Study On The Catastrophe Characteristics And Mechanism Of The Coal Wall Of 8303 Large Mining Working Face Of No.1 Coal Mine Of Yangquan

Mining technology of working face with large mining height had achieved high production and efficiency.However,the coal wall stability problems restricted the safe and efficient production.Theoretical analysis,field studies and numerical analysis methods are mainly used in this paper to research the catastrophe characteristics and mechanism of coal wall with large mining height under the synthetic action of multi-factors.The influence of cutting height,length of the mining working face,coal working face advancing speed,the strength of the bracket support,the strength of the face guard,the strength of the roof of the coal seam,the strength of the coal seam,coal seam buried depth,and the angle of coal seam to the stability of coal wall were mainly discussed.Main factors influencing the stability of the working face of coal wall were analyzed from the point of view of the residual energy by adopting the numerical simulation.By orthogonal experiment and regression analysis,the stability evaluation formula and the evaluation index of working face with large mining height were got,and the instability possibility of 8303 working face was verified.In combination with field study and numerical simulation,the characteristics and mechanism of the coal wall instability.of 8303 working face were studied.Based on the above research,the stability control technology measures of coal wall with large mining height were put forward.Papers research content and results are as follows:(1)The characteristics and mechanism of the stability of the coal wall under the influence of Cutting height,length of the mining working face,coal working face advancing speed,the strength of the bracket support,the strength of the face guard,the strength of the roof of the coal seam,the strength of the coal seam,coal seam buried depth,the angle of coal seam and fault were analyzed.Cutting height,coal working face advancing speed,the strength of the coal seam,coal seam buried depth were the major influence factors.The significance order was the strength of the coal seam>coal seam buried depth>cutting height>coal working face advancing speed.(2)The power function relationship between the coal cutting height,face advancing speed,coal hardness and coal seam buried depth with the coal wall stability was found.Stability evaluation formula of the coal wall under the influence of multiple factors isY =-9E7 + 4.01E7 f-1.526 + 0.233H2.8011 + 4.62E5M2.641 + 9.66E3V1.4972<107 J,and the instability of the coal wall of 8303 working face of was verified.(3)The main instability form of the coal wall of 8303 working face was cracking type broken of central coal seam triggering shear type broken of the upper coal seam.(4)The destruction condition for cracking type broken of central coal seam was Rt ? 2KP/(?R arcs in b/R);the instability conditions for shear type broken of theupper coal seam wasCh sec ?+[QL+?(2h-H+b/2L-H-b/2 tan ?)](sin ? tan ?-cos ?)? 0.(5)Combined type of rib falling was mainly related to cohesion,angle of internal friction,tensile strength,shear strength,coal properties and roof pressure.The measures that improving the strength of coal seam,reducing coal seam coal cutting height,accelerating coal seam advancing speed,strengthening supporting management to guarantee the bracket support strength,strengthening the management of roof,and avoiding up-dip mining when designing mine and so on could reduce the roof pressure,reduce the rotation and sink of the roof,and improve the coal wall stability.