Abstract: Based on the transversely isotropic elastic constitutive model in the local coordinate system of bedding plane, according to the occurrence of layer, the stress conversion method from the global to local coordinate system is derived. For the anisotropic characteristics of the layered rock mass, the failure mode is subdivided into five kinds, for which the discrimination function, yield criterion and corresponding stress modified iteration calculation are respectively established according to plastic flow rule. A second development is carried out with VC++ programming language to generate a dynamic link library DLL file called by FLAC3D main program at any time. The strength and deformation properties of layered rock mass are studied through uniaxial and triaxial compression numerical experiments which indicate that the inclination angle and the confining pressure have an important influence on mechanical behaviors of layered rock mass. Compared with transversely isotropic elastic model as well as ubiquitous-joint model in FLAC3D, the correctness and accuracy of the new model are verified. Finally, the new model is applied to the calculation of an ideal circular tunnel in triaxial equal pressure in which the variation rule of failure modes of the layered rock mass influenced by the azimuth is analyzed. The results indicate that the altitude of bedding planes of layered rock mass is playing a control role to deformation distribution, failure mode and the propagation direction of plastic zones.

Key words: layered rock mass, failure mode, numerical test, FLAC3D