深基坑施工支护对邻近地铁隧道影响模拟与分析

摘要目前随着社会和经济的迅速发展，我国的各大城市正面临着人口增多、住房紧张和交通堵塞等城市化现象。从交通和住房的角度上来看，各大城市在面对城市化现象的时候大多都采用常见的技术施工手段，比如推进地铁建设以解决交通拥挤问题，加快高层商品住房的建设步伐来应对住房紧张问题，但是当同时解决这两大问题时，就只能采取在地铁建设的数公里范围之内完成高层住房工程的方法，由于基坑施工的原因，就会使得周边的土体受到扰动，这样的情况会给地铁的建设带来十分严重的影响，因此，为了有效的解决这个问题，需要专门研究基坑施工将会给附近的地铁带来什么样的影响。本文以某临近地铁隧道的基坑开挖项目作为背景。在基坑支护变形和受力分析计算的基础上，根据施工现场的实际情况，并结合目前国内的仿真数值模拟技术进行分析研究。应用先进的数值模拟技术，对工程完成三维的数值模拟研究，主要结论如下：(1)对基坑支护变形与设计计算理论进行分析和论述，提出基坑施工对地铁隧道结构的危害及变形控制措施。对有限元数值模拟的基本理论进行阐述，总结说明建筑基坑三维数值模拟的基本步骤和方法。(2)依托实际工程，利用理正深基坑分析软件。根据预先制定好的施工工况进行计算分析，从而能够知道支护结构的内力和变形值，而后有针对性的对稳定性、承受水压力和抗隆起性进行施工后的验算。验算结果显示：这个区域基坑支护的设计是满足规定要求的，在施工时产生的内力和变形都在安全范围内，结合理正软件进行运算，以及后面的有限元分析软件对位移云图的相互比较，证明有限元模型是正确的。(3)基坑开挖对周边的地铁隧道造成一定的影响，例如水平移动、竖向沉降，总的位移变化，而且还改变了隧道的受力状态。由此可见，深基础开挖对地铁隧道的安全产生影响。因为隧道的衬砌底片基本和基坑开挖的底面在同一水平高度，也就是说，在第二道支撑与基坑底面之间的位置是隧道结构。所以，在工况三和工况五情况下，隧道位移变化较大。(4)基坑在开挖的过程中，会对周围地铁隧道区间产生应力，导致对地铁周边的地基结构产生一定的位移，影响整个工程的安全性；同时，因为南京地区的地下水确实比较多，所以在基坑施工的过程中，基坑内的积水是影响地铁的因素之一，基坑施工时要注意这样的问题出现。II关键词：基坑开挖，有限元分析，地铁隧道，监测数据，基坑降水AbstractWiththerapiddevelopmentofsocietyandeconomy,majorcitiesinourcountryarefacingurbanizationphenomenasuchaspopulationincrease,housingshortageandtrafficjams.Fromtheperspectiveoftransportationandhousing,mostmajorcitiesusecommontechnicalconstructionmethodswhenfacingthephenomenonofurbanization,suchaspromotingsubwayconstructiontosolvetheproblemoftrafficcongestion,andspeedinguptheconstructionofhigh-risecommercialhousingtodealwithhousingshortagesHowever,whenthetwomajorproblemsaresolvedatthesametime,theonlywaytocompletethehigh-risehousingprojectwithinafewkilometersofthesubwayconstructionistocompletethesurroundingsoilduetothefoundationpitconstruction.Thesituationwillhaveaveryseriousimpactontheconstructionofthesubway.Therefore,inordertoeffectivelysolvethisproblem,itisnecessarytostudytheimpactoftheconstructionofthefoundationpitonthenearbysubway.Thisarticleisbasedonafoundationpitexcavationprojectnearasubwaytunnel.Basedontheanalysisandcalculationofthedeformationandforceofthefoundationpitsupport,theanalysisandresearcharecarriedoutaccordingtotheactualsituationoftheconstructionsiteandcombinedwiththecurrentdomesticsimulationandnumericalsimulationtechnology.Applyingadvancednumericalsimulationtechnologytocompletethethree-dimensionalnumericalsimulationresearchoftheproject,themainconclusionsareasfollows:(1)Analyzeanddiscussthedeformationanddesigncalculationtheoryoffoundationpitsupport,andproposethehazardsanddeformationcontrolmeasuresofthefoundationpitconstructiontothesubwaytunnelstructure.Thebasictheoryoffiniteelementnumericalsimulationiselaborated,andthebasicstepsandmethodsforthethree-dimensionalnumericalsimulationofbuildingfoundationpitsaresummarized.(2)Relyingontheactualproject,usetherationaldeeppitanalysissoftware.Calculateandanalyzeaccordingtothepre-establishedconstructionconditions,soastobeabletoknowtheinternalforceanddeformationvalueofthesupportstructure,andthenperformthepost-constructionverificationonthestability,thewithstandwaterpressureandtheresistancetoheave.Theverificationresultsshowthatthedesignofthefoundationpitsupportinthisareameetstherequirementsoftheregulations.TheIVinternalforcesandtheliquiditygeneratedduringtheconstructionarewithinthesafetyscope.ThecalculationsarecombinedwithRicohsoftwareandthefollowingfiniteelementanalysissoftwareisusedforthedisplacementcloudmap.Thepurposeofcomparingeachotheristoprovethatthefiniteelementmodeliscorrect.(3)Theexcavationofthefoundationpitwillcausecertaininfluencesonthesurroundingsubwaytunnels,suchashorizontalmovement,verticalsettlement,totaldisplacementchange,andalsochangethestressstateofthetunnel.Itcanbeseenthatthedeepfoundationexcavationhasanimpactonthesafetyofsubwaytunnels.Becausetheliningbaseofthetunnelissubstantiallyatthesamelevelasthebaseoftheexcavation,thatis,thepositionbetweenthesecondsupportandthebaseoftheexcavationisatunnelstructure.Therefore,underconditionsofthreeconditionsandfiveconditions,thetunneldisplacementchangesgreatly.(4)Intheprocessofexcavation,thefoundationpitwillstresssurroundingsubwaytunnelsections,resultinginacertaindisplacementofthefoundationstructurearoundthesubwayandaffectingthesafetyoftheentireproject;atthesametime,becausethegroundwaterinNanjingisindeedmoreTherefore,intheprocessoffoundationpitconstruction,wateraccumulationinthefoundationpitisoneofthefactorsaffectingthesubway.Attentionshouldbepaidtosuchproblemswhenthefoundationpitisconstructed.KeyWords:Foundationexcavation,finiteelementanalysis,subwaytunnel,monitoringdata,foundationpitprecipitation目录摘要..........................................................................................................................................IAbstract....................................................................................................................................III目录...........................................................................................................................................V1绪论........................................................................................................................................11.1