3.3地下水排水工程课件讲解

SubgradedrainageengineeringconstructionRoadbedConstructionTechnologySubgradedrainageworksTheoreticalknowledgeThestrengthandstabilityofsubgradesarecloselytowater.Therearemanydiseasesofroadbed,andtherearemanyreasonsfortheformationofdiseases,buttheeffectofwaterisoneofthemainfactors.Thepurposeofsubgradedrainageistoensurethatthesubgradeisalwaysdry,firmandstable.Groundwaterentersthesubgradesoil,reducingthestrengthofthesubgrade,causingchurnandmud,anditiseasytocausefrostheavedamageinwinter.Thegroundwaterflowingonthesubgradeslopewillalsoscourtheslope,whichisnotconducivetothestabilityofthesubgrade.Theoreticalknowledge1.UndergrounddrainagefacilitiesAstructurethatintercepts,collectsanddischargesgroundwater,orlowersthegroundwaterleveltopreventdamagetotheroadbed,iscalledanundergrounddrainagefacility.Commonundergrounddrainagefacilitiesincludeunderdrains,seepagetrenchesandseepagewells.Theoreticalknowledge1.Undergrounddrainagefacilities1.Underdrain(blindditch)Comparedwiththeopenditchforgrounddrainage,theblindditch,alsoknownastheblindditch,referstotheditchsetbelowthegroundtoguidethewaterflow.Orthewaterflowcollectedbytheseepageditchiscollectedintotheditch,anddischargedalongtheditchtothedesignatedlocation,cuttingoffandremovingthegroundwaterfromthehillsidesubgrade,andstrengtheningthestabilityofthesubgrade.Theoreticalknowledge1.Undergrounddrainagefacilities2.SeepageditchAcommonundergrounddrainageditch.Whenthesubgradesoilcontainstoomuchwater,itcanbeusedtoabsorb,reduce,collectanddischargegroundwater.Itcanalsobeusedtointerceptthegroundwaterflowingtotheroadbed,collectthegroundwaterintheditchbymeansofinfiltration,anddischargethewatertothedesignatedlocationthroughthechannelatthebottomoftheditch.Thisundergrounddrainagefacilityiscollectivelyreferredtoastheseepageditch.Itsfunctionistolowerthegroundwaterlevelorinterceptgroundwater,anditshydrauliccharacteristicsareturbulent,butitsstructureisdifferentfromthatofasimpleunderdrain.Theoreticalknowledge1.Undergrounddrainagefacilities2.SeepageditchTheoreticalknowledge1.Undergrounddrainagefacilities2.SeepageditchDuringconstruction,payattentiontothefollowingissues:(1)Thearrangementofseepageditchshouldbeperpendiculartothegroundwaterdirectionasmuchaspossible.(2)Thetransversewidthoftheseepageditchgenerallydependsontheburialdepth,drainagerequirements,andconvenienceofconstructionandmaintenance.(3)Whencollectingwaterflow,inordertopreventthesandintheaquiferfrombeingsqueezedintotheseepageditch,areversefilterlayershouldbesetup.(4)Theconstructionofseepageditchshouldbeconstructedfromdownstreamtoupstream.(5)Fortheconvenienceofinspectionandmaintenance,inspectionwellsshouldbesetup.Theoreticalknowledge1.Undergrounddrainagefacilities3.SeepagewellWhentherearemultiplelayersofaquifersunderground,theupperaquiferthataffectsthesubgradeisthin,thedrainagevolumeisnotlarge,andthehorizontalseepageditchesaredifficulttoarrange.Theuppergroundwaterwithintherangeisintroducedintoadeeperaquifertolowertheuppergroundwaterlevelorremoveitentirely.Theoreticalknowledge1.Undergrounddrainagefacilities3.SeepagewellTheoreticalknowledge2.ConstructionofundergrounddrainagefacilitiesDependingonthelocationoftheundergrounddrainagefacilities,theconstructionmethodsvarygreatly.Generally,theundergrounddrainagefacilitiesareconstructedinconjunctionwiththesurfacedrainagefacilities.Theblindchannelisusuallyrectangularortrapezoidal,andthebottomandmiddleoftheblindchannelarefilledwithlargergravelorpebbles.Diametercrushed,gravel,formblindditch.Asaclosedlayeronthetopoftheblindditch,itispavedwithdouble-layerreverseturforothermaterials(suchasgeosyntheticanti-seepagematerials),andaclaywaterprooflayerwithathicknessofnotlessthan0.5misrammedonit.Theoreticalknowledge2.ConstructionofundergrounddrainagefacilitiesTheoreticalknowledge2.ConstructionofundergrounddrainagefacilitiesTheburieddepthoftheblindditchshallmeettherequirementthatthetopoftheseepagematerial(belowthesealinglayer)shallnotbelowerthantheoriginalgroundwaterlevel.Whenremovinginterlayerwater,thebottomoftheblindditchshouldbeburiedonthelowestimpermeablelayer.Whenthegeotextileisusedasthefilterlayer,thebottomandbothsidesoftheditchwallshouldbelaidinplacefirst,andtherequiredgeotextileshouldbereservedonthetop,anditshouldbestraightenedandsmoothlyattachedtothelowercushion.Thelapjointsshallbealternatelystaggered,andthelaplengthshallnotbelessthan300mm.Theblindditchshouldonlybeusedinthesectionwhereseepageisnotlong,andthelongitudinalslopeshouldnotbelessthan1%.Theelevationofthebottomsurfaceofthewateroutletshouldbe0.2mhigherthanthemaximumwaterleveloutsidetheditch.Theoreticalknowledge3.ConstructionqualitycontrolofundergrounddrainagefacilitiesThefilterlayeroftheblindditchshallbefilledinlayerswithwater-permeablematerialssuchasscreenedmediumsand,coarsesandandgravel.Thedrainagelayershouldbefilledwithlar