Abstract: Due to the change of stress field and the seepage field caused by tunnel excavation, unloading deformation is extremely complicated mechanical process in rich fracture rock. Viscidity elastic fracture and creeping theory are adopted, two-field coupling creep model of tunnel excavation in rich fracture rock is established; and Laplace transformation is applied to educe the expression of radial deformation function, in order to illuminates the influence of stress unloading distributions, seepage force and crevasse distribution on radial deformation. FISH language is used to compiles the FISH function; and FLAC inner model is used to calculate result of tunnel model. Comparing with the measured data, the applicable scope of the model is accounted. The result of the model shows the radial biggest displacement mutative quantities are not in the orientation of the principal stress and in the tunnel crown; mainly affected by geostress distribution, hydraulic pressure and joint distribution. Hence, academic reference for tunnel supporting is offered.

Key words: tunnel unloading, analysis of two-field coupling creep, radial deformation function, FLAC simulation