映秀-北川断裂带北川段唐家湾滑坡活动历史与形成机制

A study of activity history and formation mechanism of Tangjiawan landslide in Beichuan section of Yingxiu-Beichuan fault zone

关键词:  同震滑坡  滑坡复活  地形条件  映秀-北川断裂  北川县

Key words:  Coseismic landslide  land slide reactivation  topographic conditions  Yinxiu–Beichuan fault  Beichuan County in Sichuan Province

摘要:

以映秀-北川断裂带北川段唐家湾滑坡为研究对象，基于地形资料、多期遥感与航拍影像，结合¹⁴C测年的方法，细分了唐家湾滑坡的活动历史，分析了2016年唐家湾滑坡再次复活的主要控制因素。研究结果表明：（1）唐家湾斜坡历史上至少发生过四期滑动，其中第一期次滑坡发生在全新世以前；第二期次滑坡发生于全新世初期；第三期次滑坡发生在2008年汶川地震时期，系龙门山断裂带活动过程中产生的同震滑坡；第四期次滑坡分别发生在2016年和2018年，属于断裂带滑坡堆积体的再次局部复活；（2）2016年唐家湾滑坡的形成与断裂活动、河流侧蚀和水等因素有关，其中，上覆滑坡堆积体、下伏高陡基岩形成的二元斜坡结构，是唐家湾滑坡发生的决定性条件；断裂活动及其导致的浅地表最大主应力偏转是唐家湾滑坡变形的重要内因；（3）以唐家湾滑坡为例，初步讨论了基于地形条件控制的断裂带滑坡堆积体复活的地质模型，其形成演化表现为断裂带活动和河流侵蚀形成滑坡（或陡峭地形）→先期滑坡后壁（或陡峭地形）接受上部老滑坡堆积→二元斜坡结构控制下的老滑坡复活变形。该滑坡为研究地形控制断裂带滑坡复活提供了独特的案例，研究成果对于理解和评估该类滑坡，开展综合防治等方面具有重要的借鉴价值。

Abstract:

This paper takes the Tangjiawan landslide in the Beichuan section of the Yingxiu-Beichuan fault zone as its research object, combines terrain data, multi-period remote sensing and aerial images, and ¹⁴C dating data, and subdivides the activity history of the Tangjiawan landslide.The main controlling factors for the resurgence of the Tangjiawan landslide in 2016 are analyzed. The research results can be summarized as follows: (1) There have been at least four periods of slippage in the history of the Tangjiawan slope. Among them, the first landslide occurred before the Holocene, the second occurred in the early Holocene, the third occurred during the 2008 Wenchuan earthquake and was a coseismic landslide generated during the activity of the Longmenshan fault zone, and the fourth occurred in 2016 and 2018, respectively, which were caused by the local resurgence of landslide deposits in the fault zone; (2) The formation of the Tangjiawan landslide in 2016 was related to factors such as fault activity, river lateral erosion, and water. Among them, the binary slope structure formed by the overlying landslide accumulation body and the underlying high and steep bedrock is the decisive condition for the occurrence of the Tangjiawan landslide. The fault activity and the maximum principal stress deflection caused by it should be the important internal cause of the landslide deformation; (3) The geological model of the resurrection of landslide deposits in the fault zone based on the control of topographical conditions has been preliminarily discussed in Tangjiawan landslide. The evolution processes are the formation of landslides or steep terrain due to fault zone activity and river erosion, the back wall or steep terrain of the previous landslide accepting the accumulation of the upper old landslides, and the resurrection of the old landslide under the control of the dual slope structure. This landslide provides a unique case for studying the landslide revival in the fault zone controlled by topography. The research results have important reference value for understanding and evaluating this type of landslide, and carrying out comprehensive prevention and control.