北川地震重灾区泥石流特征与减灾对策
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摘要
汶川大地震的同震次生灾害以滑坡、崩塌居多,泥石流相对较少。但地震导致滑坡、崩塌为震后泥石流提供了极为丰富的物质来源,使得地震灾区在一年多的时间里已经多次暴发了大面积的泥石流。以北川地震重灾区的苏宝河和魏家沟流域为研究区域,通过野外实地考察、遥感图像分析、历史资料对比等方法,概括总结出受地震强烈影响区域的泥石流具有成因多样、时间同步、颗粒粗大、多灾种复合、空间近似对称和小沟大灾等特征。并提出了"面上监控为主、点上工程为主、分类防治和开展风险评估"的减灾对策。
Coseismic geologic hazards of the Ms 8. 0 Wenchuan Earthquake included a great amount of landslides,rockfalls and avalanches,but few debris flows. However,numerous mass movements such as landslides and avalanches are becoming a plentiful mass source for the formation of debris flows,and many debris-flow events have occurred widely since the earthquake,especially in the meizoseismal area. In this paper,debris-flow ravines at Subaohe and Weijiagou rivers in Beichuan's Meizoseismal area,southwestern China are studied by field investigation,remote sensing image interpretation and historical data analysis. It is summarized that the formation of these debris flows in the study area can be mainly divided into three classes,viz. direct mobilization from landslide,erosion of unstable slope,and outburst of blocked flood. Other disasters such as flood,landslide,and avalanche were accompanied with the debris flows. The distribution of grains in the debris deposits concentrates on sand,cobble and boulder. The events were closely synchronous because they were triggered by the rainstorms on September,23 ～ 24,and the locations of the ravines show some kind of space symmetry. Another notable feature is that the magnitude of debris flows is large even for those ravines with small catchment area. Finally,four countermeasures mitigating debris flows are proposed against the debris-flow hazards,which can be practically applied to debris-flow prevention.
Coseismic geologic hazards of the Ms 8. 0 Wenchuan Earthquake included a great amount of landslides,rockfalls and avalanches,but few debris flows. However,numerous mass movements such as landslides and avalanches are becoming a plentiful mass source for the formation of debris flows,and many debris-flow events have occurred widely since the earthquake,especially in the meizoseismal area. In this paper,debris-flow ravines at Subaohe and Weijiagou rivers in Beichuan's Meizoseismal area,southwestern China are studied by field investigation,remote sensing image interpretation and historical data analysis. It is summarized that the formation of these debris flows in the study area can be mainly divided into three classes,viz. direct mobilization from landslide,erosion of unstable slope,and outburst of blocked flood. Other disasters such as flood,landslide,and avalanche were accompanied with the debris flows. The distribution of grains in the debris deposits concentrates on sand,cobble and boulder. The events were closely synchronous because they were triggered by the rainstorms on September,23 ～ 24,and the locations of the ravines show some kind of space symmetry. Another notable feature is that the magnitude of debris flows is large even for those ravines with small catchment area. Finally,four countermeasures mitigating debris flows are proposed against the debris-flow hazards,which can be practically applied to debris-flow prevention.
引文
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[16]吴珍汉,张作辰.汶川8级地震地质灾害的类型及实例[J].地质学报,2008,82(12):1747～1757.
[2]Cui P,Chen X Q,Zhu Y Y,et al.The Wenchuan Earthquake(May12,2008),Sichuan Province,China,and resulting geo-hazards[J].Natural Hazards,DOI10.1007/s11069-009-9392-1.(in press)
[3]崔鹏,韦方强,陈晓清,等.汶川地震次生山地灾害及其减灾对策[J].中国科学院院刊,2008,23(4):317～323.
[4]黄润秋,李为乐.“5·12”汶川大地震触发地质灾害的发育分布规律研究[J].岩石力学与工程学报,2008,27(12):2585～2592.
[5]崔鹏,韩用顺,陈晓清.汶川地震堰塞湖分布规律与风险评估[J].四川大学学报(工程科学版),2009,41(3):35～42.
[6]陈晓清,崔鹏,程尊兰,等.5.12汶川地震堰塞湖排险应急评估[J].地学前缘,2008,15(4):244～249.
[7]谢洪,王士革,孔纪名.5.12汶川地震次生山地灾害的分布与特点[J].山地学报,2008,26(4):396～401.
[8]陈晓清,崔鹏,赵万玉.汶川地震区泥石流灾害工程防治时机的研究[J].四川大学学报(工程科学版),2009,41(3):125～130.
[9]唐川,梁京涛.汶川震区北川9·24暴雨泥石流特征研究[J].工程地质学报,2008,16(6):751～758.
[10]四川省北川羌族自治县地质灾害补充调查与区划报告[R],四川省地矿局成都水文地质工程地质队,2006.
[11]张德藩.北川县城区山地灾害成因及防治对策[J].水利水电技术报导,1992,4(1):22～28.
[12]陈晓清,崔鹏,游勇,等.关于汶川地震灾区泥石流灾害工程防治标准的讨论[M].汶川大地震工程震害调查分析与研究,北京:科学出版社,2009,297～303.
[13]柳金峰,游勇,范建容,等.汶川地震触发潜在性泥石流研究-以岷江上游关山沟为例[J].四川大学学报(工程科学版),2009,41(增刊):70～75.
[14]游勇,柳金峰.汶川8级地震对岷江上游泥石流灾害防治的影响[J].四川大学学报(工程科学版),2009,41(增刊):16～22.
[15]姚令侃,陈强."5.12"汶川地震对线路工程抗震技术提出的新课题[J].四川大学学报(工程科学版),2009,41(3):43～50.
[16]吴珍汉,张作辰.汶川8级地震地质灾害的类型及实例[J].地质学报,2008,82(12):1747～1757.
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