设伸缩缝圆形水池的池壁内力计算方法
第3期(总第159期
)2012年6月
CHINAMUNICIPALENGINEERING
DOI:10.3969/j.issn.1004-4655.2012.03.020
No.3(SerialNo.159)
Jun.2012
设伸缩缝圆形水池的池壁内力计算方法
张达石
(上海市城市建设设计研究总院,上海200125)
摘要:对于内径>15m的钢筋混凝土圆形水池,由于在池壁上设置伸缩缝,该类圆形水池池壁不再是整体的圆柱壳。以单悬臂板简化方式计算了池壁底部竖向弯矩;同时,采用有限元程序计算了3种内径的1/4圆弧壳池壁的竖向弯矩,给出了池壁弯矩等高值图。对比显示:有限元计算的池壁竖向弯矩值为单悬臂板计算值的60%~70%。采用考虑空间效应的计算模式进行设计计算比较合理。
关键词:圆形水池;伸缩缝;有限元;圆柱壳;内力中图分类号:TU991.343
文献标志码:A
文章编号:1004-4655(2012)03-0058-02
给排水工程构筑物中常见圆形水池结构。对于采用钢筋混凝土结构且内径较大的圆形水池结构(内径>15m),为了避免施工及使用过程中的温度内力设计中一般采用在池壁上设置伸缩引起的水池开裂,
缝的方式。由于伸缩缝的设置,池壁将不再是整体的圆柱壳,所以无法按照圆柱壳的计算方式进行池壁内力计算。日常设计中往往会按照单悬臂板来计算此类结构的池壁内力;而设缝后的池壁按照圆弧形板壳进行内力计算更为合理。因此,按圆弧形板壳计算了不同直径圆形水池的池壁内力,并与按单悬臂板计算的结果相比较,探讨该类圆形水池结构池壁内力计算的合适方法。1
计算假定及计算方法
如果圆形水池的直径过大,设计时会采用预应力不设置变形缝;而如果直径较小,则温度混凝土结构,
力影响较小,无需设缝。因此,一般考虑设缝的圆形30、40m3种,池体高度H为5m,水池直径分别有20、
壁厚统一按40cm考虑,均考虑设4道缝,即整个圆柱壳被分成4个1/4圆弧壳。
计算采用有限元计算程序Midascivil2011。计算中仅考虑池内水压力作用引起的池壁内力。水压
3
力按照三角形分布,水容重γ水=10kN/m,池壁底
图1池壁受力图示
2
悬臂板计算池壁竖向弯矩结果
三角形荷载分布下,按照传统方法,中心距处的
(1)
集中力F简化式见式(1)。
F=1/2×q×H
kPa,式中:q为三角形底部最大荷载,水压力下q=
m。池壁底部竖向弯矩计算γH;H为三角形高度,见式(2)。
My=Fl
式中:l为中心距与池底距离,三角形分布的l=
(2)1
H。3
按简化的单悬臂板计算的池壁底部竖向弯矩:1111My=×q×H××H=×50×5××5
2323=208.3kN·m/m。3
有限元计算模型及结果
1)计算模型。计算采用4节点板单元,单元尺寸为
端按固结考虑,顶端按自由考虑。池壁结构受力见图1
。
收稿日期:2012-02-10
作者简介:张达石(1975—),男,工程师。
0.1m×0.1m,边界条件为底部所有节点均固结,其余3边均自由。1/4圆弧壳的计算模型如图2所示。
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张达石:设伸缩缝圆形水池的池壁内力计算方法2012年第3
期
图21/4圆弧壳计算模型
2)图3~图5分别为20、30、40m内径圆形水池1/4圆弧壳的池壁竖向弯矩计算结果。图中仅显示了1/8圆弧,图中线条为弯矩值的等高线
。
4
图540m内径池壁竖向弯矩计算结果(kN·m/m)
计算结果分析及比较
由图3~图5可见,在1/4圆柱壳范围内,池壁底部的竖向弯矩在2个侧边较大,而到了1/4圆柱壳的正中间,则基本上接近于整体圆柱壳的结果,总体趋势为从两边向中间逐渐减小(如图示的等值线)。不同内径时的底部最大竖向弯矩如表1所示。
表1
圆弧内径/m
不同内径1/4圆柱壳底部最大内力计算值
有限元计算结果与/kN·m·m-1/kN·m·m-1单悬壁计算的比值
130.8138.1145.9
208.3208.3208.3
0.630.660.70
图320m内径池壁竖向弯矩计算结果(kN·m/m
)
203040
从表1比较可知,当水池内径为20~40m,考虑空间作用的1/4圆柱壳有限元计算的池壁竖向弯矩值基本上为按照单悬臂板计算的弯矩值的60%~70%。
根据上述分析计算结果及比较,对于设缝的圆形水池,采用考虑空间效应的计算模式进行设计计算比较合理,这将减少土建工程的投入。同时,该类结构较合理的设计应该是靠近变形缝附近3~4m范围竖
向配筋或者截面较大。
櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅櫅
3结语(上接第57页)
图4
30m内径池壁竖向弯矩计算结果(kN·m/m
)
Ra=89kPa时,fspk=复合地基承载力由式(1)得,103kPa(>97.6kPa),满足实际荷载的需求。
根据以往经验及实际计算,搅拌桩打穿软土层,“端承桩'”采用时,复合地基的沉降<10cm,路基的工后沉降能够满足规范要求,因此本项目水泥土搅拌桩桩间距复合地基处理参数最终采用桩长11.5m,1.1m,梅花桩布置。
本文分析了复合地基承载力的影响因素,并通过水泥土搅拌桩复合地基在城市道路软基处理中的应用,分析了常见水泥土搅拌桩复合地基设计中存在的误区,着重分析了复合地基承载力与桩长的关系。
从承载力的角度出发,水泥土搅拌桩存在一个“有效桩长”。在工程实践中,不能为了提高复合地基承载力,盲目地增大桩长;否则,既增加了工程投资,又没有起到应有的效果。
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adoptedforpipelinerepairingproject.Toavoidleakingundergroundwaterwashingoutlinerresinmaterialandpartialwaterpackageafterconstruction,thepretreatmentofpartialresinsolidificationlinermethodisdoneformoreseriousandbiggerleakingpointbeforereversingliner.Severalkeypointsofthemethodareintroducedsuchastechnologyfeatures,standardsformaterial&technologyandconstructionprocedures.Finally,thereare35leakingpointstreatedtotallyandtheconstructioneffecthasarrivedatexpectation.
Keywords:trenchless;
partialresinsolidificationlinermethod;
pipelinerepair;BaotuSpringOnConfirmationofSuspenderTensileForceduringConstructionControlofSelf-anchored
SuspensionBridge1
ZHAOYong-jun1,YANGJun2XIEZhi-gang,
(1.HubeiYichangYilingDistrictHighwayAdministrationBureau,Yichang443100,China;2.CollegeofCivilEngineering&Architecture,
ChinaThreeGorgesUniversity,
Yichang443002,China)
Abstract:Itisveryimportantofcontrollingsuspendertensileforceduringself-anchoredsuspensionbridgeconstructionprocesstomakethebridgearriveatidealdesignstateafterthecompletion.Combinedwithmechanicscharacteristicsduringtheconstructionprocess,theinfluencematrixbasedongeometricallinear&non-linearisproposedtoconfirmtheconstructiontensileforceofself-anchoredsuspensionbridge.Theresearchcanshowthatthemethodisofsimplecalculationandtheresultscanmeetwiththerequirements.
Keywords:self-anchoredsuspensionbridge;
influencematrix;
suspendertensileforce
ARelationshipStudyofCompositeFoundation
BearingCapacityandPileLengthof
CementSoilMixingPile
JIANGXiao-lu2YANGGuo-bao1,
(1.ArchitectureDesign&ResearchInstitute,ZhejiangUniversity,Hangzhou310012,China;2.ShanghaiUrbanConstructionDesign&Research
Institute,Shanghai200125,China)
Abstract:Withthedevelopmentofmodernsciencetechnology,therearemoreandmorefoundationtreatmenttechnologiesappliedinhighwaysandurbanroadsconstructionandcementsoilmixingpilecompositefoundationtreatmenttechnologyisoneofthese.Theprincipleofcompositefoundationisexplainedfurtherandcommonmistakesoccurredincementsoilmixingpilecompositefoundationdesignareanalyzedwithfocusingontherelationshipbetweencompositefoundationbearingcapacityandpilelength.Fromtheaspectofbearingcapacity,thereisaneffectivepilelengthforcementsoilmixingpile.Inpractice,thepilelengthcannotbeincreasedblindlynotforincreasingcompositefoundationbearingcapacity;otherwise,itwilladdprojectinvestmentandhavenopropereffects.
Keywords:compositefoundation;
cementsoilmixingpile;bearingcapacity;effectivepilelengthOnSide-wallInternalForceCalculationMethod
ofCircularTankwithExpansionJoint
ZHANGDa-shi
(ShanghaiUrbanConstructionDesign&Research
Institute,Shanghai200125,China)
Abstract:Forreinforcedconcretecirculartankwithinnerdiameter>15m,thisside-wallofthetankisnotthewholecylindricalshellanylongerduetosettingupexpansionjointonit.Theverticalbendingmomentofside-wallbottomiscalculatedbysinglecantileverplatesimplifiedmethod,andmeanwhile,theverticalbendingmomentsof1/4cylindricalshellside-wallof3innerdiametersarecalculatedbyfiniteelementprocedure,andthen,theside-wallbendingmomentcontourmapisgiven.Thecontrastcanshowthattheside-wallverticalbendingmomentvaluecalculatedbyfiniteelementisthe60%~70%ofsinglecantileverplatecalculationvalue.Itisreasonable
107
relativelytoadoptthecalculationmodeconsideringspaceeffecttomakedesigncalculation.
Keywords:circulartank;
expansionjoint;finiteelement;cylindricalshell;internalforce
OnLandscapeDesignalongChongqi
ChannelExpresswayWANGGuo-feng
(ShanghaiChangjiangTunnel&BridgeConstruction
DevelopingCo.,Ltd.,Shanghai201600)
Abstract:CombinedwithChongqiChannelProjectandenvironmentalcharacteristics,thegreeningdesignguidelineandfeaturesofChongqiChannelarepresentedtotallyfromtheaspectofbuildingecologicalexpresswaygreeninglandscape.Thereare4landscapedesignprinciplesdiscussedincludingtrafficsafety,ecologysafety,landscapepriorityandconvenientmaintenance&economy.Andtheplantsselectionprincipleisdeterminedbyhighsoilalkalinityandfinesandsubgrade.Finally,greeningdesignsofsixpartsareanalyzedindetailinvolvingcentralgreeningbelt,sideslope,twosideplatformsofthemainline,interchange,servicearea&tollstationandseparatesubgrade.Thewholeexpresswaywillformanecologicallandscapegallerywithdifferentfeatures,complementaryfunctionsandcloseconnectionbymeansofecologicallandscapeofdiversityformedbydifferentsectionplantslayout.
Keywords:landscapedesign;
greening;
ChongqiChannelNumericalAnalysisofConstructionParametersofLarge-diameterSlurryBalancedTypePipeJacking
WANGXin
(ShanghaiUrbanConstructionDesign&Research
Institute,Shanghai200125,China)
Abstract:Iftheparametersareselectedirrelevantlyoflarge-diameterslurrybalancedtypepipejacking,thesurroundingswillbeaffectedseriouslyandevidently.Forstudyingdifferent108
constructionparameter’sinfluence,theinitialmodelissetupbynumericalanalysissoftwareandthepipejackingconstructionissimulatednumerically.Severalparametersareanalyzedbycontrollingparameters,suchasdepthofsoil,pressureofslurryanddiameterofpipe.Theresultsshowthat:1)withincreasingofsoildepth,surfacesettlementisdecreasedgradually
8m),theandifthedepthwillexceed1.6D(1D=2.
maximumofsurfacesettlementwillextendtostabilization;2)basedonstabilityofdiggingsurface,lesspressureispropitioustocontrolsurfacedeformation;3)withincreasingofexcavationdiameter,themaximumofsurfacesettlementwillbeincreasedgradually,andtheobviousupheavalwillbeappearedandenlargedgraduallyfrom2Doftheaxes;4)basedonstabilizationofstructure,thicknessofthepipewillaffectsurfacesettlementindistinctively.
Keywords:slurrybalancedtype;
pipejackingconstruction;numericalsimulation;analysisofparametersOnMovingSteelSupportSystemAppliedin
Long&NarrowDeepFoundation
PitExcavation
ZHANGZhong-jie,XUZheng-liang,
DENGChang-mao
(ShanghaiUrbanConstructionDesign&Research
Institute,Shanghai200125,China)
Abstract:Foundationpitmovingsteelsupportsystemisthesystemtosetuptheassembledsupportstablyandrapidlythroughpresetrailandspecifichoistingequipment.Accordingtonumericalsimulationandfieldtest,forlong&narrowfoundationpit,movingsteelsupportsystemisprovedtoincreasethesupportsetupspeedinsidethefoundationpit,toshortenthedevelopingtimeofsoftsoilconsolidationandcreepdeformation,toimprovetheenclosureeffectoffoundationpitsupportstructure,toguaranteethesafety&stabilityoftheexcavationperiodandtocontroltheinfluencetothesurroundings.Inaword,movingsteelsupportsystemhascertainpromotionvalueforsimilarprojects.
Keywords:movingsteelsupport;