In order to study the mechanical mechanism of chamber surrounding rock in the process of excavation-supporting,
the circular chamber was divided into elastic zone,plastic softening zone and plastic residual zone in accordance
with mechanical characteristics of surrounding rock. The surrounding rock softening,dilatation,spatial effect and
anchorage mechanical effect were considered and the softening modulus of strength parameters,coefficients of dilatancy
and dilatation angle were introduced. The analytical solutions of elastoplastic stress,displacement and plastic zone radius
were obtained. In addition,an example was analyzed to study the effect of different factors on the stress of plastic
zone,surrounding displacement and plastic zone radius of chamber. The results show that anchorage mechanical effect
can decrease plastic range and plastic zone radius for the large softening modulus of surrounding rock. While considering
spatial effect when the shorter distance from excavation face to supporting face named value of x is,the bigger
stress and displacement are and when value of x is greater than 10 m,the spatial effect is fail basically. Dilatancy coefficient
h3 has a more important influence than h2 for surrounding displacement. Surrounding displacement of chamber
under anchor bolt of different lengths can provide reference for the reserved rock deformation of supporting structure.
The study in this paper can provide a theoretical basis for excavation-supporting of chamber.