香港理工大學(xué)殷建華老師之市公開(kāi)課金獎(jiǎng)市賽課一等獎(jiǎng)?wù)n件

深基坑開(kāi)挖與支護(hù)設(shè)計(jì)

殷建華TheDepartmentofCivil&StructuralEngineeringTheHongKongPolytechnicUniversity,HongKong,China1第1頁(yè)OutlineofLecturesbyJHYIN:Lecture1:SubsoilExploration(Chapter2-Das)Lecture2: ShallowFoundations(Chapter3-Das)Lecture3: MatFoundations(Chapter4-Das)Lecture4: LateralEarthPressureandRetainingWalls(Chapter5-Das)Lecture5: SheetPileWalls(Chapter6-Das)Lecture6: BracedCuts(Chapter7-Das)Lecture7: PileFoundations(Chapter8-Das)Lecture8: SoilImprovementandGroundModification(Chapter11-Dasplusothers)EssentialReferences:Das,BrajaM.().PrinciplesofFoundationEngineering(6thedition),Thomson,UnitedStates(ISBN0-534-40752-8)2第2頁(yè)6.1Introduction6.2ConstructionMethods(施工方法)6.3CantileverSheetPileWalls（懸臂板樁墻）6.4CantileverSheetPilingPenetratingSandySoils6.5CantileverSheetPilingPenetratingClay6.6AnchoredSheetWalls6.7FreeEarthSupportMethodforPenetrationofSandySoil6.8MomentReductionforAnchoredSheetPileWalls6.9FreeEarthSupportMethodforPenetrationofClayLecture6:SheetPileWalls(Chapter6-Das)板樁墻3第3頁(yè)6.10Anchors6.11UltimateResistanceofAnchorPlatesandBeamsinSand（錨板和錨梁極限承載力）6.12UltimateResistanceofAnchorPlatesandBeamsinClay(fu=0condition)6.13FactorSafetyforAnchorPlatesandBeamsLecture6:SheetPileWalls(Chapter6-Das)板樁墻4第4頁(yè)6.1IntroductionPurposes:

supportingexcavation,retainingsoil,stoppingwaterinflow,…支撐開(kāi)挖，擋土，阻止水滲流5第5頁(yè)Diaphragmwallsareundergroundstructuralelementscommonlyusedforretentionsystems,permanentfoundationwalls,deepgroundwaterbarriers.地下連續(xù)墻普遍用于支撐體系，永久性基礎(chǔ)外墻，擋水地下結(jié)構(gòu)體。Diaphragmwallsareconstructedusingtheslurrytrenchtechnique,whichwasdevelopedinEuropeandhasbeenusedinHongKongsincethe1970‘s.地下連續(xù)墻施工過(guò)程中采取了泥漿護(hù)壁。Thetechniqueinvolvesexcavatinganarrowtrenchthatiskeptfullofanengineeredfluidorslurry.泥漿護(hù)壁技術(shù)是開(kāi)挖窄槽..Theslurryexertshydraulicpressureagainstthetrenchwallsandactsasshoringtopreventcollapse.泥漿給窄槽壁施加水壓，預(yù)防坍塌Slurrytrenchexcavationscanbeconstructedinalltypesofsoil,evenbelowthegroundwatertable.泥漿護(hù)壁溝渠開(kāi)挖適合用于各種土層Diaphragmwalls（地下連續(xù)墻）:6第6頁(yè)BentoniteSlurry（工程中配置泥漿原理圖）7第7頁(yè)3-DViewofDiaphragmWallConstruction8第8頁(yè)9第9頁(yè)Woodensheetpileandconcretesheetpile（木板樁，混凝土板樁）:10第10頁(yè)Steelsheetpile(usedalotinHongKong):11第11頁(yè)SteelsheetpilesfromJapanandUKareoftenusedinHongKong.

BelowisfromUSA.12第12頁(yè)13第13頁(yè)6.2ConstructionMethods(后填土支護(hù)施工過(guò)程)14第14頁(yè)15第15頁(yè)6.3CantileverSheetPileWalls（懸臂板樁墻，實(shí)際變形、受力圖）Rotationpoint:Howtofindit?旋轉(zhuǎn)點(diǎn)？16第16頁(yè)FromSoilMechanicsbyCraig()(7thEdition)兩種力學(xué)模型Fixedearth(bendinghere)Freeearth(nobendinghere)(simpleandgood)17第17頁(yè)6.4CantileverSheetPilingPenetratingSandySoilsFixedearthmethod(bendinghere)18第18頁(yè)P(yáng)urpose:TodesignD（入土深度）forthesheetpiletobesafe!Seeequationsbelow:Nowaterpressureisconsidered:self-balanced（自平衡）19第19頁(yè)20第20頁(yè)21第21頁(yè)22第22頁(yè)23第23頁(yè)取得壓力圖形步驟24第24頁(yè)最大彎矩計(jì)算剪力為0點(diǎn)25第25頁(yè)26第26頁(yè)27第27頁(yè)28第28頁(yè)29第29頁(yè)30第30頁(yè)31第31頁(yè)6.5CantileverSheetPilingPenetratingClayL3=D-L4TwoequationsforDandL4Fixedearthmethod(bendinghere)32第32頁(yè)33第33頁(yè)L3=D-L4TwoequationsforDandL434第34頁(yè)35第35頁(yè)36第36頁(yè)37第37頁(yè)38第38頁(yè)39第39頁(yè)40第40頁(yè)41第41頁(yè)Freeearthmethod(nobendingat“O”)(simpleandgood):fromSoilMechanicsbyCraig()42第42頁(yè)Watertablesinfrontandbackofthesheetpileisthesame.Thereisnoseepage.Thewaterpressureisself-balanced.2.25m0.225m>0.25mDepthd=2.75m6.25m7m6.625m43第43頁(yè)44第44頁(yè)FromTable5.6(a)withd=2.75andhorizontalforceequilibriumWhy6.625m?45第45頁(yè)Freeearthmethod:morefromDrYMChengR=?andcheckingD46第46頁(yè)R=?andNOcheckingDH47第47頁(yè)水頭差滲流路徑水力梯度48第48頁(yè)R=?andNOchecking試算時(shí)，可取D=h49第49頁(yè)50第50頁(yè)51第51頁(yè)6.6AnchoredSheetWallsFreeFixedbyearthTwomethods:Freeearthsupport(simpleandgood)Fixedearthsupport(complicatedandmoreaccurate)Dfreeearth<Dfixedearth52第52頁(yè)53第53頁(yè)6.7FreeEarthSupportMethodforPenetrationofSandySoil(c’=0)

Arevisedapproachcanbeusedforcohesivesoilwithc’andf’–how?54第54頁(yè)55第55頁(yè)56第56頁(yè)57第57頁(yè)

Revisedapproachcanbeusedforcohesivesoilwithc’andf’–how?58第58頁(yè)Freeearthmethod:fromSoilMechanicsbyCraig()59第59頁(yè)Twoequations(momentatAandhorizontalforceequilibriums)fortwounknowns(dandT)60第60頁(yè)61第61頁(yè)62第62頁(yè)63第63頁(yè)ConsideringeffectivestressincreaseduetoseepageConsideringeffectivestressdecreaseduetoseepageThisisatrialanderrormethod64第64頁(yè)Seetherightfigure,forFr=2.0,dis6.3mForlimitcaseofFr=1.0,dis4.2m65第65頁(yè)Thisisonsafeside.66第66頁(yè)67第67頁(yè)Themaximumbendingmomentandshearforcecanbefoundfordesignpurpose.68第68頁(yè)Freeearthmethod:morefromDrYMChengDredgelinex69第69頁(yè)Noconsiderationontheeffectivestressincrease/decreaseduetoseepage;butokasasimpleapproach70第70頁(yè)71第71頁(yè)6.8MomentReductionforAnchoredSheetPileWallsWhyreduction?Mmaxfromthepreviousmethod(freeearthmethod)maybereducedsincesheetpilesareflexible,leadingtoredistributionofearthpressures.Howtomakecorrectionforthereduction?Notcoveredinthissubject!

72第72頁(yè)73第73頁(yè)74第74頁(yè)75第75頁(yè)76第76頁(yè)6.9FreeEarthSupportMethodforPenetrationofClay77第77頁(yè)78第78頁(yè)79第79頁(yè)80第80頁(yè)81第