Anchor Cable Breaking Mechanism And Control Technology Of Composite Roof In Goaf Under Near Coal Seam Goaf

Due to the influence of the residual coal pillars and mining disturbance,the sliding and instability of the roof high rock strata in the goaf roadway under the composite roof in the near coal seam lead to the stress concentration in the local area.Under the action of high stress,the composite roof is prone to bed-separation,which leads to the failure of the support structure.In this paper,taking 7324 N goaf roadway(coal pillar width 7.0m)under 7224 N goaf area(average layer spacing 8.0m)in North Anhui Coal Power Renlou Mine as an example,the site investigation and analysis of the roof anchor cable breaking position and breaking characteristics of the roadway,and the establishment of a mechanical calculation and numerical simulation model of the composite roof anchor cable breaking under the goaf area in the near coal seam.The breaking mechanism of the roof anchor cable and the stress distribution law of surrounding rock of this kind of roadway are revealed.Based on this,the key technologies of roof stability control and prevention of anchor cable breaking are put forward.The main research results are as follows:Based on the field investigation and analysis,the failure of the roof support structure of this kind of roadway is mainly caused by the broken anchor cables.The analysis shows that the main factors of the broken anchor cables are respectively the dislocation of the composite roof,the overlying residual coal pillars and the high stress concentration caused by roadway excavation along the gob.By means of theoretical analysis,numerical simulation and field measurement,the development law of composite roof fissure,the asymmetrical distribution characteristics of bed separation and roadway excavation along gob,as well as the influence of roof high stress caused by overlying residual coal pillars on the breakage of anchor cable are studied,and the mechanism of causing high stress and composite roof breakage in this kind of roadway is revealed.Based on the field measurement and theoretical analysis,it is concluded that the bed separation is mainly concentrated in the area where the anchor cables are anchored,and the bed separation is the main reason for the anchor cables to break.According to the above research results,a technical system based on optimizing the supporting structure and improving the active supporting strength of the goaf roadway under the composite roof in the near coal seam goaf was put forward.Engineering practice results show that the optimized close distance coal seam goaf underlying compound roof caving roof of roadway surrounding rock control technology scheme,effective control of the compound roof abscission layer and the stability of roof support structure,to meet the 7324 n during excavation and mining production safety requirements,and other similar in renlou coal mine,for mining under the condition of roadway stability control provides a useful reference.This paper has 58 views,10 tables,and 76 references.