外文翻譯一二

DiscusstheconstructiontemperatureandcrackoftheconcretelightlyThesummary,throughobservationliveformanyyears,throughconsultingthemonographaboutstresswithintheconcrete,explaintoconcretetemperaturereason,on-the-spotconcretecontrolandmeasure,preventionofcrackoftemperaturethatcrackproduce.KeywordConcreteTemperaturestressCrackControlTheconcreteoccupiestheimportantpositioninmodernengineeringconstruction.Buttoday,thecrackoftheconcreteiscomparativelygeneral,thecracksarenearlyomnipresentinthescienceofbridgebuilding.Thoughwetakevariouskindsofmeasuresinconstructing,careful,butthecrackstilloccursnowandthen.Tracingittoitscause,itisoneofthemincompletelythatourchangetoconcretetemperaturestresspaysattentionto.Inthelargevolumeconcrete,temperaturestressandtemperaturecontrolaresignificant.Thisismainlybecauseofthereasonoftworespects.Firstofall,concreteoftenappearthetemperaturecrackinnotconstructing,influencetheglobalityanddurabilityofthestructure.Secondly,inthecourseofoperating,thetemperaturechangehasremarkableinfluencethatcan'tbeignoredonthestressstateofthestructure.Whomwemeettoconstructtemperaturecrackinmainly,soonlytoorigincauseofformationandtreatmentmeasure,concreteofcrackmakeadiscussioninconstructingthistext.ReasonofacrackHavemanykindsofreasonstoproducethecrackintheconcrete,itismainlythechangesoftemperatureandhumidity,fragilityanddisparityoftheconcrete,andthestructureisunreasonable,therawmaterialsnotuptostandard(ifthealkaliaggregatereact),thetemplateisoutofshape,thefoundationdoesnotsubsideetc.evenly.Thecementemitsalargeamountofheatofhydrationwhentheconcreteishardenned,insidetemperatureisrisingconstantly,causethestressofdrawingonthesurface.Inthecourseofloweringthetemperature,isitcongealfoundationpayrestraintomixalwayslaterstage,willpresentthestressofdrawingwithintheconcrete.Reducingoftemperaturecansurfacecauseheavystressofdrawingveryinconcretetoo.Whenthesedrawthestressandgobeyondresistingtheabilityofsplittingofconcrete,namelywillpresentthecrack.Alotofinsidehumidityofconcretechangeverylightorchangerelativelyslow,surfacehumiditymightchangeheavytheviolentchangetakesplacing.Suchasmaintainingthoroughly,when婚g秀e屋t用t規(guī)i惹n團(tuán)g到守w仿e斯t定t匯e嘴r榨速w腫h核e娃n陣煩n踐o鍬t垂轎d柳o駛i徹n萍g突,脊c保o踐n格t計r晃a嫩c率t知還s勒u城r盒f承a仿c鴨e頃腔t像h碌e離r蔑e窩橫a標(biāo)r筋e蒜n適'溫t掀已d滋e暫f摘o哥r漂m子a繭t踐i鏈o枯n廳鬼d享o吃i漢n秧g棋,幕姓o塵f揮t立e咬n枯把c珍a答u見s鼓e河凈t堪h霧e餓憤c襖r構(gòu)a壽c天k尤看t狂o糠o齒.句至T況h堪e秒諒c身o腰n眠c院r燭e陷t柜e吧暑i黎s父譜a本噴k銹i執(zhí)n競d弱摘o慮f閑今f懼r區(qū)a檢g冊i期l奧i啄t叉y郊蓄m磨a鍬t羽e馳r躲i獄a努l惕尖,倍帳t裁e心n汗s稈i堪l(fā)傘e賭延s通t途r嘗e顧n殘g句t鑰h未踢i弦s蟻睡a乏b麻o蘭u朽t挎給1衡/籮1幅0轉(zhuǎn)惱o甘f跟狠t疏h獎e績火c婦o譯m蓮p撲r再e篇s讓s敗i綠o并n筋環(huán)s浮t快r壞e保n替g倘t捐h趟,屆膛i戰(zhàn)s受花i銷t配恥c墨a勞r冷r阿y爬造o犁n萌委o稅n虜e能'平s槐前s拼h綱o友u丟l樸d兼e滋r獸芒o懲r邁諸b慕a辮c蔬k嗓哈l疼i充m蒼i宋t臟揚w廁h短e視n墓枝d食r淘a飼w叨失o錯u相t茄它o沉f蒼頸s池h姿a撇p駕e盤詢t百o屋懸h坦a處v古e傷槽*油1譽(yù)0旁4匠括o昌n淚l專y位牛,聽想i央s月恢i潤t階晉c略a雨r交r爽y活堤o蟻n崗期o返n典e揭'椒s部鞋s雜h膜o爆u贏l陳d督e歉r蘭制o投r指陰b羽a屑c靜k傲示l付i錘m鏟i尼t(yī)鞏松l源o逢c持a玩t災(zāi)i勉o魚n哈響w揮h擊e屠n蹤果s偷t泛r厚e建t茫c際h內(nèi)駝o券u遭t素甘o聯(lián)f情帳s役h們a尸p貌e舅叔t蛇o礎(chǔ)莖t易h怒e諒r利e蜂曉i寺s還膨*套1等0棗4因賭t揚o勾扭a吩d刺d巨烤f濤o擊r辦望a呢公l州o瓣n精g播濁t(yī)胸i乘m把e恥果t但o掀淋a聰d址d偷窗a短翼s愛h軌o好r賺t釋譯t盯i抗m撕e框.存扎B餅e絞c礦a世u茫s副e經(jīng)倦r茄a(bǔ)期w嫩攔m鏡a今t說e桂r吼i逐a極l奸s央針e賺v狐e我n揮,餓命w丟a篇t腫e全r譽(yù)蘋d妙u杜s拌t好銹t醉h仆a解n園眉u炮n藥s供t枯a捧b夜l并e苗,悼手t國r御a最n諒s肝p作o浙r昨t餃恥a招n盼d葵斬b侵u芬i雕l奏d鍛壁p醫(yī)h挎e龍n償o以m美e略n灶o蒜n調(diào)宣o甜f效掏e捧m鋒a欄n阻a席t減i歉n況g茄坦o腸f辱辯c葉o粒u濃r示s悉e從,周船i內(nèi)t翁s告餐t殿e鐮n索s密i絮l慈e慮書s騎t始r助e款n幣g件t劈h例稻i畏s堂餐n日o線t輔睡e乘v獎e封n紙?zhí)搃拼n議勻t把h轟e晶常s納a還m智e開呆c徐o沸n棒c秧r吸e荷t伙e暢,白爺a吐理l螞o拍t虛檢o煎f鐮燙r酸e遍s接i旬s扶t塘摔t射h勢e披砍a再b俯i斧l榮i味t在y底堤o啊f旨昂d朱r服a俱w坦i疊n軌g慰扛v巨e摟r稈y艱炎l副o辨w客,亦斧i寇t窯帝i狹s雖裂a(bǔ)砌p索t傾宋t番o腳誼p巖r四e拘s舉e袍n符t服殲t袖h依e強(qiáng)惰w縮e需a兄k額丙p料o暴s圾i項t摩i伯o捷n菠憶o析f距同t鑄h壟e熟雷c袋r快a餃c偵k揭.途促A張m舒o悠n義g紅紅a染r耳m肌o廊r屆e癥d硬頓c肥o消n蚊c副r綱e災(zāi)t壩e萌允,貧兔d勿r化a螞w分禿s晨t復(fù)r判e淋s償s痛倘t想o彼寸u轉(zhuǎn)n眉d凈e麥r宅t竟a弓k墻e階松b插y帥佛r撇e呈i井n燭f構(gòu)o跪r檔c麥i矮n絹g載蜜b租a憑r賭劍m樣a糠i例n聯(lián)l哲y紅查,圈患c銜o坐n留c員r羅e盒t然e拳禮b悔e祝a報r憐缺s束t喬r挨e孩s億s司榨o誓f大烤k伐e給e勸p柴i盒n使g載雁j噸u刊s播t奶.著棕O奏r控堵r墓e姜i往n繭f襪o吃r烏c額i俘n撐g攪噸b蝴a摟r誼彼m供i中x跌沸i劍f很逢e手d籍g腥e絡(luò)宵p約o浪s姜i拌t利i甘o萌n框貪g鄉(xiāng)o那n咐e眨半t嚴(yán)o與鐵t廚o列艙c鐵o攏n夜g縱e續(xù)a嫩l惜既p禮r綢e嘗s蓬e盆n養(yǎng)t厲猜t橡h命e止印s凈t況r救e趁s態(tài)s繞尚o亂f斗粘d喂r覽a惕w世i燈n畝g膚貴i距n沉血t付h蒙e叮廈s恨t愿r饞u昂c悶t混u注r私e傻械i賞n頓辜p廈l點a杜i聚n疼遵c屬o何n刻c姑r叔e練t廣e桶,輩完m繳u斥s可t窮誦r有e友l格y企菠o略n粉夠t回h倆e濟(jì)略c凈o各n侮c莫r吸e妄t敲e側(cè)柜o陵n鞋e波s首e邀l蕩f訂霜t氣o軍抬b阿e齊a箱r潛稀.書循R濫e均q轎u右i迫r繩e蝴糠t歲o隔凍a無v悶o閘i柴d脖用t嚷h底e杜餃s鉛t酬r拘e志s暖s詞被o肥f抱歐d塘r肌a耍w英i燕n玉g超播o鋒r婚選o雙n弊l綱y你未v途e燕r盞y沙環(huán)s誰m李a沙l村l字悟s竄t抱r趕e做s嘩s擾趨o樣f燦輪d廳r匪a評w金i紋n擊g牽蜓a(bǔ)窩p憶p燃e末a陰r碗s貧輸o渾f召括t柄h篩e固恢t易h嶼e但愚g把e究n慎e鏡r宏a幸l伴科d國e型s禽i姐g遼n萌.饑破B夠u己t糠桐t括h翠e握對c淹o遣n敵c秤r親e蜘t減e纖粘i冰s偉溜c駐o棵o嚼l為e植d紛撥f閱r消o蒜m拍去m降a罩x研i仙m賢u霸m風(fēng)金t尋e松m頸p沉e舍r從a鏈t掀u號r昨e弟終t隱o迷是t講h討e礦檔s秋t勢e潛a茫d盾y舟鐮t悟e幸m鐵p答e捧r木a特t慕u姓r群e器匯o郊f購鋪o涉p積e它r詠a鑰t予i央n壽g本群p瓦e扎r家i社o射d時康i飾n葡波c犧o析n梅s惡t粉r裳u街c乘t繼i傭n夕g依,鉆丟o候f夏t梅e否n結(jié)搜c世a熄u縮s獅e傭劇s灑i廊z仁a株b兩l圣e握醒t墨o猶纖d喂r眠a倉w港先t劣h尸e宗評s梳t(yī)論r車e容s裝s燕勝w險i貧t振h鉛i源n采呀t額h涉e款番c系o姑n展c陳r壟e濤t財e帝.違功T抱h胡e逃院t泳e閱m歌p皇e腫r鋪a泄t狠u竊r墊e畝妙s蠟t相r抵e短s對s乒鐵c煙a匪n饞漏e稱x菠c房e鴉e村d哈烏o魔t容h暗e灑r暢啦o斗u叫t智s侄i是d謝e釘s造酷a長n功d停謊l萄o刑a抵d糾金t兄h趁e齒顛s樣t異r劉e蛾s昆s喊e認(rèn)s異奇c臂a劉u帥s皇e更d雖悉s牙o涉m烈e宋t根i應(yīng)m積e粉s尼,愉登k訂n藍(lán)o拋w施濟(jì)c棍h架a拐n懷g處e俊便l隙a濱w須坦,描知t感e洪m遵p征e默r晌a鉗t際u奪r總e嫌罰o狀f金攝s閱t囑r輛e朗s展s祖凳f互o歡r藍(lán)輔c逢a伸r煎r限y孕池o處n蠅適r蘿e種a之s驕o辭n尋a叮b象l速e閣因s蛙t夸r逮u淹c抬t俯u逃r敬a完l易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裕A忙n刻a牛l財y傅s扎i候s攝擴(kuò)o獨f宏制2親礦t梅e視m恨p掙e際r痰a墨t倘u瓦r邊e喜承s怖t縫r名e評s箱s朽e課s期Canbedividedintofollowingthreestagesaccordingtotheformingprocessofthetemperaturestress:(1)Itisearly:Buildconcreteisitisitoverbasicallytosendoutheattocementtobegin,generallyoneonedaybyoneself.Twocharacteristicsatthisstage,first,thecementemitsalargeamountofheatofhydration,second,mixandcongealthechangingsharplyofelasticmodelquantity.Becauseofthechangeofelasticmodelquantity,formtheremainingstressintheconcreteinthisperiod.(2)Middleperiod:Uptilltheconcreteiscooleduntilstabilitytemperaturefromcementsendoutheatfunctionbasicallywhenexpiring,inthisperiod,thetemperaturestressismainlybecausethecoolingoftheconcreteandexternaltemperaturechangecause,thesestressesandremnantsstressesthatisformedinearlydaysaresuperposed,mixandcongealtheelasticmouldamountthatgoestoanddoesnotchangemuchduringthisperiod.(3)Laterperiod:Operationperiodafterthecompletecoolingofconcrete.Temperaturestresswhetherexternaltemperaturechangecausemainly,thesestressesandfirsttwokindsofremnantsstressesesarechangedandadded.Canbedividedintotwokindsaccordingtothereasonwhythetemperaturestresscauses:(1)Spontaneousstress:Therearenotanyrestraintortotallystaticstructureattheborder,ifinsidetemperatureisnon-lineardistribution,temperaturestressappearingbecausestructurerestrainsfromeachother.Forexample,thebodyofmoundofthebridge,thephysicaldimensionisrelativelylarge,surfacetemperatureislowwhentheconcreteiscooled,insidetemperatureishigh,presentthestressofdrawingonthesurface,presentthestressofpressinginthemiddle.(2)Restrainthestress:Allofthestructureonesoritrestrainexternalonesomeborder,can'toutofshapeandstressnotcausenotfree.Suchascaseroofbeamroofconcreteandguardrailconcrete.Thistwokindsoftemperaturestressesdrawbackstressescausedtoactonwiththedoingofconcretetogetherfrequently.Itisamorecomplicatedjobtowanttoanalysethedistribution,sizeofthetemperaturestressaccuratelyaccordingtoknowntemperature.Incaseofgreatmajority,needtorelyonthemodeltestorthenumbervaluetocalculate.Toisitmaketemperaturestresshavesizablelimptocreepconcrete,atthestressaccountingtemperature,mustconsidertheinfluencethatcreep,calculateconcretlythatnolongerstatesthinlyhere.Controlandpreventingthemeasureofthecrackof3temperatureForpreventcrack,lightentemperaturestresscanfromcontroltemperatureandisitisitsetabouttorestraintermsfromtwotoimprove.Themeasureofcontrollingtemperatureisasfollows:(1)Isitimproveaggregategrademix,isitdorigidconcretetospend,mixmixturetoadopt,isitguideangrypharmaceuticalorplastificationpharmaceutical,etc.measureinordertoreducecementconsumptionofconcretetoadd;(2)Addwaterorthewatertocoolthebrokenstoneinordertoreducethetemperatureofbuildingoftheconcretewhilemixingandshuttingtheconcrete;(3)Reducethethicknessofbuildingwhilebuildingtheconcreteonhotday,utilizeandbuildtheaspecttodispeltheheat;(4)Burythewaterpipeundergroundintheconcrete,enterthecoldwatertolowerthetemperatureopenly;(5)Stipulaterationalformremovaltime,thetemperaturekeepswarmthesurfacewhileloweringsuddenly,incasethattherapidtemperaturegradienttakesplaceintheconcretesurface;(6)Theconcretewithmediumandlong-termandexposedconstructionbuildsapieceofsurfaceorthinwallstructure,takethemeasureofkeepingwarmincoldseason;Themeasureofimprovingconditionofrestrainingis:(1)Divideandsewanddivideonerationally;(2)Preventthefoundationfromrisingandfallingtoobig;(3)Rationalarrangementconstructionprocess,preventthetoobigdiscrepancyinelevationandsidefromexposingforalongtime;Inaddition,improvetheperformanceoftheconcreteandimproveandresisttheabilityofsplitting,strengthenmaintenance,preventthesurfacefrombeingdoneandcontracted,especiallyguaranteethequalityoftheconcreteisveryimportanttopreventingthecrack,shouldpayspecialattentiontoavoidingproducingandrunningthroughthecrack,theglobalityresumeditsstructureafterappearingisverydifficult,soshouldrelymainlyonpreventingtheemergenceoftherunningthroughcrackwhileconstructing.Inconstructionofconcrete,forraiseturnoverrateoftemplate,demandconcreteformremovalassoonaspossiblethatbuildnewlyoften.Shouldconsiderformremovaltimeproperlywhenconcretetemperatureishigherthanthetemperature,soasnottocausethesuperficialearlycrackofconcrete.Buildingtheearlyformremovalnewly,causeverylargestressofdrawingonthesurface,thephenomenonthat"temperatureisassaulted"appears.Buildinitialstageinconcrete,becauseheatofhydrationissentout,thesurfacecausessizabletodrawthestress,surfacetemperatureisalsohigherthantemperatureatthismoment,removethetemplateatthismoment,surfacetemperatureisloweredsuddenly,mustcausetemperaturegradient,thusaddanddrawthestressonthesurface,changeandaddwiththeheatofhydrationstress,inaddition,theconcretedriesandcontracts,thesuperficialstressofdrawingreachesverygreatnumbervalue,havedangerofcausingthecrack,butcoveralight-dutyheatinsulatorwithonthesurfaceintimeafterremovingthetemplate,forinstancefoamsponge,etc.,forpreventconcretesurfacefromproducethetoobigstressofdrawing,haveremarkableresults.Addmuscleinfluencetolargevolumetemperaturestressofconcreteverylight,becauselargevolumeconcreteincludemuscletoberateverymuchlow.Justhaveinfluenceonthegeneralarmoredconcrete.Ontermsthattemperatureisnotveryhighandthestressislessthanlimitofsurrendering,everyperformanceofthesteelissteady,andhavenothingtodowithstressstate,timeandtemperature.Linebloatedcoefficientofsteelandconcretelinebloatedcoefficientdifferenceverylight,takeplacelittleinternalstressveryonlybetweenthetwowhilechangingintemperature.Becauseelasticmouldamountofsteelconcreteelasticmould7~15ofquantity,reachasinteriorconcretestresstensilestrengthandwhenfracturing,thestressofthereinforcingbarwillnotexceed10000kg/cm2..Soisitisitpreventtinyappearancedifficultyverymuchofcrackfromtomakeuseofreinforcingbartowantamongconcrete.Butthecrackinthestructuregenerallybecomesnumerous,theintervalislittle,thewidthanddeptharesmallerafteraddingthemuscle.Andifdiameterofreinforcingbardetailedandwhenintervaldense,toimproveconcreteresistresultofpersonwhosplitbetter.Concreteandsurface,armoredconcreteofstructurecantakeplacedetailedandshallowcrackoften,amongthemthegreatmajoritybelongtoanddoanddrawbackthecrack.Thoughthiskindofcrackisgenerallyallrelativelylight,itstillshavecertaininfluenceontheintensityanddurabilityofthestructure.Inordertoguaranteeconcreteprojectquality,preventfracturing,improvethedurabilityoftheconcrete,usetheadmixturetoreduceoneofthemeasuresthatfracturescorrectly.Whetherisitreducewaterisitsplitpharmaceuticaltodefend,Isummarizehismainfunctioninpracticetouse.(1)ThereisporeDaoofalargenumberofmaointheconcrete,producecapillarytensioninthecapillaryafterwaterisevaporated,makeconcreteisitcontractoutofshapetodo.Increasingthethinapertureofhaircanreducethecapillarysurfacetension,butwillmaketheintensityofconcretereduce.Thissurfacetensiontheoryhasalreadybeenconfirmedintheworldasfarbackasthesixties.(2)Waterdustthaninfluenceimportantfactorthatconcreteshrink,isitreducewaterisitsplitpharmaceuticalcanmakeconcretewaterconsumptionreduceby25%todefendtouse.(3)Cementconsumptionimportantfactor,concreteofpersonwhoshrinktoo,isitaddandsubtractwaterisitsplitconcretereducible15%ofthecementconsumptionontermsthatkeeptheintensityofconcreteofpharmaceuticaltodefendtomix,itsvolumeissupplementedbyincreasingaggregateconsumption.(4)Reducewaterisitsplitpharmaceuticalcanimproveconsistencyofgrout,reduceconcretesecreteinktodefend,reduceandsinkanddrawbackdeforming.(5)Improveglueingthestrengthofformingofthegroutandaggregate,theconcreteimprovedresiststheperformanceofsplitting.(6)Concreteisitproducestressofdrawingtorestrainfromwhileshrinking,crackwhendrawingthestressandisgreaterthanconcretetensilestrengthcanproduce.Reducewaterisitsplitpharmaceuticaleffectiveconcretetensilestrengthofimprovementverytodefend,improveresistingtheperformanceofsplittingofconcretebyawidemargin.(7)Itcanmaketheconcretedensitygoodtoaddtheadmixturetomix,canimproveresistingcarbonizationofconcreteeffectively,reducecarbonizationtoshrink.(8)Isitreducewaterisitsplitslowcoagulationtimeproperconcreteunderpharmaceuticaltodefend,onthebasisofpreventingthefastwaterofcementfromsendingoutheateffectivelytomix,preventtheplasticityshrinkthatbringsbecausethecementisnotcongealedforalongtimefromincreasing.(9)Mixadmixtureconcreteandgettingeasyandkind,surfaceeasytofeelflat,formlittlemembrane,reducethemoisturetoevaporate,reducedrilyandshrink.Alotofadmixtureallhavethefunctionsofslowcoagulation,increasingandapt,improvementplasticity,theexperimentthatweshouldcarryoninthisrespectmoreintheprojectpracticeiscomparedwithandstudied,thanleanagainstnotimprovingtermsmoresimple,maygettingsimpleandmoredirect,economy.Earlymaintenanceof4concretePracticehasproved,thecommoncrackofconcrete,mostisthesurfacecrackofdifferentdepth,mainreasonitswhethertemperaturegradientcausecoldtemperatureofarealowertooeasytoformcracksuddenly.Sosaythewarm-keepingoftheconcreteisespeciallyimportanttopreventingtheearlycrackofsurface.Fromtheviewpointoftemperaturestress,shouldreachandrequiretokeepwarmfollowingly:1)Preventconcreteinternalandexternaltemperaturepoorandconcretesurfacegradientfrom,preventthesurfacecrack.2)Preventconcretefromtobeultraandcold,shouldisitisitmaketheminimumtemperatureisnotlowerthanthesteadytemperatureofconcreteservicetimeconstructiontimeinconcretetotrytotryone'sbest.3)Preventtheoldconcretesubcooling,inordertoreducetherestraintamongtheoldandnewconcrete.Theearlymaintenanceoftheconcrete,themainpurposeliesinkeepingthesuitablewarmandhumidcondition,inordertogettheresultoftworespects,ontheotherhandmaketheconcreteavoidtheinvasionandattackoftheunfavorableandwarm,humidityoutofshape,theonesthatpreventfromharmfullyarecoldtocontractanddotocontract.Ononehandmakecementwaterfunctiongoonsmoothly,isinthehopeofreachingtheintensitydesignedandresistingtheabilityofsplitting.Thesuitablewarmdampconditionisinterrelated.Mixwarm-keepingmeasurepaidtocongealoftenprotectwetresultstoo.Analyse,waterconcreteincludemoisturecanmeetdemand,cementofwaterhaveenoughandtosparenewlytheoretically.Butbecausethereasonofevaporatingetc.oftencauseslossesofthemoisture,thuspostponeorhinderwaterofthecementfrom,thesurfaceconcretereceivesthiskindofadverseeffecteasiestlyanddirectly.Keyperiodwhenmaintainedininitialafewdaysaftersotheconcreteisbuilt,shouldpayattentiontoconscientiouslyinconstructing.5、ConclusionsConstructiontemperatureandrelationofcrackinconcretetheabovecarryonpreliminarydiscussionoftheoryandpractice,thoughtheacademiahasdifferenttheoriestoorigincauseofformationandcomputingtechnologyoftheconcretecrack,buttoconcretepreventionandimprovingthemeasuresuggestiontorelativelyunify,applicationinpracticeresultfinetooatthesametime,concretetoisitobserve,comparemoremorebyustowantinconstructing,analysemore,summarizemoreaftergoingwrong,combinemanykindsofpreventionanddealwiththemeasure,thecrackoftheconcretecanbeavoided.淺談混凝土的施工溫度與裂縫摘要通過多年的現(xiàn)場觀察，通過查閱有關(guān)混凝土內(nèi)部應(yīng)力方面的專著，對混凝土溫度裂縫產(chǎn)生的原因、現(xiàn)場混凝土溫度的控制和預(yù)防裂縫的措施進(jìn)行等進(jìn)行闡述。關(guān)鍵詞混凝土溫度應(yīng)力裂縫控制混凝土在現(xiàn)代工程建設(shè)中占有重要地位。而在今天，混凝土的裂縫較為普遍，在橋梁工程中裂縫幾乎無所不在。盡管我們在施工中采取各種措施，小心謹(jǐn)慎，但裂縫仍然時有出現(xiàn)。究其原因，我們對混凝土溫度應(yīng)力的變化注意不夠是其中之一。在大體積混凝土中，溫度應(yīng)力及溫度控制具有重要意義。這主要是由于兩方面的原因。首先，在施工中混凝土常常出現(xiàn)溫度裂縫，影響到結(jié)構(gòu)的整體性和耐久性。其次，在運轉(zhuǎn)過程中，溫度變化對結(jié)構(gòu)的應(yīng)力狀態(tài)具有顯著的不容忽視的影響。我們遇到的主要是施工中的溫度裂縫，因此本文僅對施工中混凝土裂縫的成因和處理措施做一探討。1、裂縫的原因混凝土中產(chǎn)生裂縫有多種原因，主要是溫度和濕度的變化，混凝土的脆性和不均勻性，以及結(jié)構(gòu)不合理，原材料不合格（如堿骨料反應(yīng)），模板變形，基礎(chǔ)不均勻沉降等?；炷劣不陂g水泥放出大量水化熱，內(nèi)部溫度不斷上升，在表面引起拉應(yīng)力。后期在降溫過程中，由于受到基礎(chǔ)或老混凝上的約束，又會在混凝土內(nèi)部出現(xiàn)拉應(yīng)力。氣溫的降低也會在混凝土表面引起很大的拉應(yīng)力。當(dāng)這些拉應(yīng)力超出混凝土的抗裂能力時，即會出現(xiàn)裂縫。許多混凝土的內(nèi)部濕度變化很小或變化較慢，但表面濕度可能變化較大或發(fā)生劇烈變化。如養(yǎng)護(hù)不周、時干時濕，表面干縮形變受到內(nèi)部混凝土的約束，也往往導(dǎo)致裂縫?；炷潦且环N脆性材料，抗拉強(qiáng)度是抗壓強(qiáng)度的1／10左右，短期加荷時的極限拉伸變形只有（0.6～1.0）×104，長期加荷時的極限位伸變形也只有（1.2～2.0）×104.由于原材料不均勻，水灰比不穩(wěn)定，及運輸和澆筑過程中的離析現(xiàn)象，在同一塊混凝土中其抗拉強(qiáng)度又是不均勻的，存在著許多抗拉能力很低，易于出現(xiàn)裂縫的薄弱部位。在鋼筋混凝土中，拉應(yīng)力主要是由鋼筋承擔(dān)，混凝土只是承受壓應(yīng)力。在素混凝土內(nèi)或鋼筋混凝上的邊緣部位如果結(jié)構(gòu)內(nèi)出現(xiàn)了拉應(yīng)力，則須依靠混凝土自身承擔(dān)。一般設(shè)計中均要求不出現(xiàn)拉應(yīng)力或者只出現(xiàn)很小的拉應(yīng)力。但是在施工中混凝土由最高溫度冷卻到運轉(zhuǎn)時期的穩(wěn)定溫度，往往在混凝土內(nèi)部引起相當(dāng)大的拉應(yīng)力。有時溫度應(yīng)力可超過其它外荷載所引起的應(yīng)力，因此掌握溫度應(yīng)力的變化規(guī)律對于進(jìn)行合理的結(jié)構(gòu)設(shè)計和施工極為重要。2、溫度應(yīng)力的分析根據(jù)溫度應(yīng)力的形成過程可分為以下三個階段：（1）早期：自澆筑混凝土開始至水泥放熱基本結(jié)束，一般約30天。這個階段的兩個特征，一是水泥放出大量的水化熱，二是混凝上彈性模量的急劇變化。由于彈性模量的變化，這一時期在混凝土內(nèi)形成殘余應(yīng)力。（2）中期：自水泥放熱作用基本結(jié)束時起至混凝土冷卻到穩(wěn)定溫度時止，這個時期中，溫度應(yīng)力主要是由于混凝土的冷卻及外界氣溫變化所引起，這些應(yīng)力與早期形成的殘余應(yīng)力相疊加，在此期間混凝上的彈性模量變化不大。（3）晚期：混凝土完全冷卻以后的運轉(zhuǎn)時期。溫度應(yīng)力主要是外界氣溫變化所引起，這些應(yīng)力與前兩種的殘余應(yīng)力相迭加。根據(jù)溫度應(yīng)力引起的原因可分為兩類：（1）自生應(yīng)力：邊界上沒有任何約束或完全靜止的結(jié)構(gòu)，如果內(nèi)部溫度是非線性分布的，由于結(jié)構(gòu)本身互相約束而出現(xiàn)的溫度應(yīng)力。例如，橋梁墩身，結(jié)構(gòu)尺寸相對較大，混凝土冷卻時表面溫度低，內(nèi)部溫度高，在表面出現(xiàn)拉應(yīng)力，在中間出現(xiàn)壓應(yīng)力。（2）約束應(yīng)力：結(jié)構(gòu)的全部或部分邊界受到外界的約束，不能自由變形而引起的應(yīng)力。如箱梁頂板混凝土和護(hù)欄混凝土。這兩種溫度應(yīng)力往往和混凝土的干縮所引起的應(yīng)力共同作用。要想根據(jù)已知的溫度準(zhǔn)確分析出溫度應(yīng)力的分布、大小是一項比較復(fù)雜的工作。在大多數(shù)情況下，需要依靠模型試驗或數(shù)值計算?；炷恋男熳兪箿囟葢?yīng)力有相當(dāng)大的松馳，計算溫度應(yīng)力時，必須考慮徐變的影響，具體計算這里就不再細(xì)述。3、溫度的控制和防止裂縫的措施為了防止裂縫，減輕溫度應(yīng)力可以從控制溫度和改善約束條件兩個方面著手?？刂茰囟鹊拇胧┤缦拢海?）采用改善骨料級配，用干硬性混凝土，摻混合料，加引氣劑或