用钢管桩对和贝雷片做现浇箱梁施工支架施工实践.doc

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11、y have learned, consciously study results into planning work, new ideas,钢管桩和贝雷片做现浇箱梁支架施工实践 钟本锋毕业论文毕 业 论 文钢管桩和贝雷片做现浇箱梁支架施工实践中铁二十三局集团第一工程有限公司钟本锋目 录1.引言32.现浇支架比较32.1军用墩与军用梁组合现浇支架32.2贝雷片和抱箍构成移动式支架32.3脚手架、万能杆件或军用墩与型钢支架42.4钢管桩、贝雷片和碗扣件支架42.5钢管桩与贝雷片支架 43.工程实例43.1工程概况43.2支架的设计和施工43.2.1贝雷桁架的设计53.2.1.1贝雷片的布置53

12、.2.1.2贝雷桁架的设计检算63.2.2贝雷片的安装和拆除63.2.2.1钢管桩支墩的设计63.2.2.2钢管的布置63.2.2.3钢管排架的设计检算73.2.2.4钢管排架的拆除83.3支架预压83.3.1预压施工及成果分析83.3.2对桁架的改进措施83.3.3预拱度设置93.4混凝土的浇注103.4.1混凝土的浇注顺序103.4.2沉降观测结果分析104.体会104.1主要优点104.2存在的不足和需进一步改进的问题11钢管桩和贝雷片做现浇箱梁支架施工实践中铁二十三局集团第一工程有限公司 钟本锋内容提要：在软弱地基上使用钢管桩和贝雷片做为现浇支架，避免了处理软基，克服了地基沉降对现浇箱

13、梁施工线形的影响；结合支架施工实例，着重介绍钢管排架和贝雷片组成的支架构造和施工。关键词：钢管桩和贝雷片 支架 实践1.引言在软弱地基上施工桥梁上部现浇梁、板，一般的施工方法是对软基进行加固处理，然后搭设满堂支架施工。由于软弱地基特殊的地质条件，地基处理难度较大；同时由于处理厚度的不均匀性，当填加施工荷载时，地基将可能出现不均匀的沉降，从而可能对混凝土的质量造成不同程度的损伤，对工程质量留下隐患。且地基处理为一次性投入，处理费用高，周转利用率低。随着工程技术的发展，人们在工程实践中摸索出减少或避免处理地基的施工方法，使支架越发安全可靠。2.现浇支架比较尽可能地利用既有墩台基础，以避免或减少处理

14、地基，根据使用器材的不同，在实践中逐步摸索出几种现浇支架模式，可用在软地基基础上。列举其中的部分结构形式如下。2.1军用墩与军用梁组合现浇支架支架基本形式见图1。军用梁承载力强，根据不同跨度在孔间设置支墩，可拼装出不同跨度的支架，但由于为制式器材，在器材型号不全时，跨度拼装将受到很大限制；军用梁自重大、对支撑墩和基础要求较高。该支架在青岛流亭立交桥、济青高速公路后刘立交桥等桥梁现浇梁施工中先后得到应用。2.2贝雷片和抱箍构成移动式支架利用贝雷片拼装成支撑横梁和纵梁，抱箍固定在桥梁墩身上，作为体系的承重构件，利用卷扬机拖动纵梁前移，实现可移动式现浇支架。见图2。该支架形式在广东肇庆大桥北岸连续箱

15、梁施工中得到应用。支架结构简单，受力明确，操作简便；缺点是适用跨度较小，适用于圆柱形墩，混凝土施工过程较复杂。2.3脚手架、万能杆件或军用墩与型钢支架用脚手架或万能杆件搭设支墩，采用型钢组成作为现浇支架，根据型钢的不同型号可根据要求做成不同跨度的支架。较常用的支架跨度一般在6M左右，跨度较大的可用至9M。结构形式见图3。使用较灵活，但支墩基础较密，处理费用相对较高。2.4钢管桩、贝雷片和碗扣件支架利用钢管将贝雷片架立地面，然后在贝雷架上支立碗扣件，构成支架。该种支架利用贝雷片代替地基处理，材料周转利用率高，适用性强，安全可靠，但材料投入较大。结构形式见图4。2.5钢管桩与贝雷片支架 图 4根据

16、现浇构造物的高度，将钢管桩制作成排架形式，做为支架的支撑墩，上部用贝雷片拼装成连续梁式桁架。用固定在贝雷片主弦杆上的方木做标高调整构件。该支架的特点是：支架材料投入少，重量轻，施工机械化程度高，适用的跨度相对较大。结合工程实例对该种支架重点介绍。3.工程实例3.1工程概况通启高速公路陈桥互通立交主线桥，位于江苏省南通市，地处长江三角洲冲积平原，地层为第四系全新系统及上更新系统，表层分布1.56.5M厚的软塑状亚粘土，下卧软塑状亚砂土，软土地基多埋藏在地表下10M以内，地基承载力较差。大桥上部结构为现浇连续箱梁，分左右两个半幅。箱梁为单箱双室断面，标准断面尺寸见图5。桥墩高度为611M。跨径20

17、M， 基础为桩柱式柔性墩。 3.2支架的设计和施工 钢管支架设计主要要解决两方面的问题：一是临时支墩的结构形式，二是由贝雷片组成的桁架整体强度、刚度和稳定性。下面着重就这两方面的问题进行分析探讨。使用的主要材料为：直径273 mm，壁厚6mm的钢管；321型的贝雷片（高1.5M，每节长3.0M）。3.2.1贝雷桁架的设计现浇支架的整体布置形式见图6。图63.2.1.1贝雷片的布置贝雷片的结构布置形式见图7。沿箱梁横断面方向设置9道贝雷片，均匀布置。桁架顶部横向布设1012CM的方木，间距30CM，用铁丝或铁钉与贝雷片主弦杆绑扎牢靠（预先在贝雷片主弦杆上绑扎调整方木）；方木在箱室肋部加密一半，间

18、距为15CM；方木长度为3M交错布置，并使位于同一贝雷片上的方木接头不超过通过该贝雷片方木总面积的50%，做为底模板横肋，兼做贝雷片的上水平联；沿支架纵向每2.8M设置横向钢结构连接系一道，以保证9道贝雷片整体受力。为保证贝雷片的整体稳定，在位于箱梁两外侧竖肋的三片桁架底部用758角钢与横向连接系焊接，组成下水平联。见图8。3.2.1.2贝雷桁架的设计检算施工荷载主要由钢筋砼自重q1、模板自重q2、贝雷桁架自重q3、施工荷载q4构成。支架承受的总荷载为：q=q1+q2+q3+q4 =229.5KN/m。强度检算 贝雷架纵向布置形式为间距6米和14米间隔布置的连续梁，最不利情况发生在14米跨度内

19、混凝土全部浇注完成，其它跨径内没有荷载时。按简支梁计算。则最大弯距：Mmax=qL2/8=229.5142/8=5621.5KNM，单片贝雷架承受最大弯距（按荷载横向均匀分布计算，不考虑不均匀分布系数）：M=Mmax/9 =5621.5/9=624.6 M=975 KNM,满足要。挠度检算因贝雷片每节结构形式相同，可看作匀质梁，并以简支梁模型检算，最大挠度为：f=（5/384）qL4/（EIIx）=(5/384)229.514004/（2.11062505009）=2.4cmL/400=1400/400=3.5cm满足施工要求（其中贝雷架的惯性矩Ix=250500cm4）。3.2.2贝雷片的安

20、装和拆除将每5片贝雷片拼装成整体桁架，用16t吊车起吊就位；一联全部贝雷片安装完毕，加设横向支撑、上平联和下平联。贝雷桁架采用整体落架法拆除。在贝雷桁架的底部（近支墩处）各设一根横梁，横梁用20T手拉葫芦悬吊在箱梁翼缘板承托上（在承托上预留悬吊孔），落架时先拆除支墩，再拆除桁架的平联，拔掉贝雷片间的连接销子，松动手动葫芦贝雷桁架脱模下落。3.2.2.1钢管桩支墩的设计支墩排架的基本结构形式见图9。3.2.2.2钢管的布置主要解决的问题是：在保证每排排架承载能力的前提下，保证钢管桩的整体稳定性和抗倾覆能力。具体措施：钢管桩顶部与工字钢焊接牢靠，底部与预埋钢板焊接，沿钢管高度方向每4M用14焊接一

21、道横向连接撑，构成一个排架；将同一个承台上的两个排架顶部用14连接，形成上平联，两排间用3道14连接成人字撑。使两个排架形成一个受力整体，增强抗倾覆能力。3.2.2.3钢管排架的设计检算9.003.381.6943.381.11.1按如下不利条件假定荷载:每两个排架承受跨度为23M的箱梁钢筋砼重量,并按简支梁模型计算支反力。作用在排架上的荷载构成如下：钢筋砼重力q1、工字钢自重q2、其他荷载q3，则每个排架承受的总荷载为：P= q1q2q3=2645.5KN由于每个排架承受的总荷载由9道贝雷片均匀分部在工字钢上，每处荷载为：q=P/9=294KN。荷载布置如图10。将每个排架看作刚架计算,并按

22、钢管最大高度9.0M计算。上述刚架为对称刚架,取一半研究，采用力矩分配法计算。 图10。CDCGCBBCBFBA14.9 -33.3 0.7 32.5 129.2 -3.3 -125.97.3 -7.3-0.5-0.5 0 -0.90.1 2.7.-2.8-0.4 0 -0.91561.5 31.1-2.5-4.9 0.2 9.8-30.129.7 0.7 29.7-60.1-60.1 -2.9 -120.259.25.7 118.3124-124GFEDCBAAEAB0.0460.9540.3280.0160.6560.4940.0120.494-5.1 -0.2 -10.3-5.21.32

23、.6 0 2.61.31.414.916.2I45b工字钢转动惯量为:I1=33.7591074; 273,壁厚6钢管转动惯量为:I2=44.848106,材料相同为A3钢,弹性模量相同。计算各节点的分配系数、计算过程见图11。图11固端弯矩MAB=-ql/8=2943.375/8=-124KNM,MBA=-MAB=124KNM由各节点的弯矩和外力,根据力矩平衡可得节点剪力;由计算出的剪力,根据节点力的平衡原理可得各杆的轴力（压力）如下:NAE=405.6KN, NBF=571.4KN,NCG=170.8KN, N中=351.8KN钢管强度检算：取压力最大杆件BF,杆件自由长度为4M，视为两端

24、铰接杆，其柔度=L/r=14000/94.4=42.4 查表可得=0.89，则钢管桩的稳定强度为：= N/(A)=571.4103（5030 0.89）=127.6MPa=170 MPa满足要求。钢横梁检算：钢横梁实际有7个支点，按5个支点计算。其中5道贝雷架架设在钢管桩桩顶，其余4道架设在跨中，钢横梁为4跨连续梁,查表得:Mmax=(0.1998-0.0368+0.0101-0.003)Pl=168.8KNmW=M/W=1206cm3 W I45b= 1500.4cm,故选用45b工字钢满足施工要求。3.2.2.4钢管排架的拆除为保证排架受力的整体性，不使用砂箱等落架构件，采用直接割除钢管落

25、架。具体做法是：将排架顶部的工字钢用钢丝绳和手拉葫芦吊在桁架上，用气割将钢管根部与预埋件割开，慢慢放松手拉葫芦将排架拆除，整体移至另半幅。3.3支架预压3.3.1预压施工及成果分析加载采用周围围砂袋中间装散砂的方法，模拟施工荷载。因砼分两次施工，预拱度参照支架在箱梁80%自重时产生的变形设置。加载前，沿模板纵横向每5M开设4040CM活动孔一个，预压结束时将运输车开到活动孔处，将砂子直接泄至车内。加载总重量为23M跨度箱梁自重。沉降观测结果见表1。可以看出实测弹性变形与计算值基本相符，但在支架跨中出现了不均匀沉降，需进一步采取加固措施。3.3.2对桁架的改进措施通过预压观测成果分析，跨中出现了

26、横向不均匀沉降。由于贝雷片跨中所受的弯矩较大，荷载出现了横向不均匀分布，原设计的横向加固结构未达到预想效果。为保证箱梁的线形，防止混凝土开裂，在桁架的中部增设4根16的型钢，间距1.0M，以加强跨中的横向分布刚度。见图七。3.3.3预拱度设置根据支架实际情况和预压成果，预拱度设置分为6M和14M跨两部分，考虑不可预料的因素及箱梁的外形美观，将预拱值提高35mm，跨中最大值设置为25MM。并按抛物线分配，见图12： 沉降观测结果 表1观测点编号荷重0荷重80%沉降量卸载后非弹性变形弹性变形观测值观测值观测值0左12.78212.778412.78022中12.87212.868412.87113

27、右12.97112.967412.967400.25L左12.70512.6852012.701416中12.78612.7662012.781515右12.89912.8801912.8936130.5L左12.63312.6102312.628518中12.73912.7083112.731823右12.83712.8162112.8325160.75L左12.53312.5181512.530312中12.62312.6081512.624015右12.73512.7201512.730510L左12.44712.442511.44705中12.53712.530712.53434右12

28、.64012.635512.63732L+3米左12.40112.399212.40011中12.49612.492412.49422右12.59312.587612.591243.4混凝土的浇注3.4.1混凝土的浇注顺序现浇箱梁分段施工，每段分两次浇注。为有利于支架的受力、减小支架变形，每段混凝土浇注顺序为：纵向从每段的起点向终点浇注；横向从起始跨的中间腹板和底板向两侧对称浇注。3.4.2沉降观测结果分析 在混凝土浇注过程中，观测支架变形，测量成果见表2。可以看出跨中最大沉降量为22mm，小于预拱值3mm，横向不均匀沉降最大为3mm。从拆模后的箱梁底板外观看，线形顺畅、美观，达到预期要求。按

29、预拱值25mm设置正确、可靠。 支架变形观测成果 表2观测点编号浇筑一次砼前第一次砼浇筑后沉降量（）第二次砼浇筑前第二次砼浇筑后沉降量（）最终沉降量（）观测值观测值观测值观测值0.25L左136921368661368613678814中135941358771358013571916右1350713501613498134908140.5L左1378213774813774137631119中13694136841013682136711121右135961358610135841357212220.75L左1386013855513854138441015中1344113435613435

30、13427814右1365913655413656136451115L左13726137233137231372036中13689136872136881368446右137111370921371013707354.体会4.1主要优点利用钢管桩和贝雷片做现浇支架，直接利用既有承台作为支架的支撑基础，不需处理地基，避免地基沉降带来的影响，节约了投资，提高了材料的回收利用率。将主要受力构件加工成大块，用机械吊装，提高了机械化作业程度和工效，节省了时间。整体落架法拆除桁架，不仅减少了高空作业量，保障了施工安全，而且提高了工效。直接利用固定在贝雷片主弦杆上的方木代替钢管调整高程，节约了投入。4.2存

31、在的不足和需进一步改进的问题钢管的接长和拆除，全部采用电焊、气割，现场焊接工作量大，对操作工人的要求高，且对钢管质量有损伤。改进措施：将钢管分段加工成型，根据需要组拼。由于贝雷片采用非标准间距布设，横向及底水平连接主要采用了焊接方式，现场焊接量大，工效低。改进措施：改焊接为栓接。参考文献：刘宗禄.流亭立交桥连续箱梁施工技术总结.铁道建设优秀论文选编.中国铁道建筑总公司1991-1993.黄绍金.刘陌生.装配式公路钢桥多用途使用手册.张克治.后张预应力连续箱梁施工.京福高速公路论文集.new measures to promote work, the courage to take respon

32、sibility, dare to break hard to ensure district, Government decisions and arrangements to implement. (B) strengthening supervision, severely punish acts of violation. One is to open the channels of supervision. Vigorously promote the party affairs public, open, widely accepted supervision by the mas

33、ses, pay attention to social groups and public opinion supervision, the powerful force formed to urge party members and leading cadres properly exercise their powers. Second, strong supervision and inspection. Democratic life into full play, important briefings, reports related to personal matters a

34、nd evaluation of cadres study of inner-party supervisory system, a comprehensive grasp of guidelines for the implementation of the independent Commission against corruption-related cases of leading cadres of party members, focus on strengthening key areas of project selection, funding, officials mon

35、itor, detect and rectify the problem, promote honesty in politics. Third, strengthen disciplinary investigation. Seriously the implementation of JI .Recently, the County leading bodies at the county level to carry out three trees practice, which is to improve the governing ability and promoting the

36、development of XX effective measure. I carefully follow your deployment requirements, and actively participate in the three trees campaign. Read Group, prepared by the Department in the near future of the ideological and political construction of leading cadres in the city reader, read the relevant

37、information, larger harvest, inspired. I think the ability of repelling is to strengthen the partys governing capacity in questions of the construction of meaning, an important topic remains in front of party members and cadres at all levels, we need to further explore and ponder. The ability of rep

38、elling the name suggests, is asking party members and cadres at all levels in particular, leading cadres at all levels, not only ourselves, establish a correct concept of the independent Commission against corruption, political integrity, self-discipline, rejection of corruption, made for the people

39、, pragmatic, honest leadership, and strengthen the sense of responsibility, earnestly implement the responsibility of uncorrupted, implementation of the baolian anti-corruption measures to ensure the realization of business-building, construction of a win-win situation. Next, I combined with their t

40、hinking, experience and contact XX practical, on how to enhance the ability of repelling, on four aspects of cognition. Irregularities, please comment. First, the construction of the propulsion system, and enhance the system of corruption since the founding of our party, have been thinking about tac

41、kling corruption. Currently, democratic legal system, management system and supervision mechanism is not perfect, administrative acts are not very standardized, Enterprise behavior and market behavior, corruption presents a diverse, pluralistic, complex trends, this shift the struggle between the two, will accompany第 11 页 共 12页