Kinematic characteristics and dynamic mechanisms of large-scale landslides in a loess plateau: a case study for the north bank of the Baoji stream segment of the Wei River, China

The number of large-scale landslide cases along the plateau edge 98 km from the city of Baoji, China, has exceeded 68 since the 1960s. This paper describes the structure and main kinematic characteristic of two active landslides that developed in the Pleistocene Sanmen Formation, which comprises flat-lying claystone and sand deposits derived from a lake environment. In order to evaluate the risks associated with these landslides, their geometries have been reconstructed using topographic data, stratigraphic data from continuous borehole cores, and inclinometer data. The analysis of kinematic features was based on computation of geological balanced sections and deep displacement data. Laboratory tests were carried out to evaluate the changes of physical characteristics and mechanical properties in the sliding zone. The results show that the large-scale landslides were governed by a sliding zone with a clay mineral content >30 %. Furthermore, testing results indicate that a viscous flow is easily induced by the creep process, leading to plastic deformation and ultimately rapid flow.