Roof control technology of complex breaking type seam gateway within flexure zone

In order to study the roof control method of the complex broken seam gateway within a flexure zone,a site observation and theoretical analysis were con ducted on several small and two large roof falling accidents occurred in the gateway driving period with the typical broken roof features.The paper summarized the five t ypical features of the roof surrounding rock along the seam gateway under the influences of the flexure zone and discussed the two collapse falling types of the loose s eparation type collapse falling and the extrusion type collapse falling in the roof falling of the complex broken seam gateway.According to the roof two collapse falling ty pe of the complex broken seam gateway,the paper proposed that the active support of the hydraulic single prop or the temporary support beam of the roadheader was a pplied to replace the passive temporary support of the forepoling beam to improve the initial pre-tension force of the bolt and to control the loose separation type collap se falling.The enlarged anchoring scope and the anchor truss system of the top corner anchoring in the gateway were applied to control the gradual bed separation and to control the extrusion type collapse falling.The paper analyzed the support principle of the anchor truss system and determined the support parameters of the anchor t russ.The site application results showed that the roof of the complex broken type seam gateway within the flexure zone mainly would cause the loose separation type C ollapse falling and the extrusion type collapse falling .Among them,the loose separation collapse falling would only weaken generally and would not be avoided.The loos e separation collapse falling would have the natural features of the broken roof surrounding rock caused by the extrusion,tension and others during the formation proce ss of the flexure structure.The anchor truss and the bolt and steel mesh combined support timely installed could control the complex roof gradual separation and could avoid the extrusion type collapse falling.