软土地区基坑开挖对既有地铁隧道影响的研究

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1、南京林业大学硕士学位论文软土地区基坑开挖对既有地铁隧道影响的研究姓名：钟定兰申请学位级别：硕士专业：森林工程指导教师：杨平20070601AbstractAsthesubwaywhichiswellknownhasbecomeanimportantmeansoftransportinbigcities，thetunnelisinevitabletobeeffectedbybuildingnearit．Thesurfacesettlementscausedbyexcavationandinflue

2、nceonadjacentsubwaytunnelaretheproblemshighlyconcernedinthedesignandconstructionprocessofexcavation．Itissignificanttostudyofinfluenceofexcavatingonanexistingsubwaytunnelinsoftsoilareas．Theeffectsoftheexistingtunnelduringexcavationhasbeensimulatedthro

3、ugh3DFEM，andthedisplacementsofthetunnelhavebeenanalyzedqualitatively．Whencomparedwithmeasureddates，ithasfoundthatthefiniteelementresultshavebeenwellconsistentwithit．TypicalsoftsoilofNanjingareasweresimulatedandanalyzed，through3DFEMithasbeensimulateds

4、everalparameterssuchastherelativeposition，eachkindofoperationsduringthepit，thedifferentdistancefromexcavation，differentdepthandthediaphragmwallatdifferentdepths，thedisplacementsofhorizontalandverticalandcurvesofforcesalongthelongitudinalaxisofthetunn

5、elhavebeenobtained，somemeaningfulconclusionsweregetasfollows：。(1)Underdifferentexcavationconditions，themaximumdisplacementsandthesmallestaxialsandlargestmomentsofthetunnellocatedatz50m．therewasasuddenincreaseofsheararoundz=l5m，thetunnelwasgreaterimpa

6、ctedduringexcavationunloadingand，lesseffectedinconstructingdiaphragmwallandsupporting．Itwouldbeincreasedasthedepthofexcavationincreased．(2)Withtheincreasingofdistance，thedisplacementsofhorizontalweregraduallydecreasedandsmallatabout12mfarfromtheexcav

7、ation．Soastheverticaldisplacements．Whenthetunnelwasneartheexcavation，theaxisforcewasgraduallyincreased．Shearandmomentweregraduallyreduced．SoastheaxisforceandShearwhenthetunnelwasundertheexcavation．Butthemomentwaschangedindirection．(3)Withtheincreasei

8、ndepth，thedisplacementoftunnelincreasesfirstandthendecreases，probablyduetothelargestdisplacementofdiaphragmwalllocatedatO．6H．Itcouldbeseenthatthedisplacementsoftunneldependlargeonthedeformationofthediaphragmwall，itwasnecessarytocontrolthedeformatione