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| Evolution process and failure mechanism of a deep-seated toppling slope in the Lancang River Basin |
| NING Yibing1，TANG Huiming1，2，ZHANG Bocheng1，DING Bingdong1，SHEN Peiwu1，XIA Ding1，CHEN Hongjie3 |
(1. Faculty of Engineering，China University of Geosciences(Wuhan)，Wuhan，Hubei 430074，China；2. Three Gorges Research Center for Geo-hazard of Ministry of Education，China University of Geosciences(Wuhan)，
Wuhan，Hubei 430074，China；3. Huaneng Lancang River Hydropower Inc.，Kunming，Yunnan 650214，China) |
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Abstract To study the evolution process and failure mechanism of a deep-seated toppling slope in the upper reaches of the Lancang River，base friction physical model test and universal distinct element code(UDEC) numerical simulation are carried out to simulate the instability process of a deep-seated toppling slope under the influence of valley evolution and reservoir impoundment. Displacement and velocity vector fields of the slope in different evolution stages and displacement variations of feature points are obtained by digital image correlation (DIC) and particle image velocimetry(PIV) methods. The test results show that the deep-seated toppling slope presents an accelerating deformation-decelerating creepage-traction by slope toe-integral sliding pattern，and landslide is the final outcome of toppling failure. Controlled by valley evolution，the deep-seated toppling failure experiences five stages including shear dislocation，initial bending，creep，formation of a throughgoing sliding plane and failure. Reservoir impoundment accelerates the evolution rate of toppling failure from the creep stage to the failure stage，and hence，it is suggested to adopt anti-seepage measures at the slope toe. Landslide induced by toppling mainly develops in highly toppled regions，and the formation of the scarps is an important sign for the evolution of toppling failure to enter the progressive failure stage.
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2021, Vol. 40 
