Method to Predict the Height of the Water Conducting Fractured Zone Based on Bearing Structures in the Overlying Strata

Numerous mining-induced water inrush hazards have been recorded in northern and eastern China, wherein landforms comprise thick unconsolidated layers. To prevent such hazards, the height of the water conducting fractured zone (WCFZ) must be determined in advance. This study presents a method to predict the height of this zone by determining the location of the key strata (KS) and considering the overburden load transfer under an arch structure in the unconsolidated layers. When the distance between the primary key stratum (PKS) and coal seam is more than 7–10 × M, where M refers to the mining height, the WCFZ tends to extend up to the floor level of the first KS, approximately the same distance (7–10 × M) above the mining seam, thereby making the height of this zone equal to the distance between the KS and coal seam. When the vertical distance between the PKS and coal seam is less than 7–10 × M, the height of this zone tends to be equal to or greater than the thickness of the bedrock strata. The theoretical results were verified by field observations.