香港理工大學(xué)殷建華老師之市公開課金獎市賽課一等獎?wù)n件

深基坑開挖與支護(hù)設(shè)計(jì)

殷建華TheDepartmentofCivil&StructuralEngineeringTheHongKongPolytechnicUniversity,HongKong,China1第1頁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6.1IntroductionPurposes:

supportingexcavation,retainingsoil,stoppingwaterinflow,…支撐開挖，擋土，阻止水滲流5第5頁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)墻施工過程中采取了泥漿護(hù)壁。Thetechniqueinvolvesexcavatinganarrowtrenchthatiskeptfullofanengineeredfluidorslurry.泥漿護(hù)壁技術(shù)是開挖窄槽..Theslurryexertshydraulicpressureagainstthetrenchwallsandactsasshoringtopreventcollapse.泥漿給窄槽壁施加水壓，預(yù)防坍塌Slurrytrenchexcavationscanbeconstructedinalltypesofsoil,evenbelowthegroundwatertable.泥漿護(hù)壁溝渠開挖適合用于各種土層Diaphragmwalls（地下連續(xù)墻）:6第6頁BentoniteSlurry（工程中配置泥漿原理圖）7第7頁3-DViewofDiaphragmWallConstruction8第8頁9第9頁Woodensheetpileandconcretesheetpile（木板樁，混凝土板樁）:10第10頁Steelsheetpile(usedalotinHongKong):11第11頁SteelsheetpilesfromJapanandUKareoftenusedinHongKong.

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

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

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

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