Study On Collaborative Mining Theory And Roof Strata Mechanical Behavior Of Deep Gently Inclined Medium-thick Orebody

The complex environment of"three highs and one disturbance"faced by deep mining,the complex mining technology and the risk of mining roof deformation and fracture caused by the difficult mining conditions of gently inclined medium-thick orebody have brought new challenges and technical problems for the safe large-scale mining of deep inclined medium-thick orebody.Therefore,the multi-unit combined collaborative mining mode and technology for deep gently inclined medium-thick orebody were proposed.By means of theoretical analysis,numerical simulation,similar model test and industrial test and other means,aiming at different geological conditions,mining technology,structural parameters,mining sequence,filling technology and other parameters,the collaborative mining theory and mechanical behavior of roof strata of deep gently inclined medium-thick orebody were studied,and the theoretical basis of collaborative mining and the movement and stress characteristics of roof strata were systematically analyzed,which provides theoretical basis and technical support for safe and efficient mining of deep gently inclined medium-thick orebody.The main research results are as follows:（1）A multi-unit combined collaborative mining technology for deep gently inclined medium-thick orebody was proposed,the collaborative mechanism of different production processes in deep ore block was explored,and the theoretical innovation of collaborative mining in deep ore block was realized.Taking multiple continuous strip stopes as units,multiple units are combined into large ore block.Intelligent mining and transportation equipment and control technology are adopted to realize the new mode of the independent operation in space and parallel operation in time of mining and cutting,rock drilling,blasting,ore drawing,filling and other processes,and the regulation of each stope process,and time-space coordination of each stope process and equipment.（2）The roof-backfill coupling mechanical model based on virtual arch theory was established.Taking the mining unit of multi-stope combination as the basic calculation unit,the roof strata mechanical model and fracture development critical equation of unit-roof-backfill structure were deduced,and the space-time evolution and stress distribution law of roof strata movement in collaborative mining were obtained.The deformation characteristics are phased.The roof strata of continuous collaborative mining experience four stages:slow subsidence,accelerated subsidence,backfill compaction and roof-backfill coupling deformation convergence.In the first step of interval mining,the roof strata sink slowly,and in the second step,the roof strata experience three stages:accelerated subsidence,backfill compaction and roof backfill coupling deformation convergence.The maximum normal stress of roof strataσ_max first increases and then decreases with the advance of mining,and tends to be stable,and the rock strata movement and stress changes of interval collaborative mining have obvious sudden jumping.（3）The numerical simulation of the mechanical behavior of the roof strata in the coordinated mining of gently inclined medium-thick orebody under different mining sequences,filling conditions and orebody burial depth was carried out,and the space-time movement evolution law and stress distribution law of the roof strata under multi-factor conditions were obtained.Compared with the continuous mining method,the interval mining method has greater fluctuation of roof strata movement and stress distribution.The smaller the subsidence amount z₀of rock strata before filling,under-roof amount z_c of the backfilling and the buried depth of orebody,the smaller the roof strata movement and stress concentration coefficient,and the easier to converge and balance.（4）The similarity model of paste filling in the collaborative mining of deep gently inclined medium-thick orebody was constructed,and the experimental research on the similarity model of mechanical behavior of roof strata in continuous mining and interval mining in the unit was carried out.The space-time evolution law of rock strata movement,stress evolution law and damage characteristics under the condition of paste filling in the collaborative mining of deep gently inclined medium-thick orebody were obtained.Affected by the dip angle of the rock strata,the displacement nephogram of the roof strata presented the characteristics of"asymmetric triangle"with right eccentricity,while the paste filling has an obvious constraint on the deformation of the roof strata,and the mining method plays an important role in the evolution of roof stress and rock movement.Compared with the continuous mining method,the interval mining method had obvious fluctuation and jumping of rock strata movement,the stress accumulation of roof rock strata was greater,the number of mining pressure relief disturbances was more,and there were large stress fluctuations before and after pressure relief activities.The maximum value of the maximum principal strain of the roof strata usually appeared in the center of the mining and filling area,indicating that the roof strata in the center of the mining and filling area was most prone to damage and failure.（5）The collaborative mining technology of deep gently inclined medium-thick orebody was empirically studied,and the industrial test of deep multi-unit combined collaborative mining was implemented to verify the reliability of the process and technical parameters.In the process of mining activities,the influence range of microseismic events,apparent stress and average displacement of roof strata was mainly concentrated in the range less than 45m from the orebody,the E-M slope value was good,the frequency of microseismic events was low,and there were no large magnitude events.The industrial test results show that the multi-unit combined collaborative mining process and technical parameters can realize the collaborative,safe and efficient mining of deep gently inclined medium-thick orebody,and can meet the requirements of mine production capacity.This paper contains 110 figures,7 tables,179 references.