Study On Anchor Cable With C-shaped Tube Structure Support In Large Section Caving Roadway

Aiming at the supporting problems such as weak and broken surrounding rock,local roof falling,extrusion of surrounding rock,slope of roadway wall and poor supporting effect of roadway due to large thickness of top coal in roadway with large section.Taking tongxin Mine 5204 roadway(coal seam thickness about 18m)as the engineering background,the integrated anchoring technology of pipe and cable was studied in detail based on the anchor cable with C-shaped tube structure developed by the team.The original rock stress test of 5204 roadway was carried out by stress relief method,and it was found that the maximum principal stress direction of 5204 roadway in Tongxin Mine was approximately 20-27 Mpa,and the lateral pressure coefficient was about 1.6.At the same time,the random observation of the surrounding rock structure of 5204 roadway was carried out,and the scope of serious weak breakage and separation was determined to be less than 2.5m of the roof.The core of representative strata roof and floor in 5204 roadway was drilled and its basic mechanical parameters were obtained through mechanical experiments.The deformation and failure characteristics of 5204 roadway are summarized by field investigation.Based on FLAC3 D numerical simulation,similar model test and theoretical derivation,the law of surrounding rock deformation and failure is systematically studied.The stress model at the stage of linear deformation is simplified,and the distribution relationship of displacement,bending moment,shear force and axial force of roadway with large section supporting coal is obtained with the position of roadway surface.The most unstable parts of roadway are the top Angle and the side near the small coal pillar.The function of anchor bolt and anchor cable in large section caving roadway is compared and analyzed.It is found that the function of anchor bolt is mainly to form reinforcement arch by squeezing rock mass,but the strength and scope of reinforcement arch are weakened by the limitation of roadway space,its own structure and bearing capacity.The function of anchor cable is mainly to provide suspension to bear the load of caving rock mass.The supporting range is large,the axial bearing capacity is high,but the shear strength and stiffness are low,and it is easy to be broken by the free broken surrounding rock or the transverse dislocation.Combined with the supporting function of anchor bolt and anchor cable,the anchor cable with C-shaped tube supporting structure with high bearing capacity,large range,high shear strength and stiffness is proposed by using C-shaped tube and anchor cable.The tensile tests of two types of anchor cables are carried out and their axial bearing performance is compared.The frictionless tension-shear test of double prefabricated structural surface against anchor cable with C-shaped tube supporting structure was carried out with self-developed equipment,and the optimal combination of anchor cable was determined.Compared with anchor bolt and anchor cable,it is found that the tubecable composite support structure has both initial shear stiffness and axial and transverse bearing capacity stronger than anchor cable.Based on the combined structure of tube and cable and the condition of soft and broken surrounding rock of large section supporting top coal roadway and high level stress,the idea of integrated support of tube and cable is put forward and the principle of integrated support of tube and cable is established.The integrated support design of pipe and cable based on the best combination of pipe and cable was carried out for 5204 roadway.The design scheme was checked according to classical support theory,and the support scheme was screened according to FLAC3 D numerical simulation software.Use self-developed equipment: Dynamic pressure roadway support physical model experiment equipment,the original support scheme and anchor cable with C-shaped tube combination plan similar to the supporting effect of model test,analysis of the original support scheme and anchor cable with C-shaped tube integration support scheme of roadway in the process of roadway excavation process and destructive load within the changing law of stress and displacement of surrounding rock as well as the deformation and failure of each stage,The rationality of anchor cable with C-shaped tube integrated support scheme is verified.Based on the integrated support scheme of anchor cable with C-shaped tube,the field support test of 100 m was carried out in 5204 roadway of Tongxin Mine,and the pulling force test of the combination of anchor cable with C-shaped tube was carried out in the field.It was found that anchor cable with C-shaped tube met the requirements of the pulling force of the supporting member in the roadway with large section supporting the top coal.In the field,three deformation monitoring stations were set up to monitor the surface displacement of the implementation section of the original support scheme and the test section of the anchor cable with C-shaped tube combination support scheme,and multi-point displacement meter was embedded to monitor the internal deformation of the surrounding rock.It was found that the anchor cable with C-shaped tube combination scheme had better deformation control effect than the original scheme.Combining with big cross section top-coal condition,in the engineering background of ore with 5204 roadway,through a series of technical means,to understand the distribution of mechanical environment,and structure of surrounding rock of roadway surrounding rock,combining with field by coring in the basic mechanical parameters resulting from the mechanics test,using numerical simulation,similar model test,the anchor cable stretching experiment,anchor cable with C-shaped tube shear test and theoretical calculation,Finally,the integrated support scheme of large section supporting top-coal anchor cable with C-shaped tube was established,and the rationality and superiority of the integrated support scheme were tested through field test.The support system of large section supporting top-coal roadway based on integrated support technology of anchor cable with C-shaped tube was established,which provided reference for similar working conditions.