Study On The Basical Requirements Of The Upward Mining On The Condition Of Underlying Seam With Great Cutting Height Fully Mechaniczed Mining

There With the large-scale promotion of large mining height fully mining method of coal,Some mining areas have begun to face the problem of mining the upper coal seam on the condition of fully mechanized mining with large mining height.The distribution of the caving zone,the roof structure type,and the formation of the equilibrium structure of the roof of fully mechanized mining with large mining height are different with the common working face.Therefore,it is necessary to study basical requirements of Uplink Mining under fully Mechanized Mining condition with large Mining height in Lower Coal seam and movement law of roof and floor of upper coal seam face.(1)Based on the analog simulation and numerical simulation,this paper studies the evolution law of the roof structure of the lower coal seam on the condition of large mining height fully mechanized mining.There are two types of roof structure in fully mechanized mining face with large mining height,which are "articulated beam" structure and " cantilever beam-articulated beam".The hard rock in the top of the roof is the starting layer of the composite cantilever beam.(2)With the direct top additional force as the dividing point,The formation types of roof balanced structure in fully mechanized mining face with large mining height are divided into two kinds,the first kind is block of basic roof breaking keep balance structure formed by the additional force;the second kind is block of basic roof breaking keep balance structure formed without the additional force.In this paper,the first kind of strata which forms the balanced structure is called part balanced structure formation horizon;the second kind of strata which forms the balanced structure is called “balanced structure formation horizon”.The formation of the equilibrium rock structure and layer is different.Based on the three types of roof structure which are put in the paper,the discriminant formula of “balanced structure formation horizon”and “ part balanced structure formation horizon” of the lower coal seam face are deduced.(3)According to the characteristics of the key parameters in the formula of the formation of the equilibrium structure lack of the direct basis,the value of stiffness of gangue of discrimination formula is fitted through laboratory experiment with the independent design and development of experimental apparatus.(4)With balanced structure formation horizon and part balanced structure formation horizon as the marker layer,when the upper coal seam is located above the balanced structure formation horizon,it is considered that the upper coal seam can be mined upward;if the upper coal seam is located below the equilibrium structure formation horizon and above the part balanced structure formation horizon,it is considered that the upper coal seam can be mined upward when the step error satisfies the relation deduced in the paper;if the upper coal seam is located below the equilibrium structure formation horizon,it is considered that the upper coal seam can be mined upward.(5)According to the movement of overlying strata into recession period,the effect of time factor on the influence degree of mining is not obvious,and the discrimination formula of reasonable time interval of upward mining is derived which is based on improved two factors time function.(6)Roof structure of upward coal face before entering upward mining area,located on the upstream mining area,after push out upward mining area is studied with analog simulation and numerical modeling,Roof structure of upward coal face before entering upward mining area,located on the upstream mining area,after push out upward mining area is studied with analog simulation and numerical modeling.There is no substantial difference about evolution of the roof structure before upper coal face being advanced to the ascending mining area;The pressure step is reduced,the pressure is not strong,and the dynamic load coefficient is not large during upper coal face being located in the ascending mining area;the roof structure of upper coal seam face is a large composite cantilever structure after the upper mining area being in the upper mining area;and then the roof structure of the upper coal seam face is returned to normal until upper coal seam face away from the upward mining area120 m.The technology of safety mining of control measures are developed based on results.The research results are verified through engineering example at last.