Theoretical framework and key technology of advance regional control of water inrush in coal seam floor

The shallow coal resources in North China have been nearly depleted so far, whereas deep coal development is challenged by karst water inrush in floor limestone. The conventional underground vertical hole grouting methods are troubled with inappropriate site location, thin drilling-met aquifer, large grouting blind area, and inaccurate target location. For this reason, we propose an advance regional control technology: bedding directional drilling-based grouting. We systematically study the slurry flow from near-horizontal grouting holes, advance grouting modes, grouting parameter control, advance identification of potential water diversion channels, as well as validation and assessment of a grouting treatment. On this basis, we formulate a theory and technology system for advance regional control of water inrush in coal seam floor, which consists of the following five parts: the classification and selection criteria of an advance regional control method of water rush in coal seam floor, the grouting mode applicable to the geological and hydrogeological conditions of coals in North China, the advance identification and management of horizontal directional drilling for potential water diversion channels, and the determination of key grouting parameters for advance regional control, and the qualitative and quantitative evaluation of multi-index for the entire grouting process. The above research results are successfully applied in an advance regional control of water inrush in coal seam floor, and provide important theoretical and technical support in the advance regional control of seam water inrush, as well as the safe mining of deep coal resources in North China.