Formation and Evolution Mechanism of Jiangdingya Ancient Landslide and Stability Evaluation of Accumulation Body
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摘要: 摘要:古滑坡堆积体复活是我国青藏高原及周边地区的主要地质灾害类型之一,也是我国西部正在建设的重大交通和水利工程面临的主要安全威胁之一。因此,对古滑坡的形成演化机理进行研究并对其堆积体进行稳定性评价,显得极为重要,可以为古滑坡堆积体复活的早期识别与防治设计提供理论支持。甘肃省舟曲县江顶崖古滑坡堆积体近十年来数次局部复活形成滑坡堵塞白龙江,对当地人民的生命财产安全造成严重威胁。本文通过现场调查和无人机倾斜摄影等手段,查明江顶崖古滑坡堆积体的形态和结构特征,在此基础上分析滑坡的演化机理和动力学过程,再结合inSAR变形数据对堆积体的稳定性进行定性评价。结果显示,江顶崖古滑坡是典型的大型地震滑坡,其滑体沿三个方向坐落式下滑,形成了如今多级台阶状的堆积体形态;在地震荷载作用下古滑坡的动力学过程可分为中上部震动-拉裂、前缘锁固段剪断-滑坡启动、后缘拉裂-滑体加速、前缘受阻-滑体减速、稳定这几个阶段;由于古滑坡在地震荷载作用下整体下滑,导致上部堆积体内存在大量结构完整的岩体,因此较为稳定;而中下部堆积体大都为断层破碎带和破碎岩体组成的软弱结构,稳定性较差,未来极有可能复活。Abstract: Abstract: The resurrection of ancient landslide accumulations is one of the main types of geological disasters in the Qinghai-Tibet Plateau in China, and it is also one of the main security threats faced by major traffic and water conservancy projects under construction in western China. Therefore, it is extremely important to study the formation and evolution mechanism of ancient landslide and evaluate the stability of their accumulations, which can provide theoretical support for the early identification and prevention design of the revival of ancient landslide accumulations. In the past ten years, the accumulation of ancient landslide in Jiangdingya, Zhouqu County, Gansu Province, has been partially revived several times, forming landslides to block the Bailongjiang River, posing a serious threat to the safety of local people's lives and property. In this paper, the morphological and structural characteristics of the ancient landslide accumulation of Jiangdingya were identified through on-site investigation and UAV oblique photography, and the evolutionary mechanism and dynamic process of the landslide were analyzed on this basis, and the stability of the accumulation was qualitatively evaluated by combining the inSAR deformation data. According to the results, the ancient landslide of Jiangdingya is a typical large-scale seismic landslide, and the sliding mass slides down in three directions, forming a multi-step accumulation body form today. Under seismic loading, the dynamic process of landslides can be divided into the middle and upper shock-pulling stages, leading edge locking section shearing-landslide starting, trailing edge pulling-sliding body acceleration, leading edge obstruction-sliding body deceleration, and stability stage. Due to the overall decline of the ancient landslide under the seismic load, a large number of rock masses with complete structure exist in the upper accumulation body, so it is relatively stable. Most of the middle and lower accumulations are weak structures composed of fault fracture zones and broken rock masses, which have poor stability and are very likely to be revived in the future.
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