肖家桥滑坡堵江机制及灾害链效应研究

 地震是滑坡灾害的一个重要触发因素，而这类形式的滑坡通常体积较大。以肖家桥滑坡为例，在对滑坡区进行详细的地质调查基础上，结合动力有限元分析技术，再现滑坡三维空间失稳过程。在此基础上，提出肖家桥滑坡形成及堵江的4个阶段：地震触发及岩体的累进破坏→滑体破坏、高速下滑→撞击解体、堵江形成堰塞体→震动密实。通过对堰塞体结构特征及不同工况下堰塞体的稳定性分析的成果表明：堰塞体边坡在天然状态下稳定性较好，当再次发生强地震时可能会发生局部的坍塌；最可能的破坏方式为“漫顶式”逐级冲刷破坏，由于其内部岩体结构相对较为完整，发生管涌及整体破坏的可能性较小。

RESEARCH ON RIVER-BLOCKING MECHANISM OF XIAOJIAQIAO LANDSLIDE AND DISASTERS OF CHAIN EFFECTS

Earthquake is considered to be one of the main factors of the generation of a landslide. Especially in high mountain gorge areas，the huge landslide body inrushes into the river and barriers the river，which may further expand the disaster areas and form a disaster chain. Taking Xiaojiaoqiao landslide for example，the three-dimensional(3D) instability process of the landslide is reconstructed by using dynamic finite element method based on detailed geologic investigation results of the landslide area. With the analytical results，the forming process and river-blocking mechanism of Xiaojiaqiao landslide can be divided into four phases：(1) earthquake triggering and progressive failure of the rock mass；(2) landslide body failure and sliding with high speed；(3) impacting the opposite slope，being disintegrated，and blocking the river and forming the landslide dam；and (4) density under the impacting. Based on the geological structure characteristics of the landslide dam and the stability analytical results under different cases，the stability of the slope of landslide dam is good under natural state，but there may induce local collapses with strong earthquake；and the most possible failure model may be the gradual erosion damage of topping. As for the internal rock structure with general stability，there is little possibility for piping failure and dam-breaking as a whole.