西南某水电站中缓倾裂隙特征及发育模式分析.pdf

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1、JournalofEngineeringGeology工程地质学报1004—9665／2014／22(6)一1301-08DOI：10．13544／j．cnki．jeg．2014．06．039西南某水电站中缓倾裂隙特征及发育模式分析水赵伟华严明黄润秋(地质灾害防治与地质环境保护国家重点实验室(成都理工大学)成都610059)摘要本文在大量的裂隙调查基础上，总结分析了西南某水电站坝址区中缓倾裂隙的地质特征，阐释了中缓倾裂隙的形成机制和发育模式。通过统计分析，结果表明：(1)岩坡中缓倾裂隙总体与岸坡大体平行，是河谷下切伴生的岸坡应力分异和卸荷回弹形成的表生压致拉

2、裂破裂体系；(2)岸坡的形成是河谷多期次下切的结果，河谷下切坡度变陡，后期形成的中缓倾裂隙亦相对早期宽缓河谷形成的中缓倾裂隙倾角增大，河谷侧向偏移致使凸岸坡体更有利于保存早期裂隙，因此凸岸坡体中上部多见中倾裂隙与缓倾裂隙同时存在现象；(3)峡谷的形成总体是间歇性快速下切，相对稳定阶段岸坡形成表生中缓倾裂隙，快速下切期间以河谷垂向卸荷为主，由此形成与间歇性快速下切各阶段相对应的裂隙密集区和裂隙稀疏区的间断分布。关键词中缓倾裂隙多期次下切间歇性快速下切形成机制发育模式中图分类号：P642．2文献标识码：ACHARACTERISTICANDDEVELoPMENTM

3、oDELoFSHEETJoINTSATHYDRoPoWERSTATIoNINSoUTHWESTERNCHINAZHA0WeihuaYANMingHUANGRunqiu(StateKeyLaboratoryofGeohazardPreventionandGeoenvironmentProtection(ChengduUniversityofTechnology)，Chengdu610059)AbstractThispaperisaboutthegeologicalinvestigationresultsataproposedlargehydropowersta

4、tionsite．Thesheetjointswithgentleandmediumdipsaredevelopedinthesuperficialslopeandmanifestedasdisjunctivedistributionofjointconcentrationareasandjointsparseareas．Theycontroltherockmassstructureandstabilityofhighslope．Thisfindingisbasedonmassivefieldinvestigation．Thepapersummarizesa

5、ndanalyzesthebasicgeologicalcharacteristicsanddistributioncharacteristicsofthesheetjointsatthedamsite，andexplainsthejoints’formationmechanismanddevelopmentmode1．Theresultsofthestudyshowthat：(1)Sheetjointsparalleledtobankslopebelongtotensionjoints—systemduetodown—cuttingofvalleyandd

6、isplacementofstress．(2)Theformationofbankslopeisaresultofrepeateddown—cuttingofvalley．Afterdown·cutting，theangleofslopebecomessteeper．That’Smeandipangleofsheetjointsformedinthelateissteeperthanthatintheearlystage．Whenthevalleygeneratesdown—cuttingandlateralerosion，theconvexbankslop

7、eisbeneficialtosaveearliergentlejoints．Thisisthereasonthatbothgentledipjointsandmoderatedipjointsareavailableintheupper—middlepartoftheconvexbank．(3)Thecanyonisformedbyintermittentrapiddown-cutting．Duringrelativestablestage，sheetjointsaredevelopedinbankslope．Duringrapiddown—cutting

8、stage，verticalunloadingmai