金沙江杀威台子巨型堵江古滑坡基本特征与成因机理研究  

Basic characteristics and mechanisms of the giant Shaweitaizi paleo-landslide dammed the Jinsha River

作　　者：刘科 周小棚 施炎 高阳阳 李化[2] 邓建辉[2] LIU Ke;ZHOU Xiaopeng;SHI Yan;GAO Yangyang;LI Hua;DENG Jianhui(China Three Gorges Construction Engineering Corporation,Chengdu 610095,Sichuan,China;Ins.of Geo-Eng.and Geohazards,State Key Lab.of Hydraulics and Mountain River Eng.,Sichuan Univ,Chengdu 610065,Sichuan,China;Three Gorges Geotechnical Consultants Co.,Ltd,Wuhan 430074,Hubei,China)

机构地区：[1]中国三峡建工(集团)有限公司,四川成都610095 [2]四川大学水力学与山区河流开发保护国家重点实验室地质工程与地质灾害研究所,四川成都610065 [3]长江三峡勘测研究院有限公司(武汉),湖北武汉430074

出　　处：《水利水电技术（中英文）》2023年第8期167-177,共11页Water Resources and Hydropower Engineering

基　　金：中国三峡建工(集团)有限公司科研项目(WDD/0569);国家自然科学基金项目(42007248)。

摘　　要：【目的】杀威台子滑坡是位于金沙江乌东德水电站河段的一个巨型古滑坡,该滑坡发育机理的深入分析与研究对加深地貌历史演化过程的认识、助力类似区域的减灾防灾及工程建设等均具有重要意义。【方法】通过野外地质调绘、无人机地形航测与解译、GIS遥感分析、沉积物年代测试等方法对杀威台子滑坡基本特征、成因机理、洪水淹没范围及溃决年代进行分析,【结果】结果显示:(1)巨型滑坡体来源于右岸,滑源区呈现了“上硬下软”地层组合、顺层岩层倾向、断层边界控制及前缘临空等滑坡发育基本条件。(2)滑源区软硬界面为典型的不整合接触面,为滑坡的形成提供了底部控滑面,加上断层的存在削弱了斜坡的结构完整性及阻滑能力,使得滑体产生高位顺层滑出,高速滑入并堆积于金沙江河床,形成对岸高、本岸低的滑坡堰塞坝。(3)杀威台子滑坡存在二次滑坡堵江现象,其滑动原因推断是由于第一次滑坡体在滑动过程中对部分区域岩体扰动剧烈而导致其产生强度劣化,最终发育为滑坡造成二次堵江。(4)杀威台子滑坡堰塞湖最大淹没高程约为1 038 m,最大库容约为188.7×10^(8) m^(3),上游回水距离达280 km,由年代测试结果推测其溃决发生在距今约1.9万年前,可推断该堰塞坝的消亡原因极有可能与大理冰期内气候变暖导致的降水量剧增、冰川消融加剧、径流增加密切相关。【结论】结果表明:GIS遥感分析是洪水淹没范围调查中一种快速且有效的方法。目前对于青藏高原周边地质灾害成因机理、构造背景、基础地质条件、地貌演化特征等的理解尚有不足,加强地质调查研究与地质风险评价,对于相关重大工程的施工、设计、运行和维护等均具有十分重要的意义。[Objective]The Shaweitaizi landslide is a giant ancient landslide located nearby the Wudongde hydropower station in the mainstem of the Jinsha River.The in-depth investigation and analysis of the landslide is of great significance to deepen the understanding of the regional landscape evolution process,which is helpful for disaster prevention and engineering construction.[Methods]In this paper,the basic characteristics,genetic mechanism,flood inundation range and burst age of Shaweitaizi landslide are analyzed by means of field geological survey,UAV terrain aerial survey and interpretation,GIS remote sensing analysis and sediment age test.[Results](1)The landslide originated from the right bank,which source area consists of hard rock underlain by soft rock.This slop failure developed on an overdip slope,and was controlled by fault and front free surface.(2)The unconformity between the hard and soft rock layers served as a basal slip surface for the landslide,and the fault probably weakened the integrity of slope structure,which facilitated the slide.The landslide body slid into the valley and deposited on the riverbed of the Jinsha River,forming a dam with a larger height on the opposite bank and a smaller height on the source-side bank.(3)A later landslide blockage caused by a secondary landslide occurred due to the rock strength reduction induced by detachment of the major Shaweitaizi failure.(4)The maximum inundation elevation of the landslide dam is about 1038 m with a distance of~280 km,and the maximum storage capacity is about 188.7×10^(8)m^(3).The dating result suggested an age of about 19000 a for the dam break,which indicated that such a breach was in a strong relation with climate warming-induced great precipitation,intensified glacier melting,and increased flow discharge within the Dali glaciation.[Conclusion]GIS remote sensing analysis is a fast and effective method in the investigation of flood inundation area.At present,the understanding of the formation mechanism,tectonic background,basic geologica

关 键 词：金沙江 巨型滑坡 高位滑坡 成因机理 防灾减灾 

分 类 号：TV213.4[水利工程—水文学及水资源]