Mechanism of landslides in the alluvial pebble layer distribution area：a case study of the landslope in a resettlement area in Anxi County

Groundwater seepage is the main controlling factor for the deformation and failure of landslides in a cobble layer. Since June in 2010, the slope of a resettlement area in Anxi has shown signs of deformation and failure many times, and the scale and scope expands year by year. At present, the trailing edge of the landslide is staggered by 1.5 m as a whole, the slope is densely covered with vertical and horizontal cracks, and the slope is in a strong deformation stage. As an example, this study focuses on discussing the characteristics of landslide and deformation and failure characteristics of the cobble layer. The control factors and disaster mechanism of deformation and failure are analyzed to predict the stability of the landslide. By taking investigations and engineering surveys, the hydrogeology, stratigraphic lithology and the material compositions of the landslide are figured out. The results shows that the alluvial cobble layer and the developed seepage system, together with the multi-source recharge of groundwater, can also lead to serious geological disasters on slopes with small height differences and gentle slopes. The groundwater level of the slope is 4 m lower than the current level, and the stability coefficient has increased from 0.987~1.048 to 1.298~1.388, reaching a stable state. The measures of using blind drainage ditch to control water are also put forward. This research is a useful exploration and challenge to the control methods of this kind of groundwater seepage, and it is also expected to provide useful reference for similar landslide researched.