Construction technology of steel corrugated pipe culvert

Preface: Steel corrugated pipe is a corrugated pipe or plate made by pressing a steel plate of a certain thickness. Steel corrugated pipe culvert has strong adaptability. The service life of steel corrugated pipe culvert after galvanizing can reach 50 years (or more).Steel corrugated pipe culvert is also called corrugated pipe culvert, which refers to the corrugated pipe for culvert buried under the highway. Steel corrugated pipe culvert adopts standardized design, centralized production and short production cycle; on-site installation civil engineering and profile installation can be implemented separately, with a short construction period, while reducing or completely abandoning conventional building materials, which has far-reaching environmental protection significance; and it has the advantages of adapting to foundation deformation, reasonable stress conditions, and reducing uneven settlement. It can solve the problem of damage to the concrete structure of bridges and pipe culverts in cold areas (frost) in the north.

1. Structural forms and classification of bellows

Steel corrugated structures can be divided into two categories according to the cross-sectional shape: closed section and open section:

Closed cross-sections include circle, vertical ellipse, pear, tubular arch, horizontal ellipse, etc.;

Opening sections include semicircular arch, low arc arch, high arc arch, horseshoe arch and box culvert;

The steel corrugated structure has a variety of cross-sectional forms, which can be applied to different use environments, and the aperture of the open cross-sectional structure can be determined according to actual needs. Therefore, it has a wide range of uses.

2. Advantages of Steel Corrugated Pipe Culvert

3. Construction process

1. Measurement and setting out  

3 .Foundation pit treatment

The foundation is gravel foundation, with an upper width of 5.5m, a lower width of 9.92m and a thickness of 0.45m. Gravel construction adopts layered paving and layered compaction, with a layer thickness of no more than 20cm. If the compaction degree does not meet the requirements, it must be compacted continuously until the requirements are met before the next layer can be paved.

4 .Pipe joint installation

(1) Construction preparation: Before construction, check the required mechanical equipment, such as cranes, generators, wrenches, jacks, etc., and check the model, length, diameter, etc. of the pipe sections transported to the site to see if they are consistent with the design drawings.

(2) Before installing the pipe body, the culvert's axis position must be accurately laid out. During assembly, attention must be paid to the position of the end pipe section and the middle pipe section. The culvert must be installed according to the correct axis and slope shown in the drawing.

(3) Measures should be taken to prevent pipe segments from being damaged during transportation and loading and unloading. Pipe segments should not collide with hard objects to prevent damage to the external galvanized material of the pipe segments. Anti-corrosion coatings damaged during transportation should be repaired. When pipe segments are transported to the site, they should be laid on top and placed on the bottom, classified by model, and random stacking is prohibited.

(4) When assembling pipe segments, the end of the previous pipe segment should be placed on the inside of the downstream pipe segment and should not be reversed. Step 1: Assemble the first pipe segment. The pipe segment is 1.5m long and each pipe segment is divided into 5 pieces. First, use a crane to install the first pipe segment at the bottom, then install the pipe segments on both sides. The bolt holes between the segments should be completely aligned. Insert the bolts into the holes and pre-tighten the bolts with a socket wrench. Finally, install the top pipe segment. Tie each piece together to ensure that the center of the pipe segment is parallel to the longitudinal center line of the steel corrugated pipe culvert. Step 2: Use the same method to install other pipe segments. Step 3: After all pipe segments are assembled, tighten all nuts one by one. In order to avoid missing any, mark each bolt with red paint after tightening. After tightening the bolts at the outer ring overlap, in order to prevent water seepage between the plate seams and the bolt holes of the corrugated steel plate, it is necessary to seal the connection between the steel plate and the bolt holes. Use special sealing materials to prevent water seepage at the connection.

The joint between each pipe section shall not be larger than 5mm. After every 4.5m of installation, the surveying team shall re-measure the position and make corrections to ensure the correct installation position. If there is any deviation, a jack shall be used to push the pipe section upward in the direction of deviation to correct it and ensure that its center is on the central axis of the culvert.

(5) After the pipe body is installed, apply two coats of a mixture of asphalt and kerosene on the outer wall of the pipe body to enhance the anti-corrosion effect, and apply anti-rust paint on the inner wall of the pipe body. The thickness of the asphalt coating should be greater than 1mm and should be applied evenly.

5. Single-line wall construction

The straight wall and foundation are made of C20 flaked concrete. The concrete joints are roughened before pouring and then moistened with water. The formwork is made of steel formwork and the end formwork is made of bamboo plywood. During construction, pay attention to check whether the position and size of the formwork are correct, whether the formwork reinforcement is reliable, and whether the joints between the formworks are flush. If there is a misalignment, make adjustments in time. The diameter of the formwork tie rod is not less than 1.4cm. A tie rod is set every 1m horizontally and every 1m vertically. The outside of the tie rod is covered with a plastic tube so that it can be pulled out and reused after the formwork is removed. The tie rod hole is sealed with mortar of the same grade. After the wing wall is constructed, pay attention to clearing the entrance and exit, and the entrance and exit are connected smoothly with the upper and lower parts.

6. Culvert backfill

(1) The coarse sand below the pipe bottom is compacted by a "watertight method" vibrator, and medium-coarse gravel is used to backfill the two sides of the corrugated culvert. The part above 2m above the top of the corrugated culvert is backfilled with roadbed filler. If corrosive substances or tree roots are found in the backfill soil, they should be cleaned up.

(2) Within 50 cm of the corrugated pipe culvert, small machinery is used for compaction to prevent large equipment such as rollers from damaging the steel corrugated pipe culvert. A 25t roller is used for rolling the part beyond 50 cm. After rolling, the compaction degree is tested. Only when it meets the requirements can the next layer of filling be carried out. The thickness of each layer is controlled within 20 cm.

(3) From the beginning to the end of the culvert backfill, the deviation between the actual cross-sectional dimensions of the culvert and the dimensions during the assembly process shall not exceed 2%. If the actual deformation of the cross-sectional dimensions exceeds the allowable range, the construction shall be suspended immediately, the cause shall be identified, and effective measures shall be taken to control the deformation to keep it within the allowable range.

7. Key points of quality control

(1) After the culvert foundation is excavated, the bearing capacity of the foundation must be tested. Only when it meets the requirements can the next step of construction be carried out.

(2) Steel corrugated pipe culverts must be pre-assembled before entering the site, and on-site construction can only be organized after the assembly is qualified.

(3) The steel corrugated pipe culvert segments are mainly connected by bolts. After the bolts are installed, they must be rechecked to prevent the bolts from being leaked or not tightened.

(4) During the assembly process, the axis and slope of the steel corrugated pipe culvert are tested to ensure the smoothness of the line.

(5) Carry out quality inspection of completed pipe culverts in accordance with relevant specifications and requirements.

(6) Attach great importance to foundation anti-seepage treatment and control of Taipei backfill particle size to prevent water floating accidents and damage that affects stress and durability.

IV. Conclusion

Practice has proved that the steel corrugated pipe culvert has incomparable advantages over the concrete culvert in terms of construction period, construction cost, environmental protection significance, etc. It is a flexible structure with strong anti-deformation ability, which can effectively avoid or reduce the phenomenon of bridge head jumping, directly affecting driving comfort and safety, and effectively solving the problem of inconsistent settlement of culvert and roadbed settlement in highway construction. Moreover, it adopts on-site splicing. Compared with cast-in-place concrete culvert, the construction process of steel corrugated pipe culvert is simple, and less material and manpower are required. It has the advantages of convenient installation and can greatly shorten the construction period of culvert. Therefore, in the project construction, we conducted on-site surveys in advance, carefully calculated and designed the product specifications of each pile number, and completed batch processing and production, and delivered them to the site on time before the start of the culvert construction project. The construction of steel corrugated pipe culvert only needs simple installation tools, and can be completed in a very short period of time by using machinery and manual installation, which greatly shortens the construction period of the engineering culvert construction and provides convenient conditions for the early completion of the project. At the same time, the main body of the steel corrugated pipe culvert is made entirely of steel. It does not use cement, sand, wood and other building materials commonly used in highway construction. Only some mortar-laid stone slabs are used on the eight-shaped wall of the culvert entrance, which effectively reduces the damage to the environment and maintains the normal development of the surrounding environment. It is an environmentally friendly building material.