Hydrogeology Characteristics Of Deep Karst And Evaluation Of Its Discharge

Limestone water inrush from coal seam floor is the main water prevention problem in Northern China type coal field. With the increasing of mining depth, the limestone aquifer head pressure beared by coal seam floor has been increased and also the threaten degree of water inrush hazard. Therefore, how to evaluate and prevent the water disaster from deep limestone has an important practical significance for how to mine deep coal resource safely.Based on consulting foreign and domestic literatures related to research status of coal seam floor of limestone water and its research method, Xieyi coal mine was analyzed as a typical case in Huainan. Hydrogeological conditions of the coal mine was complicate, and group A coal resources above the level of -480m almost had been mined. Now, A1 coal of deep level is being threatened by limestone water inrush from coal seam floor. Taiyuan limestone water of A1coal seam floor in level -660m was taken as the research object at the north of XieYi mine, and the hydrogeology characteristics of the region Taiyuan limestone systemically was analyzed. The failure depth of seam floor was simulated and calculated under the condition of mining A1 coal seam by the FLAC3D numerical simulation technology. The hydrogeology conceptual model and mathematical model of Taiyuan limestone of A1 coal seam floor were established, and the hydrogeological parameters was identified with Visual Modflow software. The water inrush coefficient of A1 coal seam floor was calculated by the modified calculation formulas of water inrush coefficient. Combined with the identified aquifer model, the drawdown and variation of water inrush coefficient were calculated under different drainage schemes. The differences of ionic compositions, which came from different water sources of aquifers, were analyzed, and water inrush sources were discriminated by the ways of cluster analysis method and stepwise discriminant method. And some measures were taken about how to prevent limestone water inrushing from the coal seam floor.