西藏玉曲河下游岸坡倾倒变形机制及稳定性分析

西藏玉曲河下游河谷由板岩组成的岸坡普遍发生倾倒变形，其变形特征在青藏高原东南部"三江"地区具有典型性。随着该地区水利水电项目的不断开发，倾倒变形边坡问题日益突出。本文根据在工程实践中遇到的倾倒变形边坡问题，采用现场调查、勘探和原位试验的方法，重点对边坡变形特征与板岩变形特性的相关性进行研究，并分析了3种倾倒类型：倾倒折断型呈脆性破坏，破坏模式主要为由前部向后部逐级后退式破坏，适合采用极限平衡方法进行稳定性分析；倾倒弯曲型属延性变形，破坏模式主要为边坡浅部的坠覆和松驰，适合采用建立在非连续介质模型基础上的应力应变分析方法；倾倒揉皱弯曲型与倾倒弯曲型类似，仅是在倾倒弯曲的基础上叠加了冰川的推覆作用而发生褶曲。

Deformation Mechanism and Stability Analysis of Bank Slope in Downstream of Yuqu River in Tibet

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.