唐家山滑坡堵江机制及堰塞坝溃坝模式分析

 在对唐家山滑坡及其堰塞坝现场进行详尽地质调查结果基础上，结合早期(地震前)资料开展研究，结果表明，该滑坡形成及堵江过程可概括为：顺层岸坡结构地震诱发→滑坡体前缘剪切、后缘拉裂→高速下滑、形成气浪、前缘刨蚀河床、对岸阻化隆起→后缘边坡坐落下滑→堰塞堵江。对堰塞坝体地质结构、不同水位条件下堰塞坝整体及上下游部位不同工况稳定性分析表明，堰塞坝以沟槽部位表层松散体水流逐级淘刷的“溢流破坏”方式为特点，整体溃坝可能性小。

ANALYSIS OF BLOCKING RIVER MECHANISM OF TANGJIASHAN LANDSLIDE AND DAM-BREAKING MODE OF ITS BARRIER DAM

On the basis of the detailed geologic investigation results which were gained on the location of the barrier dam，combining the early information before earthquake，the forming process and blocking river mechanism of the landslide can be summarized as follows：(1) there were shearing surface in forward edge of the landslide on dip slope which was caused by earthquake and drawing open in back edge；(2) the air wave was formed by the high speed sliding，and the riverbed was ploughed by its forward edge，and the thither slope was uplifted for inhibition；(3) the back edge of the landslide stood and glided；and (4) then it dammed and blocked river. Meanwhile，according to the geological structure and different water levels of the barrier dam，the barrier dam¢s stabilities in upstream and downstream are studied. It is shown that the scouring mode of the barrier dam is overflow breakdown mechanism which stepwise scours the surface layer of loose media on the groove position，and the possibility of dam-breaking is small.