Forming Mechanism of Landslides in the Seasonal Frozen Loess Region in China

In the area of Northern China, the landslides and other geological disasters frequently occur in the two seasons of autumn and early spring. Those occurred in the autumn are definitely induced by rainfalls; but in the early spring it is supposed to be induced by the freeze-thaw processes. This chapter introduces the fundamental characters and failure mechanism of the landslides related to freeze-thaw process. Monitoring of the ground temperature and the pore-water pressure at the landslide located at the side of the Heifangtai loess platform, Gansu province suggested freezing can build an underground water reservoir at the deep position within the slope in frozen season. Later, thawing water can be released out in warmer season. Consequently, it produces a high pore-water pressure in winter as well as a high water gradient in spring. Both the static high pore-water pressure in winter and the high water gradient in spring can decrease the slope stability and trigger landslide.