| 金沙江断裂带雄巴巨型古滑坡发育特征与形成机理 |
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| 引用本文： | 李雪,郭长宝,杨志华,廖维,吴瑞安,金继军,何元宵.金沙江断裂带雄巴巨型古滑坡发育特征与形成机理[J].现代地质,2021,35(1):47-55. |
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| 作者姓名： | 李雪 郭长宝 杨志华 廖维 吴瑞安 金继军 何元宵 |
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| 作者单位： | 1. 中国地质科学院地质力学研究所,北京 1000812. 新构造运动与地质灾害重点实验室,北京 1000813. 四川省地质调查院,四川 成都 610081 |
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| 基金项目： | 中国地质调查局项目(DD20190319,DZLXJK202009);国家自然科学基金项目(41877279,41731287,41941017,42007280)。 |
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| 摘 要： | 雄巴古滑坡位于西藏贡觉金沙江右岸、金沙江活动构造带内,该区地形地貌和地质构造极为复杂,多高山峡谷且河流纵坡降大,岩体结构破碎,发育一系列大型、巨型古滑坡和斜坡变形体。通过遥感解译和现场调查,认为雄巴古滑坡堆积体方量为2.6×10 8~6.0×10 8 m 3,为地质历史上形成的巨型古滑坡。雄巴古滑坡在平面上有滑坡滑源区和滑坡堆积区2个大的区域,其中滑坡堆积区又分为相对稳定区和前缘强变形区。滑坡体上2个深孔钻探资料揭露雄巴古滑坡主要发育2级深层蠕变滑带,其中第一级滑带埋深51 m(ZK1孔)至55 m(ZK2孔),第二级滑带埋深101 m(ZK1孔)至115 m(ZK2孔),坡体内发育的深层承压水对斜坡稳定性影响较大。雄巴古滑坡的形成受地层岩性、断裂构造、降雨和河流侵蚀等作用影响强烈,目前仍处于深层蠕滑中;其深层“锁固段”对滑坡的稳定性起关键控制作用,但在降雨-地下水渗流、河流侵蚀和地震等因素作用下,该古滑坡潜在失稳可能性较大,并有形成堰塞金沙江、溃坝、洪水等灾害链的风险。
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| 关 键 词： | 青藏高原 古滑坡复活 金沙江断裂带 雄巴 形成机理 |
| 收稿时间： | 2020-01-12 |
| 修稿时间： | 2020-04-15 |
Development Characteristics and Formation Mechanism of the Xiongba Giant Ancient Landslide in the Jinshajiang Tectonic Zone |
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| LI Xue,GUO Changbao,YANG Zhihua,LIAO Wei,WU Ruian,JIN Jijun,HE Yuanxiao.Development Characteristics and Formation Mechanism of the Xiongba Giant Ancient Landslide in the Jinshajiang Tectonic Zone[J].Geoscience——Journal of Graduate School,China University of Geosciences,2021,35(1):47-55. |
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| Authors: | LI Xue GUO Changbao YANG Zhihua LIAO Wei WU Ruian JIN Jijun HE Yuanxiao |
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| Institution: | 1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China2. Key Laboratory of Neotectonics Movement and Geohazards, Beijing 100081, China3. Sichuan Institute of Geological Survey, Chengdu,Sichuan 610081, China |
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| Abstract: | Xiongba giant ancient landslide is located on the right bank of Jinshajiang River(Gongjue County,Tibet),and located in the Jinshajiang active tectonic zone.The terrain and geological structure in this area is very complex,with many high mountains and gorges,large longitudinal slope drop,fragmentary rock mass,and a series of large and giant ancient landslides and slope deformation bodies were developed and pose serious hazards.On the basis of remote sensing interpretation and field investigation,we investigated the characteristics and formation mechanism of the Xiongba ancient landslide.We revealed that the accumulation volume of Xiongba ancient landslide is about 2.6×10~8-6.0×10~8 m~3,which is of giant scale in the regional geological history.The Xiongba ancient landslide comprises two large areas on the surface,i.e.,the source area and accumulation area,among which the latter is divided into the relatively-stable zone and frontal-edge strongly-deformed zone.Through two deep-drilling on the landslide body,it is found that the Xiongba ancient landslide contains two-level deep creep slip zone:the shallow and deep slip zones have burial depths of 51 m(borehole ZK1)to 55 m(borehole ZK2)and 101 m(borehole ZK1)to 115 m(borehole ZK2),respectively.Hydrogeological conditions of the landslide body are complex with deep confined water developed,which greatly impact the slope stability.Our results show that the Xiongba ancient landslide may have formed under the coupling of internal and external dynamic factors,which include stratigraphic lithology,fracture activity,gravity,rainfall,groundwater,and river erosion.The landslide is currently creeping deeply,and the control of the"lock-up section"developed under the landslide platform is the key to the landslide stability.Under the influence of rainfall-groundwater seepage,river erosion and earthquake,the ancient landslide has a high possibility of instability,and may form a chain of disastrous events,such as blocking the Jinshajiang River and dam-broken floods. |
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| Keywords: | Qinghai-Tibetan Plateau ancient landslide reactivation Jinshajiang fault zone Xiongba formation mechanism |
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