Application of surface nuclear magnetic resonance technology in detecting water abundance in concealed burnt zone

The overlying bedrock composite aquifer(including weathered bedrock and burnt rock aquifer) in the concealed burnt zone of coal seams is one of the main threats to coal mining. It is of great significance to clarify the water enrichment of the concealed burnt zone for the prevention and control of coal mine water hazards. Ningtiaota Coal Mine, which has experienced a large water inrush accident, was used as the research object, and the Surface Nuclear Magnetic Resonance(SNMR) was used to detect the water enrichment of the aquifer in the concealed burnt area. The results show that there are two aquifers in the concealed burnt zone, namely Quaternary loose sand aquifer and 1^-2 coal overlying bedrock aquifer. The water enrichment of the Quaternary sand aquifer is affected by the topography of the surface and the top undulating shape of the lower aquifer, and the level changes greatly. The water content of the bedrock aquifer overlying 1^-2 coal is generally lower in the southwest and higher in the northeast. The thickness of the aquifer is 9-30 m, relatively thicker parts, which is presumed to be the superimposed reflection of weathered bedrock and burnt rock aquifer in the burnt area. In the study area, the overlying bedrock aquifer of 1^-2 coal generally shows relatively larger water quantity in the western and central southeast regions and relatively weaker water abundance. The conclusions obtained by using SNMR are roughly the same as the results of water inflows from water detection holes and hydrological holes, which indicates that the exploration results of this method are relatively reliable and can be used for the detection of water enrichment in hidden burnt areas.