temporary structures外语英文电子书

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1、UNIVERSITYOFWASHINGTONDEPARTMENTOFCONSTRUCTIONMANAGEMENTCM420TEMPORARYSTRUCTURESWinterQuarter2007ProfessorKamranM.NematiTemporaryStructuresExcavationsandExcavationSupportsCM420TEMPORARYSTRUCTURESLesson5:ExcavationsandExcavationSupports(Earth-RetainingStructures)OverviewTheseventhlessonprovi

2、desanoverviewonexcavationsupportsandearth-retainingstructures.Excavationsupportsystemsaretemporaryearthretainingstructuresthatallowthesidesofexcavationtobecutverticalornearvertical.Theyareusedtominimizetheexcavationarea,tokeepthesidesofdeepexcavationsstable,andtoensurethatmovementswillnotca

3、usedamagetoneighboringstructuresortoutilitiesinthesurroundingground.LessonObjectivesBytheendofthislessonyouwillbeableto:•describestabilityofslopesforexcavationsandmethodsofpreventingthemovementofexcavationwalls;•recognizeshallowtrenchesanddeepcuts;•describesoldierbeamandlagging;•describesoi

4、lnailingsystems;•recognizeexcavationbracingsystems.ReadingAssignmentClassnotes.OptionalReading-Ratay,Chapter8“Earth-RetainingStructures.”CM420–TEMPORARYSTRUCTURESLESSON5:EXCAVATIONSANDEXCAVATIONSUPPORTSIntroductionInmanyconstructionjobsdeepexcavationsmustbemadebeforethestructurecanbebuilt.E

5、xcavationsupportsystemsaretemporaryearthretainingstructuresthatallowthesidesofexcavationtobecutverticalornearvertical.Thisisdonetomaximizethesizeofanexcavation;whenthepriceofrealestateishighorspaceislimitedbypropertylines,utilitiesorexistingstructures.Whenexcavationshavethepotentialtoendang

6、erlivesoradjacentproperties,bracingtosupportthesoilmustbedesigned.TheOccupationalSafetyandHealthAct(OSHA)requiresthatalltrenchesexceeding5feetindepthbeshored.Inlargeconstructionareas,excavationwallsmaybesloped,insteadofprovidingstructuralsupport.Slopefailuremechanismscanbeclassifiedinthreec

7、ategories:rotationalslumpinhomogeneousclay,translationalsliceincohesionlesssandorgravel,andslipalongplaneofweakness.Drivingforcesarethecomponentofsoilweightdownslope(forcescausinginstability),andresistingforcesarethesoilstrengthactingintheoppositedirecti