上海软土地铁隧道变形影响因素及变形特征分析概况 - 图文

沉降变形图。沉降量最大处的隧道横向变形较小,在最大沉降与最小沉降的中间存在一个反弯点,此处的沉降量不一定最大,但隧道的横向变形反而最大。在一定范围内,隧道的纵横向变形存在着一定

的相关性。

图5 某线路区间下行线沉降曲线

注浆并辅以相应内撑来保持隧道椭圆度,否则,后果不堪设想。图5是某下行线隧道发生漏砂漏水经抢险后的沉降曲线。因施工不慎引发隧道漏水漏砂,环间发生了较大错台沉降变形,导致纵向累计变形和差异沉降变形都很大,后经抢险隧道危情才得以控制。过大的错台变形势必引起隧道结构开裂和防水失效,最终导致隧道破坏,几处隧道施工过程中发生了大变形或产生了险情的工程都验证了这一点。

通过对隧道管片间的构造关系和变形过程得知,在管片拼装良好的情况下,环间错台变形量非常小。理论分析和现场测量表明,隧道纵向沉降变形一般以错台变形为主,以刚体转动变形为辅。3.5 横向变形与纵向沉降之间的关系

因节能和排水需要,上海地铁线路采用/高站位低区间0的线路型式,隧道需要穿越不同的地层,加之隧道外部荷载变化,当隧道纵向发生沉降变形时,因隧道装配因素,在一定范围内,横向变形也会随之发生变化。图6是某区间隧道横向变形与纵向 图6 隧道纵横向变形关系 4 结语

本文结合地铁监护对软土隧道变形现象、原因及变形特征进行了分析。实际变形和破坏以及所进行的分析都表明,隧道纵向变形以错台变形为主。一般来讲,只要隧道横向变形<2%D、环缝错动变形在毫米级范围内,管片接头不发生渗漏水,隧道是安全可控的。在实际工程中,还需严密注意/竖鸭蛋0发生时纵缝的渗漏水。因此,隧道安全在很大程度上取决于管片之间的变形协调和防水体系的可靠,隧道周围土层的稳定是防水可靠的前提。 (收稿日期:2009-01-12)

)6)

UNDERGROUNDENGINEERINGANDTUNNELS (Quarterly)No.1Mar.2009 AbstractsofMainContents

(1)FactorsInfluencingDeformationofShanghaiSoftSoilMetroTunneland

DeformationAnalysis…………………………………………………………………………WangRuluShieldtunnelisthemostcommontypeformetrotunnelinShanghaisoftsoilarea.Theextralargedeformationintunnels'longitudinalorintransversedirectionsendangersthestructuralsafety.Accordingtothedatafromlong-termstructuralmonitoringpracticeuponshanghaimetrotunnelandmetrotunnelprotectionpractice,analysisismadetothemechanism,processandcharacteristicsofstructuraldeform-ation.Theresultswillbebeneficialtoguidetheroutinemaintenanceanddeformationcontro.l (7)SubwayMinedTunnelFullProfileExcavationFreezingCurtainOptimizationDesignMethod

byLongDistanceHorizontalFreezing………………………………………………WangWenshengTurn-backlinetunnelandventilationductofTianheStationofGuangzhouRailTransitLine3wereminedbyfullprofilehorizontalfreezing,drillandblastexcavation.TheoptmialdesignschemeoffreezingcurtainwascomeupwithbytheFEMcalculation,whichdeterminesthatthemostacceptableparametersofstressanddeformationoffreezingcurtain,.ie.whenthefreezingcurtainis2.0

mthickandtheaver-agetemperatureis-10e,andthesafetyanalysisunderthestressanddeformation.

(11)ShieldConstructionRiskEvaluationofShanghaiQingcaoshaRawWaterRiverCrossingTunnel ………………………………………………………………………………………GuYun FangJunTakethefirstsingleliningwatertunne-lShanghaiQingcaoshaRawWaterTunnelasengineeringbackground,onthebasisofdeepunderstandingofengineeringcharacteristics,clientdemand,engineer-inggeotechnicalcondition,nearbyenvironmen,tmainrisksexistingintheshieldconstructionwereident-ifiedandmaderiskrating.Combinedwiththeriskmechanism,controlmeasuresfortheserisksweregiv-en.

(16)RiskandCountermeasuresinConstructionofShanghaiRailTransitUndergroundStation ………………………………………………………………………………………………………DingLiAroundtheconstructionsequenceofrailtransitundergroundstation,analyzetheconstructionrisksandproposethetargetedcontrolmeasures.Thestudyofpotentialriskmechanismwillbenefittoestab-lishtheriskcontrolsystemofrailtransitconstructionsoastoreducetheaccidents. (20)FreezingConstructionofCrossPassageofShanghaiYangtzeRiverTunnel

………………………………………………………………SunWei ChenXiangke ChenShaojianItmainlyintroducestheconstructiontechnologiesusedforthecrosspassageofShanghaiYangtzeRiverTunne,lincludingthefreezingcurtaindesign,freezingholelayou,tcrosspassageexcavationandsuppor,tmeasuresforfrostheaveandthawsubsidencecontro.lAndmaintechnicalinnovationsofcrosspassageconstructionareanalyzed.

(24)DiscussionandControlofHighStrengthSelf-compactNegativeTemperature

ConcreteStructureDamage…………………………………………………………………LinZhengCombinedwiththeactualengineeringcase,itdealswiththefreezingdamageofthehighstrengthnegativetemperaturesel-fcompactedconcrete.Itconsidersthatthelowwater-binderratio,reasonable)52)