震后泥石流沟内滑坡堰塞坝的侵蚀特征分析——以银洞子堰塞坝为例
Eroding Characteristics of Landslide Dams in Debris Flow Gullies After Earthquakes-Case Study of Yindongzi Landslide Dam
作者：赵高文(中国科学院 水利部 成都山地灾害与环境研究所, 四川 成都 610041;中国科学院大学, 北京 100049)；王萌(中国科学院 水利部 成都山地灾害与环境研究所, 四川 成都 610041)；杨宗佶(中国科学院 水利部 成都山地灾害与环境研究所, 四川 成都 610041)；田宏岭(中国科学院 水利部 成都山地灾害与环境研究所, 四川 成都 610041)；姜元俊(中国科学院 水利部 成都山地灾害与环境研究所, 四川 成都 610041)
Author：ZHAO Gaowen(Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China;Univ. of Chinese Academy of Sciences, Beijing 100049, China)；WANG Meng(Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China)；YANG Zongji(Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China)；TIAN Hongling(Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China)；JIANG Yuanjun(Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China)
收稿日期：2018-05-26 年卷（期）页码：2019,51(5):68-77
期刊名称：工程科学与技术
Journal Name：Advanced Engineering Sciences
关键字：滑坡;堰塞坝;泥石流;漫顶破坏;侧向侵蚀;下切侵蚀;陡坎侵蚀
Key words：landslide;landslide dam;debris flow;overtopping failure;lateral erosion;undercut erosion;headcut erosion
基金项目：长江科学院开放研究基金项目（CKWV2015228/KY）；国家自然科学基金面上项目（41471012；41471429）；国家自然科学基金青年基金项目（41502334）
中文摘要
强烈地震后的沟内滑坡堰塞坝是泥石流地质灾害的重要物质来源，由于季节性降雨的间歇性和沟道地形的特殊性，泥石流沟内滑坡堰塞坝的侵蚀破坏过程与堵河型滑坡堰塞坝有明显区别，本文以银洞子滑坡堰塞坝为例，对此类堰塞坝的侵蚀破坏特征进行了研究。通过多年的现场地质调查和理论分析，主要得出以下结果：1）银洞子堰塞坝受到的侵蚀效应包括降雨导致的坡面汇流冲刷，溃口水流或泥石流的下切侵蚀、侧向侵蚀和溯源陡坎侵蚀；2）横向巨大高差导致该堰塞坝漫顶溃决时的初始溃口位于坝体侧面，水流或泥石流对溃口边坡的侧向侵蚀过程为单向侵蚀，在这种侧向侵蚀和下切侵蚀共同作用下，堰塞坝的溃口边坡越来越高，堰塞坝的稳定性降低；3）银洞子沟上、下游土体强度不同导致堰塞坝的坡面侵蚀效果不同，下游一侧坝体强度较弱，坡面汇流冲刷导致堰塞坝表面被两道大型拉槽分割，堰塞坝的整体性受到影响；4）银洞子堰塞坝特殊的物质结构导致溯源侵蚀陡坎向上游的发展速度缓慢，堰塞坝的侵蚀过程不一致。在多种侵蚀效应的共同作用下，银洞子沟滑坡堰塞坝下游部分的溃口边坡高度大、完整性差，很可能失稳形成二次滑坡，将导致大量松散物质进入新形成的沟道内，从而为泥石流活动提供物源储备。
英文摘要
Landslide dams induced by strong earthquake in gullies are the important material source of debris flow hazards. Due to the intermittence of seasonal rainfall and the particularity of the gully topography, the eroding process of a landslide dam in the gully is obviously different from that of a landslide dam in the river channel. Taking the Yindongzi landslide dam as an example, the eroding characteristics of such dams were investigated. Based on years of on-site geological surveys and theoretical analysis, several results were found as follows: 1) The Yindongzi landslide dam suffered from the confluence erosion on the dam surface and a serial of eroding effects derived from the water flow or debris flow in the breach, including undercut erosion，lateral erosion and headcut erosion. 2) The huge height difference in transverse direction caused the initial breach of the Yindongzi landslide dam to occur on the side of dam and the direction of the lateral erosion induced by the water flow or debris flow in the breach was unidirectional. Under the joint action of this lateral erosion and the undercut erosion, the height of breach slope was gradually increased and the stability of dam was reduced. 3) The difference of soil strength in the upstream and downstream of Yindongzi landslide dam led to the different effects of confluence erosion on the dam surface. As the soil strength in the downstream was relatively low, the dam surface in this area was divided by two large cutting gullies and the integrity of dam was affected. 4) The special material structure of Yindongzi landslide dam led to a slow development of headcut erosion to the upstream and the eroding progress of the dam in downstream and upstream was inconsistent. With the combined action of various erosion effects, the height of breach slope in the downstream of the Yindongzi landslide dam was large and had a poor integrity. It is, therefore, likely to fall into instability and to form a secondary landslide. The secondary landslide will cause a large amount of loose material to enter the newly formed gully, providing a source of material for debris flow activity.
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