Abstract:
During the bolt support process in coal mine roadway,the shear failure phenomenon of anchor bolt has oc- curred frequently,which seriously affects the stability of roadway support,especially the development area of joint rock around the roadway,and the shear failure occurs most frequent. Aiming at the problem of shearing and breaking of bolts in coal mine roadway,the main reason for the shear failure of coal mine bolts was determined through the site in- vestigation of bolt damage and the literature review. According to the theoretical analysis,the method of reaming an- chorage body at the shear joint surface was proposed to increase the diameter of the anchor section at the shear joint plane and reduce the maximum shear stress of the bolt at the shear joint plane. The overall stiffness of the anchoring system was improved,thereby the overall shear resistance of the anchoring system was increased. Using the method of numerical simulation,and anchorage stress analysis,the stresses of three types of anchoring,general anchoring,positive wedge reaming anchoring and cylindrical reaming anchoring were investigated. Based on the shear displacement of the anchorage,the influence range of the shear deformation of the bolt and the stress of the bolt,the optimal anchoring mode of the shear joint was determined as the positive wedge reaming anchor. On the basis of the positive wedge-shaped reaming anchoring,the shear displacement and shear load of the bolt were analyzed by changing the different reaming positions,and the reaming position was determined to be optimal at 50 mm. The corresponding bolt shear test device was designed and processed,and it was further verified from the two aspects of shear load and axial spacing of shear plastic hinge that the positive wedge reaming anchor can effectively improve the stress state of the anchor at the shear joint surface. Moreover,the shear load of the bolt rod can be reduced,the axial spacing of the shear plastic hinge can be increased,the shear deformation of the bolt can be reduced,the adaptability of the bolt rod to the displacement of the surrounding rock can be enhanced,and the anchoring system can be improved for the overall shear resistance.