Study on influence of different mining sizes on movement law of overlying rock under waterproof key layer
The height of the water conducted zone is one of the most concerned factors in the"three under"mining of coal mines.In order to explore the relationship between different mining sizes and the development height of the water conducted zone,taking the Sha-ozhai Coal Mine as the research object,the deformation analysis method was used to determine the influencing factors of the development of the overlying water conducted zone on the working face.The numerical simulation software was used to simulate the caving morpholo-gy of the overlying rock after the mining of the working face with different lengths during the mining of the No.2 coal seam in Shaozhai Coal Mine.The research results indicate that the waterproof key layers covering 65 m and 112 m thick above the No.2 coal seam are the inhibition layers for the development of the water conducted zone of the coal seam.They are all composed of a harder rock layer in the middle as the skeleton,and the upper and lower layers are covered with each layer of soft rock.When the water conducted zone develops to the inhibition layer,the inhibition layer inhibits the longitudinal expansion of the water conducted zone and tends to expand laterally.At the same time,it increases the caving angle of the overlying rock.When the range of the caving rock mass exceeds the limit span of the inhibition layer,the water conducted zone tends to expand upward.The caving of the overlying rock of the working face with different open-off cut lengths only occurs within the mining space of the working face,and has no obvious effect on the overlying rock within the range of 60 m on both sides;the main factor affecting the overall overlying rock movement law is the advancement of the working face,when the length of the working face open-off cut is less than 180 m,the overlying rock movement is mainly manifested in the caving of the Yan'an Formation,when the length of the open-off cut increases to 220 m,the rock layers of Anding Formation begins to accelerate and sink with the advancement of the working face,but it has not completely collapsed,when the length of the open-off cut increases to 300 m,the Anding Formation and the Luohe Formation have completely collapsed at 120 m behind the working face.The research re-sults can guide the reasonable design of the open-off cut length of the working face under the condition of protecting the waterproof key layer,which has a certain reference for the prevention and control of mine water damage.
water conducted zonedeformation analysis methodwaterproof key layernumerical simulation
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