Development And Experimental Study Of A Fully Recoverable Drilling Anchor And Its Matching Equipment

In some supporting projects,ordinary bolts are not recyclable,which results in waste of steel after the support is completed;while recoverable bolts can be reused many times,reducing support costs,and will not affect the normal operation of subsequent mining machinery and transport equipment.Therefore,it is of practical significance to develop a new type of recoverable bolts and anchors,and the development and application of installing and disassembling equipment.Relying on the research and application project of fully recoverable screw bolt production and installation equipment,taking the roadway support of Xinzhou kiln mine of Tongmei Group as the background,the specific research contents are as follows:(1)Through theoretical analysis of the pull-out force and supporting anchor force of the screw anchor,the pull-out force and supporting anchor force of the screw anchor are obtained.The maximum principal stress,displacement and shear strain of bolt and surrounding rock are obtained by numerical simulation analysis under three working conditions A,B and C.The maximum principal stress of bolt under A condition is larger than that under B and C condition,the maximum displacement is smaller than that under B and C condition,and the maximum shear strain is smaller than that under B and C condition,which shows that the bolt under A condition bears better pull-out force.Analyzing the working conditions of A1 and A2,it is found that the maximum principal stress of bolt under A2 condition is greater than that under A1 condition,and the maximum displacement and shear strain are less than that under A2 condition.It is concluded that the length of screw section is 285 mm and the diameter is 18 mm,that is,the working condition of A1 is the best.(2)According to different coal seam Pu's coefficient,the corresponding anchorage length and the tolerance between borehole and bolt are designed.According to the design parameters and manufacturing requirements,the triangular steel strip treatment and winding processing of the recoverable anchor rod are carried out,and the processing equipment and process are described.Research and development of drill pipe and bit,and transformation of the original power moment multiplier.(3)Whether the designed bolt meets the rationality of installation and disassembly through underground test detection.The results of the first underground test are as follows: 1 bolt is pulled to fracture,the rest of the bolts fail to meet the design requirements,and the pull-out test results are not good.The reason is that the drilling hole is too large,the anchoring force is not enough,the drilling efficiency is low,the drilling time is long,the distance between the hand-held drill joint is insufficient,the size of the bit and the drill joint,the length of the bolt screw section,the diameter of the bolt body is not appropriate,etc.The second pull-out test of five recoverable bolts is carried out,using small-sized drill pipe,and adjusting the distance between the hand-held drill joint and the size of the joint.The test results are as follows: 1 bolt is drawn to the puller to relieve pressure,and the pulling force reaches 20 MPa at this time;1 bolt is pulled to fracture,the maximum pulling force is 26 MPa;the other three bolts are also pulled out at 23~25 MPa.In the recovery test,the pull-out force of the four bolts is less than the second test value,but all of them are greater than 17 MPa,which meets the anchorage design requirements.There are 65 papers,15 tables and 62 references.