Abstract: Load transfer differential equation for rock bolt is established according to the stress equilibrium and load transfer mechanism of small-section bolt, and the axial load transfer equation of rock bolt is also set up according to the strain deformation before and after the installation of rock bolt in the tunnel wall rock. In combination with the radial deformation equation of brittle wall rock in circular tunnel, the computing model for the axial stress of the grouted rock bolt in ideal brittle wall rock and the one for the friction resistance between the anchoring section and the rockmass interface are deduced. The stress distribution characteristics of rock bolt and the factors influencing its distribution trend and magnitude are analyzed, with the highlight on the shearing expansible angel of the rockmass.

Key words: Rock mechanics, Grouted rock bolt, Anchoring mechanism, Frictional resistance