The failure modes of stratified rock slopes are simulated by FLAC(3D) (fast Lagrangian analysis of continua), while the relationship between dip angles of structure planes and stability of slope is analyzed by shear strength reduction method at the same time. Calculation results show that; 1 for horizontal layered slope, horizontal deformation failure at the top of slope occurs earlier than that on the surface and toe of slope, which leads to the tensile failure zones. For consequent slope, when dip angle of structure plane is small, the mainly failure mode is slippage; when dip angle is large, the failure is buckling. For vertical layered slope, the failure mode is bending-fissuring-slump. For anti-dip rock slope, the mainly failure mode is slippage for small dip angle of structural plane, and toppling failure for large dip angle of structural plane 2 for consequent slope, the total safety factor F of slope first increases then decreases with structural plane dip angle beta; the outline of curve for the relationship between F and beta is like shoulder which is higher on both side, and lower at the middle place. When beta= 30 degrees, F reaches its minimum value. For anti-dip rock slope, the outline of curve for the relationship between F and beta shows the trend of increase-decrease-increase. And the most parts of its curve are higher than that of consequent slope, which is in accordance with practical case 3the elastoplastic element with lower strength can reasonably simulate the deformation of weakness plane.
