Analysis And Appliaction Of Movement Rules Of Overlying Strata In Fully Mechanized Top-Coal Caving Face In Steeply Dipping Seam

The system stability between support and strata of variable-angle zone is hard to control due to the specialty of destruction and movement of roof in the steeply dipping coal seam.Take thefully mechanized top-coal caving face 120210 which with big dip and variable angle as the research background, through field observation, physical similar material simulation experiment and numerical simulation analysis, by using the existing large dip angle coal seam mining theory,asystematic research on movement rules of overlying strata infully mechanized top-coal caving face with big dip and variable angle is conducted, and the supportadaptability is analyzed. The research shows that:The overburden falling of coal seam with big dip and variable angle has obvious characteristics in sequent and uniformity. All the stress field distribution, failure distribution, gob filling characteristics and support resistancedistribution in variable angle sectionshow different law and characteristics from normal seam. In this section, stress concentration, high degree of deformation, the low gob filling degree and the poor restrain effect between support and roof are the key influencing factors of the strata movement characteristics of the face.The roof stress of face with big dip and variableangledistributesas a asymmetricshape of hump. Stresses of upper and lower section superpose together in variable angle section, causing stress concentration, high extent of damage and large tensile damage range. The maximum roof vertical stress of upper and lower section decrease with the increasing of variable angle, but its peak is closer to variable angle section, thus aggravatethe asymmetry of the whole roof stress distribution.The dip angle of coal seam of upper section is small, the slip filling effect along the inclined direction of caved rock is inadequate. In the variable angle section and the top of lower section, therooffragmentation degree is high and caving fully. The caved rock movetoward the lower section, therefore the whole face has a characteristic of: the lower section is filled and compacted, the variable angle section is partial filled, and the upper section is completed filled. Meanwhile, the caved rock in upper section cannot effectively fill the gob of variable angle section, where the constraint effect of the caved rock to roof is weak, the motion degree of overlying strata is aggravated and instability in complex formsA viewpoint, named“the upper curtate for the subject of high-efficient production,the lower curtate for the basis of safe,then the section of variable angles for the key to transform between the curtates”,which guide the product practices of variable large inclined angle faces of Zaoquan coal,is proposed based on the characteristics of loaded support and its stability on the120210 working face of Zaoquan coal verified the characteristics of overburden movement and failure on variable large inclined angle faces.