Numerical Stability Analysis of the Multi-Layered High-Filled Embankment Slope Subjected to Rainfall Infiltration

At a high-filled embankment, the slope is often composed of sections of varied gradients and berms of different widths, which means that a couple of potential instable sliding surfaces might exist in the embankment, and it is difficult to determine which surface is most likely to slide first. Subjected to rainfall infiltration, it is even more difficult to decide the most instable sliding surface in the embankment. Infiltration depth in gentle section of the slope is obviously bigger than that of steeper section with the same rainfall duration. Due to large rainfall penetration, the originally safe gentle section might become instable, and could even lead to the slide of adjacent steeper sections of the slope. Based on water-air two-phase flow theory, slope stability of a given high-filled embankment is analyzed by shear strength reduction method. The results show that single-sectional slope instability might be induced under rainfall of long duration and high intensity, while multi-sectional slope instability is always formed when the rainfall is of short duration and low intensity.