rock stratums on Lower Coal Seam Floor in Xinglongzhuang coal mine had been proposed. On basis of this, evaluation model based on condition of water-resisting property had been established.Risk of water inrush on Lower Coal Group Floor in Xinglongzhuang coal mine had been evaluated and parted through water inrush coefficient and condition of water-resisting property. The results show that there was possibility that NO.13 limestone water inrushed from normal floor in southeast following first、following third mine etc. of mine when mining NO.17 coal. Floor at fault zone had been evaluated and parted according to the thickness of rock stratum between coal seam and aquifer. The results show that there was possibility that NO.13 limestone water inrushed from fault zone. Ordovician limestone water could not inrushed from fault zone in condition of the fault throw less than 8m and thickness of rock stratum more than 60 m when mining NO.16 coal. The critical condition to produce seepagefailure was the fault throw achieving 5m when mining NO.17 coal.At last, the applicability of evaluating safety conditions of mining with pressure on Lower Coal Group Floor through water inrush coefficient and condition of water-resisting property had been comparative analysised on basis of analysising two mining faces of Lower Coal Group Floor in Yanzhou mining area. The results show that the water-resisting strength coule reflect the ability of preventing water veritably.The evaluation results about conditions of mining with pressure on Lower Coal Group Floor in Xinglongzhuang coal mine, on basis of water-resisting condition, could guide mining Lower Coal Seam effectively. It could provide technical support on prevention and cure of water damage about mining Lower Coal Seam with pressure in mine.