Abstract: In order to explore the effects of nonlinear slopes on slope safety, based on the simplified Bishop theory, the relationship of the values between the sliding force and the anti-slip force generated by the slice's weight on different positions of sliding surface is studied for each slice. Further, effects of the section morphology on slope stability was examined and a concept of section shape effect of slope is introduced. Taking the west slope of the Heishan opencast mine as an example, its stability as a function of the section shape is calculated by simplified Bishop method and numerical simulation with strength reduction method. The results indicate that the bottom angle α_i has always a definite value θ dividing a given slip plane into two parts, anti-skid and slip, that when the shape discrepancy is mainly distributed on the anti-slip surface, the shape effect is favorable to the slope stability, and vice versa, that for open pit slopes, the section shape effect caused by the reasonable convex slope is not only conducive to the stability of the slope, but also reduces the cost of stripping significantly.

Key words: slope shape, slope stability, open-pit mine, simplified Bishop method;strength reduction method