Research On Cross Uphill Mining Technology Under Hard Roof

With the amount of coal used and production increased year by year in our country, mining accidents often occurs as the improvement of production difficulty. Hard roof control is difficult because of components of hard roof strata is different and there is no obvious signs of roof caving and a huge impact load characteristics. Our country’s coal reserves is restircted due to the difficulty of hard roof control and the effects of gas, permeable, fires and other important factors. Therefore, it is very crucial to figure out the specific mining geological conditions and the use of science and technology before coal mining. A large number of coal pillar will not be wasted as a result of the application of mining technology of cross uphill. Then, the continuation of the time for the use of energy in our country.The article is based on the Linfen Tianyu Hengsheng Coal 9202 fully mechanized top coal caving face cross uphill mining as the research background. Research methods including the measured data collection and collation, laboratory analysis of rock samples, mechanical model calculation and numerical simulation of FLAC3 D and so on. Cross uphill mining technology under hard roof has conducted in-depth research. Achieving the cross uphill mining technology under the premise of safety mining. There is improving economic and social benefits of the mine.First, describing the Linfen Tianyu Hengsheng Coal 9202 fully mechanized top coal caving face cross uphill mining project in detail. Support and arrangement and two schemes of cross uphill are proposed. The stress-strain curve was drawn through laboratory uniaxial and triaxial compression experiments. And the experimental results compared with unit weight, compressive and tensile strength of the physical and mechanical properties of the working face of rock samples. The data is consistent and can provide the basis for numerical calculation and theoretical analysis.Secondly, 9202 working face of roof and floor in which a total of seven rocks were carried out to simulate by using the FLAC3 D software. The compressive stress is near the Machine road is smaller than the Wind by the stress diagram. The tensile stress of the Wind road surrounding rock is larger than the Machine. After crossing uphill, the compressive stress of the Wind road is 52 MPa and the tensile stress of roof and floor also reached 1.05 MPa.After crossing uphill in turn, the distribution of plastic zone is more and more widely and extend to roof and floor gradually by the plastic figure. Front and rear sections of stope beared the shear stress and caused shear failure.The vacant area of roof and areas of vertical displacement are increasing because of the advance of working face. The areas of maximum displacement is in the middle of the roof in the cross uphill mining. The displacement is increasing and the maximum displacement is 581.49 mm.Finally, there is the analysis and calculation theory of the mechanical model of weighting distance. First weighting step is 22.00~49.97 m. It is very closer with the 30 m of field measurements. The periodic weighting step is 7.21~14.49 m. It is closer with the 12~18m of the actual measured. The calculated value of 14.49 m and the measured value are very close. It is calculating two models of working resistance of bracket. The bracket can do it when considering the old roof support the immediate roof and not caving or direct roof or the full height of caving and direct roof have the supporting force of crushed gangue. The bracket to exactly meet the requirements of effective support when only considering the full height of caving and direct roof have the supporting force of crushed gangue and not the old roof support the immediate roof.