汶川地震触发窝前滑坡特征及失稳机制探讨

 为弄清汶川地震触发窝前滑坡特征，探讨该滑坡的失稳机制，笔者先后多次赴滑坡区开展调研。调研结果表明：(1) 窝前滑坡为上陡下缓、上硬下软型地形地质结构，属于拉裂–走向滑移型的斜坡失稳破坏模式；(2) 由于石坎断层活动，在近断层上盘效应、强地震动集中性、地震波长持时累积效应、地形放大效应和地震动水平加速度效应作用下，直接触发的一起剧动式高速远程滑坡；(3) 表现出一系列与一般重力环境下滑坡迥异的运动和堆积特征，如高陡粗糙的滑坡壁、弯道超高和侧向抛撒、颗粒分异堆积等特征，运动中形成滑源区、陡坡加速区、碎屑流通区(流槽区和爬高区)、堆积区和抛撒区；(4) 主要经历山体震动拉裂、高速溃滑、碎屑流和堆积4个阶段。滑坡运动至800 m左右时，峰值速度达56.1 m/s，全程运动时间约57.1 s，平均速度35.6 m/s；高位势能和滑体碎屑化是窝前滑坡产生高速远程运动的主要原因。

DISCUSS ON FAILURE MECHANISM AND GEOLOGIC CHARACTERISTIC OF WOQIAN LANDSLIDE TRIGGERED BY WENCHUAN EARTHQUAKE

In order to find out the characteristics of Woqian landslide triggered by Wenchuan earthquake and discuss the instability mechanism of the landslide，the author has investigated the landslide area many times. The investigation results show as follows：(1) The geologic structure of Woqian landslide is up hardness and down softness，and up steep and down slow，belongs to a kind of landslide with pattern of rips-tend towards slide. (2) Woqian landslide is an intense start-up and long run-out landslide triggered by Shikan fault movement，and its hanging-wall effect，energy convergence release effect，long time and repeat effect of earthquake wave，zoom in effect of terrain，level acceleration effect. (3) Woqian landslide behaves a series of movement and accumulation characteristics differing from landslide by gravity，for example landslide cliff of high and coarse，centrifugal super high in curve，throw to side，classify accumulation，come into being 5 areas，i.e. landslide source，steep accelerate segment，sturzstroms，accumulation and side throw. (4) Woqian landslide comes through four stages，i.e. slope shake fissure，high speed canker，sturzstrom and accumulation. The peak velocity is 56.1 m/s when sliding distance is about 800 m. The whole moving time is 57.1 s，and the average velocity is 35.6m/s in the sliding process. High potential energy and fluidization is the main reason for Woqian long run-out landslide.