“Down Three Zones” in the Prediction of the water inrush from Coalbed Floor Aquifer theory,Development and Application

The development and application of the “Down Three Zone” in nearly recent two decades are summarized;the concept,origination,the determination,application principle,in situ measurement and effect evaluation are systematically exposed.Twenty years of researches and production practice has made the “Down Three Zone” theory more and more perfect.The theory plays an important role in the safety mining evaluation of the coal seams above high pressure aquifers and the prediction of the water inrush from coal seam floor.This paper aimed to the intensive comprehension to the theory and the extensive application of the methods in the coal mining production.