investigation of failure angle in rock slopes against flexural toppling failure

A common issue in anti-inclined rock slopes is flexural toppling failure. this instability is one of the main kinds of toppling failure and usually happens in rock slopes. the stability analysis of this failure has been studied by many researchers. the determination of the total failure plane in flexural toppling failure has a high degree of uncertainty. frequently, this plane is above the plane normal to dominant discontinuities. in this paper, a brief literature review of toppling failure is introduced with an emphasis on the angle of failure plane. udec software, as a distinct element method, was employed to conduct a series of numerical simulations where the voronoi joint model was applied. the results of numerical modeling show a reasonable agreement, when compared to corresponding experimental models. these results confirm that the distinct element method is a reliable method in simulation of flexural toppling failure. it is concluded that the failure plane, appeared inside the slope body, intersect the toe of the slope and has a dip angle ranging from 5 to 25 degrees.