Study On Mine Pressure Law And Control Technology Of Small Mining And Fully Mechanized Top Coal Caving Face In Buertai Coal Mine

Coal all along plays an important role in the energy structure of modern China,and coal as the main energy of the country,which occupies more than 60%in the structure of primary energy production and consumption,and other energy sources are hard to replace it.Although the construction and production of super large mine has substantially promoted the safe and high-efficient exploitation.However,with the coal mine several meets,the increasing mining depth of roadway and excavation outspread,especially big coal mine face with many new problems in the laws of mine pressure and roof control,which are unique and complex.The Buertai coal mine is an extra large mine with a production scale of 20Mt/a.The extraction-caving ratio of42106 fully mechanized face of the main mineable coal seam 42 coal is small,and the movement rule of roof is not strong.In the process of mining,the pressure in secondary working affect the rock pressure appearance and the roof control instability in the advance support section of the mining roadway,which seriously affects the safety production in the working face.In this paper,42106 fully mechanized top-coal caving face and its actual mining roadway is research object.According to the geological conditions of production,devised the pressure law of the working face and the observation scheme of the characteristics of the two actual mining roadway.By means of statistical analysis and field measurement,the rule of the roof movement and the characteristics of the pressure appearance of the two coal mining face are mastered.The initial study found that the two mining action is the key factor affecting the safety production of the working face,and it needs to be solved urgently.In accordance with the principle of taking effect as the main consideration of cost,through the method of field observation and effect evaluation,three schemes of roadway support optimization,two reinforcement and large resistance advance support are compared,and the large resistance and advanced support is finally determined.In order to solve the serious problem of ore pressure,the roof oriented hydraulic fracturing pressure unloading technology is introduced.On the basis of the borehole peeping and the in-situ test of the strength of the surrounding rock,the fracturing pressure relief scheme is designed.The pressure unloading effect is evaluated through the comparison of the deformation of the tunnel section,the contrast of the pressure step distance and the microseismic monitoring.The width of coal pillar is closely related to the degree of underground pressure.Finally,the width of coal pillar is determined by numerical simulation of FLAC~3DD software.The research results show that the regularity of the old top pressure in the 42106fully mechanized coal caving face in Buertai coal mine is not obvious,the dynamic load coefficient is larger,the average distance of the two mining action affects of the strong mining roadway pressure is 45.3m,but there is no significant regularity.The support effect of the large resistance ahead support is good,and the latter should be popularized.Roof directional hydraulic fracturing technology can weaken the roof strength,increase the energy release frequency of the roof,and reduce the risk of energy accumulation and release to a certain extent.The numerical simulation results show that the reasonable retention width of the coal pillar in the 42106 fully mechanized caving face is 20m.