雅鲁藏布江流域嘎贡沟巨型滑坡变形破坏模式及演化过程研究

Deformation and Failure Model and Evolution Process of Giant Landslides in Gagong Valley in the Yarlung Zangbo River Basin

中国西藏雅鲁藏布江流域嘎贡沟左岸发育巨型滑坡,滑坡堆积体堵塞河谷,形成高约130m的堰塞体。通过滑坡现场实地调查,室内滑坡区域地质资料收集、滑坡遥感影像解译、滑坡三维地质建模、滑源区斜坡持平投影分析和滑源区斜坡变形破坏模式研究,得到以下结论:河水对河谷凹岸的侵蚀作用不仅加剧了嘎贡沟滑坡的孕育和形成,而且控制了滑坡堆积体后期改造演化;嘎贡沟滑坡变形破坏模式为顺坡内J1优势结构面的滑移-拉裂;嘎贡沟滑坡主要经历三个演化阶段,即滑坡孕育阶段、滑移堵江阶段和堰塞体溃决阶段。最后提出了以“滑坡-堵江-淹没-洪水”为主线的滑坡演化地质灾害链。以期对青藏高原地区,特别是对高原大河大江河谷区巨型滑坡的演化过程研究和地质灾害防治提供一定的参考。

Giant landslides developed on the left bank of Gagong Valley in the Yarlung Zangbo River Basin in Tibet,and the landslide deposits blocked the valley,forming a barrier body about 130 m high.Through the on-the-spot investigation of landslides,the regional geological data collection,the remote sensing images interpretation,the three-dimensional geological modeling of landslides,the analysis of flat projection of slope,and the study of deformation and failure model of slope in sliding source area,we obtained the following results:The erosion of river water on the concave bank of the valley not only aggravates the breeding and formation of Gagong Valley landslide,but also controls the late transformation and evolution of the landslide accumulation body.The deformation and failure mode of Gagong Valley landslide is slip-pull fracture of J1 dominant structural plane along the slope.The Gagong Valley landslide mainly undergoes three evolutionary stages,i.e.the landslide incubation stage,the sliding river blocking stage,and the bursting stage of the barrier body.A geological hazard chain with a main line of“landslide-river blocking-submergence-flood”in this paper is put forward.The results have certain guiding significance and reference value for future researches on the evolution process of giant landslides in the Qinghai-Tibet Plateau,especially in the large rivers and valleys of the plateau,as well as for the prevention and control of geological hazards in the future.