Occurrence Mechanism and Movement Characteristics of Landslides in Bei’an to Heihe Expressway Area in China Under the Climate Change

In recent years, landslide occurrence is increasing in the section of Sunwu County to Xigang Town where the intersection of the Bei’an to Heihe Expressway and the northwest section of Lesser Khingan Mountain, China, is located. These landslides threat the stability of sub-grade and operation safety. The shape and movement characteristics of these landslides have significant difference with those in other areas. Based on the data of annual average temperature from 1954 to 2011 in Sunwu County, which was published by “China National Science and Technology Infrastructure Platform”, and the data of cumulative monthly average air temperature, ground temperature, precipitation and maximum frozen soil thickness from 1971 to 2000 in Sunwu County, authors analyzed the relationship between the annual average temperature change and permafrost distribution. Based on the geological data, ground temperature, moisture, and landslide deformation monitoring data from 2009 to 2012 of the K178+530 and K177+550 cross section of the Bei’an to Heihe Expressway which pass through the northwest section of Lesser Khingan Mountain, authors comparatively analyzed the landslide formation mechanism and motion characteristics in the Bei’an to Heihe Expressway area combining with the temperature and atmospheric precipitation data of Sun Wu weather station in related time. The study results show that the annual average temperature in Sunwu region shows a clear upward trend in the past 50 years. After 1995, the annual average temperature in the region rises to 0 °C, and permafrost degradation process is accelerated. Landslides occurrence in this road area is the result of the combined effects of atmospheric precipitation, melting permafrost seepage water and geological condition. Sliding process of the landslides in this region is controlled by seasonal temperature change, water content change. It is also related to geological condition with low angle, intermittent and creeping characteristics.