Abstract:

The deformation of deep tunnels in soft rocks is a complex mechanical process under the effects of strainhardening and dilatation of surrounding rock. To describe this process, a combination model of a Burgers body with a friction plate considering DruckerPrager criterion is used when the excavation are finished, and the surrounding rock performed as an elastoplastic material. Under this condition, the timevarying displacement analytical solution of the surrounding rock is deduced considering dilatancy for the deep tunnel in soft rock. The results show that the timedependent deformation of surrounding rock increases with the increase of powerhardening index or that of dilatancy angle. When the tunnel surrounding rock is affected by both strainhardening effect and dilatancy effect, the powerhardening index and dilatancy angle become severer, the displacement is more sensitive, and the powerhardening index is more sensitive to the displacement of surrounding rocks. So, strainhardening and dilatancy of soft rock influence greatly on the creep of surrounding rock. The calculated results of coincide with the actural measured data very well.

Key words: deep soft rock tunnel, strain hardening, dilatation effect, powerhardening model, timevarying displacement analytical solution, dilatancy angle, powerhardening index