喜马拉雅东构造结地区滑坡发育特征及危险性评价

发布时间：2018-04-12 22:05

本文选题：喜马拉雅东构造结 + 滑坡　；参考：《中国地质科学院》2017年博士论文

【摘要】：喜马拉雅东构造结位于青藏高原东南部,是现今地球上构造活动最强烈、地表隆升速率最快的地区之一。在地壳快速抬升的同时,伴生各种剥蚀和地表侵蚀作用,塑造了现今的高山峡谷地貌特征。在内外动力耦合作用下,地质灾害极其发育,不仅类型多,而且危害大,对该区公路、铁路和水电工程规划建设提出了严峻的挑战。论文在总结以往地质灾害资料的基础上,结合遥感解译和现场调查,分析研究了喜马拉雅东构造结地区滑坡发育特征和分布规律,开展了滑坡易发性评价、潜在地震作用下的滑坡危险性预测评价等,主要取得如下成果和认识:(1)研究区滑坡是在隆升大背景下,接受河流的侵蚀切割,形成有利的地形地貌和地质构造条件,并在重力和内外动力地质作用触发下形成的。滑坡主要沿雅鲁藏布江、帕隆藏布江和拉月曲呈条带状展布,在切割严重地带密集分布。滑坡的活动具有周期性特点,与地震活动及气候波动的关系极为密切。(2)以鲁朗脚不弄滑坡为例,在对滑坡区的地质背景分析和滑坡特征详细调查的基础上,提出脚不弄滑坡的形成演化经历了 4个阶段:河谷卸荷结构面初始变形阶段→斜坡体岩体碎裂化阶段→震动拉裂及破坏阶段→滑坡堵江及自稳定阶段。采用动力离散元分析方法,再现了滑坡的失稳过程,对认识研究区巨型滑坡成因机理有一定的启示意义。(3)在分析研究区滑坡相关影响因素的基础上,提出了层次分析-信息量和逻辑回归-信息量的滑坡易发性评价方法,并选取地层岩性、坡度、坡向、坡形、高程、断裂、河流和道路等8个影响因子,对喜马拉雅东构造结地区的滑坡进行了易发性评价。通过对评价结果的检验和影响因子的敏感性分析得出:易发性评价的结果不仅与所选用的评价模型有关,而且与所选取的评价因子的种类、数量也有关系。最后,将评价结果划分为极高易发区、高易发区、中易发区和低易发区四个等级,其准确地反映了研究区滑坡的分布规律。(4)研究区属国际著名强震区,地震地质灾害是制约该区重大工程规划建设和防灾减灾的主要因素。综合考虑河流冲刷、活动断裂对岩体结构强度的影响以及地形对地震动的放大效应,采用基于概率地震的Newmark累积位移模型,开展了喜马拉雅东构造结地区50年超越概率10%地震诱发滑坡危险性评价研究。结果表明:极高危险区主要位于念青唐古拉、喜马拉雅和岗日嘎布雪山的角峰、刃脊,河流两岸陡峻的山坡处;高、中危险区主要分布在雪山角峰、刃脊以下,沟谷两岸以及断裂经过的相对较高的陡坡地带;低危险区主要分布在地形坡度相对平缓的地带。基于预测评价结果,着重对雅鲁藏布江直白-扎曲段地震滑坡-碎屑流堵江的危险性进行了分析,并进一步探讨了该段50年超越概率2%地震滑坡-碎屑流堵江的危险性。
[Abstract]:The eastern Himalayan tectonic junction is located in the southeast of Qinghai-Xizang Plateau. It is one of the strongest tectonic activities and the fastest uplift rate on the earth.Along with the rapid uplift of the crust, various denudation and surface erosion have shaped the geomorphological features of the present mountain canyons.Under the interaction of internal and external dynamic forces, geological hazards are extremely developed, not only in many types, but also in great harm, which poses a severe challenge to the planning and construction of highway, railway and hydropower projects in this area.On the basis of summarizing the previous geological hazard data, combining with remote sensing interpretation and field investigation, this paper analyzes and studies the development characteristics and distribution law of landslides in the eastern Himalayan tectonic junction area, and carries out the landslide vulnerability evaluation.The prediction and evaluation of landslide risk under potential earthquake mainly obtained the following results and cognition: 1) the landslide in the study area is under the background of uplift, accepting the erosion and cutting of the river, and forming favorable topographical and geomorphological and geological structural conditions.And formed under the trigger of gravity and internal and external dynamic geological action.The landslide mainly distributes along the Brahmaputra River, the Palong Zangbo River and the Layue qu, and is densely distributed in the cutting serious area.The activity of landslide is characterized by periodicity, which is closely related to seismic activity and climate fluctuation. (2) taking Lulangjionong landslide as an example, based on the analysis of geological background of landslide area and the detailed investigation of landslide characteristics,It is put forward that the formation and evolution of Jiabunong landslide experienced four stages: the initial deformation stage of the unloading structure plane of the valley and the rock mass fragmentation stage of the slope body.The dynamic discrete element analysis method is used to reproduce the process of landslide instability, which has some enlightening significance for understanding the formation mechanism of giant landslide in the study area.The evaluation method of landslide susceptibility based on analytic hierarchy process (AHP) and logical regression (LRIC) is put forward, and eight influencing factors, such as stratigraphic lithology, slope gradient, slope direction, slope shape, elevation, fault, river and road, are selected.The susceptibility of landslides in the eastern Himalayan tectonic junction area was evaluated.Through the test of the evaluation results and the sensitivity analysis of the influencing factors, it is concluded that the results of the susceptibility evaluation are not only related to the selected evaluation model, but also related to the type and quantity of the selected evaluation factors.Finally, the evaluation results are divided into four grades: extremely high risk area, high susceptible area, middle susceptible area and low prone area, which accurately reflect the distribution rule of landslide in the study area.Seismic and geological hazards are the main factors restricting the planning and construction of major projects and disaster prevention and mitigation in this area.Considering the influence of river scour, active fracture on the strength of rock mass structure and the magnification effect of topography on ground motion, the Newmark cumulative displacement model based on probabilistic earthquake is adopted.In this paper, the risk assessment of landslide induced by earthquake induced by 10% earthquake in the east Himalayan tectonic junction area is studied.The results show that the extremely high risk areas are mainly located at the corner peaks, edge ridges and steep hillsides on both sides of the river in Nianqing Tanggula, Himalaya and Gangri Gabu Mountains, and the high and middle dangerous areas are mainly located at the corner peaks of the snow mountains and below the edge ridges.The two sides of the gully and the relatively high steep slope through which the fault passes, and the low dangerous area is mainly distributed in the area with relatively gentle topographic slope.Based on the prediction and evaluation results, the risk of seismic landslide and debris flow plugging the river in Zhanbai Zakui section of Yalu Zangbo River is analyzed, and the risk of landslide and debris flow plugging the river in the 50 years' exceeding probability of 2% earthquake is further discussed.
【学位授予单位】：中国地质科学院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P642.22

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