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1、大面积超长无粘结预应力混凝土技术在南通市政府大楼施工中的应用叶文启 蒋云昌 李晓奇（江苏省启东市建筑安装工程有限公司 226200）提要：本文介绍南通市政府大楼工程140米长、25米宽楼面结构设计不留伸缩缝，采用无粘结预应力混凝土施工方法。1 概述南通市政府大楼工程平面总长度为140米，宽度为25-30米，板厚110-140厚，受建筑立面影响，不设伸缩缝，进行超长预应力混凝土楼面施工。采用下述方案：各层楼面以两道后浇加强带为界，分为3个施工段浇筑，留2条施工缝，每段混凝土浇筑间隔2-4天。在混凝土中掺6%NEA膨胀剂。在每层楼面设置两个1.5米宽的后浇加强带，加强带NEA膨胀剂掺量8%，带中和
2、带外掺量不同，形成邻位限制条件，从而减少超长混凝土引起的后期收缩，并在加强带位置增加配筋。纵向分三段张拉，先张拉中间段，待后浇加强带封闭，并达到设计强度后张拉两端，两端张拉采取一端张拉。对梁内无粘结预应力筋采用连接器张拉。对超长束预应力张拉采用超张拉大回松技术。2 工程概况南通市政府大楼工程地上19层，地下1层，结构总高度75.3米，建筑面积57105平方米，全现浇框架剪力墙结构，平面布置为扇形。该工程X向总长度为140米，Y向长度为25-30米，板厚为110140毫米，受建筑立面影响，不设伸缩缝，进行超长混凝土楼面施工。因此，在每层楼板内设置X向无粘结预应力筋，以免混凝土因温度应力过大而开裂
3、。板内无粘结预应力筋间距为330660毫米，单根直线型布置，位置在板厚一半处。预应力筋均采用1860级j15.2低松驰预应力钢绞线，控制应力con=0.71860=1300N/mm2，超张拉1.03。无粘结张拉端锚具采用OVM151型，固定端采用挤压锚OVM151P型。工程由南通市建筑设计院设计，南通爱普达监理公司负责现场监理，启东市建筑安装工程有限公司总承包施工。该工程于2001年10月开工，2002年8月主体结构封顶。施工主要难点：在预应力张拉前，其混凝土硬化过程中不能产生收缩裂缝，以及140米预应力筋的铺放、张拉工艺要采取相应的措施进行控制。尤其是X向长达140米，不设伸缩缝，要求板内无
4、粘结预应力筋连续张拉。3 楼面混凝土施工方案施工前，曾考虑将楼面混凝土由两条后浇带划分为3个施工段施工，待楼面混凝土施工60天后进行后浇带浇筑，由于楼面Y方向的连续次梁内布置通长无粘结预应力钢绞线，设计要求混凝土强度达到设计值的100%方可张拉，然后才能拆除主、次梁下支撑，钢管、钢模和多层胶合板要积压60天，不仅影响了工期，而且模板不能及时周转。为了确保工期，加快材料周转，决定采用以下方案：（1）各层楼面以两道后浇加强带为界，分为3个施工段浇筑，留2条施工缝，每段混凝土浇筑间隔24天（详见主体结构阶段标准层预应力施工与土建配合施工的进度安排）；主体结构施工阶段标准层顶应力施工与土建配合施工的进
5、度安排（按土建约12天层）主要施工技术参数：有粘结预应力梁47根层，12t层；无粘结预应力板23t层；一、二、三层无粘结预应力量略大。（2）在混凝土中掺6%NEA膨胀剂；（3）在每层楼面设置两个1.5米宽Y向后浇加强带，加强带NEA膨胀剂掺量8%，带中和带外掺量不同，形成邻位限制条件，从而减少超长混凝土引起的后期收缩（即混凝土的收缩补偿得以完成），以防止混凝土产生收缩裂缝。并在加强带位置增加配筋。C40混凝土施工配合比表（按重量计）材料NEA水泥水砂石子防冻早强剂C40304642127859607.4加强带C40404542127859607.4(4)在段与段的施工安排上，应注意：a、 施工
6、中间区域，确保先张拉中间区域，在后浇带封闭并达设计强度后再张拉两端、区域。中间区域采用两端张拉，两端区域采用一端张拉。板内超长温度预应力筋分段锚固示意b、工期安排上尽可能使混凝土浇筑、预应力张拉选择在阴凉天气进行，一是有利于楼板在施工阶段不裂，二是有利于有效预应力的建立。预应力张拉采用“数层浇筑，顺向张拉”，按此顺序完成整个预应力分项工程的施工。3 楼面混凝土结构施工3.1 模板工程楼面梁板底模分3个施工段流水作业。采用48钢管作支撑，梁板采用18厚多层胶合板，下垫木格栅，梁底模支撑时，按规范要求1/10002/1000起拱。梁的张拉端采用塑料穴模。楼板的模板在大梁预应力张拉前拆除，梁底支撑在
7、主、次梁预应力张拉后拆除。3.2 钢筋工程3.2.1无粘结预应力钢筋施工工艺流程：清理下料场地放线下料编号修补成盘吊运梁钢筋绑扎（楼板底筋铺放）铺无粘结筋封模（绑扎楼板面筋）验收浇筑混凝土拆模张拉切筋封头3.2.2现场无粘结筋的制作无粘结筋的下料制作场地宜选在使用点附近，即无粘结筋进场时就应卸在下料地点，以减少场内运输。无粘结预应力筋下料长度为无粘结筋长度张拉端工作长度（每端300400毫米），成盘供应的无粘结筋（成盘重约1.5吨），在放线时应尽量减少破损。现场用砂轮切割机下料，挤压锚固系统制作时剥去不大于100毫米长外皮，穿入锚垫板后用专用挤压机挤压成型，要求尾部钢绞线外露，钢丝饱满。下料中
8、仔细检查无粘结个别破损处，及时用胶粘带封裹。下料时对不同长度的无粘结筋分类编号。3.2.3无粘结预应力筋铺放（1）纵向无粘结筋铺放工艺流程：搭满堂钢管支架铺板底模板 铺放短向的板底非预应力钢筋铺放长向的板底非预应力钢筋安装马凳钢筋按预应力筋布置平面图依次铺放无粘结筋 安装固定张拉端与固定端板内线管预埋绑扎板面钢筋安装板端模板作隐蔽工程检查（2）无粘结预应力筋布置要点a、无粘结预应力筋绑扎要求位置正确；b、板内预应力筋位于板厚中间，用马凳控制，当无粘结预应力设置间距较小时，可采用间距为1000马凳钢筋（直径12mm的级钢筋），马凳上电焊统长直径不小于14mm的级钢筋作为支架；如无粘结预应力筋设置
9、间距较大，可直接采用1000马凳作为支架。c、一般情况下各种管道应在预应力筋布置好铺设，并尽量为预应力筋让路。d、无粘结筋与锚垫板垂直。张拉端承压钢板与螺旋筋点焊固定，挤压锚的承压钢板与螺旋筋用扎丝固定。e、本工程预应力筋的张拉端采用凹入式构造（用塑料穴模）。安装时，穴模应紧贴板端模板，承压钢板要垂直，并与板内钢筋电焊固定。1、夹片2、锚环3、垫板4、螺旋筋5、无粘结筋6、穴模张拉端凹入混凝土表面单根钢绞线夹片锚具示意图f、隐蔽工程检查时，检查重点是无粘结筋塑料套管有无破损；无粘结预应力筋标高是否与设计要求一致；张拉端和固定端安装是否妥当，张拉端外露长度是否足够；无粘结预应力筋远看是否是一条直
10、线，检查后作好记录存档，立侧模前纠正。3.2.4楼面加强带处,单向板增加双向配筋,受力筋原设计10150,加强带处改为10100,分布筋原为6200,改为10120。3.3 混凝土工程3.3.1原材料。砂的细度模数、碎石的压碎指标值及含泥量都应符合规范要求，经试验合格后进场。NEA微膨胀剂、防冻早强剂及42.5级水泥均有出厂合格证。3.3.2混凝土搅拌。现场集中搅拌、泵送施工。配合比根据气候条件和施工要求先经过试配，防冻早强剂掺量根据气候情况和分段施工时间决定。3.3.3浇筑混凝土应注意以下几点：a、在浇筑混凝土之前，需再对无粘结筋数量和关键位置及埋入端锚具进行认真检查，发现问题及时纠正。b、
11、浇筑混凝土之前，应进行隐蔽工程检查、验收，并填写隐蔽工程检查验收单进行分项工程交接。c、浇筑混凝土时，严禁踩踏无粘结筋及触碰锚具，确保无粘结筋的束形和高度的准确。d、混凝土应振捣密实，尤其是张拉端和固定端的预埋承压垫板处不允许出现漏振和孔洞。3.3.4加强混凝土养护，夏季应防止水分蒸发、冬季应防冻。无论是夏季，还是冬季，楼层混凝土浇筑完成后，用彩条布或塑料薄膜满盖一层，再覆盖草袋一层，使混凝土起到保温养护作用。3.4 预应力张拉3.4.1预应力筋和锚具的选用预应力筋采用J15.2低松弛钢铰线，其标准强度为1860N/2。锚具采用OVM锚具。3.4.2预应力张拉 为确保预应力张拉值的正确建立，在
12、预应力张拉前对各套张拉设备在标准试验机上进行标定，给出各台设备的标定曲线。正常张拉中按施工规范要求，定期进行中间标定。浇筑砼后一定时间，砼达到能拆端模的强度时，先拆除端头模板，派人清理端部，拔去穴模的锥形前套，检查张拉端承压钢板上与锚环接触部位的砼是否清理干净等。按设计要求，砼强度达到设计标准值100%后方可进行张拉。预应力筋张拉控制应力con=1.030.7fptk（根据设计要求可适当张拉到5%）。预应力筋的张拉控制力Ncon=con.Ap。预应力筋的张拉程序为：00.2con（初读数）0.6con(中读数)1.03con(最后读数)。预应力筋的张拉伸长值按施工图和规范要求进行计算。张拉顺序
13、均注意对称张拉。张拉步骤：a、剥除张拉端承压钢板外露的塑料套管，清理端部，安装锚具夹片；b、张拉时采用应力控制，伸长值校核，具体操作为：穿入前卡千斤顶，张拉至初应力（0.2con）时的记录初读数，张拉至0.6con时记录中间伸长值，张拉至1.03con记录伸长值，卸载锚固；c、实际伸长值与计算伸长值偏差应在-5%+10%之内，否则应暂停张拉，查明原因并采取措施后方可继续张拉；d、锚具张拉回缩值应控制在5mm范围内。3.4.3锚具端头封闭张拉后的无粘结筋应立即进行封端保护，用手提式砂轮切割机切除张拉后多余的预应力筋，切割处离夹片不小于30mm。对留有穴模的凹槽先套入特制塑料盖帽，再用微膨胀混凝土
14、或低收缩防水砂浆密封。张拉后中间锚具用专用塑料封盖封闭3.5 大面积超长楼板预应力施工技术困难及对策。3.5.1纵向设置后浇带处预应力筋的接长张拉特点：纵向长达140m，不设伸缩缝，要求板内无粘结预应力筋连续接长张拉。对策：a、纵向分三段张拉，每段之间设1.5m宽的后浇加强带。先张拉中间段，待后浇加强带封闭并达到设计强度后张拉两端，两端张拉采用一端张拉。b、根据以往经验，对梁内无粘结预应力腰筋采用连接器接长。先张拉中间区域。后在锚具部位作连接结长，再分别张拉两侧区域。对于板内无粘结筋接长，考虑到数量较多，以及经济性，采用中间锚具在后浇带锚固预应力筋，用开口双缸千斤顶进行张拉。1、锚板2、工作夹
15、片3、连接套4、15挤压套5、15挤压弹簧连接器构造1、连接套管2、锚板3、连接套4、带油脂与塑料套管的钢绞线单根钢绞线的中间锚具1、连接套管2、锚板3、带油脂与塑料套管的钢绞线4、连接锚具5、连接套筒用套筒连接的中间锚具板内超长温度预应力筋中间锚具处安装示意图用23t开口双缸千斤顶对中间锚具进行张拉简图3.5.2超长束的预应力张拉由于预应力束长度超长，为增加连续跨中间跨的有效预应力，采用超张拉大回松技术，超张拉至0.75fptk，回松的锚具回缩量控制在10mm左右。115（英文版 ） easily blame, to prevent the broken window effect. Sup
16、ervise the leading cadres to play an exemplary role, take the lead in the strict implementation of the and , lead to safeguard the solemnity and authority of the party discipline, ensure that the party discipline and the laws and regulations for implementation in place. Throughout the discipline in
17、the daily supervision and management, strengthen supervision and inspection, from the thorough investigation of violations of discipline behavior. Strengthen to key areas, key departments and key projects as well as the masses reflect the concentration of the units and departments for supervision. -
18、 strengthening supervision, discipline inspection and supervision of cadres to set an example for compliance with the and is a man must be hexyl, blacksmith needs its own hardware. Discipline inspection organs as the executor of the party discipline, and supervisor of the defenders, for its supervis
19、ion must be more strictly, discipline inspection and supervision of cadres to firmly establish the awareness of Party Constitution, sense of discipline and rules consciousness, politics loyalty, sense obey. Action speak Ji Ordinance to set an example of the regulations of the rule of law, strengthen
20、 supervision and accept the supervision of the firmness and consciousness, do comply with and . To firmly establish the discipline must first be disciplined, the supervisor will be subject to the supervision of concept, and consciously safeguard and implement party compasses party, take the lead in
21、practicing three strict real strict, so loyal, clean, play. To be good at learning, the Constitution and the as morality, politics and brought to fruition; to implement , do not want to, dare not, not with disciplinary ruler to supervision; to discipline a ruler, often the control inspection, and co
22、nsciously in the ideological red line to draw the row Ming Good accumulation is indeed the bottom line, so that the heart has fear, said to have quit, the line has ended. Attached: indifferent to heart, calmly to the table in our life, there are many unpredictable things will happen, some good, some
23、 bad things, we cannot control is powerless to stop, but with time, you will find in life sometimes turns out to be not good, some bad things finally turned out to be a good thing, but then we muddy however did not know, this is the life teach us things. 1, life can be complex, can also be simple. W
24、ant simple life of precipitation, to have enough time to reflect, to make Become more perfect. Life is the most important thing is not to win, but the struggle; not to have conquered, but to have fought well. 2, the plain is the background of life. Live a plain life, give up on themselves is not a c
25、oward, but the wise answers; not disillusioned after the heart, such as ashes, but experience the storm after the enlightenment; not unrewarding perfunctorily, but calm attitude of life of unrestrained self-confidence. Plain living, there is no noise noisy, no earthly troubles, more did not fill in
26、the discontent of desire, some just a calm, a calm. 3, memory of heart will not good things to erase the, life is a When no movie, pain is a beginning, the struggle is a kind of process, death is a kind of ending. Give up this giving up is the helpless, do not give up the abandoned, do not give up t
27、his giving up is ignorance, do not give up should not give up is persistent. 4, a thing figured is heaven, think impassability is hell. Since the living, to live better. Sometimes we because of too narrow-minded, too care around the chores and penny wise and pound foolish, not worth the candle. Some
28、 things to attract trouble and worry, completely depends on how we look at and deal with it. Dont always take everything back to things, and dont get into a blind alley, dont want to face, dont be narrow-minded. Poke to care, is a kind of open-minded, a free and easy. 5, I am not afraid of others be
29、hind me a knife, I afraid to look back and see stab me, is my intention to treat people; I am not afraid of the truth to tell the best friend, Im afraid he turned to it as a joke to tell dont 6, when we are in a positive frame of mind, you will find many good things; and when we are in a negative st
30、ate of mind, you will find many depressed things; life happy and worry, all is you of life attitude, optimistic, good luck; loss of sink, Eritrea company. When you are in adversity, may wish to change a point of view to think everything over to the good Think, because good mentality decided the fate
31、 of the! 7, people are tired, rest; heart tired, calm. Grow up, mature, this society read. Tired and sad, squat down, to their a hug. Because the world no one can sympathize with you, have mercy on you. You cry, tears is your own; you pain, no one can understand. Then you only tears to smile. 8, eac
32、h people have youth,Each youth are a story, the life of the world never gets easier, I want what, wish the world all know, as has been the same; now want anything, for fear that others know, or like to lose the same. 9, the heart move, everything in the world is followed by birth, Rangrang, importan
33、t thing is often the most difficult to open ones mouth, because words will reduce its importance; to let strangers people care about your life in the good things, the original is not easy 10, do not blame, do not laugh at who, also dont envy who. Like a person is a kind of feeling, not like a person
34、 is true. The truth is easy to explain, I feel Is unspeakable. The best travel life is that you in a strange place found a long lost touched. 11, happy life not in the bustling in, and in the peace of mind; no matter how many grievances, how uncomfortable, and ultimately to heal themselves or their
35、own, others may got you to comfort, but never know your heart is how wanjianchuanxin. 12, maam, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and goodness, helping others. Instead of accusing the society, as into one; and an exception is better to give than to what 13, do
36、nt envy him A sum of, dont lose your life and the life, respectively is: the former is a we experienced cannot escape in a day finally will last minute, while the latter is our persistent, we want to cherish the memory of those people and things. 14, learn to smile, learn to strong, the world you kn
37、ow so many people, so many people and you are, you cannot change also cant let everyone like you, so also do not want to do. Life is too short to go crazy to love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their o
38、wn emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expensive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of w
39、isdom. 16, life is not perfect, sometimes, growth is not a cry, not an eyeful of tears, there is no trace of emotion, there is no gleam of hope, no desire, no action, no static, there is only one kind of downward sinking feeling, sink A murky? 6? 7? 6? 7 sink? 6? 7? 6? 7 toward the bottom of the sin
40、k. 17, in some way, do not go, you will not know the other side scenery is beautiful. To you is not good, you do not mind too much, no one has an obligation to you; you learn knowledge, is you have weapons, you can start from scratch, but not unarmed; how do you treat people, does not represent how
41、others treat you, if cannot see through this point, only inviting worry. 18, time is like a sponge in the water, as long as you are willing to squeeze, the total water is still there. Every life, after the ups and downs The best test of live, to life, survival and continuation, do not stop the strug
42、gle in the joys and sorrows of life on the road, so that different soul to bear life beat, acceptance of suffering. 19, indifferent to heart, calmly in table, elegant and comfortable life, do not take what is so important. The pursuit will be disappointed; to be alive, you will have trouble. Life is
43、 the most afraid of what all want to care about, but also what all grasp is not firm, without scenery, separated populations, such as not to desire, all docked in the fate of the end. Why is too rigid, the natural, to go stay not to live, let go of obsession, revel is 20, if the fate of the broken H
44、opes of sailing, please dont despair, the coast is still, if the fate of the withered petals of the beautiful, please do not sink, the spring is still, life will always be endless trouble, please dont helpless, because they are still alive, is still a dream, the sun still, we still. Lost, keep memor
45、ies; to get, must work to; but the most important is good to cherish their own. 21, life, select the complex, is to choose the pain; choose a simple, is choose to be happy. The complex world like aSignificance of pride. Hope is the ornate palace, outside people admiring the magnificent, living in th
46、e deep knowledge of living it to pay the price. Simple world as a simple log cabin outside ridiculed shabby, the heart is willing to go live to know the joy. Suffering and joy is their own choice. 22, learn how to use a single powerful heart, let the past be the past, let the future come. Life is re
47、ally the end of the end of an eagle is flying wings, life is constantly pursuit. Dont miss to regret, dont wait for old just miss. Time to return, seize every moment, again painstakingly again tired also Those struggling to fly. 23, life could not Yimapingchuan, even flat pavement, inevitably there
48、will be a few pieces of roadblocks. Some of the rocks around the past, while others have to move it out. Just move others put the stone is very easy, because the stone from the appearance we can discern; difficult to myself to move away the heart of stone head. Leave time to spend with her, often reflect my heart, so as to remove your heart of stone. 24, everything does not have t