Formation Mechanism and Slide Prevention Methods of Soil Deposits at the Toe of Anlesi Landslide in Wanzhou

The material of 144 boreholes of Xixipu and Nongjijixiao soil deposits at the toe of Anlesi landslide was analyzed, types of soil were classified and the formation mechanism was analyzed based on the properties of soil deposits in a single borehole. The same type of soil was connected to one layer in a profile with several boreholes. The continuity and extent of a soil layer was determined with profiles. The results show that most of the soil deposits at the toe of Anlesi landslide slipped from the foot of the landslide, and other soil deposits are residual, colluvial, talus and alluvial. The soil deposits were formed by co-action of gravity, running water, mechanical and chemical weathering. In the soil deposits, many sliding surfaces which are plane and smooth were found, and these can be classified into two kinds. There are a few large scale sliding surfaces, which are found at some depth, and many small sliding surfaces, which occur near the surface of the soil deposits. The distribution of sliding surfaces mentioned above indicates that the soil deposits have been deformed discontinuously for a long time. Slide prevention methods, considering the geological structure underlain by gravel sand, include driven piles, rip-rap and surface drainage as a means of stabilizing the soil deposits. The driven piles should be embedded in stable ground under the gravel sand to avoid being displaced.