Practice and adaptable conditions classification of aquifer-protective mining in longwall coalface for shallow seam with thin bedrock

A set of adaptable conditions classification of aquifer-protective mining in thelongwall coalface for shallow coal seams with thin bedrock was put forward to deal withthe conflict between water protection and high efficiency for the mining field in west China.This classification was suitable for shallow coal seams with different thickness and wasbeneficial to the local environmental protection.Using the 3-Universal Distinct ElementCode (3DEC) numerical software, the height of the fractured zones for shallow coal seamswith thin bedrock was calculated and analyzed, and its predicting formula was achieved.Meanwhile, according to the lithology and the weathering degree of the shallow coal seam,the thickness of the protective layer was determined as 10 m and the overlying water bodyof loose water-bearing sand for shallow coal seams with thin bedrock was divided intothree types, namely, weak, medium and strong.Based on these, the necessary bedrockthickness of the longwall coalface for shallow coal seams with thin bedrock was confinedaccording to the different mining height and water yield nature of the overlying loose water-bearing sand.Combined with the present mining status, a set of new methods ofadaptable conditions classification of aquifer-protective mining technology in the longwallcoalface for shallow coal seams with thin bedrock was put forward.

A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.