Abstract: In the process of roadway excavation, the surrounding rock is disturbed by the outside world,and the surrounding
rock at different positions shows different strength characteristics. By constructing the stress model of the bolt anchorage
interface and using the Mindlin solution calculation method,the stress-strain expression of the bolt suitable for the bolt pullout
system is obtained,which can analyze the stress-strain distribution law of the bolt under different pull-out forces. At the
same time,the numerical model of the bolt anchorage system is established by using the finite element simulation software,and
the influence of different confining pressures on the stress characteristics of the bolt is analyzed. The results show that the confining
pressure is the key factor affecting the mechanical behavior of the bolt-anchoring agent interface,which can cause the
stress and displacement concentration zone to move towards the end of the bolt. The increase of confining pressure can significantly
reduce the peak level of shear stress at the bolt-anchoring agent interface (especially at the transverse rib),thereby reducing
the risk of large slip failure between the anchoring agent and the bolt,and improving the integrity and stability of the anchoring
system. It is of great significance to optimize the design of bolt support and improve the reliability of anchoring.

Key words: rock bolt support,confining pressure conditions,mechanical behavior,stress distribution,displacement characteristics