Abstract: A significant amount of soft and hard interbedded rock slopes is existed in Guizhou Province. Affected by the difference in lithology, the difference in degrees of weathering of the soft and hard interbedded slopes is obvious. In addition to the complex structural geological conditions and other factors, weak structural planes are formed in the soft rock strata which resulting in a rockfall collapse or a landslide. A landslide occurred during the excavation and construction of the H ramp HK0 + 200 ～HK0 + 300 section of an expressway in Zunyi City, Guizhou Province. Throughout the geological mapping and exploration, it was found that one of the main causes of the landslide was the soft and hard interbedded slopes in marl and shale bedrocks. In the interbed, long-term rainfall infiltration causes the shale to soften and form a weak plane, which becomes the sliding surface of the landslide. After determining the shape and nature of the landslide and the scope of the landslide, the transfer coefficient method is used to establish a geological model, and the landslide stability safety factor and landslide thrust in the natural state and in the saturated state is calculated respectively, which provides a basis for landslide treatment.

Key words: Highway High Slope, Landslide, Triggering Mechanism, Stability Analysis