Burst behavior and its proneness evaluation of bedding coal
Coal burst seriously restricts the safe mining of deep coal resources.It is important to establish reasonable coal burst proneness indicators from the perspective of inherent material properties to assess the coal burst risk.Due to the significant influence of the bedding structure on the mechanical behavior of coal,uniaxial compression experiments and discrete element numerical simulations were carried out on coal samples with different bedding angles in this study.The effect of bedding angle on the mechanical properties and burst behavior of coal was then analyzed.The experimental and numerical simulation results show that:with the increasing bedding angle,the strength,deformation,and burst feature of the coals decreased firstly and then increased;the fine-scale fracture mode gradually evolved from shear-dominated to tensile-dominated.Coal burst is a dynamic fracture issue;and the kinetic energy generates when the energy release rate is higher than the energy demand of dynamic fracture.Accordingly,a new indicator,realistic energy release rate(RERR),was proposed as a criterion for coal burst proneness based on the experimental results.It considers the contribution of post-peak energy to coal burst and the time effect of failure,reflecting the intensity of energy release during the dynamic fracture process.By combining the actual failure situation(sound,ejection)and the comparison with the traditional indicators(including the uniaxial compressive strength USC,elastic stain energy index WET,bursting energy index KE,and duration of dynamic fracture DT),the burst proneness of coals with different bedding angles was comprehensively assessed.The RERR was found to be highly linearly correlated with traditional indicators,the reasonableness and validity of the RERR were verified.Finally,the standard for classifying the coal burst proneness grade based on the RERR was established.
mining engineeringcoal burst pronenessbedding coaldiscrete element methodrealistic energy release ratekinetic energy
万方数据
维普
