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1、城市桥梁桩基利用钢护筒跟进穿透流砂层施工技术李洪松 曹志毛（中建三局建设工程股份有限公司 湖北 武汉430070）摘要 介绍了城市桥梁桩基在遇到流砂层的一种施工工艺，桩基在遇到流砂层时，通过钢护筒跟进的方式完成桩基施工，在施工过程中未发生塌孔现象，保证了桩基质量，确保了施工进度。关键词 城市桥梁；流砂层；护筒跟进；施工进度0 前言桩基是一种古老的基础形式，历经几千年的发展施工技术趋于成熟，目前桥梁工程主要采用灌装桩。灌注桩施工主要难点是如何克服深淤层、流砂层、溶洞等不良地质情况，保障桩基质量和进度。根据武汉市中北路延长线工程的地勘资料局部区域存在细粉砂层，对此我司根据现场实际情况，借鉴其它工程
2、施工经验，采用钢护筒跟进穿透细粉砂层（流砂层）的施工工艺，保证了桩基质量，确保了施工进度。1 工程概况1.1 项目简介中北路延长线工程位于武汉市杨春湖城市副中心、东湖风景区北侧，西起二环线红庙立交以东，东至三环线青化立交西侧，设计道路长度4.77km。其中本标段起止桩号为k0+169.939k1+458，主线桥桥长1074m，共174根桩基，流砂层主要出现在22#24#墩位处，共计12根桩基，原设计桩长为45米，实际施工长度为52米。1.2 地质状况据场区地质资料，可以将沿线场地地层自上而下分为：耕植土，松散，厚度0.51.2m；淤泥质粘土，软塑，厚度1.02.2m；粉质粘土，可塑，2.12.
3、8m；细粉砂，流塑，厚度2.24.1m；残积土，可硬塑，厚度3.14.2m；粘土，硬塑，厚度1115m、粗砂，密实，11.316m；强风化泥质粉砂岩，硬，3.116.8m；强风化砂砾岩，硬，2.220.8m；中风化泥质粉砂，坚硬，1.125.6m；微风化泥质粉砂岩，坚硬，厚度1.419.4m。1.3 施工难点（1）工期紧，任务重本标段共计174根桩基，业主要求在50天内完成，平均每天施工3.5根桩基。（2）施工组织难度大城市桥梁工程其施工场地狭小，桩基施工机械相互制约较多，做好施工组织，协调好每根桩基施工时间确保施工进度。（3）质量目标高本工程要求创武汉市市政工程银杯奖，桩基施工时，在各道施工
4、工序过程中要求严格控制施工质量，确保达到武汉市市政工程银杯奖要求。（4）文明施工目标高本标段位于武汉市市区内，对施工噪音、渣土、泥浆等要求严格控制，避免因泥浆污染城市道路影响市容。2 方案选比由于桩基需要穿过细粉砂层，且粉砂层呈现流塑状，含水量大，无约束呈流动状态，目前可选的施工工艺有以下几种：（1）冲击钻钻孔，钢护筒跟进法先埋设钢护筒，随着冲击钻机的深入，同时下沉钢护筒，直至穿透细粉砂层下2米。该方法可以有效的防止流砂、塌孔；但冲击钻成孔效率低，施工工期，无法满足施工要求。（2）旋挖钻钻孔，钢护筒跟进法先埋设钢护筒，随着旋挖钻机的深入，同时下沉钢护筒，直至穿透细粉砂层下2米。该方法可以有效的
5、防止流砂、塌孔；且保障了成孔效率，施工工期及桩基质量都满足要求。（3）冲击钻钻孔，抛填片石和黏土加固法随着冲击钻钻孔的深入，在细粉砂层中抛填片石和黏土加固的方法进行施工，该方案施工控制较为困难，施工效率低，且噪音较大。根据该工程地质实际情况，经专家论证比较，选用施工第2方案。3 工艺机理在桩基孔位上埋设钢护筒，护筒定位后，旋挖钻机就位钻头对中，旋挖钻钻进，同时钢护筒跟进，直至穿透细粉砂层（流砂层）2m后停止钢护筒跟进。待桩成孔后，安放桩基钢筋笼，浇筑混凝土。其成孔后的状况如图1所示。图1 钻孔桩成孔图4 施工方法4.1 工艺流程施工工艺流程图如图2所示。图2 桩基施工流程图4.2 施工准备（1
6、）钢护筒制作：钢护筒按设计尺寸在钢结构加工厂内制造，使用12mm厚钢板卷制，钢板的卷制方向应与钢板的轧制方向一致。钢护筒焊接采用二级双面坡口焊，相邻两节钢护筒的纵缝错开90；每节钢护筒制作长度为2m；垂直度偏差不大于3mm，总垂直度偏差不大于5mm。（2）混凝土配合比的选配：严格按照施工设计图纸及规范要求进行混凝土的试配其坍落度控制在180220mm之间。（3）场地平整：本工程桩基桩位基本位于原道路的绿化带内，施工前应先清除地表杂物，平整场地。4.3 施工要点按设计桩孔位置，先埋设好第一节钢护筒，再把旋挖桩机定位并复核，确定无误后开始进行桩基施工，主要施工要点如下：4.3.1 导向架的设置护筒
7、跟前应设置护筒跟进导向装置，以防止钢护筒跟进过程中，桩位放生倾斜，影响桩基成桩质量。导向装置高1m，其外边框采用18#工字钢，切线边框采用10#工字钢，同时利用木枋来调节和限位钢护筒。桩机钻进前把导向平台定位并固定好，护筒跟进时利用导向平台控制好护筒跟进的垂直度，待护筒穿透流砂层后，移走导向平台。导向平台具体形式见图3。图3 钢护筒导向装置示意4.3.2 钢护筒跟进采用旋挖钻机进行桩基钻孔工作，钻孔每挖深2m即进行钢护筒跟进工作，同时辨别土质情况。当发现刚进入流砂层时，停止钻进，采用DZ90型振动锤振动下沉，先点振，再连续振动，下沉深度根据详勘确定，以确保穿透流砂层下2m为准则。待完成护筒跟进
8、后，在继续进行钻孔工作，直至成孔。钢护筒采用焊接连接，并加设缀板以提高其抗剪能力。4.3.3 清孔（1）桩基成孔后应及时进行检孔工作，主要检查孔径、垂直度、孔深等项目；确认满足设计要求后，及时进行清孔，采用注入纯度较高的化学泥浆，置换出孔内的钻孔泥浆，保证清孔后的各项指标符合现场实际地质情况的需要。（2）待钢筋笼安装、导管安装就位后，利用导管进行二次清孔，直至达到设计要求。4.3.4 钢筋笼的制作和吊装（1）钢筋制作在钢筋加工棚制作，材料堆放分类标示清楚，钢筋原材及钢筋笼应架离地面并有防雨棚。（2）钢筋笼制作前，钢筋原材应按规范要求进行送检，经检验合格后，方可投入使用；钢筋笼在钢筋笼加工场地分
9、段预制。（3）钢筋笼入孔后，牢固定位；钢筋笼与护壁应有一定空隙，以保证钢筋保护层厚度要求。（4）下放钢筋笼时，要稳定缓慢下降，避免摆动碰撞孔壁，造成塌孔。（5）钢筋笼间采用滚轧直螺纹连接。4.3.5 灌注水下混凝土（1）灌注过程中应注意管内砼下降和孔口的返水情况，用检验后的测绳及时测量孔内砼面标高，正确指挥拆管、提管。每次拆管前，应反插12次，保证孔内砼密实，并保持导管埋深26m。（2）灌注开始后应紧凑地连续不断进行，防止先灌注混凝土初凝后再续灌混凝土。如出现交通堵塞等原因导致混凝土不能连续供应，则采取应急措施，（3）为确保桩顶质量，根据设计要求保证混凝土的超灌量。5 结束语（1）本工程通过护
10、筒跟进的方式，顺利的施工了存在流砂层地质的桩基工程，有效的防止了坍孔，缩孔和流砂现象的放生。（2）该施工工艺简单易于操作，桩基成孔速度快，作业时间大幅度的缩减，保证了工期进度。（3）该方式同样可供深淤泥层、溶洞等不良地质条件施工借鉴。参考文献1 JGJ94-2008 建筑桩基技术规范2 周建新.温福铁路福田特大桥桩基穿过中细流砂层的钻孔桩施工技术，铁道建设技术，2007（增）3 赵红专.钢护筒二次跟进在深水桩基施工中的应用，铁道建设技术， 2007（5）4 CJJ2-2008 城市桥梁工程施工与质量验收规范作者简介李洪松，中建三局建设工程股份有限公司工程总承包公司，13986281240曹志毛
11、，中建三局建设工程股份有限公司工程总承包公司，18627024326（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 strategic plan, implementation in accordance with the rules and discipline to manage the party
12、, 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, enough to get a high standard; around the party discipline, disciplinary ruler requireme
13、nts, 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 first part introduces two party Revised regulations the necessity and the revision proce
14、ss; 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 to grasp several key problems; the fourth part on how to grasp the implementation of t
15、he 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 and column 1 by 2015 to strengthen party laws and regulations focus. Two party regula
16、tions 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 innovation; follow the correct direction, grasp the limited goals, adhere to the party
17、s 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, reflecting the experience of studying and implementing the General Secretary Xi Jinping
18、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 2010, to strengthen the construction of the contingent of leading cadres play an import
19、ant 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 remember, and also difficult to put into practice; the second is concisely positive ad
20、vocated 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 other laws and regulations repeat; the fourth is to clean the theme is not prominent, n
21、ot 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 the party play very important role. Along with the development of the situation, which
22、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 Repetition; two is the political discipline regulations is not prominent, not specific
23、, 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 cover all Party members. Based on the above situation, need to and the two is likely
24、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 constitution of party compasses party consciousness. (II) two party regulations revision pro
25、cess 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 Central Commission for Discipline Inspection, on the revised regulations made clear instruct
26、ions. 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 Discipline Inspection 4 review revised. Comrade Wang Qishan 14 times held a special meetin
27、g 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 committee, Secretary of the Discipline Inspection Commission, part of the central ministries
28、 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 Communist Party of China, on 7 September 2015, the general office of the Central Commi
29、ttee 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 Political Department of the military, every 3 people organization of Party of two regulati
30、ons 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 Political Bureau Standing Committee and the Political Bureau of the Central Committee A
31、fter 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 the whole party, embodies the party. Second, and revision of the basic principles of t
32、wo 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 instructions on the revised and , highlighting the ruling party characteristics, serious disc
33、ipline, 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 constitution about discipline and self-discipline required specific, awaken the party c
34、onstitution 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, the party must follow the general rules. In early 2015 held the eighth session of the C
35、entral 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. the revision of the and is Method in adhere to the regulations established for the p
36、urpose 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 party constitution about discipline and self-discipline specific requirements. 4 second
37、 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 closely linked to the self-discipline, insisting on the positive initiative, for all mem
38、bers, 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, as a negative list, emphasizing the heteronomy, focusing on vertical gauge. Is this
39、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 Party members and cadres provides benchmarking and ruler. Third, insist on to. In view o
40、f 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 eighteen years strict political discipline and political rules, organization and discip
41、line 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 reality, pragmatic and effective. After the revision of major changes, major changes in t
42、he 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 and cadres and Party members in existing main problems of self-discipline, put forwar
43、d 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 self-discipline, removal and no direct relation to the provisions of . the second is a
44、dhere 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 leadership of the party members and cadres to expand to all Party members, fully embodies
45、 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 is to simplify, and strive to achieve concise, easy to understand, easy to remember.
46、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 solemn commitment. criterion of a clean and honest administration consists of 4 parts, 18,
47、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-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 styl