Abstract: The instability of gently inclined bedding rock slope is difficult to be recognized and detected because of its gentle dip angle. The Yunpantou landslide in Guizhou, China, is a typical gentle dip bedding rock slope with four sets of weak intercalated layers in the slope. Probing into its deformation and failure mechanism is of practical significance for the research of gently inclined bedding rock slope failure. In this paper, the deformation and failure mechanism of Yunpantou landslide is examined by establishing a geological structural model based on engineering geological survey in association with various approaches such as bottom friction test, two-dimensional discrete and finite element simulations. Results reveal that the deformation and failure process of landslide can be divided into four stages, namely, microcrack growth stage, crack propagation stage, landslide deformation stage, and complete destruction stage. Key blocks exist in slope toe. The main causes of the landslide can be depicted as the exposure of weak intercalated layers resulted from excavation, and tension cracks perpendicular to the weak layers developed and divided the sliding body into blocks; with the sliding of key blocks in slope toe towards the free face, secondary blocks moves correspondingly and generates a Domino effect leading to the integral sliding of slope, which, therefore, is a typical sliding tension landslide.

Key words: gently inclined bedding rock slope, engineering geological investigation, geological model of slope, bottom friction test, slip tension crack, Yunpantou landslide