| Compared with general mining height,fully mechanized mining with super-large mining height has many advantages,such as high efficiency and low cost,but there are many uncertainties in super-large mining height.In order to ensure the stable operation of coal mine production and the physical and mental health of workers,it is necessary to realize the comprehensive understanding and effective control of uncertain factors in order to guide production.In this paper,DahaiZe Coal Mine No.2 coal seam 6.9m super-high fully mechanized mining face as the research object,through numerical simulation,field measurement,theoretical analysis and other methods to carry out research and analysis,and strive to explore the DaHaiZe Coal Mine super-high fully mechanized mining face pressure display law and control technology.This paper mainly analyses the characteristics of strata pressure,the regularity of strata pressure,the operating characteristics of support load and the distribution law of abutment pressure of working face in DaHaiZe Coal Mine;studies and analyses the characteristics of roof in DaHaiZe Coal Mine,and classifies them;and uses numerical simulation to simulate and classify the characteristics of roof in DaHaiZe Coal Mine.The stress field,displacement field and plastic failure field of fully mechanized mining face are studied.In addition,the mechanical model of coal and rock of fully mechanized mining face with super high mining height in DaHaiZe is established,and the condition of coal wall is calculated by fractal theory.According to the field observation and numerical simulation,it is concluded that the initial weighting will occur in the range of 40 to 60 meters from the working face in No.2coal seam of DaHaiZe Coal Mine,the height of roof fracture zone and caving zone are roughly analyzed.On this basis,it is deduced that the stress reaches its peak value at the initial weighting.With the passing of the initial weighting,the stress will be greatly reduced,but will not disappear.It mainly concentrates at 6 to 7 meters in front of the coal wall of theworking face.During the process of the stress reduction,the coal wall of the working face will be affected,which is shown as the coal wall sheet.When the working face advances continuously,the state of the pressure relief zone above the gob also changes.When it advances to 260-320 meters,the state of the pressure relief zone shows double peaks,which indicates that the top of the fracture zone has reached.When the thickness of coal seam is 6.9meters,the part above 4.5 meters must be protected to ensure the smooth mining,that is,the height of protection must exceed 2.4 meters.The study on the control of strata pressure shows that because the support load of the working face is mainly static load and combined with the suspended gravity existing in the goaf area,the roof control requirement of the fully mechanized mining face with super-large mining height can be realized by calculating the working resistance required by the support under static load.For statistical analysis of current support types shows that the maximum height should be 7.2m,the support types are twopillar shields hydraulic support.In order to further stabilize the working face,the upper and lower noses need to be equipped with transition brackets,three brackets at the upper and lower ends.In addition,considering such factors as strong labor and difficult management at the lower end of the working face,the four head brackets are further installed. |
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