岩溶及采空区桥梁桩基桩端岩层安全厚度研究

251Vol.25No.120041RockandSoilMechanicsJan.20042002-10-08.195610007598(2004)0100640511211.4100822.421000TU473AStudyonsafethicknessofrockmassatendofbridgefoundation’spileinkarstandworked-outmineareaZHAOMing-hua1,CAOWen-gui1,HEPeng-xiang2,YANGMing-hui1(1.GeotechnicalEngineeringInstitute,HunanUniversity,Changsha410082,China;2.Yueyanghighway&BridgeEngineeringCorporation,Yueyang421000,China)Abstract:Aimingatthesafethicknessofthebridgepileend'ssupportrockmassinkarstandminingregion,thedeterminationmethodhadbeencomprehensivelyprobedbyathoroughanalysisofthedistortioncharacteristicsandthedestroyedmechanismofrockmassattheendofthebridgepile.Aseriesofeconomic,reasonableandsafetyformulashavebeenproposed;andtheyareeasytoapplyinengineering.Finally,theproblemssuchastheformula'susingrange,notices,influencingfactorandthereasonableselectionofthesafetyfactorhavebeendiscussed.Keywords:karst;destroyedmechanism;pilefoundation;safetythickness12-[1,2][3]1-Coulomb-Mohró2Griffith1651Fig.1Failureoftheterraneatpiletip[4,5]33.1hrhd22Fig.2Rush-cutsktechoftheterraneatpiletipPpèQ1Q2KPpQ1Q2Rtu0hRdF(1)KRtu0u0ð(dhtanè)RdFnnh/dPpðd2Rj/4(Rj)m1Rt/Rjm2Rd/RjK4n(1ntanè)m1(12ntanè)2m2(2)è45°Q10.75K3n(1n)m1(12n)2m2(3)Rc1/101/201/3m10.15RtRc/20m20n1.5,2.0,2.5,3.0,4.0,5.03K1.7,2.7,3.9,5.4,9.0,13.52.5K3.95K13.53.2[6]GB50010-200245°RtRc/20RjRc/3K0.36n1n(4)n1,2,3,4K0.72,2.16,4.32,7.233.320046633Fig.3CalculatingsketchforShearingmodeK4nô/Rj(5)uuðdôôcótanönôRjô=Rc/12RjRc/3Knn3K333.4bddb866.04/ð2==(6)lb/lbHRblbHlMj⎥⎦⎤⎢⎣⎡--+=8))((242maxgg(7)bHRblHlMj⎥⎦⎤⎢⎣⎡-+-=8)(122mingg(8)Hg[ó]K6M/bh2(9)[ó]44.1K34234.2[7]4t4Fig.4Fracturedrockresistingrush-cut5ô1675Fig.5Fracturedrockdestroyforshearl/d15204.3PpPrîî01.0î0PpP-Ps-îPrP-PsPPs4.4[8]5551.01.5m5.07.5m1d6.09.0m33.0m5209.011.0m45m8#615.30md=1.2m10.7015.30m17.00m3.0m8#66mh68Fig.6Constructiondesignofpile#8200468(1)Rc120MPaRtRc/20RjRc/3Rd0K3m10.15m203n2.13h2.556m(2)ôRc/8(5)n2h2.4m(3)l2.5mH8.0mã20.0kN/m3[ó]Rc/4(7),(8)Mmax7.899103kNmMmin=-13.532103kNm(9)h2.8m8#3.0m6(1)(2)(3)[1].[M].:,1999.[2]JaegerJC,CookNGW.FundamentalsofRockMechancs[M].London:ThirdEditionChapmanandHall,1979.[3].[J].,2000,(1):4143.[4]KutterHK.Failuremechanicsofjoinedrock[A].RockMechanics[C].In:MüllerLed.NewYork:springer,1974.[5]GoodmanRE.IntroductiontoRockMechanics[M].NewYork:JohnWiley&Eons,1980.[6].[A].[C].:[s.n.],1984.[7].[J].,1995,(1):2425.[8]JGJ94-94.[S][e-mail]@whrsm.ac.cn430071