Research On Development Regular Of The Height Of The Caving Zone And Fractured Zone In Coal Mining In Southern Shenmu Minefield

The height of the caving zone and fractured zone is an important symbol to determineif the water in bedrock, gob and the earth’s surface can flow into the mining area in coalmining, so there is significance to accurate calculate it to predict and prevent the mine waterdisaster. The mine in most part of Jurassic coalfield of the Northern Shaanxi is buried veryshallow, which has the characteristics of thin bedrock,thick soil and large scale mining, sothe existing formulas for the caving zone and fractured zone are nor very suitable to thisregion. In this paper, the main coal seam2-2,3-1and5-2in Zhang Jiamao minefield, NingTiaota minefield and Hong Liulin minefield of Southern Shenmu are chosen to be the objectto study the method for the height of the caving zone and fractured zone, and provide a newbasis for prediction and prevention of the mine water disaster in shallow buried coal mining.On the basis of analyzing the boreholes data in the study area and the spatial distributioncharacteristics of each layers, the seam thickness distribution contour map of the coal seams2-2,3-1and5-2, the bedrock thickness contour map and the soil thickness distribution contourmap are made in the pepper. Each layer of the bedrock is differentiated into the brittle-typebedrock, the middle hard type bedrock and the soft hard type by the physical and mechanicalproperties and the thickness. Then the combination types of the bedrock over the main coalseams are inducted. The FLAC3Dis used to build up the models to calculate the height of thecaving zone and fractured zone, at last there are30groups and210models are build in thispaper. The simulation results show that the height of the caving zone and fractured zoneheightens with the chickening of the thickness of the coal seams, the bedrock and the soil.Among the types of factors, the mining height has the biggest affect, then the hardness of thebedrock, and the most least is the thickness of the soil. The impact of the bedrockassemblages is different with changing of the thickness of the bedrock. By analyzing the numerical results,6formulas are fitted to calculate the height of the caving zone andfractured zone under different thickness of soil, bedrock hardness and assemblages with theargument of the mining height and the thickness of bedrock. As a result, a new method ismade to forecast the height of the caving zone and fractured zone for the shallow buried coalseams.