任務精讀：明挖法（雙語）課件講解

隧道施工技術明挖法TunnelConstructionTechnologyOpen-cutMethod明挖法目錄TableofContentsOpen-cutMethod放坡明挖法1SlopingandOpen-cutMethod懸臂支護明挖法2MethodofOpen-cutwithCantileverSupport圍護結構加支撐開挖法3MethodofOpen-cutwithEnclosureStructureplusSupport課程小結4Summary優(yōu)點Advantages在覆蓋層薄、人口稀少、車輛不多的地區(qū)采用最經(jīng)濟。缺點Disadvantages施工產(chǎn)生的噪聲、振動等公害極大的干擾附近居民的生活和工作。明挖法Open-cutMethod基坑法foundationpitmethod明挖法又稱基坑法Theopen-cutmethodisalsoknownasthefoundationpitmethod.施工作業(yè)面寬敞Spaciousconstructionworkingface施工速度快Fastconstructionspeed方法簡單易行Asimpleandeasy-to-domethod主體結構受力條件較好GoodstressconditionsforthemainstructureItisthemosteconomicalmethodtobeadoptedinareaswiththinoverburden,sparsepopulationandfewvehicles.破壞地面Causesdamagetotheground中斷交通Disruptionoftraffic拆遷工作量大HeavyworkloadofdemolitionPublichazardssuchasnoiseandvibrationgeneratedduringconstructiongreatlyinterferewiththelifeandworkofnearbyresidents.露天情況從地面向下挖出基坑，在基坑內(nèi)進行結構施工，然后回填恢復地面。Itistodigafoundationpit

fromthegrounddowninanopen-airsituation,

constructthestructureinthefoundationpit,andthencarryoutbackfillingto

restoretheground.明挖法Open-cutMethod放坡明挖法SlopingandOpen-cutMethod懸壁支護明挖法MethodofOpen-cutwithCantileverSupport圍護結構加支撐開挖法MethodofOpen-cutwithEnclosureStructureplusSupport放坡明挖法SlopingandOpen-cutMethod01放坡明挖法是指根據(jù)隧道側向土體邊坡的穩(wěn)定能力，由上而下分層放坡開挖隧道所在位置及其上方的土體至隧道基底高程后，再由下而上順作隧道襯砌結構和防水層，最后施作結構外回填土并恢復地表狀態(tài)的施工法。明挖法Open-cutMethod放坡明挖法SlopingandOpen-cutMethod

Accordingtothestabilityofthelateralsoilslopeofthetunnel,thesiteofthe

tunnelandthesoilmassaboveitshallbesubjecttoslopingexcavationinlayersfromtoptobottomtotheelevationofthetunnelfoundationbase.

Then,thetunnelliningstructureandwaterprooflayerareconstructedsuccessivelyfrombottomtotop.

Finally,thesoiloutsidethestructureisbackfilled,andthegroundsurfaceisrestored.FoundationbaseelevationGradeIIIslopingGradeIIslopingGradeIslopingGroundelevation放坡明挖法SlopingandOpen-cutMethod優(yōu)缺點Advantagesanddisadvantages主要適用于埋深較淺，邊坡土體穩(wěn)定性較好，且地表沒有過多限制性條件的隧道工程。邊坡穩(wěn)定性較差時，可采用噴射混凝土進行邊坡防護或采用錨桿加固邊坡土體。適用條件Applicationconditions遇到受地下水影響的工程時，可采用井點降水的方法，以便提高邊坡的穩(wěn)定性及改善基坑內(nèi)循工環(huán)境。明挖法Open-cutMethod放坡明挖法SlopingandOpen-cutMethod放坡明挖法SlopingandOpen-cutMethod開挖方量大Largeexcavationvolume機械化程度高Highlevelofmechanization施工速度快Fastconstructionspeed質(zhì)量易于保證Easytoensurequality

Whentheprojectisaffectedbygroundwater,themethodofwellpointdewateringcanbeused,soastoimprovethestabilityoftheslopeandtheconstructionenvironmentinthefoundationpit.

Itisoftenusedfortunnelengineeringconstructionwheretheburialdepthisshallow,thestabilityofslopesoilmassisgood.andtherearenoexcessiverestrictiveconditionsonthegroundsurface.Whentheslopestabilityispoor,shotcretingcanbecarriedoutforslopeprotection,oranchorrodscanbeusedtoreinforcetheslopesoilmass.懸臂支護明挖法MethodofOpen-cutwithCantileverSupport02懸臂支護開挖法是將基坑圍護結構插入基坑底部以下一定深度,然后在圍護結構的保護下開挖基坑內(nèi)的土體至設計隧道基底高程，再由下向上順作隧道主體結構和防水層，最后施作結構外回填土并恢復地表狀態(tài)的施工方法。明挖法Open-cutMethod懸臂支護明挖法MethodofOpen-cutwithCantileverSupport懸壁支護明挖法MethodofOpen-cutwithCantileverSupport

Thismethodistoinserttheenclosurestructureofthefoundationpitintothebottomofthefoundationpitatacertaindepthbelow,undertheprotectionoftheenclosurestructure,thesoilmassinthefoundationpitisexcavatedtothedesignedelevationofthetunnelfoundationbase,then,themainstructureofthetunnelandwaterprooflayerareconstructedsuccessivelyfrombottomtotop,andfinally,thesoiloutsidethestructureisbackfilled,andthegroundsurfaceisrestored.懸臂支護開挖ExcavationofbottomsurfaceUndergrounddiaphragmwallInsertiondepthExcavationdepthExcavationwithcantileversupport由于有圍護結構的保護，開挖士方量小，且基坑內(nèi)無支撐，便于基礎開挖和主體結構施工的機械化，也易保證工程質(zhì)量。圍護結構較復雜，增加了造價及施工難度，此法有時也用在有支撐開挖基坑的上部。明挖法Open-cutMethod懸臂支護明挖法MethodofOpen-cutwithCantileverSupport懸壁支護明挖法MethodofOpen-cutwithCantileverSupport優(yōu)點Advantages缺點DisadvantagesUndertheprotectionoftheenclosurestructure,theexcavationvolumeissmall,andthereisnosupportinthefoundationpit,whichfacilitatesthemechanizationoffoundationexcavationandconstructionofthemainstructureandalsohelpstoensurethequalityoftheproject.Theenclosurestructureiscomplex,whichleadstoanincreaseincostsandconstructiondifficulty.Thismethodissometimesusedintheexcavationoftheupperpartofthefoundationpitwithsupport.主要適于埋置較淺，邊坡土體穩(wěn)定性較差，且地表有一定限制性要求的隧道工程中。明挖法Open-cutMethod懸臂支護明挖法MethodofOpen-cutwithCantileverSupport懸壁支護明挖法MethodofOpen-cutwithCantileverSupport木樁Woodenpiles鋼樁Steelpiles鋼筋混凝土預制樁Precastreinforcedconcretepiles挖孔樁/灌注樁Boredpiles/cast-in-situpiles適用條件Applicationconditions

Methodofopen-cutwithcantileversupportismainlyusedfortunnelengineeringconstructionwheretheburialdepthisshallow,

thestabilityofslopesoilmassisgood,andtherearecertainrestrictiveconditionsonthegroundsurface.外因：Externalfactor:明挖法Open-cutMethod懸臂支護明挖法MethodofOpen-cutwithCantileverSupport內(nèi)因：Internalfactor:常采用下列工程措施：Thefollowingengineeringmeasuresareoftenadopted:支護結構設計成剛度較大截面形式。Designthesupportingstructureintoasectionformwithhighrigidity.在支護結構頂部設圈梁等，以改善其整體受力狀況，提高整體剛度。Setringbeamsatthetopofthesupportingstructuretoimproveitsoverallstressconditionsandoverallrigidity.基坑外一定范圍內(nèi)挖去表層覆蓋土，以減少側壓力。Removethecoveringsoilwithinacertainrangeoutsidethefoundationpittoreducethelateralpressure.基坑外進行井點降水，采用壓密注漿、攪拌樁或粉噴樁等方法加固。Outsidethefoundationpit,carryoutwellpointdewatering,andadoptcompactiongrouting,mixingpilesorcementinjectionpilesandothermethodsforreinforcement.基坑內(nèi)用井點降水和加固土體方法，使坑底土體固結，增加土體抗力。Inthefoundationpit,adoptthemethodofwellpointdewateringandsoilreinforcementmethodstoconsolidatethesoilmassatthebottomofthefoundationpitandincreasetheresistanceofthesoilmass.基坑內(nèi)設置護腳。Providetoeprotectioninthefoundationpit.施工中應經(jīng)常檢查支撐狀態(tài)，必要時對其應力進行監(jiān)控。Frequentlycheckthesupportstatusduringconstruction,andmonitorthestresswhennecessary.自身強度和剛度不夠Insufficientstrengthandrigidity土體、地下水soilmassandgroundwater圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport03明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport施工工藝Constructionprocess明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport圍護結構Enclosurestructure開挖至第一道支撐所需的高程、安裝支撐并施加預應力Excavatetoelevationrequiredforfirstsupport,erectthesupport,andapplytheprestress挖槽法Trenchingmethod開挖支撐設計位置處土體(保留其兩側土體)挖至第二道支撐高程時，安裝第二道支撐并施加預應力Excavatethesoilmassatthedesignpositionofthesupport(withthesoilmassonbothsidesretained).Afterexcavatingtotheelevationofthesecondsupport,erectthesupportandapplytheprestress由上向下開挖土體至適當高度Excavatethesoilmassfromtoptobottomtoanappropriatedepth繼續(xù)用挖槽法安裝下道支撐，重復以上方法，最后開挖至基底高程Continuetoerectthenextsupportusingthetrenchingmethod,repeattheaboveprocedures,andfinallyexcavatetothefoundationbaseelevation依次澆筑板底、下層側墻、中板、上層側墻、頂板Carryoutthepouringoftheslabbottom,lowersidewall,middleplate,uppersidewallandtopslabinsequence.明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport支撐Support適用條件：基坑深度較大，側壓力較大的情況。Applicationconditions:Wherethedepthofthefoundationpitandthelateralpressureisrelativelylarge.斜支撐Diagonalsupport圍護結構加斜支撐開挖法methodofexcavationwithenclosurestructureplusdiagonalsupport圍護結構加水平支撐開挖法methodofexcavationwithenclosurestructureplushorizontalsupport圍護結構加錨桿支撐開挖法methodofexcavationwithenclosurestructureplusanchorrodsupport錨桿Anchorrod水平支撐Horizontalsupport水平支撐Horizontalsupport明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport水平支撐開挖支護簡圖SketchofSupportforExcavationwithHorizontalSupportGroundFirstsupportSecondsupportExcavationfaceElevationDrawingAnglebraceTransversebraceEnclosure橫撐Transversebrace角撐Anglebrace優(yōu)點Advantages

墻體水平位移小；安全可靠，開挖深度不受限制。但要求圍護結構的平面形狀比較規(guī)則，以矩形為最佳。開挖基坑寬度較大時，支撐應加設中間支柱來保持其穩(wěn)定性。中間支柱應在開挖前按設計位置做好。明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport

Horizontaldisplacementofthewallissmall.Themethodissafeandreliable,andtheexcavationdepthisnotlimited.However,itrequiresarelativelyregularplaneshapeoftheenclosurestructure,andrectangleispreferred.Whenthewidthoftheexcavatedfoundationpitisrelativelylarge,thesupportshallbeprovidedwithanintermediateposttomaintainitsstability.Theintermediatepostshallbemadeaccordingtothedesignpositionbeforeexcavation.施工工藝：采用中心挖槽法開挖基坑內(nèi)土體至斜支撐基礎底部高程,澆筑基礎，及時安裝支撐，使支撐端支撐在圍護結構上，另一端支撐在已澆筑的基礎上，并施加預應力，然后開挖其余土體。設有兩道或多道斜支撐時，先安裝外側的長支撐,后安裝內(nèi)側的支撐，并把所有斜支撐基礎連為整體,形成結構板底。最后依次澆筑下層側墻、中板、上層側墻、頂板，并按要求的時序拆除支撐，完成結構體系轉換。明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport斜支撐Diagonalsupport斜支撐立面圖GroundElevationDrawingofDiagonalSupportExcavationfaceFoundationFirstdiagonalsupportSeconddiagonalsupportEnclosurestructureConstructionprocess:Itadoptsthecentraltrenchingmethodtoexcavatethesoilmassinthefoundationpittotheelevationofthefoundationbottomofthediagonalsupport,andthenthefoundationispoured.Thesupportsaretimelyerected,sothatoneendofthesupportissupportedontheenclosurestructure,andtheotherendissupportedonthepouredfoundation.Thentheprestressisapplied,andtheremainingsoilisexcavated.Whentwoormorediagonalsupportsareprovided,thelongsupportontheoutersideshallbeerectedfirst,andthenthesupportontheinnersideiserected,Afterthat,alldiagonalsupportfoundationsareconnectedtoformawholestructureof

thestructuralslabbottom.Finally,thelowersidewall,middleplate,uppersidewallandtopslabarepouredinsequence.Thesupportsareremovedaccordingtotherequiredsequence

tocompletestructuresystemtransformation.明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport斜支撐Diagonalsupport斜支撐立面圖GroundElevationDrawingofDiagonalSupportExcavationfaceFoundationFirstdiagonalsupportSeconddiagonalsupportEnclosurestructure適用條件Applicationconditions適用于對沉降要求不嚴格，且基坑深度不大的情況。斜支撐基礎及結構底板需分批施工，工序交錯復雜，施工難度大。

Themethodisapplicabletosituationswheretherearelessstrictrequirementsforsettlement,andwherethedepthofthefoundationpitisnotlarge.Thediagonalsupportfoundationandstructuralbaseplateshallbeconstructedindifferentbatches,whichleadstothestaggeredandcomplexconstructionprocess,andgreatconstructiondifficulty.施工工藝：圍護結構完成后，開挖至錨桿的設計高程，鉆孔插入鋼索后注漿，7-10d后對錨桿施加預應力。明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport錨桿anchorrod錨桿立面圖ElevationDrawingofDiagonalSupportUndergroundconnectingwallExcavationfaceFreesectionAnchoragesectionAnchorrodhitintotheinclinedtopofthetunnelfaceMiscellaneousfillMuddysoilMediumsandSandgravelSandyloamStronglyweatheredrockConstructionprocess:Aftertheenclosurestructureiscompleted,Excavationshallbecarriedouttothedesignelevationoftheanchorrod,andgroutingshallbedoneafterdrillingandinsertingthewirerope.Prestressshallbeappliedontheanchorrodsafter7-10days.施工空間寬敞，有利于機械開挖和組織結構主體施工。能夠較好的控制圍護結構的水平位移，減少地面及建筑物的沉降量，并能適用于各種形狀的圍護結構。錨桿可設成單層或多層，開挖深度不受限制。工藝復雜，錨桿不易回收造價較高。當圍護結構四周建筑物有密集的深基礎時，不宜采用。錨桿的蠕變會降低其承載力。在流沙底層中若錯頭預留孔口與錨桿套簡之間的空隙過大，易發(fā)生涌水涌砂，引起坑外地面和建筑物沉降。明挖法Open-cutMethod圍護結構加支撐開挖法MethodofExcavationwithEnclosureStructureplusSupport錨桿anchorrod錨桿立面圖ElevationDrawingofDiagonalSupportUndergroundconnectingwallExcavationfaceFreesectionAnchoragesectionAnchorrodhitintotheinclinedtopofthetunnelfaceMiscellaneousfillMuddysoilMediumsandSandgravelSandyloamStronglyweatheredrock優(yōu)點Advantages缺點DisadvantagesSincetheanchorrodsaresetoutsidethefoundationpit,aspaciousconstructionspacecanbeprovidedwhichisconducivetomechanicalexcavationandorganizationoftheconstructionofthemainstructure.Thehorizontaldisplacementoftheenclosurestructurecanbebettercontrolled,sothatthesettlementofthegroundandbuildingsisreduced.Anchorrodscanbeusedforenclosurestructureswithvariousshapes,andtheycanbesetinsingleormultiplelayers.Moreover,theexcavationdepthisnotlimited.Theconstructionprocessismorecomplex,itisnoteasytorecycletheanchorrods,andtheconstructioncostsarehigh.Meanwhile,itshouldalsobenotedthat,Whenthebuildingsaroundtheenclosurestructurehavedense,deepfoundations,anchorrodsshouldnotbeused.Thecreepoftheanchorrodscanreducetheirbearingcapacity.Inthebottomlayerofquicksand,ifthegapbetweenthestaggeredreservedholeandtheanchorrodsleeveistoolarge,watergushingandsandgushingarelikelytooccur,causingsett