Movement Law And Control Strategy Of Overlying Strata With Cemented Backfilling Mining Technology Using Continuous Mining And Continuous Backfilling Method

As an important part of the green mining technology system,filling mining technology is an important way to implement the development concept of "green water and the green mountain is the silver mountain of gold" and to achieve safe,efficient,and green development of coal resources.In this thesis,in order to reduce the cost of filling mining,improve the efficiency of filling mining and effectively control the surface deformation,a new coal mining technology is proposed for continuous mining and continuous backfilling(CMCB).Using a typical CMCB workforce as the engineering background,the methods of theoretical analysis,numerical simulation,and indoor test methods were used to systematically study the deformation characteristics of the roof plate of the CMCB field,the dynamic migration law of surrounding rock stress,and the evolution characteristics of overburden fracture development,and reveal the mechanism of overburden movement control.The field test was carried out,and great application results were achieved,with significant economic and social benefits.The following main conclusions were reached.(1)In view of the main problems of the current backfilling mining technology,a new technology of coal mining with CMCB is proposed,and the influence law of different backfilling material ratios on the flow characteristics of the backfilling slurry and the mechanical properties of the backfilling body is obtained.(1)The CMCB has been developed,which enables parallel mining and filling operations.And the working face layout and the main supporting equipment have been determined;the backfilling mining mode adapted to different fields surrounding rock conditions has been proposed,which enables continuous mining and continuous backfilling of the working face.(2)The main physical properties of gangue,fly ash,and cement was analyzed.The flow characteristics of the filling slurry and the aging strength of the filling body were studied under different filling material ratios.And a series of cementitious filling material ratios were formed.(3)An efficient and continuous transport system of filling materials adapted to different coal seam inclination angles and the corresponding method of compact filling in the working face have been proposed,forming a perfect system of CMCB technology.(2)Based on the elastic foundation beam theory,a mechanical model of the roof plate of the CMCB field is established,and the deformation characteristics of the roof plate at different stages of the whole mining and filling process are obtained by considering the differences in the foundation coefficients of the coal pillar and the filling body,as well as the effect of the goaf.(1)Based on induction,the force characteristics of the roof in each stage are summarised,the deformation characteristics of the roof in each stage are mechanically analyzed,and the critical conditions for direct roof breakage are obtained by combining the maximum tensile stress theory.(2)During the filling stage of the odd-numbered lines,the direct top produces a small bending sink with a wavy distribution of overall deformation,while during the filling stage of the even-numbered lanes,the direct top produces significant deformation,gradually shifting from a deep V-shaped distribution to a wide U-shaped distribution as the filling of the even-numbered lanes advances,and the smooth section of the wide U-shape in the middle of the field gradually extends as the filling advances.(3)The following rules are obtained by analyzing the influence of various factors on the direct roof deformation.The elastic modulus of the filling body plays an important role in the direct roof deformation.The higher the elastic modulus of the filling body,the smaller the direct roof deformation.And when its elastic modulus exceeds a certain value,its influence effect gradually weakens.The influence of coal seam height on the sinking of the roof of the field is linear,but when the mining height exceeds a certain value,the deformation of the roof increases significantly.(3)Numerical simulations were used to obtain the dynamic migration pattern of the surrounding rock during the whole process of coal mining under the influence of three different filling mining modes,namely,"Jumping mining one branch by one branch,Jumping mining one branch by two branch,and Jumping mining one branch by three branch ".(1)Under the influence of different infill mining modes,the larger the width of the coal pillar,the smoother the vertical stress variation in the mined surrounding rock,which is conducive to the control of the roof.However,increasing the width of the coal pillar will increase the number of steps of the retrieval work and correspondingly increase the distance of the working face moving backward,which is not conducive to concentrated production.(2)The dynamic migration characteristics of the surrounding rock stresses during the filling process are wave-like.The coal pillar and the filling body alternately bore during the mining and filling process.And there is a primary and secondary bearing structure,which protect each other,providing a stable filling space for the filling material.Multi-stage back mining creates time for the cementation and curing of the filling body,avoiding premature bearing of the filling body and damage and destruction caused by insufficient strength.(3)The selection of the filling mining model needs to take into consideration factors such as the conditions of the mine roof and the strength of the coal body.When the stability of the mine roof is good,and the strength of the coal pillar is strong,the filling mode of " Jumping mining one branch by one branch " is preferred.The filling mode of " Jumping mining one branch by three branch " is preferred in the case of soft and broken coal seams.The filling mode of " Jumping mining one branch by two branch " is preferred while the coal seam is medium stable.(4)The displacement evolution characteristics and the fracture development laws of the overburdened rock were studied by a similar simulation test.The interaction between the filling body and the surrounding rock of the mining field was elucidated,and the mechanism of overburdened rock movement control under the CMCB method was revealed.(1)The roof of the CMCB field is dominated by slow bending and sinking.As the working face advances forward,the direct roof of the working face appears to be separation layer,separation layer extended and separation layer closed in turn;the main roof only appears to be slightly fissured;some of the rock layers above the main roof appear to be delaminated in the parallel direction.When the workings advance to a certain distance away from the branch lane,the detachment and fissures of the overlying rock layers within the influence of the branch lane gradually close,and the overlying rock structure begins to be more stable.(2)During the first stage of mining,the roof of the field did not produce significant damage,and there were no vertical fissures.During the second stage of mining,the filling body gradually began to bear the load of the overlying rock layer,and vertical fissures appeared.As the workings continued to advance,the vertical fissures in the filling body gradually expanded.The load-bearing body of the overburden is changed from the coal pillar to the filling body.The filling body limits the deformation of the overburden and reduces the degree of separation layer of the roof of the support lane.(3)The working face adopts step-by-step filling,in which the coal pillar and the filling body are carried alternately during the whole filling mining process,ensuring the stability of the filling space and the gelling and curing time of the filling material.Mining and filling do not interfere with each other,the working face can be continuously mined and continuously filled,those can be operated in parallel to the maximum extent,which can improve the efficiency of filling mining and increase the production capacity of the filling mining mine.(5)Based on the engineering and geological characteristics and coal seam conditions of three typical coal mines,namely the Yuxing,Haoyuan,and Huangbaizi mines in western Inner Mongolia,a reasonable CMCB method is proposed to replace coal resources underground.Engineering tests have shown that the CMCB method can maintain the stability of the surrounding rocks,effectively control the movement of the overburden structure and realize the requirements of surface deformation control by spacing the coal out of the supporting lane and replacing it with step-by-step filling.This method has the characteristics of multi-circulation and small disturbance,which is conducive to the safe,green,and efficient mining of coal resources.