Study On The Temporal And Spatial Laws Of Overburden Instability Motion And Interstice Change In Fully Mechanized Caving Face Of Xiadian Coal Mine

With the continuous development of green mining,grouting in separated-bed to control ground subsidence has become an important technical route for green mining.Especially in the conditions of fully-mechanized caving mining of extra-thick coal seams,the time-space law of overburden instability motion and fracture development has important theoretical and practical significance for the technical design of grouting in separated-bed and rock movement control.Using the combination method of numerical simulation and similar simulation experiments to explore the time-space law of overburden instability motion and fracture development and coming up with the designing scheme of the grouting in separated-bed of the 3116 working face of Xiadian Coal Mine based on the geological conditions of fully-mechanized caving mining of the extra thick coal seam of Xiadian Coal Mine.(1)The UDEC numerical simulation is used to analyze the characteristics of the mining pressure and the separated-bed developing laws.It is concluded that the separation space span has experienced four stages with the advance of the working face,namely the accelerated development stage-deceleration development stage-acceleration reduction stage-residual separation stage;the shape of the separated-bed generally experiences three stages,namely L-shaped-T-shaped-basin shape;the relationship between the development of the separated-bed and the key layer is analyzed and the distribution law of the fracture in the overlying rock layer with the advancement of the work surface;through the analysis velocity field vector of overlying strata of the working surface,the sinking velocity field of the overlying strata is divided into five regions,namely the pre-moving zone?the accelerated sinking zone?the slow sinking zone?the stable zone and Bending deformation zone.(2)The physical similarity simulation is used to further reveal the spatial law of the overburden instability motion and the fractures are classified and the effects of different kind of fractures on the overburden instability motion are discussed.The time effect of the overburden instability motion and fracture development is revealed and the concept of hysteresis and synchronization effect of frcture development is proposed.(3)Based on the actual situation of the 3116 working face,the design scheme of the grouting in separated-bed is proposed,and the optimal the position and the time of the grouting are discussed.The feasibility of the separated-bed grouting was verified by monitoring,regulation and data analysis.