Design parameters such as initial bonding section, prestress, and bonding stiffness have a significant impact on the mechanical properties of the full-length bonded prestressed bolt. In order to understand the influence of the above three parameters on the axial force and shear stress of anchor bolts under the condition of rock separation, theoretical and numerical models were established, and the sensitivity of different parameters was analyzed based on the grey correlation method. Results indicate that the bonding stiffness had the greatest impact on the mechanical properties of the bolt and largely determined the peak axial force, peak interfacial shear stress, and number of sliding elements. Moreover, prestress had a significant impact on the peak axial force and the distribution of shear stress in the initial bonding section, while the length of the initial bonding section had a significant impact on the number of sliding elements and the peak axial force after sliding. The grey correlation method results show that the correlation degrees of the initial bonding section, prestress, and bonding stiffness were 0.8932, 0.9023, and 0.9775, respectively.

For tunnel-support engineering, the bed separation of surrounding rock has a great influence on the support performance of bolts. In order to reveal the mechanical properties of the full-grouted prestressed bolt under the influence of bed separation, three typical working conditions of single-separation, multi-separation and different separation positions were set up, and theoretical models and numerical models were established. Furthermore, the characteristics of bolt axial force and anchorage–interface shear stress were analyzed by numerical method, and the sensitivity based on an orthogonal test was studied by means of range analysis and variance analysis. The results showed that: (1) under the single-separation condition, the separation value has a significant effect on the mechanical properties of the bolt, and with the increase in the separation value, the sliding failure unit of the bolt increases; (2) for multi-separation conditions, if the total separation value is the same, the increase in the number of separation interfaces is beneficial to the force of the bolt; (3) for the case where the separation layer is located at different positions, the separation layer on the right side is more likely to cause the overall slip failure of the bolt; and (4) for the above three influencing factors, the separation value has the greatest influence on the mechanical properties of the bolt, and the separation position has the least influence.