Study on technology of deep-hole blasting combined cutting of hard thick roof in fully mechanized caving face of extra-thick coal seam
Aiming at revealing the law and mechanism of deep-hole blasting combined cutting of com-posite hard roof,the simplified mechanical models of roof characterized with"four-end fixed support","three-end fixed support,one-end simple support",and"mixed support"were established based on the theory of elasticity,and then the laws of roof deformation and failure under different support forms and parameters were analyzed.Moreover,based on the actual geological conditions of the 8210 working face of Tongxin Coal Mine,the deep-hole blasting combined roof cutting program of"open-off cut+two tun-nels"was proposed,and the technical parameters of combined roof cutting were given.Finally,on-site engineering verification was carried out.The results reveal that the thickness of the hard thick roof con-siderably influences the integrity of the roof.In the presence of a thick hard roof or a composite roof in the formation,the method of roof cutting at the open-off cut alone may fail to break the roof,and lateral roof cutting from roadway sides can serve as an auxiliary method to achieve sufficient roof breakage.The deep-hole blasting combined roof cutting method of"open-off cut+two tunnels"can effectively shrink the suspended area of the thick hard roof,and the initial caving step distance of the main roof is con-trolled at about 40 m.This step distance is shortened by more than 50％compared with previous prac-tice,marking effective management of the large suspended area of the thick hard roof.The purpose of this study is to provide theoretical basis for the management of roof disasters in working faces under the same geological conditions,and to provide technical guidance for the safe mining of coal seams with a thick hard roof.
thick hard roofroof structure modeldeep-hole blastingroof cuttinginitial caving step distance
万方数据
维普
