长江三峡库首顺层岩质滑坡典型孕灾模式及遥感识别标志

    Typical disaster-pregnant patterns and remote sensing identification indicators of bedded rock landslides in the head area of the Three Gorges Reservoir, Yangtze River

    • 摘要:
      研究目的 揭示孕灾模式是开展隐患识别的重要前提,然而目前对秭归盆地特定地质环境下顺层岩质水库滑坡的孕灾模式认识与总结仍不全面,且缺乏针对性的遥感早期识别标志,亟需开展系统研究予以完善。
      研究方法 以三峡库首秭归向斜盆地构造区顺层岩质滑坡灾害易发、高发的3处典型顺层岩质岸坡段—沙镇溪镇周边岸坡段(青干河与锣鼓洞河交汇流域)、吒溪河左岸段、泄滩河左岸段为研究区,通过资料收集、现场调查、无人机调查等手段与方法,对其中已发生的7处典型顺层岩质滑坡的孕灾模式进行分析总结。
      研究结果 系统概化并提出5类典型模式,分别为顺层滑移-弯曲式、顺层推移式、楔形体-顺层滑移式、顺层滑移-拉裂式和楔形体组合-阶梯滑移式;在此基础上,根据其共同孕灾特征,建立了由5个一级标志(结构特征、地层岩性、地形地貌、水文信息、边界条件)与8个二级标志(岸坡结构、地层时代、地层颜色、表面形态、地貌条件、河流特征、前缘边界、两侧边界)构成的三峡库首顺层岩质滑坡遥感识别标志体系。
      结论 该体系提出的5类孕灾模式与“5一级+8二级”遥感标志可以较好地指导室内隐患识别,为三峡库首同类顺层岸坡段提供了可复制、可推广的隐患早期识别技术方法,也可为其他库区相似地质条件的滑坡调查提供方法参考。

       

      Abstract:
      Objective Revealing disaster−pregnant patterns is an important prerequisite for hidden danger identification. However, comprehensive understanding and summarization of such patterns for bedded rock reservoir landslides in the specific geological setting of the Zigui basin are still lacking, and targeted remote−sensing indicators for their early detection rcemain absent—making systematic research urgently needed.
      Methods Three bedding−rock slope sectors with frequent landsliding in the Zigui syncline basin at the head of the Three Gorges Reservoir—namely the Shazhenxi reach (at the confluence of the Qinggan and Luogudong rivers), the left bank of the Zhaxi River and the left bank of the Xietan River—constitute the study area. Data collection, field investigations and UAV−based surveys were conducted to analyse the disaster−pregnant mechanisms of seven typical bedded rock landslides.
      Results The system is generalized and five typical models are proposed, which are bedding slip−bending type, bedding slip−pulling type, bedding push type, wedge−bedding slip type and wedge combination−step slip type. On this basis, according to its common disaster−pregnant characteristics, a remote sensing identification sign system of bedding rock landslide in the head of the Three Gorges Reservoir is established, which is composed of five first−level signs (structural characteristics, stratigraphic lithology, topography, hydrology information, boundary conditions) and eight second−level signs (bank slope structure, stratigraphic age, stratigraphic color, surface morphology, geomorphological conditions, river characteristics, leading edge boundary, bilateral boundary).
      Conclusions The five disaster−pregnant patterns together with the "5 first−level + 8 second−level" remote−sensing indicators can effectively guide desktop hazard identification, provide a transferable workflow for early detection of similar bedding slopes in the Three Gorges head region, and serve as a methodological reference for landslide investigations under comparable geological conditions in other reservoir areas.

       

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