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1、摘要：本文通过工程实例，介绍了长螺旋钻孔泵压混凝土后插筋灌注桩钢筋笼下放施工技术及该施工技术在实际操作中经常遇到的一些难点和相应的解决办法。 关键词：灌注桩；后插筋；施工技术 中图分类号：TU74 文献标识码：A 文章编号： 长螺旋钻孔泵压混凝土后插筋灌注桩是近几年发展起来的一种地基加固处理的新工艺，由长螺旋钻机和混凝土泵结合成孔、成桩，然后利用振动器将预制好的钢筋笼插入桩身混凝土中。该工艺具有施工速度快，效率高，无泥浆污染，工程造价低，环保等特点。 本文以某工程为例介绍了长螺旋钻孔泵压混凝土后插筋灌注桩施工工艺及影响钢筋笼下放深度的一些主要因素。 1、工程概况 某新建工程地上4层，地下1层，
2、为框架结构，独立基础，基础埋深5.0m，地基持力层为第层粉土。桩基采用钢筋混凝土灌注桩，设计单桩承载 力特征值400kN，施工桩长16m，设计桩长15.5m，桩端持力层为第层中砂，钢筋笼长13.0m，桩径600mm，桩身混凝土强度等级C25，共 布桩139根。本工程重要性等级为二级，场地等级为二级，地基等级为二级。 根据设计要求，桩端持力层为第层中砂。根据勘察报告可知，桩身需穿过第层粉细砂、第层细砂和第层中砂三层砂层。若采用干成孔、后灌注 工艺，在成孔过程中容易造成塌孔；而采用泥浆护壁钻孔灌注桩工艺，该建筑物场地又不具备施工条件，所以采用长螺旋钻孔泵压混凝土后插筋灌注桩工艺进行施 工。 2、工
3、程地质条件 地基土层分层见表1。 表1地基土层分层表 3、桩基施工 3.1施工前的准备工作 3.1.1制作振动锤 选用功率较大的振动电机，为了方便吊装，用钢板做套将振动电机包裹起来。选用直径100mm的无缝钢管（长度以能将钢筋笼下插到指定标高为准），将一头牢固的焊接在振动电机外套底部，另一头管口用钢板包裹加固。 3.1.2制作钢筋笼 钢筋笼按设计要求制作。制作完成后，钢筋笼最后一个加强圈以下的主筋应焊接在一起，焊接长度为10d，焊好后呈锥形，并在其内部焊一个直径为 100mm，高度为1cm的钢圈。此钢圈是振动锤振动下放钢筋笼的受力点。钢筋笼的第一道加强圈和最后一道加强圈需要加固，以保证在吊车吊
4、起和振动器振 动过程中钢筋笼不会损坏。 3.1.3连接、吊装 振动锤底部预焊挂钩，用钢丝绳将振动锤和钢筋笼连接在一起。将振动钢管穿入钢筋笼，吊车吊起就位。见图1。 图1钢筋笼制作及下放示意图 3.2施工工艺 3.2.1测放轴线、桩位 根据建筑物主要轴线及设计图纸，用钢卷尺施测建筑物各细部轴线。可用细白灰线标志于槽底。细部轴线测放完毕后，依据素混凝土桩平面布置图用钢卷尺施测桩位，桩位中心点用钢钎打入地下，深度宜取1020cm,并用白灰明示，桩位偏差小于160mm。 3.2.2钻机就位 派专人指挥钻机前后左右移动，使钻尖对准桩位白灰点，落钻及护桶，调整钻杆垂直度指针指正垂直度盘中线，确保钻杆垂直。
5、 3.2.3钻孔 钻机成孔过程中，应匀速钻进，避免形成螺旋孔。 3.2.4终孔至设计深度 钻孔前，在钻杆上明确标记成孔深度，待钻至成孔深度标记处，保持该钻进深度继续旋转钻杆12min。 3.2.5边提钻边灌注混凝土 钻机钻至设计深度后，先提钻1020cm再开始泵压混凝土，保证钻尖上的两个叶片能顺利打开。提钻速度应与泵压混凝土的速度协调一致，始终保持钻杆内存有2.0m左右混凝土为宜。 3.2.6下放钢筋笼 灌注混凝土至施工标高后，应立即下放钢筋笼。孔口四周应有专人把扶，钢筋笼垂直、对中下放。开始先靠钢筋笼的自重下放，当钢筋笼下放的速度放缓时，开启振动电机下放钢筋笼至设计标高。 2.2.7成桩 成
6、桩后做好现场保护工作，配合检测及下步施工。 3.2.8施工工艺流程 施工工艺流程图如图2所示。 图2施工工艺流程图 4、钢筋笼下放施工 该工程在施工过程中遇到的主要问题就是钢筋笼能否下放到设计标高，也是这一工艺的施工难点，钢筋笼下放深度由两个力决定，振动电机向下的振动 力和钢筋笼下放过程中遇到的向上的阻力。当下放过程中遇到的向上的阻力大于振动电机向下的振动力时，钢筋笼就不能下放到设计标高。下面就具体分析这两个方 面的影响因素。 4.1振动电机 施工前，应根据桩的设计参数来考虑所采用振动电机的功率。只有振动电机的功率足够大才能克服钢筋笼下放过程中遇到的向上的阻力。 4.2钢筋笼 钢筋笼在下放过程
7、中应保持垂直对中，避免钢筋笼上绑定的混凝土垫块保护层剐蹭孔壁加大钢筋笼下放的阻力。钢筋笼就位后，先靠钢筋笼的自重下 放，当钢筋笼下放的速度放缓时再开启振动电机下放钢筋笼至设计标高，这样做会减少钢筋笼振动的时间，避免钢筋笼底部的混凝土由于长时间振动而离析。这一过 程中与吊车司机的操作技术水平也有一定影响。 4.3混凝土 混凝土的塌落度应控制在2022cm，如果条件允许最好采用细石混凝土，粗骨料粒径控制在0.51.0cm，和易性良好，严禁离析。混凝土从搅拌到灌注间隔时间越短越好，否则造成混凝土塌落度损失，或伴有离析现象，会增大钢筋笼在下插过程中的阻力。 4.4灌注过程 泵压输送混凝土时，应首先泵压
8、1.0m3左右的水泥浆润滑管道。整根桩从初灌到灌注完成应一气呵成，避免间隔等料。灌注过程中若发生长时间不 能泵压混凝土，应及时拆卸混凝土输送管倒出管内混凝土，避免混凝土在管内凝固堵塞输送管道。这些措施都是为了保证混凝土的塌落度及和易性，尽量减小钢筋笼 下放的阻力。 5、结束语 长螺旋钻孔泵压混凝土后插筋灌注桩技术是在长螺旋钻孔泵压混凝土灌注桩工艺的基础上发展起来的，具有施工速度快，效率高，无泥浆污染，工程造价低，环保等 很多优点，本文通过工程实例介绍了该工艺在施工过程中的一些重点、难点及解决办法，为今后该工艺的施工提供了一定的实践支持。 参考文献: 1 JGJ94-2008.建筑桩基技术规范.
9、 2 DB11/T582-2008.长螺旋钻孔压灌砼后插钢筋笼灌注桩施工技术规程. 3 乔先兴，张威.长螺旋孔底压力砼灌注桩的应用J.土工基础，2006（5）. 4 吴彦明，长螺旋钻孔管内泵压CFG桩施工及质量控制J.山西建筑，2010. （英文版 ） Two regulations promulgated for implementation is in the party in power for a long time and the rule of law conditions, the implementation of comprehensive strictly strategi
10、c plan, implementation in accordance with the rules and discipline to manage the party, strengthen inner-party supervision of major initiatives. The two regulations supporting each other, the adhere to a positive advocate, focusing on morality is of Party members and Party leading cadres can see, en
11、ough to get a high standard; around the party discipline, disciplinary ruler requirements, listed as negative list, focusing on vertical gauge, draw the party organizations and Party members do not touch the bottom line . Here, the main from four square face two party rules of interpretation: the fi
12、rst part introduces two party Revised regulations the necessity and the revision process; the second part is the interpretation of the two fundamental principles of the revision of laws and regulations in the party; the third part introduces two party regulations modified the main changes and needs
13、to grasp several key problems; the fourth part on how to grasp the implementation of the two regulations of the party. and revised the necessity and revised history of the CPC Central Committee the amendment to the Chinese Communist Party members and leading cadres honest politics several guidelines
14、 and column 1 by 2015 to strengthen party laws and regulations focus. Two party regulations revision work lasted a Years, pooling the wisdom of the whole party, ideological consensus, draw historical experience, respect for the wisdom of our predecessors, which reflects the unity of inheritance and
15、innovation; follow the correct direction, grasp the limited goals, adhere to the partys leadership, to solve the masses of the people reflect a focus on the problem. The new revision of the and , reflects the partys 18 and the eighth session of the third, the spirit of the fourth plenary session, re
16、flecting the experience of studying and implementing the General Secretary Xi Jinping series of important speech, reflects the partys eighteen years comprehensive strictly practice. (a) revised two regulations of the party need of in based on revised, the promulgation and implementation of January 2
17、010, to strengthen the construction of the contingent of leading cadres play an important role. But with the party to manage the party strictly administering the deepening, has not been able to fully meet the actual needs. Content is too complicated, eight prohibition, 52 are not allowed to hard to
18、remember, and also difficult to put into practice; the second is concisely positive advocated by the lack of prohibited provisions excessive, no autonomy requirements; the third is banned terms and discipline law, both with the party discipline, disciplinary regulations repeat and Criminal law and o
19、ther laws and regulations repeat; the fourth is to clean the theme is not prominent, not for the existing problems, and is narrow, only needle of county-level leading cadres above. is in 1997 based on revision, in December 2003 the promulgation and implementation, to strengthen the construction of t
20、he party play very important role. Along with the development of the situation, which many provisions have been unable to fully meet the comprehensive strictly administering the practice needs. One is Ji law, more than half of the provisions and criminal law and other countries laws and regulations
21、Repetition; two is the political discipline regulations is not prominent, not specific, for violation of the party constitution, damage the authority of Party Constitution of misconduct lack necessary and serious responsibility to pursue; third is the main discipline for the leading cadres, does not
22、 cover all Party members. Based on the above situation, need to and the two is likely to be more relevant regulations first amendment. By revising, really put the authority of Party discipline, the seriousness in the party tree and call up the majority of Party members and cadres of the party consti
23、tution of party compasses party consciousness. (II) two party regulations revision process the Central Committee of the Communist Party of China attaches great importance to two regulations revision . Xi Jinping, general books recorded in the Fifth Plenary Session of the eighth session of the Centra
24、l Commission for Discipline Inspection, on the revised regulations made clear instructions. According to the central deployment, the Central Commission for Discipline Inspection from 2014 under six months begin study two regulations revision. The Standing Committee of the Central Commission for Disc
25、ipline Inspection 4 review revised. Comrade Wang Qishan 14 times held a special meeting to study two regulations revision, amendment clarifies the direction, major issues of principle, path and target, respectively held a forum will listen to part of the province (area) secretary of the Party commit
26、tee, Secretary of the Discipline Inspection Commission, part of the central ministries and state organs Department The first party committee is mainly responsible for people, views of experts and scholars and grassroots party organizations and Party members. Approved by the Central Committee of the
27、Communist Party of China, on 7 September 2015, the general office of the Central Committee of the Party issued a notice to solicit the provinces (autonomous regions, municipalities) Party, the central ministries and commissions, state ministries and commissions of the Party (party), the General Poli
28、tical Department of the military, every 3 people organization of Party of two regulations revision opinion. Central Commission for Discipline Inspection of extensive solicitation of opinions, careful study, attracting, formed a revised sent reviewers. In October 8 and October 12, Central Committee P
29、olitical Bureau Standing Committee and the Political Bureau of the Central Committee After consideration of the two regulations revised draft. On October 18, the Central Committee of the Communist Party of China formally issued two regulations. Can say, two laws amendment concentrated the wisdom of
30、the whole party, embodies the party. Second, and revision of the basic principles of two party regulations revision work and implement the partys eighteen, ten eight plenary, the spirit of the Fourth Plenary Session of the Eleventh Central Committee and General Secretary Xi Jinping important instruc
31、tions on the revised and , highlighting the ruling party characteristics, serious discipline, the discipline quite in front of the law, based on the current, a long-term, advance as a whole, with Bu Xiuding independent and . Main principle is: first, adhere to the party constitution to follow. The c
32、onstitution about discipline and self-discipline required specific, awaken the party constitution of party compasses party consciousness, maintaining the authority of the constitution. General Secretary Xi Jinping pointed out that no rules, no side round. Party constitution is the fundamental law, t
33、he party must follow the general rules. In early 2015 held the eighth session of the Central Commission for Discipline Inspection Fifth Plenary Session of the 16th Central Committee, Xi Jinping again pointed out that constitution is the party must follow the general rules, but also the general rules
34、. the revision of the and is Method in adhere to the regulations established for the purpose of combining rule of virtue is to adhere to the party constitution as a fundamental to follow, the constitution authority set up, wake up the party constitution and party rules the sense of discipline, the p
35、arty constitution about discipline and self-discipline specific requirements. 4 second is to adhere to in accordance with the regulations governing the party and the party. The Party of rule of virtue de, mainly refers to the partys ideals and beliefs, excellent traditional style. The revised the cl
36、osely linked to the self-discipline, insisting on the positive initiative, for all members, highlight the vital few, emphasized self-discipline, focusing on the morality, and the majority of Party members and the ideological and moral standards. The revised Ji method separately, Ji, Ji Yan to Method
37、, as a negative list, emphasizing the heteronomy, focusing on vertical gauge. Is this one high and one low, a positive reaction, the strict party discipline and practice results transformation for the integration of the whole party to observe moral and discipline requirements, for the majority of Pa
38、rty members and cadres provides benchmarking and ruler. Third, insist on to. In view of the problems existing in the party at the present stage, the main problems of Party members and cadres in the aspect of self-discipline and abide by the discipline to make clearly defined, especially the partys e
39、ighteen years strict political discipline and political rules, organization and discipline and to implement the central eight provisions of the spirit against the four winds and other requirements into Disciplinary provisions. Not one pace reachs the designated position, focusing on in line with rea
40、lity, pragmatic and effective. After the revision of major changes, major changes in the and modified and needs to grasp several key problems (a) adhere to according to regulations governing the party and party with morals in combination, for at the present stage, the leadership of the party members
41、 and cadres and Party members in existing main problems of self-discipline, put forward principles, requirements and specifications, showing Communists noble moral pursuit, reflected at all times and in all over the world ethics from high from low 5 common requirements. One is closely linked to the
42、self-discipline, removal and no direct relation to the provisions of . the second is adhere to a positive advocate, eight prohibition 52 are not allowed to about the content of the negative list moved into synchronization amendment . Three is for all the party members, will apply object from the lea
43、dership of the party members and cadres to expand to all Party members, fully embodies the comprehensive strictly required. The fourth is prominent key minority, seize the leadership of the party members and cadres is the key, and put forward higher requirements than the ordinary Party members. Five
44、 is to simplify, and strive to achieve concise, easy to understand, easy to remember. The revised is the ruling Party since the first insists on a positive advocate forAll Party members and the self-discipline norms, moral declaration issued to all members of the party and the National Peoples solem
45、n commitment. criterion of a clean and honest administration consists of 4 parts, 18, more than 3600 words. After the revision of the , a total of eight, 281 words, including lead, specification and Party member cadre clean fingered self-discipline norms, etc. Part 3 members low-cost clean and self-
46、discipline, the main contents can be summarized as four must eight code. Lead part, reiterated on ideal and faith, fundamental purpose, the fine traditions and work style, noble sentiments, such as four must the principle of requirements, strong tone of self-discipline, The higher request for 6 and supervised tenet, the foothold in permanent Bao the partys advanced nature and purity, to reflect the revised standards requirements. Members of self-discipline norms around the party members how to correctly treat and deal with the public and private, cheap and rot thrifty and extravagance bitter