Seam Floor Impermeable Layer Impedance High-pressure Water Intrusion Mechanism

Along with the upper part coal resources dried up gradually in our country, it is most necessary to mine deep coal seam. It is straightly faced with the high water pressure, the high gas and stress along with the mining depth increasing continuously, which is increasingly outstanding. It is vital that how to safely and effectively mine the coal above high water pressure. Water inrush coefficient is always a traditional and valid method to evaluate the aquifer mining feasibility of the coal seam, which is a hotspot problem, too. However, these researches were mainly focused on configuration and mechanical character of the coal seam scaleboard during the development of water inrush coefficient. Those rarely refer to the researches about water pressure function mechanism. In fact, the water flow intrudes upwards with a loss of the distance water and energy wastes for splitting rocks when confined groundwater intrudes upwards through coal seam water-resisting layer. The water flow under the coal seam scaleboard consumes more energy after it intrudes at a certain height. The actual water pressure, which acts on the effective confining bed, is more less than the water pressure which is observed. The actual water pressure is the remaining water pressure P_c. The effective water pressure, which breaks the effective water-resisting layer, is the remaining water pressure. Therefore, it is more meaning for mining evaluation above confined aquifer to study the forming, development and distributing rule of the remaining water pressure. Which is pivotal science problem of this paper, too.The paper is based on the theory of inter-function between water and rock, and losing energy in rock mass, brought forward that the water flow has head loss during water flow intruding through the coal seam effective water-resisting layer and energy waste concept for splitting rock mass, and analyzed the form of the remaining water pressure. Through the simulation experiment in the preventing water capability of water-resisting rocks in the coal seam scaleboard, studied the law, character of the losing in water head waste and the relation to pressure, water-resisting of hydrogeology and engineering geology character. Brought forward the new method of calculating the water inrush coefficient.