Full-length bonded bolts are widely used in deep mining engineering and an in-depth understanding of their mechanical characteristics under complex and high ground stress conditions is of great significance for deep roadway support systems. Based on a quantitative GSI rating system of surrounding rocks and rock nonlinear dilatancy angle model, a nonlinear dilatancy angle model suitable for jointed rocks was developed. The Hoek–Brown strain-softening model parameters were transformed into equivalent Mohr–Coulomb strength parameters, and a numerical model of the deep roadway was constructed using FLAC 3�� numerical simulation software as a tool. The force characteristics of fulllength bonded anchors under different constitutive model and dilatancy angle model conditions were analyzed, and the effects of different lengths of anchors on the stability of the surrounding rock were studied. The obtained results revealed a big difference between the axial forces of bolts calculated by strain-softening and ideal elastic-plastic models. It was also found that bolt shear force was less influenced by the strain-softening behaviors of surrounding rocks. Dilatancy angle greatly affected bolt axial force. Therefore, if the dilatancy angle was neglected, great errors would be created in the calculation results of supporting structure designs. The nonlinear dilatancy angle model of jointed rock masses more accurately captured the stress properties of bolts after field monitoring and analysis. The findings of the study can serve as a guide for calculating the stability of surrounding rocks in deep mining engineering.