In order to cope with the shortcomings of anchorage performance of traditional bolts in the field of slope, and tunnel disaster prevention, a graded lateral expansion bolt was developed, whose structural mechanical properties and anchoring mechanism are analyzed in this paper. Firstly, the constitutive relation and ultimate pullout force formula of graded lateral expansion bolt under radial load-bearing deformation are obtained based on elastic mechanics theory and physical ring model. Secondly, through the static pull test, the bearing capacity transmission law and the bearing deformation mechanism of the bolt are obtained. Finally, it is found that the bolt not only has better performance in shear resistance, torsion and energy absorption, but also has more advantages in improving the overall stability of surrounding rock and releasing the deformation energy of surrounding rock by comparing the structural characteristics of graded lateral expansion bolt and NPR bolt. The results prove that the characteristics of the graded lateral expansion bolt are more suitable for the geological environment with poor stability. This study provides ideas for the research and development of new bolts, as well as new solutions for tunnel and slope disaster prevention projects.

For the purpose of studying the calculation of composite anchor force of anchor rod and the influence of anchoring angle on the surface shear force of anchored structures under the condition that the shear direction and the anchor rod tend to be coplanar, FLAC3D finite element software is used for numerical simulation. Firstly, the numerical calculation models were established based on the solid elements and contact surface elements, and the parameters required for the numerical simulation are inverted by the physical experiment results. Secondly, fish language in FLAC3D was utilized to record the variation of shear force of structural plane with the increase of shear displacement during shearing. Finally, according to the geometric relationship in the mechanical model, the distribution function of the reaction force of the compressive side along the anchor rod was obtained. On the basis of the classical beam theory, the mechanical model was established, and the shear force calculation formula of the anchor rod at the structural surface was derived using the principle of minimum potential energy and the displacement variational method. The results demonstrate that the shear force on the anchorage structure surface first increases and then decreases with the increase of the anchoring angle. When the anchoring angle β≤ 90°, the “guide rail effect” of the anchor rod is more significant; When the anchoring angle β>90°, after shear deformation, the rocks are separated due to the deformation of the anchor rods.