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Abstract The excavation and supporting of a deep circular tunnel is a complex mechanical process related to time. To describe this process，the surrounding rock of the tunnel is supposed to a viscoelastoplastic combination model of a Burgers body and Drucker-Prager criterion. At the instant time that the excavation and supporting were finished，the surrounding rock of the tunnel performs as a elastoplastic material. Under this condition，the influence of intermediate principal stress was considered，and the stress field under the combined action of the primary rock stress and supporting force could be obtained. With the assumption of constant stress field，the surrounding rock exhibits creep properties of time-dependence. Furthermore，the analytical solution to the creep displacement of the surrounding rock was deduced considering shear dilatancy for the deep-buried circular tunnel. A practical engineering instance was given and the regularities that the supporting force and dilation angle of the surrounding rock affect the creep displacement in deep circular tunnel were analyzed. The results show that the change of dilation angle could produce significant influence on the creep displacement，while the supporting force could not completely control the sustained increase of displacement of the surrounding rock with time in the deep circular tunnel.
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Received: 11 April 2012
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2012, Vol. 31 
