后压浆施工技术规范
Technical Specification of Post Pressure Grouting
一、设计design
1、对桩径800mm桩长40m采用复式注浆法即桩端与桩侧注浆法。桩端与桩侧各对称安装二根注浆管。
Double pressure grouting to be adopted for 800mm dia./40m long pile, i.e. side and bottom grouting. Two grouting pipes shall be arranged for bottom and side respectively.
2、注浆位置grouting position：
1）桩端注浆：注浆花管应埋入终孔孔底下100-300mm，
Bottom grouting:  grouting pipe should penetrate 100-300mm below the bottom of borehole.
2）桩侧注浆：桩长30m/40m的桩注浆花管应设置在地面下20m/25m处的砂层中，或者15-20
m/20-25m处的砂层与粘性土层界面上500mm处，具体位置由各区段工勘探孔及桩钻进时的反渣情况综合判断确定，同一建（构）筑物注浆位置宜相同（详见附图二）。
Side grouting: grouting pipes for 30m/40m piles should be embedded in sand strata 20m/25m underground, or 500mm above the intersection of 15-20m/20-25m silty sand and clay sand. Exact positions shall be reasonably decided as per out-coming soil condition in test boring and actual piling. Grouting position for the same structure (building) is preferably identical. (see diagram 2)
3、注浆管的长度：由实际施工的孔深确定，其长度为实际孔深+0.6m。
Length of grouting pipe:  shall be as per actual borehole depth and should be 0.6m longer than borehole depth.
4、注浆管采用DN20、δ=2.75的焊管，相邻注浆管采用丝扣连接，并用14#铁丝绑扎固定在钢筋笼的外侧。注浆管底端用丝堵封闭，距底端400mm长度范围内对称均匀钻12个φ6的注浆孔，用胶带及图钉封孔。注浆管顶部应高出砼面0.5以上，且高出地面0.2-0.3m。 管顶要用丝堵封闭且用不同颜的胶带缠绕，将桩底注浆管与桩侧注浆管区分开来。
Grouting pipe type: DN20、δ=2.75 welded pipe to be adopted, and adjacent pipes to be connected with threads and tightly fixed to the outer side of rebar cage with 14# galvanized wire. Bottom end of grouting pipe to be sealed with plug and 12 nos ofφ6 grouting holes to be evenly drilled within the bottom 400mm of grouting pipe, and the same should be sealed with tapes and thumbnails. Top of grouting pipe should be 0.5m above concrete level and 0.2-0.5m above ground level. Pipe tops to be sealed with plugs and wrapped with tapes of different colors to differentiate bottom and side grouting pipes.
5、注浆压力：桩侧：桩长30m为1.5 MPa，桩长40m为2.0 MPa ；桩端：桩长30m为2.0 MPa，桩长40m为2.5MPa。
Grouting pressure： pile side: 1.5MPa for 30m piles and 2.0Mpa for 40m piles; pile bottom: 2.0MPa for 30m piles and 2.5 for 40m piles.
6、注浆材料及注浆量：采用普通42.5级水泥，每根桩水泥用量暂定为3.0t。初始压浆时水灰比为1：1，体积为200L，余下水灰比为08:1。
Grouting material and quantity: normal OPC 42.5 grade cement to be adopted and 30t of cement for each pile. Initial grouting water-cement ratio should be 1:1, volume should be 200L and trailing water-cement ratio should be 8:1.
7、成桩2天后开始注水打开通道。28天内进行注浆。
Water to be injected into grouting pipes after 2 days of pile concreting completion so as to clean grouting pipes and pressure grouting to be carried out within 28 days of pile completion
8、注浆顺序：先桩侧后桩底，二者时间间隔不小于2小时。先外围后中间。注浆点距未施工或者正在施工的桩的最小距离为15m。
Grouting sequence: first pile sides and then pile bottom and minimum 2 hours interval to be maintained between the two; first outer and then inner and minimum clearance between pressure grouting pile and installation on-going piles should be at least 15m. 
9、终止注浆条件：采用注浆压力与注浆量双控，以注浆量控制为主，注浆压力控制为辅。
Condition for pressure grouting suspension: two references to be considered, i.e. grouting pressure and grouting quantity whereas the latter should be taken as primary and the former secondary.
二、范围scope：
1、烟囱基础（内4圈除外）；446根
Chimney foundation (excluding inner 4 circles)，total 446nos
2、全部三个水塔的环基基础；每个水塔约552根，共1656根
Ring beam foundation of three NDCT.Each CT 552nos，total 1656nos
3、其他需要后压浆的基础，现场与业主协商确定。
Other foundations that requires pressure grouting—to be discussed with the Owner at site.
三、施工方案 methodology
1、工艺流程technique steps：
后压浆工艺流程为：制作压浆管 →安装压浆管 → 检查压浆管质量 → 灌注混凝土→打开压浆管，并做注水试验→配制水泥浆，桩侧压浆→ 配制水泥浆，桩底压浆→养护。
Steps of post pressure grouting: grouting pile fabrication---grouting pipe installation---grouting pipe quality inspection-concreting---open pressure grouting pipe and water injection test---cement slurry mixing and side grouting---cement slurry mixing and bottom grouting---curing
2、注浆管制作grouting pipe fabrication：
1）注浆管材料grouting pipe material：
采用DN20壁厚2.75mm的焊管。
Welded pipe of DN20 and 2.75mm thick
2）注浆管的制作fabriaction：
采用车丝机在焊管的二端车丝，每个车丝段的长度为50mm，车出来的丝应平正圆滑，不得出现偏丝滑丝，若出现应用切割机将该段切除后重新车丝。车丝后应用生胶带缠绕3-5圈，然后在下节管的上端安装直通并拧紧。安装时应用管钳拧紧，防止在整个注浆管管道安装过程中出现脱离或者是不封闭，导致漏浆现象的发生。同时根据实际孔深制作相应的短节，短节的二端按上述要求车丝。
Tthread技术hread to be made at two ends of grouting pipe with threading machines and length of each thread should be 50mm. Threads made should be smooth and even, and distorting or sliding threads are not allowed. In case distorted or slide threads are made, the same should be chopped and remade. Finished threads should be wrapped with 3-5 rounds of thread tape, and then straight coupling shall be tightly fixed to one end of the pile with pipe wrench so as to avoid leakage or disconnection during pressure grouting. Grouting pipes shall be prepared in view of pile depth and threads of connections shall be made as required.

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