汶川震区文家沟泥石流成灾机理与特征.pdf

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1、JournalofEngineeringGeology工程地质学报1004-9665／2011／19(2)-0262—09汶川震区文家沟泥石流成灾机理与特征倪化勇郑万模唐业旗徐如阁王德伟陈绪钰宋志(成都地质矿产研究所成都600081)摘要文家沟位于绵竹市清平乡，属于5·12汶川Ms8．0级地震极重灾区。地震发生后的3个汛期内，文家沟曾先后发生5次典型泥石流灾害，其中以2010年8月13日泥石流灾害最为严重，规模与灾情巨大，社会影响深远。在对文家沟泥石流跟踪调查的基础上，探讨了泥石流的成灾机理和特征。研究表明：(1)文家沟泥石流是地震和强降雨共同作用的结果，其成因可归纳为震

2、因与物源以及雨因与水源两个方面，在整个泥石流形成和发生的过程中，呈现出洪流一侵蚀下切一崩滑一席卷一进一步侵蚀下切一进一步崩滑一增大泥石流规模一⋯⋯的“滚雪球式”循环过程；(2)泥石流发生所需的雨量、雨强条件和水动力条件都显著降低，泥石流规模和雨量之间呈现出明显幂函数关系；(3)发生过程呈现出持续时间长、运动距离远的特征；(4)成灾过程呈现出明显的链式效应，危害形式多样；(5)泥石流频率呈现出高发性，规模呈现出放大性。最后提出了文家沟泥石流研究与防治的建议。关键词文家沟泥石流成因特征地震滑坡链式效应中图分类号：P642．23文献标识码：AMECHANISMANDCHARAC

3、TERISTICSoFWENJIA—GULLYDEBRISFLoWINEPICENTERAREAoFWENCHUANEARTHQUAKENIHuayongZHENGWanmoTANGYeqiXURugeWANGDeweiCHENXuyuSONGZhi(ChengduInstituteofGeologyandMineralResources，Chengdu610081)AbstractWenjiagullyislocatedattheepicenterareaofthe2008WenehuanEarthquake．Ahugelandslidewasevertriggered

4、bytheearthquake．Duringthepassedthreefloodseasons，atleastfivetypicaldebrisflowsoccurredatWenjiagully．Inparticular，aseverestdebrisflowoccuredonAug．13，2010．Ithadavolumeupto3．1X10m．Fiveresidentslosttheirlivesunfortunatelyandhundredsofnew-builthouseswereburiedduringthecatastrophice—-vent．Howev

5、er，itwasfortunatethatalmostalltheresidentsevacuatedsuccessfullybeforethedebrisflowoccurred．Inthispaper，onthebasisoftrackinginvestigation，themechanismandcharacteristicsoftheWenjia—gullydebrisflowswerediscussedandsomesuggestionswereputforward．Theacknowledgesobtainedafterinvestigationanda—na

6、lysisareasfollows：(1)ThedebrisflowswerecausedbybothWenchuanearthquakeandstrongrainfal1．Asthedebrisflowformationisconcerned，acirclewaspresentedasrunof-erosion-collapse-engulfment-erosion-collapse-enlargement一，andSOon；(2)Thecriticalrainfallinitiateddebrisflowwassignificantlydecreasedandapow

7、er—lawrelationisexistedbetweendebrisflowmagnitudeanddailyrainfall，whichcanbeusedtopredictthevolumeofdeb—risflowonthebasisofweatherforecasting；(3)Astheoccurrenceprocessisconcerned，thedebrisflowlastedforalongdurationandmovedafardistance；(4)Intermsofdestroyingprocess，a