PE排污管施工技术交底之施工工艺

　在之前的文章中详细介绍了PE排污管施工前需要准备的工作步骤，今天继续带来PE排污管技术交底的第二部分，施工工艺的详细步骤及技术参数，给大家参考。

施工工艺

工艺流程

　测量放线→沟槽开挖→柔性基础→管道铺设与连接→密闭性检验→管道回填→管道变形检验

操作工艺

　　1.测量放线:施工测量放线参照由测量队制订的市政工程施工测量专项方案执行。

　　2.沟槽开挖:

　　(1)沟槽开挖、边坡设置及沟槽支护等参照“管线基坑明挖土方”进行施工。

　　(2)沟槽开挖后，应将沟底的岩石、砾石等坚硬物体铲除至设计标高以下150mm～200mm，然后铺上砂土整平夯实。

　　(3)基底标高、轴线位置、基底土质应符合设计要求。管道每侧工作宽度若设计无要求时，可参照表1-47执行。

管道每侧工作宽度

　　3.柔性基础:

　　 (1)管道基础应按照设计要求铺设,设计无规定时，对一般土质，基底可铺设一层厚度为100mm的粗砂基础；对软土地基，且槽底处在地下水位以下时，铺筑厚度不小于200mm的柔性基础，分两层铺设，下层用粒径为5mm～40mm的碎石，上层铺砂，厚度不小于50mm。

　　(2)管道基础根据设计要求确定，一般分为三种形式，如表1-48。

管道基础形式表

　　 4.管道铺设与连接:

　　(1)电源或交流发电机的准备见表1-49。

　　(2)电热熔带的连接:

　　1)检查管道和电热熔带是否有损伤。

　　2)对齐管道和清除杂物。

　　 ①通过水平杆或砂袋将要连接的管道放置在离地面200mm～300mm处(地基上挖有操作凹槽的可将管道直接放置在地基上)，并水平对齐。

　　 ②用布彻底将管道的外表面和电热熔带内壁上的杂物清除干净(包括水汽)，油类污物可用甲醇擦拭。 

　　 3)用夹钳和扣带紧固焊接片

　　 ①用电热熔带将已水平对齐的管道的要连接部分紧紧包住，电热熔带接头应重叠100mm～200mm。包的时候有连接线的一端在内圈。PE棒也应插在此端，从两侧分别插入，紧靠此端头。D400以下插入约50mm，D450以上插入约90mm～100mm。见图1-19、图1-20。

　　 ②外面用钢扣带套住，钢扣带不带衬板的端头应与电热熔带内圈同向并在同一位置。用夹钳上紧，使电热熔带与管壁紧紧地靠在一起。钢扣带边缘要与焊接片的边缘对齐。

　　 4)连接：将焊接器的输出线端的夹子与电热熔带的连接线头相连接。

　　 5)焊接：在焊接机上设定好时间和电压挡，根据操作规程进行焊接。焊接时间结束时，取下连接线夹子，再夹紧一次夹钳约1／4～1／2圈。

　　 6)冷却：焊接时间结束时风音器鸣响，电源自动断开，开始冷却。在接线被断开，钢扣带和夹钳夹紧的状态下，冷却时间在夏天一般为20min，冬天为10min。在冷却期间，可以进行下一个焊接。

　　 7)焊接检查：经过一定的冷却时间后，打开钢扣带，观察焊接状况。

　　(3)管道与检查井的连接：管道与检查井的连接，一般采用中介层、混凝土圈梁加橡胶圈、特制管件，见图1-21、图1-22。

　　1)采用中介层连接时，在管件或管材与井壁相连部位的外表面预先用粗砂做成中介层，然后用水泥砂浆灌入井壁与管道的孔隙，将孔隙填满。中介层的做法：先用毛刷或棉纱将管壁的外表面清理干净，然后均匀地涂一层塑料粘接剂，紧接着在上面撒一层干燥的粗砂，固化10～20min，即形成表面粗糙的中介层。

　　2)采用现浇混凝土圈梁加橡胶圈连接时，圈梁的混凝土强度等级不应低于20MPa。圈梁的内径按相应管外径尺寸确定，圈梁应与井壁同厚，其中心位置必须与管道轴线对准。安装时可将自膨胀橡胶密封圈先套在管端与管子一起插入井壁。

　　3)对于软土地基，为防止不均匀沉降，与检查井连接的管子宜采用0.5m～0.8m的短管，后面宜再接一根或多根不大于2m的短管。

　　5.密闭性检验:

　　(1)污水管道安装完毕经检验合格后，应进行管道的密闭性检验。可采用闭水试验方法检验。

　　(2)管道密闭性检验应在管底三角区回填密实后、沟槽回填前进行。

　　(3)闭水试验水头应满足下列要求:

　　1)试验段上游设计水头不超过管顶内壁时，试验水头以试验段上游管顶内壁加2m作为标准试验水头。

　　2)试验段上游设计水头超过管顶内壁时，试验水头以试验段上游设计水头加2m计。

　　3)当计算出的试验水头小于10m，但已超过上游检查井井口时，试验水头以上游检查井井口高度为准，但不得小于0.5m。

　　(4)试验管段灌满水后的浸泡时间不应小于24h。 

　　(5)管道密闭性检验时，外观检查，不得有漏水现象，管道24h的渗水量应满足下式计算结果：Q≤0.0046d(1-5)

　　　　式中：Q——每1km管道长度24h的允许渗水量(m3 ／24h·km)；

　　　　d——管道内径(mm)

　　6.管道回填:

　　(1)管道隐蔽工程验收合格后，沟槽应立即回填至管顶以上1倍管径高度处。

　　(2)沟槽回填应从管道、检查井等构筑物两侧对称回填，确保管道及构筑物不产生位移，必要时可采取限位措施。 

　　(3)回填时沟槽内应无积水，不得带水回填，不得回填淤泥、有机物及冻土。

　　(4)槽底管基支承角2α+20°范围内必须用中砂或粗砂填充密实，与管壁紧密接触，不得用土或其他材料填充。

　　(5)从管底基础顶至管顶以上0.4m范围内的沟槽回填材料，可采用碎石屑、粒径小于40mm的砂砾、中砂、粗砂或符合要求的原状土，再往上可回填符合要求的原状土或路基土。

　　(6)沟槽应分层对称回填、夯实，每层回填高度不应大于200mm。在管顶400mm范围内不得用夯实机夯实，在管顶400mm～700mm范围内不得使用重型机械碾压。 

　　7. 管道变形检验：

　　(1)管道变形检验包括安装变形检测和施工变形检测。管道安装变形检测应在管道安装后进行。管道施工变形检测应在管道覆土达到设计要求后进行。

　　(2)管道施工变形检测数量，应遵守下列规定： 

　　1)每施工段最初50m不少于三处，每处平行测两个断面，在测量点管轴垂直断面测垂直直径。

　　2)相同条件下，每100m测三处，取起点、中间点、终点附近，每处平行测两个断面，在测量点垂直断面测垂直直径。

　　3)在地质条件、填土材料、压实工艺或管径等因素改变时，应重复1)的做法。

　　(3)管道变形检测中，管道径向变形率SV。应按下式计算：

　　　SV=ΔdV／(d+2e)×100%SV＜5%(1-6)

　　　　式中：ΔdV——管道径向直径变化量；

　　　　e——管道纵截面形心高；

　　　　d——管道处于自由状态的内径。

　　以上就是PE排污管施工技术交底第二部分，在市政排污工程施工过程中，要根据当前的施工环境来决定施工工艺，小到土壤的不同，选择掩埋管材的土壤配比也要随之变化，根据季节气候的变化也要做好相应的准备，这样才能保证施工质量的保障。

In the previous article, the work steps that need to be prepared before the construction of the PE sewage pipe are introduced in detail. Today, we will continue to bring the second part of the technical explanation of the PE sewage pipe, the detailed steps and technical parameters of the construction process, for your reference.

Construction technology

Process flow

　Measuring and laying out → trench excavation → flexible foundation → pipeline laying and connection → tightness inspection → pipeline backfilling → pipeline deformation inspection

Operation process

　　1. Surveying and setting-out: Construction surveying and setting-out are carried out with reference to the special plan of municipal engineering construction survey formulated by the survey team.

　　 2. Trench excavation:

　　(1) Construction of trench excavation, slope setting and trench support shall be carried out with reference to "pipeline excavation and earthwork".

　　(2) After the trench is excavated, the rock, gravel and other hard objects at the bottom of the trench should be removed to 150mm～200mm below the design elevation, and then spread with sand, leveled and tamped.

　　 (3) The elevation of the base, the position of the axis, and the soil quality of the base shall meet the design requirements. If the working width of each side of the pipeline is not required by the design, please refer to Table 1-47.

Working width on each side of pipe

　　3. Flexible foundation:

(1) The pipeline foundation should be laid in accordance with the design requirements. If the design is not specified, a layer of coarse sand foundation with a thickness of 100mm can be laid on the base for general soil; for soft soil foundation, and the bottom of the tank is below the groundwater level, pave The flexible foundation with a thickness of not less than 200mm shall be laid in two layers, the lower layer shall be gravel with a particle size of 5mm-40mm, and the upper layer shall be sanded with a thickness of not less than 50mm.

　　 (2) The pipeline foundation is determined according to the design requirements, and is generally divided into three forms, as shown in Table 1-48.

Basic form of pipeline

　　 4. Pipeline laying and connection:

　　 (1) See Table 1-49 for the preparation of power supply or alternator.

　　 (2) Connection of electric heating tape:

　　 1) Check whether the pipeline and the electric heating tape are damaged.

　　 2) Align the pipes and remove debris.

　　 ①Place the pipe to be connected at a distance of 200mm～300mm from the ground through a horizontal rod or sand bag (the pipe can be directly placed on the foundation if the operation groove is dug in the foundation), and aligned horizontally.

　　 ② Use a cloth to thoroughly remove the debris on the outer surface of the pipe and the inner wall of the electric fuse belt (including water vapor), and the oily dirt can be wiped with methanol. 

　　 3) Fasten the welding piece with clamps and buckles

　　 ① Tightly wrap the connecting parts of the horizontally aligned pipes with electric heating tape. The joints of the electric heating tape should overlap by 100mm～200mm. When wrapping, there is one end of the connecting wire in the inner ring. The PE rod should also be inserted at this end, inserted separately from both sides, close to this end. Insert about 50mm below D400, insert about 90mm-100mm above D450. See Figure 1-19 and Figure 1-20.

　　 ②The outside is covered with a steel buckle belt. The end of the steel buckle belt without liner should be in the same direction and in the same position as the inner ring of the electric melting belt. Tighten it with clamps to make the electric heating fuse tightly close to the pipe wall. The edge of the steel buckle should be aligned with the edge of the welding piece.

　　 4) Connection: Connect the clamp of the output wire end of the welder with the connection wire end of the electric heating tape.

　　 5) Welding: Set the time and voltage block on the welding machine, and perform welding according to the operating procedures. At the end of the welding time, remove the connecting wire clamp, and clamp the clamp again for about 1/4 to 1/2 turn.

　　 6) Cooling: When the welding time is over, the wind buzzer will sound, the power will be cut off automatically, and the cooling will start. When the wiring is disconnected and the steel buckle and clamp are clamped, the cooling time is generally 20 minutes in summer and 10 minutes in winter. During the cooling period, the next weld can be performed.

　　 7) Welding inspection: After a certain cooling time, open the steel buckle and observe the welding condition.

　　(3) The connection between the pipeline and the inspection well: The connection between the pipeline and the inspection well generally uses an intermediate layer, a concrete ring beam plus a rubber ring, and special pipe fittings, as shown in Figure 1-21 and Figure 1-22.

　　1) When the intermediate layer is used for connection, the outer surface of the pipe fitting or pipe connecting with the well wall is made into an intermediate layer in advance with coarse sand, and then cement mortar is used to pour the pores between the well wall and the pipeline to fill the pores. Intermediary layer method: first clean the outer surface of the tube wall with a brush or cotton yarn, and then evenly apply a layer of plastic adhesive, then sprinkle a layer of dry coarse sand on it, and cure for 10-20 minutes to form Intermediate layer with rough surface.

　　 2) When the cast-in-place concrete ring beam and rubber ring are used for connection, the concrete strength level of the ring beam should not be less than 20MPa. The inner diameter of the ring beam is determined according to the outer diameter of the corresponding pipe. The ring beam should be the same thickness as the shaft wall, and its center position must be aligned with the pipeline axis. During installation, the self-expanding rubber sealing ring can be sleeved on the end of the pipe and inserted into the well wall together with the pipe.

　　3) For soft soil foundation, in order to prevent uneven settlement, the pipe connected to the inspection well should be a short pipe of 0.5m～0.8m, and one or more short pipes of no more than 2m should be connected to the back.

　　 5. Airtightness inspection:

　　 (1) After the sewage pipeline is installed and passed the inspection, the tightness inspection of the pipeline should be carried out. The closed water test method can be used for inspection.

　　 (2) The tightness inspection of the pipeline should be carried out after the triangle at the bottom of the pipe is backfilled and before the trench is backfilled.

　　 (3) The closed water test head shall meet the following requirements:

　　 1) When the upstream design head of the test section does not exceed the inner wall of the pipe top, the test water head shall be the standard test water head with the inner wall of the upstream pipe top of the test section plus 2m.

　　 2) When the design water head upstream of the test section exceeds the inner wall of the pipe top, the test water head shall be calculated based on the design water head upstream of the test section plus 2m.

　　3) When the calculated test water head is less than 10m, but has exceeded the upstream inspection well head, the test water head shall be based on the upstream inspection well head height, but shall not be less than 0.5m.

　　 (4) The immersion time after the test pipe section is filled with water shall not be less than 24h. 

　　(5) When inspecting the tightness of the pipeline, visually inspect it, and there must be no water leakage. The water seepage volume of the pipeline for 24 hours should meet the following formula: Q≤0.0046d(1-5)

　　　　 In the formula: Q——the allowable water seepage volume per 1km pipeline length 24h (m3/24h·km);

　　　　D——pipe inner diameter (mm)

　　 6. Pipeline backfilling:

　　 (1) After the pipeline concealment project is qualified, the trench should be immediately backfilled to the height of 1 times the pipe diameter above the top of the pipe.

　　(2) The trench backfill should be backfilled symmetrically from both sides of the pipelines, inspection wells and other structures to ensure that the pipelines and structures are not displaced, and limit measures can be taken when necessary. 

　　(3) When backfilling, there should be no accumulated water in the trench, no backfilling with water, no backfilling of silt, organic matter and frozen soil.

　　(4) Medium sand or coarse sand must be used to fill the tank bottom pipe base support angle 2α+20° tightly, in close contact with the pipe wall, and no soil or other materials should be used to fill it.

(5) The trench backfill material within the range of 0.4m from the top of the pipe bottom to the top of the pipe can be made of crushed stone chips, gravel with a particle size of less than 40mm, medium sand, coarse sand or undisturbed soil that meets the requirements, and then up It can be backfilled with undisturbed soil or roadbed soil that meets the requirements.

　　(6) The trench should be backfilled and compacted in layers and symmetrically, and the height of each layer should not be greater than 200mm. No tamping machine shall be used for compaction within the range of 400mm from the top of the pipe, and heavy machinery shall not be used for compaction within the range of 400mm～700mm from the top of the pipe. 

　　7. Pipe deformation inspection:

　　(1) Pipeline deformation inspection includes installation deformation inspection and construction deformation inspection. The pipeline installation deformation detection should be carried out after the pipeline installation. Pipeline construction deformation detection should be carried out after the pipeline covering soil meets the design requirements.

　　 (2) The quantity of pipeline construction deformation detection shall comply with the following regulations:  

　　1) There are no less than three places in the first 50m of each construction section, and two sections are measured in parallel at each place, and the vertical diameter is measured at the vertical section of the pipe axis at the measuring point.

　　2) Under the same conditions, measure three places every 100m, take the starting point, the middle point, and the end point, measure two sections in parallel at each place, and measure the vertical diameter at the vertical section of the measuring point.

　　3) The method of 1) should be repeated when the geological conditions, filling materials, compaction process or pipe diameter are changed.

　　(3) In the pipeline deformation detection, the radial deformation rate of the pipeline SV. Should be calculated as follows:

　　　SV=ΔdV/(d+2e)×100%SV＜5%(1-6)

　　　　 In the formula: ΔdV——the radial diameter change of the pipe;

　　　　E——The centroid of the longitudinal section of the pipe is high;

　　　　D——The inner diameter of the pipe in a free state.

The above is the second part of the technical disclosure of PE sewage pipe construction. During the construction of municipal sewage engineering, the construction process must be determined according to the current construction environment. As little as the soil is different, the soil ratio of the buried pipe should also be changed accordingly. According to seasonal climate changes, corresponding preparations must be made to ensure the quality of construction.