Supporting stress characteristics and zonal cooperative control technology of long working face in deep thick coal seam

Increasing the length of working face is the development trend of intelligent and efficient fully mechanized longwall mining.When the length of the working face is lengthened,the mining pressure will generally change significantly,that is,it is more difficult to control the surrounding rock and hydraulic support of the working face.In this paper,based on the method of field measurement and theoretical calculation,the change characteristics of frequency,peak value and range of weighting of long working face in 1 000 m deep shaft of Kouzidong coal mine are studied.Based on the elastic independent support,the mechanical model of group support is developed,the force characteristics and attitude change characteristics of the support at the 121304 working face of the mine are studied and analyzed.The theoretical calculation and the actual measurement are in good agreement.Based on the above model,the 140502 working face supporting parameters and control technology are studied.The results show that as the length of the working face increases,the support stress gradually transforms from a single peak value to a multi-peak value,and expands to both ends of the working face.The pressure in different areas of working face is characterized by obvious timing and great difference in strength.The deterioration of surrounding rock in deep mine (low strength roof) increases this trend.When the face length is 300 m,the multi-peak characteristics of super-long working face appear.The “M” type three peak value can be used as the criterion of super long working face.The reasonable working face length should be determined synthetically by coal seam occurrence condition,working face parameter and equipment ability.According to the different attributes of hydraulic supports in space and function,combined with the characteristics of different subareas of long working face,the criterion of super-long working face and the principle of group subarea cooperative control are revealed,a group cooperative control method of working face equipment based on state error and cost function is put forward,and the three-level cooperative control strategy and implementation method of “single support control→multiple support control→group control” are formulated.It can effectively guide the equipment group for the super-long fully mechanized mining face in deep and thick seams to achieve optimal coordinated control.