Development and evolution of deep-seated toppling landslide by rapid river downcutting

摘要

A large-scale deep-seated toppled rock mass was located upstream of the Lancang River. The toppling deformation mechanismof layered steeply dipping rock masses and its evolution process into landslide were studied in this work by using thebase friction experiment and the PFC numerical simulation. The deep and steep landform with a slope height exceeding250 m and slope angle exceeding 50° caused by the rapid and continuous downcutting of the river was an essential conditionfor the formation of deep-seated toppling deformation. Three early warning signals, including the emergence of numeroustoppling fracture zones, intensive compression of rock masses in the front part of the slope, and shearing deformation alongthe toppling fracture zones, should be considered as indications of the evolution of toppling deformation into a landslide.Destruction of the frontal part of the toppled rock masses caused the accelerated evolution of the slope into a landslide. Theslip zone was formed mainly by tracing the toppling fracture zones.