Landslide susceptibility assessment in mountainous area: a case study of Sichuan–Tibet railway, China

In the southeastern Tibetan Plateau with complex geological conditions, the frequent and disastrous geological hazards have posed a severe challenge to the construction and operation safety of the planning Sichuan–Tibet railway. Based on the remote sensing and field investigation, the detailed landslide inventory of Jiacha–Langxian segment of Sichuan–Tibet railway was established. After analyzing the general development characteristics of landslides, a total of seven causative variables were selected as input parameters to evaluate landslide susceptibility using the weight of the evidence model. Combined with the probability prediction map and field validation, the landslide susceptibility was classified into four categories: very high, high, moderate and low susceptibility. Based on the landslide susceptibility assessment map, the very high and high susceptibility zones are mainly distributed on the both sides of the Yarlung Zangbo river and its tributaries, and the moderate and low susceptibility zones are located 5 km north to the river. Considering the terrain and landslide disaster prone situation in this region, the planning railway line in tunnel on the north bank of the Yarlung Zangbo river is considered to be reasonable. As for the subgrade and bridge section of the railway, especially for tunnel entrance, necessary slope reinforcement should be carried out. Considering the objective safety threat from landslides to the railway, we hold the opinion that it is necessary to compare the scheme of changing route and taking engineering protection measures in the Langzhen–Langxian segment.