ISSN 1003-8035 CN 11-2852/P

    董志塬地区降雨诱发型黄土流滑的发育特征与成因机制分析

    Development characteristics and genetic mechanism analysis of rainfall-induced loess flowslides in the Dongzhiyuan area

    • 摘要: 黄土流滑是斜坡表层黄土在非饱和状态下即向坡底发生以“流”和“滑”相结合为运动特征的一类地质灾害,具有群发性、数量多、破坏深度浅的特点,流滑体含水率较高、呈塑性流动状态,且易转变为冲击力更强、危害性更大的黄土泥流,对黄土地区人民生命财产安全造成了巨大威胁。文章以庆阳董志塬地区的降雨诱发型黄土流滑为研究对象,归纳总结其分布和发育特征,并根据无限边坡模型,建立了非饱和黄土斜坡的稳定性评价模型。结果表明:(1)董志塬地区的降雨诱发型黄土流滑可分为崩滑堆积体流滑、植被覆盖型黄土流滑、冲沟侧蚀型黄土流滑以及单体型流滑、群发型流滑,其中,群发型流滑根据物源区的相对位置又可分为并列型流滑和汇流型流滑。(2)降雨诱发型黄土流滑规模较小,因董志塬地区地形的限制,绝大部分流滑具有流动性差、运动距离小的特征,与灌溉及地震诱发型黄土流滑具有很大区别。(3)提出了非饱和状态下植被覆盖黄土斜坡的稳定性评价模型以及工程、生物、化学方法相结合的黄土流滑治理措施,对于降雨条件下斜坡稳定性预测以及黄土流滑的灾害预警和防治具有一定意义。

       

      Abstract: Under extreme rainfall conditions, loess flowslide is widely developed in the loess plateau. Loess flowslides refer to a type of geohazard involving a combination of “flow” and “slide” movements occurring in the unsaturated surface loess on slopes. These events are characterized by their high frequency, shallow failure depths, and widespread distribution. The sliding mass typically exhibits high moisture content and plastic flow behavior, and may evolve into more hazardous and destructive loess mudflows, posing significant threats to life and property in loess regions. In this paper, the rainfall-induced loess flowslide in Qingyang Dongzhiyuan area is taken as the research object. Based on field investigation and UAV survey, 80 detailed flowslide cases were documented and analyzed to summarize their spatial distribution and developmental characteristics. A slope stability evaluation model for unsaturated loess slope was established using the infinite slope model. The results indicate that: (1) Rainfall-induced loess flowslides in the Dongzhiyuan area can be divided into five types: landslide accumulation flowslide, vegetation cover loess flowslide, gully lateral erosion loess flowslide, monomer flowslide, and group flowslide. Group flowslides can be further subdivided into parallel and convergent types based on the relative location of their source areas. (2) These flowslides are generally small in scale due to the terrain constraints of Dongzhiyuan area, often exhibiting low mobility and limited travel distance, making them significantly different from irrigation- or earthquake-induced loess flowslides. (3) A stability evaluation model for vegetation-covered loess slope under unsaturated conditions is proposed, along with integrated mitigation strategies combining engineering, biological, and chemical approaches. These findings offer valuable insights for the prediction of slope stability under rainfall conditions and for the early warning and mitigation of loess flowslide hazards.

       

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