Analysis of formation mechanism of Lajinshengu landslide in Lancang River
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摘要: 涉水型古滑坡是西南水电工程区常见的灾害类型,揭示这类滑坡的成灾机理有助于降低链式灾害发生风险概率。以云南省德钦县燕门乡拉金神谷古滑坡为例,基于野外地质调查、InSAR监测和数值模拟研究,结合滑坡区工程地质条件,分析了滑坡的变形特征和破坏演化全过程。研究结果表明: ①拉金神谷滑坡成灾过程为前缘局部变形阶段→后缘拉裂阶段→滑坡—堰塞湖阶段→堰塞湖溃决阶段; ②库水位上升和降雨共同作用是诱发滑坡大变形的直接原因; ③若该滑坡的地质环境条件持续恶化,发生滑坡堵溃型链式灾害的风险很高。通过对拉金神谷古滑坡的成灾机理研究,提出了引入InSAR等监测调查技术手段开展类似涉水古滑坡排查的地质灾害早期识别建议,这对防范类似的高位链式地质灾害具有重要实践意义。Abstract: Ancient fording landslide is a common disaster for hydropower projects in Southwest China. Revealing the disaster mechanism of such landslides is helpful for reduction of the risk probabi-lity of chained disaster. Taking the Lajinshengu landslide in Deqin County of Yunan Province as an example and based on the field geological survey, Synthetic Aperture Radar Interferometry (InSAR) and numerical modeling, the authors in this paper analysed the formation characteristics and the failure progress of the landslide, combining with the engineering geological elements of the landslide area. The result show that: ① The disaster processes of Lajinshengu landslide are the local deformation stage of the front, tension stage of trailing edge, sliding--barrier lake stage and collapse stage of the barrier lake. ② The direct reasons for the landslide deformation are synergy of rising water level and rainfall. ③ The possibility of a landslide blocking chain disaster is very high, if the geological environment of the landslide continues to deteriorate. The InSAR and other monitoring techniques are suggested to carry out the early identification of similar wading ancient landslides in this paper through the study of the disaster mechanism of the ancient landslide in the Lajinshengu landslide, which are of great significance to reduce the risk caused by chain disasters.
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