非饱和土Iran-2010PPT

J.L.Briaud–TexasA&MUniversity.UNSATURATEDSOILS:SOMEFUNDAMENTALSANDSOMEAPPLICATIONSJean-LouisBriaudPresidentofISSMGE,ProfessorTexasA&MUniversity,USARemonAbdelmalakGeo-Engineer,DarAl-HandasahGroup,Cairo,EgyptXiongZhangAssistantProfessor,UniversityofAlaska,USAJ.L.Briaud–TexasA&MUniversity.•SOMEFUNDAMENTALS–SUCTION–EFFECTIVESTRESS–STRENGTH–DEFORMATION•SOMEAPPLICATIONS–ULTIMATEBEARINGCAPACITY–MOVEMENT–COMPACTION–SLABSONGRADE–TREES–EARTHPRESSURES–SLOPESJ.L.Briaud–TexasA&MUniversity.SoilStateSwellShrinkUnsaturatedYesNoSaturatedYesYesSaturatedNoYesGWLTHETHREEZONESJ.L.Briaud–TexasA&MUniversity.WATERNORMALSTRESSTENSIONCOMPRESSION0(SUCTION)(pF)uw(kPa)(POREPRESSURE)J.L.Briaud–TexasA&MUniversity.u0+-hcaaTTGlassContractileSkinWater-1,000kPadWatercw4TcosαhdγwhereT72mN/mhAtmosphericpressurehgwhcgw0kPaMATRICWATERTENSIONJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.TheWaterStriderForce=72mN/mThickness=afewAngstromsStress?20MPaJ.L.Briaud–TexasA&MUniversity.PureWaterSaltWaterInitialstateInitialstateAftertimetAftertimeth=OsmoticSuctionOSMOTICWATERTENSIONJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.WaterTension200kPaWaterTension100,000kPaWaterContractileSkinSmectiteAl2Si4O10(OH)2WaterQuartzSiO2QuartzSiO2J.L.Briaud–TexasA&MUniversity.GARNER’SSTUDY(2002)3samplesat3watercontentssentto8laboratories.WATERCONTENT,%Sample1Sample2Sample3WATERTENSIONlog(uwinkPa)Sample1Sample2Sample3WATERTENSION,kPaSample1Sample2Sample3051015202530%012345logkPa015000300004500060000kPafcifaifwiFAt00ciwiaittttfffFAAAA'wiaaiwttuauaAA'wauuaJ.L.Briaud–TexasA&MUniversity.Saturateduw0ua=0’=-uwOccludedAiruw=ua’=-uwS85%ContinuousAiruw0ua=0’=-auwS85%soilgrainwatersoilgrainwaterairsoilgrainwaterairJ.L.Briaud–TexasA&MUniversity.ForUnsaturatedSoilsTheeffectivestressisσ’=σ–αuwwithα~STheeffectivestresscontrolsthebehaviorofthesoilskeletonforsaturatedsoilsandforunsaturatedsoils(inmostcases)ShearStrength-unsaturated''tan'sc'()tan'wascuua'()tan'scuwa(?)Sa'tanApparentCohesionwcuaShearStrength-unsaturated(Lu&Likos,2004)αvsSShearStrength-unsaturated(Fredlund&Rahardjo,1993)J.L.Briaud–TexasA&MUniversity.SHEARSTRENGTH-exampleJ.L.Briaud–TexasA&MUniversity.Examplecalculations(unsaturated):c=5kPa,φ=30degrees,z=1m,S=35%,uw=-1000kPa,ua=0s=5+(20–0.35x(-1000))tan30s=218.6kPaExamplecalculations(saturated):c=5kPa,φ=30degrees,z=1m,S=100%,uw=10kPa,ua=0s=5+(20–1x10)tan30s=10.8kPaJ.L.Briaud–TexasA&MUniversity.EXAMPLEOFSTRESSPROFILESDepth,m0123456704080s,kPa04080120’,kPa00.51a04080120,kPaUnsaturatedG.W.LTopofCapillaryZone-80-400au,kPa-400-2000-100u,kPaSaturatedbyCapillarityUnsaturatedSaturated1234567Depth,mJ.L.Briaud–TexasA&MUniversity.Jean-LouisBriaud–TexasA&MUniversityTHISBEARINGCAPACITYEQUATIONDOESNOTWORKFORUNSATURATEDSOILS12ucqpcNBNDNgggJean-LouisBriaud–TexasA&MUniversityJean-LouisBriaud–TexasA&MUniversity,,,LCUrpqNsupkrTHISBEARINGCAPACITYEQUATIONALWAYSWORKSJ.L.Briaud–TexasA&MUniversity.iiiiiEΔHΔεHSei+Deieiev’ovD’i’ovvWEIGHTINDUCEDSETTLEMENTvD’i’ovHizPJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.iwiiiiEΔwfHΔεHSwwi+Dwiwiei+DeieievMOISTUREINDUCEDMOVEMENTwHiDwiwizJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.wwSWDV/VwSH0gw/gdShrink-SwellIndex1J.L.Briaud–TexasA&MUniversity.CLASSIFICATIONOFSHRINK-SWELLPOTENTIALACCORDINGTOSHRINK-SWELLINDEXPotentialVeryHighHighModerateLowIss60%40–6020–4020%J.L.Briaud–TexasA&MUniversity.WATERCONTENTVARIATIONASAFUNCTIONOFTIMEAverageWaterContent0.350.300.250.200.150.100.050.00FallWinterSpringSummerFallWinterSpring1992199319931993199319941994CC=CorpusChristi(0-0.5m)SA=SanAntonio(0-0.5m)CS=CollegeStation(0-1.5m)OUTSIDE=OutsidetheFoundationImprintUNDER=UndertheFoundationImprintTimeforSAandCCTimeforCSFallWinterSpringSummerFallWinterSpring1993199419941994199419951995CCOUTSIDESAOUTSIDECCUNDERSAUNDERCSOUTSIDEJ.L.Briaud–TexasA&MUniversity.iwiiiiEΔwfHΔεHSJ.L.Briaud–TexasA&MUniversity.Depth,mLegendRF:ReferenceW:WaterinjectedBM:Benchmark1.522.530.510Su=179.8kPawmean=19.74%h=3.41pFLL=40.4,PL=17.12m2m0.6mBrownSiltyClay,tracefineSand:Calcareousgt=20.4kN/m3Ew=0.869,f=0.39%SW=4.31%0.002=45.5NorthA’W120m10m10mRF2W2RF1ABM2BM1Su=151.5kPawmean=20.73%h=3.42pFLL=51.3,PL=22.3DarkGraySiltyClay:TraceFineSandgt=20.3kN/m3Ew=0.752,f=0.39%SW=5.17%0.002=47.7AA’GWL:4.27m(Jun./25/99)4.8m(Feb./1/01)4m(Jul./15/01)SiteinArlington,TexasTexasA&MUniversityJ.L.Briaud–TexasA&MUniversity.WATERINJECTIONJ.L.Briaud–TexasA&MUniversity.TexasA&MUniversityJ.L.Briaud–TexasA&MUniversity.FOOTINGSJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.WATERCONTENTANDSUCTIONvs.DEPTH0.00.51.01.52.02.53.03.54.0012345B:BoringB1B2B3B4B5B6B7B8B9Depth,mSuction,pF0.00.51.01.52.02.53.03.54.00.000.050.100.150.200.250.3B:BoringB1B2B3B4B5B6B7B8B9Depth,mWaterContentFootingRF1atasiteinArlington,TexasJ.L.Briaud–TexasA&MUniversity.J.L.Briaud–TexasA&MUniversity.FOOTINGMOVEMENTOVERTWOYEARS08/1/199909/1/199910/1/199911/1/199912/1/199901/1/200002/1/200003/1/20000