Abstract: Wedge failure is an important form of instability in rock slopes. Previous research mainly used the block theory to analyze the stability from the mechanical point of view, and to a certain extent ignored the evolution process of geological action. To comprehensively analyze the hazard incubation mechanism and deformation characteristics of the wedge failure of rock slopes, a layered wedge rock slope generalized centrifugal model with two sets of structural planes was designed based on the geological prototype of Guanjiazui Zhongqiao wedge landslide in Lueyang county. With the field geological investigation and analysis, the centrifugal model test was successfully completed. The results show that: 1) Different from the traditional wedge landslide, the wedge will slide in a disintegrated manner along the intersection line of the wedge plane when the lithology of the slope is soft and the joint fissure is developed. This kind of wedge-shaped landslide is difficult to be identified geometrically due to its poor shape, and lithologic and structural conditions are its controlling factors. 2) Meanwhile, it is also found that the apparent deformation of such layered wedge-shaped soft rock slopes is not obvious. Under the action of gravity, the deformation mainly extends from the inside of the slope to the surface and bottom of the slope longitudinally, and the pressure and strain changes of the wedge-shaped sliding body are small, which is mainly manifested as tensile failure. 3) In addition, the landslide can form a multi-level wedge sliding surface, and develop multi-level instability wedges. The slope automatically searches for the "optimal" sliding surface, causing collapse and landslide disasters of different scales. At 1 260 s and 50g, a first-level wedge instability occurs, and at 2 016 s and 92g, the secondary deep wedges fails. The test reveals the deformation evolution process and disaster model of this kind of wedge landslide under the action of gravity, which provides a reference basis for the in-depth understanding of this type of landslide and the disaster prevention.

Key words: wedge landslide, centrifuge model test, multi-stage wedge sliding surface, deformation evolution, disaster pattern