Presently, the studies of collapse mechanism and failure mode of tunnel surrounding rock considering the influence of unfavorable structural planes in jointed fractured rock mass are not well understood. To investigate the effect of the unfavorable structural planes on the stability of deep-buried tunnel rock mass, failure mechanisms of the rock mass with unfavorable structural planes existing at roof and spandrel of the tunnel are constructed by using the spatial discrete technology. Based on the Hoek-Brown failure criterion and the upper bound theorem of limit analysis, the objective function of the rock mass safety factor with the consideration of unfavorable structural planes is derived. The upper bound solution of the rock mass safety factor and the collapse range under the limit state are obtained through optimization calculation. Taking Hushan Tunnel as engineering background, a numerical model of the rock mass with unfavorable structural planes is constructed and numerical results of the rock mass safety factor and the collapse range of the rock mass is obtained. By comparing the theoretical results with the numerical results, the validity of the theoretical method proposed in this paper is verified. Parameter analysis indicates that the safety factor of the rock mass with unfavorable structural planes at roof and spandrel increases with the increase of geological strength index GSI and rock material constant mi. The collapse range of rock mass increases with the increase of GSI while decrease with the increase of mi.