Research On Reinforcement Technology Of Inflatable Lock-type Of Narrow Coal Pillar Of Gob-side Entry Driving

The bidirectional-reinforcement technology of the inflatable lock-type anchor is a new method for supporting narrow coal pillar in the gob-side entry driving.Under the engineering background of the coal pillar set in the gob-side entry driving of 04 working face under 123 coal seam in the Jining No.3 Coal Mine,the in-depth research on the bidirectional-reinforcement technology of the inflatable lock-type anchor by the anchorage method through the laboratory test and numerical simulation combined with the theoretical analysis.Main research is as follows:1.To study the supporting mechanism and the optimization scheme of the inflatable lock-type anchor,the coal pillar set in the gob-side entry driving of 04 working face under 123 coal seam in the Jining No.3 coal mine was taken as the engineering background,the similarity simulation experiment to test the bearing capacity of narrow coal pillar in different methods of reinforcement was conducted.The influence of different reinforcement methods on the failure mode,the law of bearing capacity and deformation of coal pillar,as well as the law of stress of anchor cable was analyzed.The results show that the maximum bearing capacity of the specimen increase with the rise of the number of the inflatable lock-type anchor,increased by a maximum of 96.05%.The deformation of specimens can be effectively controlled by the inflatable lock-type anchor,the vertical deformation and horizontal deformation can be reduced by a maximum of 46.21% and 46.23% respectively.The inflatable lock-type anchor,in the condition of small deformation and stress,can have a better effect of the reinforcement with the proper reinforcement method.2.In order to further study the reinforcement mechanism and optimizing the support scheme of inflatable lock-type anchor,the coal pillar set in the gob-side entry driving of 04 working face under 123 coal seam in the Jining No.3 coal mine was taken as the engineering background,combined with the relevant conclusions of laboratory experiments and field industrial test,the FLAC3 D numerical calculation software was applied to analyze the internal rupture characteristics and evolution process of coal body and load characteristics of inflatable lock-type anchor of the anchoring unit,the law of narrow coal pillar deformation and stress distribution and force of inflatable lock-type anchor of different reinforcement methods.The results show that the deformation of narrow coal pillar can effectively controlled by inflatable lock-type anchor.The area of compressive stress produced by prestress of anchor cable is distributed symmetrically.The conjugate shear failure zone is generated inside the anchor solid,and the Angle between the conjugate shear band and the horizontal plane is about 45°.The distribution of axial load of cable has significant characteristics of stages.In the pre-peak stage,the axial force of the anchor cable is basically stable.In the post-peak stage,the axial force of the cable increased significantly,and the load in the middle of the rod body is larger than both ends.inflatable lock-type anchors are more reasonable in a double-row arrangement with an interval between 0.8×1.0m~1.5×1.0m.3.Aiming at the serious deformation of the roadway of gob-side entry driving in Jining No.3 Coal Mine.Bidirectional-reinforcement Technology of narrow coal pillar of gob-side entry driving based on inflatable lock-type was used.The on-site industrial test was carried out in the tape transportation lane of the 04 working face under 123 coal seam in the Jining No.3 coal mine.The results show that the inflatable lock-type anchor can reduce the deformation of the roadway by more than 70%.And during reinforcement,the inflatable lock-type anchor has a balanced load and does not reach the breaking force.The research results can provide a strong support for the improvement of the theory of bidirectional-reinforcement for coal pillar of gob-side entry driving with inflatable lock-type anchor and the further popularization of this technology.The paper has 38 pictures,11 tables,80 references.