Abstract: The toppling deformation is common in the downstream slopes of Yuqu River in Tibet, and the deformation characteristics are typical in the southeast "three river area" of the Qinghai-Tibet plateau. As the development of hydro projects in this region, the slope toppling deformation is becoming more and more prominent. The correlation of the deformation characteristics of slopes and slates which compose the slopes was mainly studied through field investigation, exploration and field test. Then three types of toppling were analyzed:1) the toppling-broken mode is brittle failure, and the feature is mainly progressive backward failure from the front to the rear, which is suitable for stability analysis by limit equilibrium method; 2) the toppling-bending mode is ductile deformation, and the failure mode is mainly the collapse and relaxation of the shallow part of the slope, which is suitable for the stress analysis based on a discontinuous medium model; 3) the toppling of crumpled mode is similar to the toppling-bending type, which only occurs when the glacier is superimposed on the basis of the toppling-bending.

Key words: toppling, deformation characteristics, genetic mechanism, stability analysis, downstream of Yuqu River in Tibet