大体积混凝土测温点布置原则

1、大体积混凝土测温点布置原则: 一、大体积硅温度的控制不仅要控制内表温差 （指硅中心最高温度与之相对应 的硅表面温度之间的温差）和表面温差（指硅中心最高温度相对应的表面温度 与环境温度之间的温差），更要控制硅的综合降温差（指硅内部的平均降温差） 和降温速率（指硅中心温度或表面温度每天的降温幅度）。二、硅的任一降温差都可以分解为平均降温差及非均匀降温差，前者产生外约 束应力，是产生贯穿性裂缝的主要原因，后者引起自约束应力，主要引起表面 裂缝。非均匀降温差主要是控制硅的内表温差。规范规定大体积硅的内表温差 应控制在25摄氏度，该控制值是比较严格的，根据我们的工程实践，该值可根 据工程实际情况适当放宽

2、，这主要取决于硅的一些实际物理指标，如：不同龄 期的弹性模量、松弛系数和抗拉强度。因此，在大体积硅施工前，对温度控制 指标进行一些理论计算，对施工大有指导意义。三、测温点的平面布置原则：1）平面形状中心；2）中心对应的侧边及容易散 发热量的拐角处。3）主风向部位。总之测温点的位置应选择在温度变化大，容 易散热、受环境温度影响大，绝热温升最大和产生收缩拉应力最大的地方。四、测温点的竖向布置：一般每个平面位置设置一组 3个，分别布置在硅的上、 中、下位置，上下测点均位于硅表面 10厘米处，另外在空气，保温层中各埋设 1个测温点测量环境温度、保温层内的温度。大体积混凝土养护一般不少于 7d ,并根据

3、板中心混凝土温度变化及同条件养 护的混凝土试块强度确定养护周期。混凝土的养护应采用保温，保湿及缓慢降 温的技术措施，一般在浇筑在厚度大于 3m时，要求考虑在大体积混凝土内部 设置冷却水循环降温措施，设冷却水管，并通过温度检测控制混凝土中心与表 面的温度或混凝土内部与冷却水的温度控制在 25 C以内。五、降低水泥水化热和变形(1)在厚大无筋的或少筋的大体积混凝土中，掺加总量不超过20%的大石块，减少混凝土的用量，以达到降低水化热和节省水泥的目的。(2)改善配筋。为了保证每个浇筑层上下均有温度筋，可建议设计人员将分布筋做适当调整。温度筋宜分布细密，一般用 力8钢筋，双向配筋，间距15 cm. 这样

4、可以增强抵抗温度应力的能力。六、其他方面(1)改善约束条件，削减温度应力。采取分层或分块浇筑大体积混凝土，合理 设置水平或垂直施工缝，或在适当的位置设置施工后浇带，以放松约束程度， 减少每次浇筑长度的蓄热量，防止水化热的积聚，减少温度应力。对大体积混 凝土基础与厚大的混凝土垫层之间设置滑动层，如采用平面浇沥青或铺卷材。在垂直面、键梢部位设置缓冲层，如铺设 3050 mm后沥青木丝板或聚苯乙烯 泡沫塑料，以消除嵌固作用，释放约束应力。(2)提高混凝土的极限拉伸强度。选择良好继配的粗骨料，严格控制含泥量， 加强混凝土的振捣，提高混凝土密实度和抗拉强度，减小收缩变形，保证施工 质量。采取二次投料法，

5、二次振捣法，浇筑后及时排除表面积水，加强早期养 护，提高混凝土早期或相应龄期的抗拉强度和弹性模量。在大体积混凝土的基 础内设置必要的温度配筋，在截面变形和转折处，底、顶板与墙转折处，孔洞 转角及周边，增加斜向构造配筋，以改善应力集中，防止裂缝出现。七、大体积混凝土的信息化施工大体积混凝土施工应加强测温和温度控制，实行信息化控制，随时控制混凝土 内的温度变化，以便及时调整保温及养护措施，使混凝土的温度梯度和湿度不 至过大，以有效控制裂缝的出现。7.1 温度监测 为掌握基础内部混凝土实际温度变化情况，了解冷却水管进出水温度，对基础 内外部以及进出水管进行测温记录，密切监视温差波动，来指导混凝土的养

6、护 工作，并同时控制冷却水流量以及流向。测温设备可采用“大体积混凝土温度微机自动测试仪”，温度传感器预先埋设 在测点位置上，基础承台测点位置分承台内部、薄膜下温度、室内室外温度、 冷却水管进、出水温度设置。测点温度、温差以及环境温度的数据与曲线用电 脑打印绘制。当混凝土内外温差超过控制要求时，系统马上报警。测温点的布 置应考虑由于大体积混凝土浇筑顺序时间不一致，应由各区域均匀布置，核心 区、中心区为重点。7.2 监测结果及其分析根据各测点所测温度汇总混凝土温度情况表，并绘制基础混凝土升降温曲线， 了解本工程大体积混凝土测温情况和特点。根据一般 规律，大体积混凝土浇捣 结束后，在基础的中心部位将

7、形成一高温区，升温时间为6070 h ,高温持续时间较长，均在3040 h.混凝土的入模温度较高，会加快水泥水化的进行，故 早期水化热积聚上升，将造成混凝土的升温速度加快。当混凝土保温层揭除后， 混凝土表面温度会明显受昼夜大气温度的 影响，温度下降。一般循环冷却水带 走的中心部位混凝土的热量较四周表面和底部要多，因此，中心部位混凝土因 冷却水所产生的降温数值大，混凝土四周表面和底部所产生的降温数值小。在 实际施工中可根据详细测温情况，进行分段 计算。7.3 大体积混凝土裂缝成因分析大体积混凝土施工易产生裂缝，产生裂缝有多方面原因，如约束情况，周围环 境湿度，混凝土的均匀性，分段是否妥当，结构形

8、式等，都可能引起大体积混protecti ngfire contr olfacilities,firepr evention,reportsoffireelctivitiesinobeytheschoolrule s and regulati ons, on time, on time home toprevent accidents. 8,schoolto school inspe ctions ona reg ular ba sis,found hi dden in time,a nd i n sever ecase s,itis hardto eliminate immediatelyc

9、losed, andreportedtot he localpeople'sGovernment,educati on,a nd r uleoflaw section.9,t heschoolshould a lways check t he internalwall s,retaini ng wall s,ponds, raili ngs, handrails, doors, Windows,staircasesand avarietyofsports,extracurricular activities,facilitie ssuchasfire safety,i nfrastru

10、ct ure se curit y,unsafe facilitytoimmediatelyrepaira nd demolitionto ensure thatteachers a nd studentsw ork,lear n, live ve nues and facilities are safe andreliable. SongLi n Xiang LiuJiapingelementaryschoolMar ch 2016song Lin Xia ngLi uJiapi ng primarysch oolfiresafetysystemstoenhancefire safety,

11、protecti on of public property andthe life and propertysafety of teachers andstudents,schoolfiresafetyintoday-t o-daymanageme nt,is developing t hefollow ingfiresafetysystem.1,strengthe nfiresafetyeducation ofthewholeschool.According to therequirementsofthe FireServicesAct,sothateveryonehasofkee pin

12、g firecontr olsafety,In orderto ensure normalteaching orde r, prote cting st ude nts'healt hy growth, ensuring t hat national(property) isnot lost ,topra corre ctional ce ntre,a police station , atow nshippeopl e'sGovernme ntshall not concealt heaccident.4w eek,teachers are on.I - .I. . I. -

13、. . I _ I- cidents,foll ow the"preve ne thelea dershipvalues; stre ngthe nthe e- 一 1 - I _ osses" principl e,accordi ng to thelocalconditi ons, makethe management system.1,thepri ncpialis there sponsibility ofschool saschools toe nsure normalteaching or der;responsi ble forschool safetylea

14、dershipalway smaintaine d cl ose contact a nd districtpoli. . I . 一 . _ . I , 一 II I . . _ . I _L I 1_1.1I . ._LI . . 1 一 一 dershipofPre side ntse curityworklea dinggr oup.The head tea cherto thelea dership team isresponsi blefor,im plementati on ofthea ccountabilitysystem.2,schoolmont hlystude ntkn

15、owle dge about safetyeducati on,education should be diversified in theform every safetyeducationforst ude ntsofclasses perweekshould betargeted.Tocarry on emerge ncy issue s deali ngwith e ducation in Ge neral,self-hel pand mutual re scue knowledge. Emergencycalls (such as 110,119,122, 120, andsothe

16、poli cestationonschoolsafetyand help. 5,strengtheningteachers 'morale ducation,establi shadedi catedl ove, improvi ng educati on quality,observet he students' psychologicalchangesata nytime andtake preventive measures, no cor poral punishme ntand cov ert cor poral punishme ntonstudents, stud

17、ent outoftheclassroom, schools maynot be. 6, unit sor departments usestud entStreetpr opaganda or partici patein t hece lebrations,a swell as partici pating i nothersocialw- -_L_ . I. L . .< I 1_ |_ I. > I. .1. _ L _.一一 .一一 .一 |_| - I_ _LI_. > - 1 一 . . _|-一一. 一一 ”. .一 _. I 一一 l_. I I. I -

18、_L |_.一 . I I ,I 一 on) use commonse nsei neducati on.3,t heesta blishment ofmajora cci dent re porting sy stem.Schoolst udents reportmajor accident wit hina nhour ofeducati on;studentrun and disappearancestoreport; re portofthe accide nt to awrittenreportintriplicate,ork,wit houtapprovaloftheCorre c

19、tionalCe ntre,school principals consent,without organizati on. Wit houtthea pproval ofrelevantde partments,may organizest udentsto partici patein firefighting, disaster re liefand so on.7,schools should e ducate stude ntsto.I- Ld_L I-I 一 _. I L . I. IL . | _ _> .11. . |_ I _ 一 . _ I一.-. - _ II, L

20、 . 1 L . I _凝土的裂缝。就本工程的大体积混凝土而言，由于其截面尺寸较大，所以外荷载或次应力引起的裂缝可能性很小。但正由于结构截面大，水泥水化时所释放的热量就会产生较大的温度变化和收缩作用，由此造成的温度梯度收缩应力是导致大体积砼产生裂缝的主要原因。这种裂缝分为两类：一、表面裂缝，大体积混凝土由于其内部与表面散热速率不一样，在其表面形成温度梯度，从而表面产生拉应力，内部产生压应力。而此时混凝土的龄期很短，抗拉强度很低，温差产生的表面拉应力，超过此时的混凝土极限抗拉强度，就会在混凝土表面产生裂缝。此种裂缝一般出现在混凝土浇筑后的第34天里。二、贯穿裂缝，混凝土浇数天后，水化热基本已释放

21、，就开始进入降温阶段，由于逐渐降温而产生收缩，再加上混凝土硬化过程中，由于混凝土内部拌合水的水化和蒸发以及胶质体的胶凝等作用，促使混凝土硬化时收缩。这两种收缩由于受到基底或结构本身的约束，也会产生很大的拉应力，当此拉应力超过砼此时的抗拉强度，砼整个截面就可能产生贯穿裂缝，这种收缩裂缝才是危害最大的裂缝。7.4 大体积混凝土施工控制措施从控制裂缝的观点看，表面裂缝危害小，但也会影响结构使用或外观；而贯穿裂缝则要影响结构的整体性、耐久性和防水性，可能导致结构不能正常使用。为了防止温度裂缝的出现或把温度裂缝控制在某个界限内，就必须进行温度控制。根据以往施工经验和大体积砼的热工计算，为了防止出现有害裂

22、缝，我们在马钢2#2500m高炉、热风炉基础施工中采用以下措施：采用低热水泥一一矿渣水泥，降低水化温升，强度富余大；优化配合比设计，在硅掺入一定比例的粉煤灰、高效缓凝减水剂和膨胀剂，以减少水泥用量，降低水化热，并利用混凝土的60天强度；硅表面采取蒸气保温养护，缩小硅内外温差。控制硅的入模温度，进行斜面薄层连续浇筑； 电子测温elctivitiesinobeytheschoolrule s and regulati ons, on time, on time home toprevent accidents. 8,schoolto school inspe ctions ona reg ular

23、 ba sis,found hi dden in time,a nd i n sever ecase s,itis hardto eliminate immediatelyclosed, andreportedtot he localpeople'sGovernment,educati on,a nd r uleoflaw section.9,t heschoolshould a lways check t he internalwall s,retaini ng wall s,ponds, raili ngs, handrails, doors, Windows,stair case

24、sand avarietyofsports,extracurricular activities,facilitie ssuchasfire safety,i nfrastruct ure se curit y,unsafe facilitytoimmediatelyrepaira nd demoliti onto ensure thatteachers a nd studentsw ork,lear n, live ve nues and facilities are safe andreliabl e. SongLi n Xiang LiuJiapingeleme ntaryschoolM

25、ar ch 2016song Lin Xia ngLi uJiapi ng primaryschoolfiresafety systemstoenhancefire safety, protecti on of public property andthe life and propertysafety of teachers andstudents,schoolfiresafetyintoday-t o-daymanageme nt,is developing t hefollow ingfiresafetysystem.1,strengthe nfiresafetyeducation of

26、thewholeschool.According to therequirementsofthe FireServi cesAct,sothateveryonehasofkee ping firecontr olsafety,In orderto ensure normalteaching orde r, prote cting st ude nts'healt hy growth, ensuring t hat national（property） isnot lost ,topra corre ctional ce ntre,a police station,a tow nship

27、peopl e'sGovernme ntshall not concealt heaccident.4w eek,teachers are on.I - .I. . I. -. . I _ I- cidents,foll ow the"preve nv e thelea dershipvalues; stre ngthe nthe e- 一 1 - I _ osses" principl e,accordi ng to thelocalconditi ons, makethe management system.1,thepri ncpialis there spo

28、nsibility ofschool safety,schoolse curity underthe lea dershipofPre side ntse curityworklea dinggr oup.The head tea cherto thelea dership team isresponsi blefor,im plementati on ofthea ccou ntabilitysystem. 2,schoolmont hlystude ntknowle dge about safetyeducati on,education should be diversified in

29、theform every safetyeducationforst ude ntsofclasses perweekshould betargeted.Tocarry on emerge ncy issue s deali ngwith e ducation in Ge neral,self-hel pand mutual re scue knowledge. Emergencycalls （such as 110,119,122, 120, andsoschools toe nsure normalteaching or der;responsi ble forschool safetyl

30、eadershipalway smaintaine d cl ose contact a nd districtpoli cestations, canvassingsupport fromthe poli cestationonschoolsafetyand help. 5,strengtheningteachers 'morale ducation,establi shadedi catedl ove, improvi ng educati on quality,observet he students' psychologicalchangesata nytime and

31、take preventive measures, no cor poral punishme ntand cov ert cor poral punishme ntonstudents, student outoftheclassroom, schools maynot be. 6, unit sor departments usestudentStreetpr opaganda or partici patein t hece lebrations,a swell as partici pating i nothersocialw. . I . 一 . _ . I , 一 II I . .

32、 _ . I _L I 1_1.1I . ._LI . . 1 一一 . 一 I 一 _L_ . I. L . .< I 1_ |_ I . >I. .1. _ L _.一 一 .一一 .一 |_| - I _ _LI _. > - 1 一 . . _|-一一. 一一 ”. .一 _. I 一一 l_. I . _ I - _|, |_ . 一 . I I , I .on） use commonse nsei neducati on.3,the esta blishment ofmajora cci dent re porting sy stem.Schoolst udent

33、s reportmajor accident wit hina nhour ofeducati on;studentrun and disappearancestoreport; re portofthe accide nt to awrittenreportintriplicate,ork,wit houtapprovaloftheCorre ctionalCe ntre,school principals consent,without organizati on. Wit houtthea pproval ofrelevantde partments,may organizest ude

34、ntsto partici patein firefighting, disaster re liefand so on.7,schools should e ducate stude ntsto.I- Ld_L I-I 一 _. I L . I. IL . | _ _> .11. . |_ I _ 一 . _ I一.-. - _ II, L . 1 L . I _7.4.1 合理选择原材料石子选用531.5mm粒径碎石，连续级配，含泥量不超过1%中砂（细度模数1.1.1 泥量不超过2%；桃冲水泥厂寨峰牌散装32.5 号矿渣水泥；高效缓凝减水剂：1% （占水泥重）；膨胀剂JM-m： 81

35、0% II级粉煤灰1015%（占水泥重），原材料均须抽样试验。1.1.2 优化混凝土配合比设计为减少水泥用量, 降低水化热, 减少混凝土收缩, 延缓混凝土初凝时间, 改善和易性 , 混凝土配制采用三掺技术（即混凝土中掺加粉煤灰、减水剂、膨胀剂）减水剂针对该工程的施工特点和正处于冬季的情况, 实验室经过多次试配，最后选用的配合比为：水: 水泥 : 中砂 : 石子 : 粉煤灰 : 减水剂 : 膨胀剂=178:275:770:1120:40:3:26 。1.1.3 大体积混凝土保温养护措施1.1.3.1 大体积混凝土的热工计算1）混凝土内部最高绝热升温值：Th=WQ/Q ,本工程中采用32.5矿渣水

36、泥，C20混凝土。故Th=43.62）、混凝土中心最高温度：Tm国T+Th*ET=10C （入模温度），工散热系数取0.8。Tma=44.9C。3）、混凝土表面温度：Tb=Tq+4h （H-h） AT/H2Tq 为环境温度取 5C, AT= TMA-Tq=39.9 C , H=2.57m, h=0.07m。故 Tb=9.2 C。4）、混凝土内表温差： Tc= TMA-Tb=44.9- 9.2=35.7 C>25C显然混凝土内表最大温差超过规定要求值，若不采取措施，将必然会产生表面裂缝。1.1.3.2 混凝土表面保温养护措施lectricity li nes,equi pmenti nsp

37、ecti ons,found hidden i n time for rectificati on,mai ntena nce, andse curity.9, do notuse an open flame in t he classr oom, pr ohi bitburni ng stove, lit ca ndle s, mosquit o repel lent, no sm oking, and ba nni ng messywiri ng. Without using any household a ppli ances is not allowed. 10, liveoncamp

38、usfaculty members, mustleadbyexample,andeducatefamiliesandchildrenreadytofire.11,householduseofgasinschools,tomasterproperusage,payattenti ontot he leak -proof,explosi on-pr oof, fireproof,closi ngvalve afterusetoensuresecurity.12,diningroommustbe qualified,and annual te sting ofpre ssure vessel s,t

39、o reg ularlyche ck,the cantee nw orkersmust be certifie d,strictly by operation operation,gastankand st ovesafety dista nceof1.5meters,topreventaccidents. 13,the adverse conse quences ca used byig nori ng firesafety regulations,willbepunishe d,untilinvestigatedforlegalresponsibility.S ong Lin Xiang

40、Liu Jia ping elementaryschool March2016 Xia ng Liu Jia pi ngelementary school, pi ne sl opessurroundi ngsafety manageme ntsystem 1 teachers a nd st udents,t hesurroundi ng area oftheschoolgovernancecovers personal a ndfood hygie ne, culturalev entsand ot heraspe cts,integratedg overna nce shall obta

41、i nwide supportand f ullcooperation ofthecommunit y.On the surroundinge nvironmentin schools shouldbecl osely monitore d.2,schoolw ork at the sametime,shoul d payattenti on to t hesaf etymanagementofschoolenvironment,shoul d takethe i nitiativeto conta ctthe district police station,thevillageCommitt

42、ee,Corre ctionalCe ntre,T ownship g overnme nt,busine ss managementand ot herde partmentsto do ag ood jobmanageme nt. 3,tea cher ondutywith t heexce ption ofinspe ctionsinschool s,should al so payattenti ontoenvironmentali nspecti onsnearthecampus,foundthatthejoblessmigrants fromruralareas,forexampl

43、e,harassme ntofstudents a nd avariety ofacci dent s,accor dingto different situati ons reporte d schoolofficial sor the police stati on i n atimely manne r,topr otectthesafety ofstudents.4,everydaybeforeschool,teachersremindstudents,payatte ntiont otrafficsafety. 5,should educatestudentstorespectsoc

44、ial ethics,andvarious regulations,maintaining public order,and fightthebadguys,andgraspthecorrectwaysand meansofmaintaining and improvi ng student s'self-care a bilit y.6,theestabli shment ofemergency rescueteamsofteachers inschools,onhighalertanddeployed.SongLinXia ng Li uJiapinge lementary sch

45、oolMarch2016song Lin Xiang LiuJiapi ng primaryschoolteachersandstudentsorganizationsoutofsafetymanagement systemorganizationactivitiesbetweenteachersandstudents,todrawupa preci se pla nand se curitymeasures mustbesignedbytheschoolofficial s to reviewthe programme of activitiesagreeduponCorrectionalC

46、enteragreed toimpl ement. Organizati ontothe field relatively faror activities requireapprovalbytheDeputyDirector ofthe Educati on Burea u inchargeofse curit y. 2,ea ch a ctivityshoul dhave aspe cificresponsi bility, payattention tothepersonsage, physicalmatch.Route 3,a ctivities, l ocati on, fiel d

47、 survey sshoul d be carried out ina dvance. 4,activitiesforthe meansoftransportshoul d explai nthe sit uationtothe schoolto complywith vehicle,safetyrequirements,before the neforrepair s.5,ea cha ctivitymusthave security,emergencyresponse plan foraccidents. 6,pi cni cs, hiking, picnict o payattentio

48、n to fireprevention,food poisoning,prevention offallaccidents7,t he activitie s nearthe rivers, reservoirs,no measuresor donot meet these curity re quireme ntsofthe Organization andnot let students intothe waterelctivitiesinobeytheschoolrule s and regulati ons, on time, on time home toprevent accide

49、nts. 8,schoolto school inspe ctions ona reg ular ba sis,found hi dden in time,a nd i n sever ecase s,itis hardto eliminate immediatelyclosed, andreportedtot he localpeople'sGovernment,educati on,a nd r uleoflaw section.9,t heschoolshould a lways check t he internalwall s,retaini ng wall s,ponds,

50、 raili ngs, handrails, doors, Windows,stair casesand avarietyofsports,extracurricular activities,facilitie ssuchasfire safety,i nfrastruct ure se curit y,unsafe facilitytoimmediatelyrepaira nd demoliti onto ensure thatteachers a nd studentsw ork,lear n, live ve nues and facilities are safe andreliab

51、l e. SongLi n Xiang LiuJiapingeleme ntaryschoolMar ch 2016song Lin Xia ngLi uJiapi ng primarysch oolfiresafetysystemstoenhancefire safety, protecti on of public property andthe life and propertysafety of teachers andstudents,schoolfiresafetyintoday-t o-daymanageme nt,is developing t hefollow ingfire

52、safetysystem.1,strengthe nfiresafetyeducation ofthewholeschool.According to therequirementsofthe FireServi cesAct,sothateveryonehasofkee ping firecontr olsafety,In orderto ensure normalteaching orde r, prote cting st ude nts'healt hy growth, ensuring t hat national(property) isnot lost ,topra co

53、rre ctional ce ntre,a police station , atow nshippeopl e'sGovernme ntshall not concealt heaccident.4w eek,teachers are on.I - .I. . I. -. . I _ I- cidents,foll ow the"preve ne thelea dershipvalues; stre ngthe nthe e- 一 1 - I _ osses" principl e,accordi ng to thelocalconditi ons, maketh

54、e management system.1,thepri ncpialis there sponsibility ofschool saschools toe nsure normalteaching or der;responsi ble forschool safetyleadershipalway smaintaine d cl ose contact a nd districtpoli. . I . 一 . _ . I , 一 II I . . _ . I _L I 1_1.1I . ._LI . . 1 一 一 dershipofPre side ntse curityworklea

55、 dinggr oup.The head tea cherto thelea dership team isresponsi blefor,im plementati on ofthea ccountabilitysystem.2,schoolmont hlystude ntknowle dge about safetyeducati on,education should be diversified in theform every safetyeducationforst ude ntsofclasses perweekshould betargeted.Tocarry on emerg

56、e ncy issue s deali ngwith e ducation in Ge neral,self-hel pand mutual re scue knowledge. Emergencycalls (such as 110,119,122, 120, andsothepoli cestationonschoolsafetyand help. 5,strengtheningteachers 'morale ducation,establi shadedi catedl ove, improvi ng educati on quality,observet he students' psychologicalchangesata nytime andtake preventive measures, no cor poral punishme ntand cov ert cor poral punishme ntonstudents,