What are The Construction Steps of Pre-embedded Iron Wire Fixing HDPE Pipe?

Construction method of pre-embedded iron wire to fix HDPE pipe is a construction method for urban construction engineering. It provides a construction method for fixing HDPE pipe with embedded iron wire before concrete pouring of flexible pipe of municipal drainage pipe with strong safety, stability and reliability, convenient and fast construction, and economy.

The Specific Construction Steps

1. Measurement and Stakeout

Before the start of construction, the plane position and elevation of the existing pipelines and structures connected with the project should be checked. When measuring, first measure the center line of the pipeline system and the position of the inspection well, set up construction control piles at the turns and branches of the pipeline and spread lime lines for excavation, and set up a level to track and measure during mechanical excavation.

2. Trench Excavation

Before trench excavation, investigation should be conducted according to construction needs, and the site topography, landform, buildings, various pipelines and other facilities along the pipeline, as well as engineering geology, hydrogeology data, drainage conditions, and compilation of drainage plans should be conducted . The water discharged from the construction drainage system shall be transported outside the pumping radius, and shall not affect traffic and damage roads, farmland, river banks and other structures.
Control the excavation depth in time during the trench excavation process to prevent over-excavation; after trench excavation, the trench centerline and elevation control should be restored in time, and the slope plate should be used to control the elevation and centerline, and the slope plate setting should be checked at any time Whether the location and elevation are accurate, to ensure that the centerline of the trench, the slope and the location of the auxiliary structures are correct.
The width of the trench should be convenient for pipeline laying and installation, as well as for backfilling operations and groundwater drainage. The minimum width of the groove should be determined by the following formula:

b ≥ D1+2S b: the minimum width of the groove (mm); D1: tube outer diameter (mm); S: The distance between the pipe wall and the groove wall (mm), as determined by the following table.

Table-distance from pipe wall to groove wall

The steepest slope of the trench side slope should be determined according to the soil quality of the trench. If necessary, the trench wall should be provided with supports or guards, and an emergency plan should be prepared. Mechanical excavation is used for earth excavation, and 20cm of the bottom of the trench is reserved for manual clearing. Over-excavation is strictly prohibited during the excavation process to prevent disturbing the foundation.
It is not advisable to install static or dynamic loads on the top of the soft soil trench slope; when it is necessary to install, the bearing capacity of the soil and the stability of the slope should be checked.
When the trench is digging deeper, the depth of layered excavation should be reasonably determined according to the mechanical properties.

3. Embedding machine bricks to tie the wire, and pouring the concrete flat base

Template: The flat base template should be installed in time after the inspection is qualified. The flat base side mold can use 10# channel steel or 100X 100mm square wood template, and the back of the template is fixed with steel drill or square wood.
Flat-base concrete: When pouring flat-base concrete, the machine bricks with tied wires should be embedded at the same time, and the flat base shall be vibrated and compacted with a flat vibrator. According to the elevation control line, the surface shall be leveled by scraping bars and wood rubbing and pressing In fact, the next process construction can be carried out after the concrete strength reaches 1.2MPa.

4. Pipeline Laying

The specifications of pipes, rubber rings and other materials should meet the design requirements, and have the product qualification certificate and product performance specification of the quality inspection department, and the product specifications and production date should be indicated.
The interface sealing rubber ring is made of neoprene, with a Shore hardness of 45~55MPa, and is supplied by the pipe manufacturer according to the specifications.
The appearance of the pipe shall be consistent, the inner wall shall be smooth and flat, the pipe body shall not have cracks, and the pipe mouth shall not have defects such as damage, cracks, deformation, etc.
The end surface of the pipe should be flat and perpendicular to the central axis of the pipe. There should be no obvious bending in the axial direction. The size and roundness of the outer diameter of the pipe socket and the inner diameter of the socket must meet the requirements of the product standard.
The compressive strength and stiffness of the pipe should meet the design requirements.
The performance and size of the rubber ring for pipe joints should meet the design requirements. The appearance of the rubber ring should be smooth and flat, and there should be no pores, cracks, wrinkles, damage, heavy leather and joints.
The pipeline installation can be manually installed. When the groove depth is not large, the pipe can be manually lifted into the groove, or a non-metallic rope can be used to slide the pipe into the groove, and then steadily placed on the sand cushion pipe position. It is strictly forbidden to hook the nozzles at both ends with metal ropes or roll the pipes from the edge of the groove into the groove.
Interface installation, the direction of the interface should be consistent with the direction of the flow surface, and install them in sequence from the low point to the high point.
The rubber ring interface shall comply with the following regulations:

(1) Before connecting, check whether the rubber ring is in good condition and confirm the position of the rubber ring. (2) During the interface operation, the interface working surface should be cleaned with cotton yarn, and there should be no debris such as dirt. (3) When using a half piece connection, first turn up the outer side of one end of the one-piece sealing rubber ring, put on a connecting pipe port, turn down the outer edge, and make the turned up rubber ring slip into the help groove; then turn up the rubber At the other end of the circle, align the other connecting tube tightly, put down the rubber ring, and insert it into the rib groove, and then install the Huff piece and tighten the bolts evenly.

Pipeline Laying

5. Wire Tying HDPE Pipe

After the pipeline is installed, the HDPE pipe is bound and fastened with embedded iron wire to prevent the HDPE pipe from floating and plane displacement when the concrete is poured, which affects the quality of the project.

6.Airtightness Inspection

After the pipeline has been lashed and passed the inspection, the tightness inspection shall be carried out. The closed water test method can be used for inspection. The closed-water test head should meet the following requirements:

When the upstream design water head 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 plus 2m;
When the upstream design water head exceeds the inner wall of the pipe top, the test water head is calculated based on the upstream design water head plus 2m;
When the calculated test water head is less than 10m, but has exceeded the upstream inspection well head, the test water head shall be subject to the height of the upstream inspection well head, but shall not be less than 0.5m.
The immersion time after the test pipe section is filled with water should not be less than 24h.
During the pipeline tightness inspection, there must be no water leakage in the visual inspection, and the water seepage volume of the pipeline for 24 hours should meet the calculation results of the following formula:

Q ≦ O.0046d
Q: Permissible water seepage per 1km pipeline length 24h (m3/24h · km)
d: Pipe inner diameter (mm)

7. Concrete Guarantee

Template: The template can be assembled on site by using a combined steel template or a plywood template. The joints of the template must be tight and not leaking, and the inside of the mold should be clean. The template release agent is applied evenly.

Wooden formwork

Production: Wooden formwork should be made of wood with solid texture, small deformation, and no decay, distortion, or cracks. The inner side and top surface of the template should be planed, the seams should be tight and firm, and the corners should be smooth.
Installation: The wooden formwork shall be erected according to the laying-out position and the plane position and elevation of the vertical form shall meet the design requirements, and the erection shall be stable, the joints shall be tight and smooth, and there shall be no staggered stubble and height inequality. Nail both sides with iron prongs and close to the template. The inner iron prongs should be higher than the template (about 100mm), with a distance of 0.8m-1. 0 m, and the top of the outer iron prongs should be the same height or 10mm lower than the template. The iron prongs at the bends should be dense, with a spacing of 0.4m-0.Sm. After the template is supported, apply the release agent evenly on the inside.

Steel formwork

Production: channel steel or section steel should be used. If steel plate is used, its thickness should meet the requirements of strength and rigidity.
Installation: The steel formwork and wooden formwork support the same method.

8.Guaranteed Concrete

Before concrete paving, a comprehensive inspection should be carried out on the formwork support, the leveling of the base layer, the embedded parts, and the wetting condition. Ensure that the concrete should be filled and compacted, and the concrete should be vibrated with a plug-in vibrator. When the concrete is poured, both sides should be leveled according to the elevation control line, and the surface should be leveled with wood rubbing and rubbing. Cover and sprinkle water to keep in good health, especially in summer, to prevent dry cracks on the surface of the concrete. After the concrete strength reaches 1.2MPa, the next procedure can be constructed.