Study on the Laws of Overlying Strata Movement of Repeated Mining of Close Distance Thick Coal Seam Under Large Surface Water

There is plentiful mineral under the water, and due to the limit of the natural environment, many difficult problems will appear in underwater mining. The paper aims at the problems in repeated mining of No.33lower01 working face, which is the close thick coal seam and under large surface water. Through field measurement, the thickness of bedrock and clay layer which above the working face was obtained. Then, using various methods to analyze the laws of overlying strata movement, and the height of the caving zone and water flowing fractured zone was measured, the heights of the two is 35.2 m and 107.6 m, respectively. At the same time, discussing the impact of working face mining on SF2 reverse fault, there is no obvious dislocation between the upper and lower plates of the fault, and the watertightness was well. Comprehensive analysis shows that repeated mining of No.33lower01 working face under the large surface water is possible.