Abstract： The folded structures are frequently encountered in roadway excavation; therefore, the combined finite-discrete element numerical method (FDEM) was used in paper to study buckling failure mechanism of surrounding rock masses containing folded structures. Firstly, the FDEM shear stress constitutive model at post-peak softening stage was improved, in which the residual shear stress could be maintained under compression-shear state. Then, numerical models of folded structures with different shapes were established by using consie function y=acos(x). Finally, the improved FDEM numerical method was used to study the failure and large deformation mechanism of isotropic and anisotropic rock mass with different in situ stress lateral coefficients λ (λ=0.5 and 2.0) and folded structure shapes (a=0, 0.5 m and 1.5 m). The study results indicated that for the isotropic rock mass, the influence of folded structures shape was weak, that was, the rock mass was fracture by X-shaped conjugated shear cracks following by few tension cracks. The large deformation was induced by the buckling failure of rock mass and the movement of the rock fragments..
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