钻孔咬合桩地下工程围护结构的新型式

1、钻孔咬合桩地下工程围护结构的新型式钻孔咬合桩是指平面布置的排桩间相邻桩相互咬合(桩圆周相嵌而形成的钢筋混凝土“桩墙”,它用作构筑物的深基坑支护结构,由我国地下工程界知名专家王振信教授在国外考察时发现,并将其引进到国内推荐给国内地铁工程。目前经过大量的工程实践,钻孔咬合桩在国内已成为一项十分成熟的支护结构施工技术。其显著优点是工程造价在同等地质条件下较低,一般比连续墙降低41%左右,比人工挖孔桩降低20%左右。由于钻孔咬合桩的钢筋混凝土桩与素混凝土桩切割咬合成排桩围护,因此对基坑开挖的防水效果也较好。Drilling occlusive piles is refers to the layout

2、 of the row between adjacent piles, interlocking (pile embedded circular phase and formation of the reinforced concrete pile wall, it is used as the structure of deep foundation pit supporting structure, the underground engineering in our country well-known expert professor Wang Zhenxin investigatio

3、n found abroad, and its introduction to the domestic recommend to domestic metro projects. Now after a great deal of engineering practice, the drilling occlusive piles in domestic construction of retaining structure has become a very mature technology. Its significant advantage is cost low, under th

4、e same geological conditions, generally about 41% lower than the continuous wall, about 20% lower than the artificial dig-hole pile. Due to the drilling occlusive piles reinforced concrete pile with plain concretepile cutting row piles retaining and so on excavation of the waterproof effect is bette

5、r also.At present domestic drilling occlusive piles of pore forming machinery MT series in addition to the introduction of Japan and Italy GC series casing drill, homebred MZ series casing drilling machine can satisfy the vertical degree of more than 0.3% of the engineering requirements. MT series d

6、rill by the host. Grab. The hydraulic system. The sleeve and so on, and by 50 t crawler crane to cooperate to complete drilling. The unearthed. Reinforcing cage and concrete pouring process; Z series drilling rig is MT type of portable, this machine can't complete work, unearthed from additional

7、 configuration of crane to complete the unearthed. The reinforcing cage, etc.钻孔咬合桩施工工艺为:施工准备.场地平整桩位测量放样施工咬合桩顶砼导墙磨桩机就位对中旋挖钻机沿平台走行就位对中吊装安放套管控制垂直度压入套管.校核垂直度旋挖取土套管钻进测量孔深清除虚土检查孔底检测桩整体垂直度。Drilling occlusive piles construction technology for: construction preparation. Field leveling measuring lofting, the

8、construction bite - pile cap concrete pile mill guide wall - to - rotating drill in place along the platform go on the line in place of lifting - control verticality - pressure into the casing pipe was laid. Check perpendicularity, spin dig earth casing drilling, hole depth measurement, clear XuTu i

9、nspection hole bottom - testing pile verticality.钻孔咬合桩作为地下工程的围护结构,一般情况下桩的数量较多,且需通过桩间咬合来保持其整体连续性.密闭性,单机作业难以满足工程进度要求,往往需采用多台钻机分区段施工,各区段自成一小段咬合排桩单元,单元间再利用节点实现咬合连接,由此能保持各单元钻孔咬合桩的整体连续性.密闭性。分区段施工成桩顺序如下图所示其成桩顺序为:A1A2B1A3B2A4B3,其中:Drilling occlusive piles as the palisade structure of the underground enginee

10、ring, in general the number of piles, and through the occlusionbetween pile in order to keep the overall continuity. Impermeability, stand-alone operations meets the requirement of construction schedule, often need to use more than one drill partition period of construction, the pile section a littl

11、e bite its own unit, recycle node implementations bite connection between the units, which can maintain the overall continuity of unit drilling occlusive piles. Closure. Partition construction pile pile order its sequence as shown in the figure below: A1, A2, B1 - A3 - B2 - A4 - B3. , including:A桩桩身

12、为超缓凝素混凝土灌注桩或异型钢筋笼(咬合体部分无钢筋混凝土灌注桩;A pile, the pile as super retarding plain concrete pile or deformed reinforcing cage (bit fit part of the unreinforced concrete filling pile;B桩标准钢筋笼混凝土灌注桩;B - standard of pile reinforcing cage concrete filling pile;钻孔咬合桩的质量控制要点:Drilling occlusive piles quality contro

13、l points:1. The drilling occlusive piles should be done before the formal construction try into the hole (quantity not less than 2, in order to check the geological data. Test equipment. Process and technical requirements is suitable. Hole casing down, if encounter GuShi, with cross impact hammer af

14、ter blunt ZaJi ground, first press again just the casing to the designed position.2.为控制桩的垂直度,首先钻机架立平整.稳固,套管中心与设计位置偏差控制在1cm以内;其次钢套管就位后在管壁两侧安设两套测斜仪,随时检测套管垂直度;再次,钻机下压钢套管时,设置两台经纬仪控制其方向,随时调整钢套管的垂直度,以保证垂直度不超过1/300。在钻孔过程中随时监控套管垂直度,发生偏移及时调整。2. For the control of pile verticality, first drill of erect smooth

15、. Solid, casing center and the design position deviation control in less than 1 cm; Second steel casing in place after install in the wall on both sides of thetwo sets of inclinometer, ready to test the perpendicularity of the casing; Again, when steel casing drill press, set up two theodolite to co

16、ntrol its direction, adjust the verticality of the steel casing, to ensure the verticality is not more than 1/300. Monitoring at any time during the process of drilling casing verticality, timely adjust the offset.3.平整场地设置排水系统。地面沿基坑围护结构边设40×40cm 厚20cmC20素砼环行排水沟形成排水系统,地面整平到冠梁顶面标高。钻机工作面往外形成一条坡度,防

17、止积水,使钻孔作业有良好的环境。3. The flat field set drainage system. The ground along the pit supporting structure sets up 20 40 * 40 cm thick edge cmc20 element formed concrete circular drainage drainage system, ground leveling to crown beam top surface elevation. Drilling working face outward to form a gradient

18、, to prevent water, make the drilling has good environment.4.桩的垂直度控制,为保证钻孔咬合桩底部有足够厚度的咬合量,除对孔口定位误差严格控制外,还要对垂直度进行严格控制,根据地下铁道工程施工及验收规范规定,桩的垂直度偏差不大于3。成孔过程中要控制好桩的垂直度,对于钻孔咬合桩垂直度的检查与校在此处不详述。4. Pile verticality control, in order to ensure the thickness at the bottom of the drilling occlusive piles have enou

19、gh amount of bite, in addition to the strict control of the orifice positioning error, and to strictly control the perpendicularity, according to the "underground railroad engineering construction and acceptance standard" regulation, pile verticality deviation is not more than 3 . Pore for

20、ming process to control the pile verticality, verticality checks for drilling occlusive piles and school here didn't elaborate.5.为了使B序桩的成孔顺利完成,A序桩砼要加入高效缓凝型减水剂,在A序桩砼处于未初凝时施做B序桩,套管机钻孔并浇注砼,消除对A序桩砼的损害。根据钻孔桩顺序的安排,A序桩的砼配合比设计按60小时初凝时间控制。5. In order to make the sequence B pile pore forming is completed,

21、 A sequence of pile concrete water reducing agent to join efficient retarding type, not in A sequence of pile concrete initial setting when doing B sequence pile, sets of machine drilling and pouring concrete, and eliminate the damage to A sequence of pile concrete. According to the order of drilled

22、 pile arrangement, A sequence of pile concrete mixture ratio design according to the initial setting time control 60 hours.6.如咬合桩施工的流水作业中断,或者需要分段进行施工时,应迅速移机对末端桩进行切割,单侧咬合面成孔,然后在孔内灌注河砂拔管形成砂桩,待后续咬合施工至该桩时重新成孔完成连续咬合桩的施工,如下图。6. Such as occlusive pile construction flow process interrupt, or need to segment

23、 during construction, should be quickly moving to cut pile at the end, unilateral occlusal surface into a hole, then the hole perfusion river sand tube drawing form the sand pile, for the follow-up construction to bite back when the pile pore forming complete continuous occlusal pile construction, t

24、he following figure.分段施工预设砂桩示意图Segmented preset sand pile construction sketch7.克服混凝土管涌的措施混凝土管涌亦可称混凝土绕流管涌,在B桩成孔过程中,由于A桩混凝土未凝固,还处于弱流塑状态,随着取土和深度的增加,可能会产生A桩混凝土不同程度地从A.B桩相交处涌入B桩孔内,称之为混凝土“管涌”。克服混凝土管涌可以采取以下方法:A桩混凝土的坍落度应尽量小一些,不宜超过16±2 cm,以便于降低混凝土的流动性,增加阻力克服管涌。施工过程中做到套管始终超前,抓土在后,以便于造成一段“瓶颈”,阻止混凝土的流动,如果钻

25、机能力许可,这个距离越大越好,但至少不应小于2.5 m。如有必要(如遇地下障碍物套管底无法超前时可向套管内注入一定量的水,使其保持一定的反压力来平衡A桩混凝土的压力,阻止“管涌”的发生。B桩成孔过程中应注意观察相邻两侧A桩混凝土顶面是否下陷,如发现A桩混凝土下陷应立即停止B桩开挖,并一边将套管尽量下压,一边向B桩内填混凝土或注水,直到完全制止住“管涌”为止。掌握施作B桩的最佳时间,避免A桩刚灌注完不久就马上被切割,通过以上措施可以有效的防止管涌现象的发生。7. To overcome the concrete measures of concrete piping can be said of

26、 piping were concrete piping flow around, in the process of pile hole B, due to unset A pile concrete, is still in the weak current plastic state, along with the increase of the depth of the soil and may lead to A pile of concrete in different degrees from a. B intersect in the pile hole, called A c

27、oncrete "piping". Overcome concrete piping can adopt the following methods: (1 A pile of concrete slump should be less as far as possible, and should not be more than 16 + / - 2 cm, in order to reduce the mobility of concrete, increase resistance to overcome the piping. (2 do casing always

28、 advance in the construction process, and stresses the soil in the, in order to cause a "bottleneck", to stop the flow of the concrete, if drillability permits, this distance is larger, the better, but at least they should not be less than 2.5 m. (3 if necessary (in case of underground obstacles casing bottom cannot advance can be added A certain amount of water to the casing, to keep A certain amount of pressure to