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1、JournalofEngineeringGeology工程地質(zhì)學(xué)報(bào)1004-9665/2016/24(5)-0752-08DOI：10.13544/j.cnki.jeg.2016.05.004平緩細(xì)粒土岸坡水庫塌岸機(jī)理研究張景順張世殊周光明徐旭馮建明(中國電建集團(tuán)成都勘測設(shè)計(jì)研究院有限公司成都610072)摘要大量工程實(shí)踐和統(tǒng)計(jì)數(shù)據(jù)表明,水庫塌岸多發(fā)生在自然坡度15°以上的松散堆積層岸坡。一般認(rèn)為自然坡度10°左右的平緩堆積層岸坡發(fā)生水庫塌岸的可能性小，但在四川省寶興河磽磧水電站庫區(qū)卻發(fā)生了大規(guī)模的平
2、緩型堆積層塌岸，螞蝗溝5#堆積體即屬于此類型。螞蝗溝5#堆積體由礫質(zhì)黏土組成，土中小于0.075mm的細(xì)粒含量約占60%,蓄水后塌岸模式為緩慢的蠕滑變形。蓄水9年多來，變形范圍由前緣的小規(guī)模塌岸逐漸向后緣擴(kuò)展至大范圍滑坡，目前變形仍然在持續(xù)。本文以該堆積體為例，通過對土體結(jié)構(gòu)、顆粒組成等的勘探試驗(yàn)，并結(jié)合水庫運(yùn)行方式和變形監(jiān)測成果，采用有限元瞬態(tài)滲流分析與穩(wěn)定性分析的耦合分析計(jì)算，系統(tǒng)地開展了其塌岸機(jī)理研究。研究結(jié)果表明:細(xì)粒為主的土體結(jié)構(gòu)及其弱透水性，是平緩堆積體在庫水位反復(fù)升降作用下蠕滑變形的根本
3、原因；平緩細(xì)粒土岸坡的穩(wěn)定性與庫水位的升降具有明顯的相關(guān)性，隨庫水位的周期性變化岸坡呈現(xiàn)出不同的穩(wěn)定狀態(tài)，其蠕滑變形速率也明顯不同。關(guān)鍵詞水庫塌岸蠕滑礫質(zhì)黏土瞬態(tài)滲流分析變形監(jiān)測中圖分類號:P642.2文獻(xiàn)標(biāo)識碼：ACOLLAPSEMECHANISMOFGENTLEINCLINEDANDFINE-GRAINEDSOILSLOPEONRESERVOIRBANKZHANGJingshunZHANGShishuZHOUGuangmingXUXuFENGJianming{PowerChinaChengduEn
4、gineeringCorporationLimited,Chengdu610072)AbstractEngineeringpracticeandstatisticsshowthatreservoirbankcollapseusuallyoccurinlooseaccumulationwhenslopeisgreaterthan15degrees.Reservoirbankcollapseissmallpossibilitywhenbankslopeis10degreesorso.Butithappen
5、sinQiaoqihydropowerstationreservoirareaonSichuanBaoxingRiver.Asanfactualexample,theMahuangvalley5#accumulationbodyiscomposedofgravellyclay.Particlesizeoflessthan0.075mmisaccountedforabout60%.Thecollapsemodeofreservoirbankisslowcreepingdeformationafterim
6、poundment.Deformationrangegraduallyexpandsbackward.Aftermorethannineyears,deformationcontinues.ThispapertakesMahuangvalley5#accumulationbodyasanexample.Itisonthebasisofexplorationandtestworkaboutsoilstructureandsoilparticlecomposition,reservoiroperation
7、modeanddeformationmonitoringresults,andcouplinganalysisoffiniteelementanalysisoftransientseepageandstabilityanalysis.Itstudiesthecollapsemechanismofgentlyinclinedslopeonreservoirbank.Theresultsshowthatfine-grainedsoilstructureandweakwaterpermeabilityare
8、themaincausesofaccumulationofcreepdeformationinQiaoqireservoirarea.Thegentlyinclinedslopestabilityandtheperiodicalchangeofwaterlevelhaveanobviouscorrelation.Withtheriseandfallofwaterlevelchange,thereservoirbankpresentsdifferentst
