软岩遇水软化膨胀特性及其对拱坝的影响

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1、第25卷第9期岩石力学与工程学报Vol.25No.92006年9月ChineseJournalofRockMechanicsandEngineeringSept.，2006软岩遇水软化膨胀特性及其对拱坝的影响刘光廷，胡昱，李鹏辉(清华大学水利水电工程系，北京100084)摘要：泥钙质胶结砾岩遇水后软化，力学性质会发生较大变化，其强度及刚度均大幅度降低；同时，软岩吸水后会膨胀。首先，通过试验研究泥钙质胶结砾岩在自由状态、受压状态下由于浸水而产生膨胀变形；然后，通过数值计算，分析几种拱坝运行期间可能出现的工况；最后，结合原型观测得出结论，在砾岩上修建结构物如拱坝时，除了要考虑岩体由于自重

2、等因素产生的初始应力场外，还需根据实际情况，考虑浸水对砾岩力学性质的影响。关键词：岩石力学；膨胀软岩；拱坝；数值分析中图分类号：TU45；TV223.1文献标识码：A文章编号：1000–6915(2006)09–1729–06BEHAVIOROFSOAKINGROCKANDITSEFFECTSONDESIGNOFARCHDAMLIUGuangting，HUYu，LIPenghui(DepartmentofHydraulicandHydropowerEngineering，TsinghuaUniversity，Beijing100084，China)Abstract：TasiRiver

3、HydraulicProjectislocatedinthe“Shimen”gorgesectioninthemiddlestreamofTasiRiverinManasiCounty，XinjiangUygurAutonomousRegionofChina.TheU-shapedgorgeisapproximately350mlongand70–80mwidthatbottom.TheRCCarchdamis109minheightwithacrestlengthof176.5m.Thethickestpartattheintradosis31m.Thebankandriverbe

4、darecomprisedofcaesiousandredrudite.Theresultofuniaxialtestsshowsthatthebehaviorofsoftrockchangeswhenimmersed.Whilesoaked，theredrudite′sdeformationmodulusdropsto3GPafrom15GPaatdryingregime.Besidesthelargedecreaseofdeformationmodulus，swellingfollowsbecauseofwaterabsorbing.Thedilatanciesofsoftroc

5、karemeasuredinlibertyorcompressioncondition.Evenincompressionthesoftrockstillswellswhilesoaked；andtheswellingdeformationiscomparableinmagnitudetothedeformationcausedbythecompressionstress.Therefore，theswellingdeformationcannotbeignored.Itseffectonthedeformationdistributionofthearchringwillalsob

6、epresentedinthepaper.Differentprocesseswillleadtodifferentresults.Inthefirstscenariowheretherockissoakedbeforethearchdamisbuilt，onlythelowdeformationmoduliatdifferentstressstatuswillbeconsidered.Inthesecondscenariowheretherockissoakedafterthearchdamisbuilt，theeffectondilatanciesofsoftrockwillal

7、sobeincluded.Inthesecondscenario，thestressdistributionmaybeinvertedandthusposeagreatdangertothearchdam.ItisalsoshownthattheTasiRiverHydraulicProjectisclosetothefirstscenariobyanalyzingitsin-situobservationdata.Thearchdamsafetywill