Study on working resistance optimization of hydraulic support in fully-mechanized top coal caving mining face with ultra strong ground pressure

According to the strong mine strata behavior at the initial mining period, high roof subsidence of the coal mining face, frequent powered support jammed problems in Suancigou Mine, a site measurement and theoretical analysis combined method were applied to the analysis study on the powered support jammed mechanism in No. 105-2 fully-mechanized top coal caving mining face in No. 6 seam (upper) of Suancigou Mine. The study results showed that the mining and caving ratio of the coal mining face was low, the toughness of the direction roof was high and the suspended roof distance was long. The advanced caving of the top coal could cause a high swinging mo ention of the roof, the working resistance of the powered support could not be fully played and the roof subsidence of the coal mining face was over 800 mm. Based on the displacement state equation, from the roof control effect, the critical working resistance of the powered support was calculated. With the replacement of the safety valve, the pressure of the high pumping station was increased. The working resistance of the old powered support could be increased to 17 946 kN and the roof subsidence of the coal mining face was less than 600 mm. In comparison with the average resistance of the powered supports, the mean bias resistance of the powered support, the average resistance and rated working resistance of the powered support related to the roof subsidence and the overlimite proportion of the roof, the rated working resistance of the new powered support applied to the new coal miming face was determined to be 21 000 kN and the measured roof subsidence was less than 300 mm.