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Abstract Based on finite difference and particle flow theory，FLAC and PFC code were used as implementation platform. Bonded particle model was embedded in finite difference grid，and communication function of computational data between continuum and discrete element was compiled using fish language. The coupled continuum-discrete model of circular tunnel in 2D plane strain mode was constructed and used to investigate the deformation and failure mechanism of surrounding rock with different confining stress from macro-meso viewpoint. The research resualts are as follows：(1) With lower confining stress，elastic deformation generates in surrounding rock after tunnel excavation. When horizontal and vertical confining stress are equal，the deformation value of surrounding rock with identical radial distance are the same，and directing the tunnel center. (2) Under the condition of higher confining stress，the failure of surrounding rock mainly generates in the upper and bottom plate of tunnel with side pressure coefficient K＞1，while the failure of surrounding rock mainly generates in the tunnel sides with K＜1. Both the failure mode of surrounding rock are the shape of felt cap，with the cap mouth directing the tunnel center. (3) With higher confining stress，the amount of crack increases and the evolution time of crack extends continually with the increase of confining stress. Meanwhile，the failure of surrounding rock exhibits obvious zonal disintegration phenomenon with K = 1.
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2015, Vol. 34 
