Intelligent Identification And Control Of Coal Pillar Stability In Goaf Under Strong Mining

In the long-term and large-scale mining of coal resources in Northern Shaanxi,under the high-intensity mining conditions with the characteristics of large mining thickness,large working face length,large cross-section of mining roadway and fast advancing speed of working face,there are potential safety hazards in surrounding rock of roadway.Taking the stability of coal pillar in the empty section of Xiaobaodang coal mine as the research object,this paper comprehensively adopts the methods of on-site geological and mining condition investigation,theoretical analysis,mechanical test,numerical simulation and field application,etc.Aiming at the main control factors of coal pillar catastrophe,stability prediction,response of damaged coal samples to different loading rates and stability control of coal pillar under strong mining,the main contents are as follows:(1)Under the disturbance of the project,the process of coal pillar disaster and the determination of the main control factors.Based on the analysis of the instability process of coal pillar,the main controlling factors can be divided into static main controlling parameters(coal rock physical and mechanical parameters,engineering design parameters),dynamic main controlling parameters(mining additional parameters and goaf time-varying parameters).(2)Considering the static main control factors,the long-term stability intelligent identification of coal pillar was based on mean impact value-genetic algorithm-neural network(MIV-GA-BP).After collecting the historical cases of coal pillar in China,the weight order of main control factors of coal pillar stability was obtained through parameter sensitivity analysis,and the prediction model of coal pillar stability based on BP optimized by GA was established.(3)Considering the dynamic factors,the response characteristics of damaged coal samples under different loading rates were revealed.Uniaxial compression tests of damaged coal samples were carried out to obtain the mechanical properties and acoustic emission characteristics of coal samples under different initial damage variables and loading rates.(4)Based on FLAC3D,the numerical model of coal pillar in goaf section under mining conditions was established.Considering the additional factors of mining(initial failure of coal pillar,mining speed and roof conditions),the dangerous area was determined and the control parameters of coal pillar stability were optimized in combination with field conditions.(5)From the aspects of coal pillar size optimization,roof presplitting,advanced support of coal wall and optimization of mining speed of working face,the control framework of coal pillar stability in goaf section under strong mining was established,combined with roadway surface deformation and fracture monitoring,the control effect was verified.The results provide reference for prevention and control of coal pillar disaster and intelligent construction of mine.