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1、JournalofEngineeringGeology工程地質(zhì)學(xué)報1004—9665／2009／17(3)-0313-04金沙江某水電站上下壩址巖體卸荷差異研究張勇①李天鵬②聶德新①劉彬①(①成都理工大學(xué)工程地質(zhì)研究所成都610059)(②中國水電顧問集團(tuán)昆明勘測設(shè)計研究院昆明650051)摘要在河流下切、斜坡成坡過程中，斜坡應(yīng)力場不斷調(diào)整和適應(yīng)坡體的變化，表淺部巖體在應(yīng)力變化過程中往坡外發(fā)生卸荷，在同一地區(qū)巖體卸荷深度應(yīng)當(dāng)相差不大。而在西南某水電站相隔僅1．4km上下壩址勘察過程中發(fā)現(xiàn)，兩壩址巖體卸荷深度卻存在較大差異，
2、上壩址巖體卸荷深度在20m以上，最大深度達(dá)到90m；下壩址巖體卸荷深度僅為5～20m。，通過現(xiàn)場調(diào)查及數(shù)值模擬成果表明，上下壩址巖層方位是兩壩址巖體卸荷差異的決定性因素，上壩址為順向坡，巖層走向與邊坡走向平行，傾角較陡的巖層形成拉裂面，易于風(fēng)化營力的侵入，巖體卸荷深度大；下壩址為橫向坡，巖層走向與邊坡走向近于垂直，巖體強(qiáng)度遠(yuǎn)大于巖層面的強(qiáng)度，且平行坡向的結(jié)構(gòu)面數(shù)量少，巖體卸荷深度在20m以內(nèi)。關(guān)鍵詞卸荷順向谷橫向谷應(yīng)力中圖分類號：P642文獻(xiàn)標(biāo)識碼：AUNLoADINGoFTHERoCKMASSATTHEUPANDDoWN
3、TREAMDAMSOFHYDRoPoWERSTATIoNINJINSHARIVERZHANGYong~LITianpeng~NIEDexinO)LIUBin~(①ChengduUnwe~i@ofTechnology，Chengdu610059)(~KunmingHydropowerInvestigation，DesignandResearchInstitute，CHECC。Kunming650051)AbstractTheprocessofstreamtrenchingandslopeformationcauseacont
4、inuouschangeinthestressfieldoftheriverbankslopes．Thesuperficialrockmassisunloadedinthechangeofstressfield．Thedepthofunloadingshouldbeindifferentinthesamearea．AninvestigationiscarriedonthestressfieldatahydropowerstationinsouthwestChina．Thestationhastwodams．Theupand
5、downtreamdamshaveadistanceof1．4kin．Theinvestigationdetec—tedthatunloadingdepthsoftherockmassesatthetwodamsiteshavewiderdifferences．Attheupstreamdamsite，theunloadindepthismorethan20m，anditsextremedepthcanreachto90m．Atthedownstreamdamsite，theunloadingdepthisonly5～20
6、m．Fieldsurveyandnumericalsimulationindicatethatorientationoftherockforma—tionisthekeyfactorforthediferenceintheunloadingdepthsattheupanddownstreamdams．Trendsofrockfor-mationandriverbankslopesattheupstreamdamareparalleled．Therockmassofsteepdipangleiseasytobecracked
7、．Theweatheringisinvaded．Thedepthoftherockmassunloadingisdeep．Atthedownstramdam，thetrendsoftherockformationandriverbankslopesarenearlyareperpendicular．Thestrengthoftherockmassisgreaterthanthebeddingplanes．Thestructuralsurfacesthatparalleltotheriverbankslopesareless
8、．Therefore。theunloadingdepthofrockmassiswithin20m．收稿日期：2008-08-01；收到修改稿日期：2008—11—27．基金項目：國家自然科學(xué)基金資助項目(編號40372127)．第一作者簡介：張勇，地質(zhì)工程專業(yè)．Email：zhangenhuall@1
