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1•••21967681000m,=68106m3=175~335,=680106m3939m=5,300m3/s32000493330m,2500m2500m=280-300106m3=290m,=1534106m30.5m4785520m5520m7955520m2264m2210m2165m2340m80mm2210m2264m553022004000080004000200060002340m81ElevationTheYigongzhangbuRiverThecrosssectionofthelandslide6——82Thenaturallake837August71998,13:1035TypicalCrossSection-378DesignofthenewdikeoftheJiujiangCity499TheJiujiangDikeafterreconstruction5098—10199881898—ThePipingthattravelsalongdistance750mWaterlevel=30.0mSandboilDiameterofthesandboil=6080cmClaySandGroundlevel=20.0m11(m)0-2525-5050-7575-100100-200200-300300-800204984045682628=25m4019893.31.30.03%100604133241160501002002503003504004505001298•;•60%505413‘’56‘’14—From1959-1989theriverbankrecessedfor1324mTheBapudikeinWubei58BankfailureatBeimenkou()•The3kmlongdikerecessedfor400monJune11,1994witharateof55m/hr•Thebankwithdrew100min3hoursonOctober,145915Jingjiangmen(AlocationthattheTongtingLakeisthreatenedtobeinvadedbytheYangtzeRiverinthenextdecades.JingjiangmenDongtingLakeYangtzeRiver6061161718••••••19Newtechnologytocombatbankfailure63PlacingGeotexileandconcretemattress6420Theconcretemattress65Rescueofthefailedriverbankbydumpingrip-raps6621A‘lumpedfailure’happenedinMarch,2000,inJiujiang67Dumpinggeotexilebagstoprotectthetoe6822Pullinggeotexileintotheriver697023Thedumpedrip-rapplacedonalayerofgeotexile7124•••198412247000m3482526271985=1.40106m310°,=8.2mm/d281986726170m,=0.87106m3F306NNWNE402930,194327430m,=127106m340m/s1003132Displacementmeasurementofthreesurfacepoints33Prediction,Δt=1Prediction,Δt=2Date(July)Displa-cement(mm)1daydisp.12llΔΔtTrΔFailuretime2daydisp.12llΔΔtTrΔFailuretime20941.9122.2211064.11.148.528-29139.4221203.50.95-132.4271.8231335.91.493.625-26197241532.91.922.725-262.112.526377.5574.5251910.41.384.2520.926at18:582431.4FailurePredictingthefailurebySato’smethodSato’smethodforLandslideForecasttconsAmoftimeStartingtfailureofTimetentDisplatcemlttttaLoglorrortanaeasurement====Δ--=Δ34:August4of1997at23:55:A2-hourconstantrainfallwithatotalprecipitationof55mm:353637198918103m=0.10106m33839APlanViewoftheManwanProject88LESSONSLEARNEDFROMSLOPEFAILURESLandslidesduetoexcavationLandslidesduetoslopeexcavation40Theholeindicatingpoorback-fillingoftheconcreteshearkeys89411996318150m,=0.2106m3427643(1)(2)(3)(4)(5)(6)WH5F121F3404445199712199811160+0400+08011270+0800+12510000m3()464748TheThree-GorgesProjectTheThree-GorgesProject49505152FactorsofsafetyassociatedwithdifferentstrengthparametersforWedgeNo.4Friction5354TheXiaolangdiProject55Theintakestructureslope5657585960CrossSectionP.0+070.761β(°)F00.869101.188201.674302.520Morgenstern1.47011.4902.038TheCaishitanReservoirProject100LESSONSLEARNEDFROMSLOPEFAILURESLandslidesduetoexcavation62101LandslideofthespillwayslopeoftheCaishitanReservoir199792710263AcloseviewofthelandslideThelandslideonSeptember27,1997TheslipsurfacecaseckPaϕF15538°1.00226031°1.003BackanalysisresultsHeavilyweathereddolemiteandclayslate10464c=11.4kPa,ϕ=25.3°105••••6510710866109Thespillwayslopeafterreinforcementabc(1)(2)(3)671.A.1a=84cm—a’=36cm—h0—A0—Ag—Ag‘—Ak—Aw—Ac—Rg—Rg‘—Rgk—Rgw—Rw—Rc—s—a—μ—μmax—μmin—682.μ=Ag/A05m×5m40mAg=3630cm2A0=250000cm2μ=0.0145μmax=0.55Rw/Rg300Rw=22MPaRg=320MPaμmax=0.0378μmin=0.0015μminμμmax3RgLcLgAgRg=Ag‘Rg‘+AcRwAg=3630cm2Rg=320MPaAg‘=1815cm2Rg‘=320MPa300Rw=22MPaAc=26400cm24.MPLc=389.4cmLg=380cmMPMP=AcRwLc+Ag‘Rg‘Lg=447024.4kN⋅mQPQP=0.07A0Rc+1.5AkRgkh0/s+0.8AwRgwsinαQP=0.07A0RcA0=250000cm2Rc=30MPaQP=52500kN540m40m/2=20mQm=22351.22kNQmQPQ=Qm22351.22kN69707172Theshearcapacityofthebounding:(1)increaseswithincreasingborebolestiffness;(2)decreaseswiththegroutedlengthupto350mmandremainslargelyindependentafterwardsJarredandHaberfield,1997Tie-backwalls-Tendonbondlength73•31000KN,21600KN11556KN;•33000KN4310KN-4318KNShouldgroutedanchorshaveshorttendonbondlength?BriaudandWeatherby,1998TIE-BACKWALLSTendonbondlength74757677•••••7835Littlejohn,1992•919835Littlejohn,1992:•••7935Littlejohn,1992•35Littlejohn,1992•19,2028081