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工程科学与技术:2020,52(5):3-15
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青藏高原东南三江流域滑坡灾害发育特征
(1.北京工业大学 建筑工程学院,北京 100124;2.四川大学 水利水电学院 水力学与山区河流开发保护国家重点实验室,四川 成都 610065)
Development Characteristics of Landslide Hazards in Three-rivers Basin of Southeast Tibetan Plateau
(1.College of Architecture and Civil Eng., Beijing Univ. of Technol., Beijing 100124, China;2.State Key Lab. of Hydraulics and Mountain River Eng., College of Water Resource & Hydropower, Sichuan Univ., Chengdu 610065, China)
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投稿时间:2020-08-06    修订日期:2020-09-05
中文摘要: 青藏高原东南三江流域横跨青藏高原东南的高山峡谷区与藏北高原区,地形地貌与气候特征差异大,新构造运动与地震活动强烈,致使该区地质环境脆弱,地质灾害频发,灾害链特征显著,对人民生命财产和工程建设安全、重要基础设施的正常运营构成了严重威胁。本文在利用遥感解译确定青藏高原东南三江流域滑坡灾害空间分布的基础上,探讨滑坡灾害的发育规律及其主要影响因素。利用GoogleEarth影像,结合现场调查进行滑坡灾害的遥感解译,得到滑坡灾害类型及其空间分布。采用分辨率为90 m的SRTM数字高程模型(DEM)进行地形地貌特征分析,得到研究区海拔高程、地形坡度、坡向、相对高差栅格图层。以1∶500 000地质图的地层岩性为基础,进行岩组划分并栅格化形成地层岩组栅格图层;以1∶500 000地质图中的主要断层为基础并与1∶1 500 000青藏高原及邻区大地构造图中的主要断裂进行整编,并进行缓冲区分析形成与主要断裂的距离图层。根据1∶1 500 000青藏高原及邻区大地构造图获得研究区大地构造单元图层。对上述栅格图层分别进行分带、分类后与滑坡灾害空间分布图层进行叠加分析,以滑坡所占面积的百分比为依据绘制直方图,从而得到研究区滑坡灾害的主要发育特征。在面积为46.2×104 km2的青藏高原东南三江流域范围内,累计解译面积不小于0.001 km2的滑坡灾害60 315处,包括滑坡体、崩塌堆积体和变形体3类,以滑坡体为主,占总数的97.73%。滑坡灾害在空间上具有沿深切峡谷成带分布的规律,沿部分断裂构造,如巴塘断裂、维西-乔后断裂、苏哇龙-雄松断裂拉哇-昌波段等密集分布;滑坡灾害多发育在坡度20°~30°、高程小于4 000 m、相对高差超过1 000 m的斜坡内。在18类地层岩组中,碎屑岩与板岩夹灰岩组合、泥页岩与粉砂岩组、蛇绿混杂岩、板岩与千枚岩岩组、火山岩等5类为滑坡灾害发育的明显优势岩组。在25个大地构造单元中,金沙江蛇绿混杂岩、中咱碳酸盐台地、那曲-洛隆弧前盆地、保山陆表海盆地、盐源-丽江陆缘裂谷盆地、北澜沧江蛇绿混杂岩、甘孜-理塘蛇绿混杂岩等为滑坡灾害明显优势发育的构造单元。尽管距主要断裂距离、坡向等因素对滑坡灾害发育有一定影响,但不显著。由此可见,青藏高原东南三江流域滑坡灾害发育,影响滑坡灾害发育的地形地貌与地质因素主要为地形坡度、高程、相对高差、地层岩组及大地构造单元,距主要断裂的距离、坡向的影响不显著。
Abstract:Three-rivers basin, which spans the deeply incised southeast Tibetan Plateau and north Tibetan Plateau with a low relief surface, is characterized by highly varied topography and climate, strong neotectonic movement and frequent seismicity, leading to fragile geological conditions, frequent occurrence of geohazards, and resulting in remarkable hazard chains. This severely threatens the safety of local residents and engineering constructions, and normal operation of infrastructures. Based on the landslide hazards interpreted from GoogleEarth, the characteristics of landslide hazards in Three-rivers basin were analyzed. The GoogleEarth images were adopted to map the types and spatial distributions of landslide hazards. The results were verified with limited field reconnaissance. The SRTM digital elevation model (DEM) data with a resolution of 90 m were used to analyze the terrain parameters, including elevation, slope angle, slope aspect, and relative relief. The lithological groups were compiled from 1∶500000-scale geological maps based on detailed lithological descriptions. The grid layer of distances to major faults was buffered from the main faults of 1∶500000-scale geological maps, compiled with the major faults obtained from 1∶1500000-scale tectonic map of Tibetan Plateau and neighboring region, in which the tectonic units were also extracted. All vector layers were rasterized and reclassified together with the raster layers, and then overlaid with the spatial distribution of landslide hazards. Percentage of landslide area (PLA) was used to create histograms and statistically analyze the significance of the factors influencing the occurrence of landslide hazards, based on geographic information system (GIS) method. A total of 60 315 landslides with an area of not less than 0.001 km2 for single landslide, including slides, rockfalls and deforming bodies, were mapped in the Three-river basins with an area of about 462 000 km2. Landslide hazards were mostly slides in type, accounting for 97.73% of the total, and characterized by banded densely distribution along the deeply incised valleys with local differentiation, and densely distribution along some major faults, e.g. Batang fault, Weixi-Qiaohou fault, and Lawa-Wangdalong segment of Suwalong-Xiongsong fault. For terrain parameters, landslide hazards mostly occurred on the slopes with angle ranging from 20° to 30°, elevation varying from 800 m to 4 000 m, and local relief exceeding 1 000 m. Among the 18 lithological groups, the following 5 groups, clastic rock and slate intercalated with limestone, mudstone and shale and siltstone, ophiolitic mélange, phyllite and slate, volcanic rocks, were mostly prone to slope failure. Among the 25 tectonic units, the following 7 units, including Jinsha River ophiolitic mélange, Zhongza limestone terrane, Yanyuan-Lijiang Continental margin rift basin, Naqu-Luonong forearc basin, north Lancang River ophiolitic mélange, Baoshan Terrestrial sea basin, and Ganzi-Litang ophiolitic mélange, were more vulnerable to landslide hazards. Although slope aspect and distance to major faults might have some influences on the landslide hazards, the role was not significant. Landslide hazards were densely distributed in Three-rivers basin of southeast Tibetan Plateau. The terrain and geological parameters significantly influencing the occurrence of landslide hazards consist of slope angle, elevation, relief, lithological group, and tectonic unit. Both slope aspect and distance to major faults have little impact on the landslide hazards.
文章编号:202000651     中图分类号:P642    文献标志码:
基金项目:国家重点研发计划项目(2008YFC1505001)
作者简介:戴福初(1967-),男,教授,博士.研究方向:地质工程与地质灾害.E-mail:2024314945@qq.com
引用文本:
戴福初,邓建辉.青藏高原东南三江流域滑坡灾害发育特征[J].工程科学与技术,2020,52(5):3-15.
DAI Fuchu,DENG Jianhui.Development Characteristics of Landslide Hazards in Three-rivers Basin of Southeast Tibetan Plateau[J].Advanced Engineering Sciences,2020,52(5):3-15.