A construction method for precast box culverts

Abstract

This invention relates to the field of precast box culvert construction technology, specifically a precast box culvert construction method, including the following steps: construction preparation, rebar processing and binding, formwork installation, concrete pouring, concrete curing, culvert section storage, transportation and installation, and joint and waterproofing treatment. This invention has the following advantages: It employs centralized precasting in a closed shed, effectively avoiding the impact of severe weather such as strong winds, rain, and snow on culvert section construction; the culvert sections are precast horizontally, reducing construction difficulty; and the use of sleeves to connect the main reinforcing bars avoids the adverse effects of strong winds on welding quality during arc welding. Furthermore, the use of an adjustable rebar binding platform enables rapid and precise rebar binding, ensuring the quality of the rebar binding spacing and protective layer. This effectively solves the binding difficulties caused by the variety of rebar types and limited space in culvert sections.

Description

Technical Field

[0001] This invention relates to the field of precast box culvert construction technology, specifically a precast box culvert construction method. Background Technology

[0002] Most of the Hexi Corridor region has a continental mid-latitude arid climate, characterized by strong solar radiation, abundant sunshine, large diurnal temperature variations, low precipitation, high evaporation, and dry air. Therefore, cold, drought, strong winds, and large temperature differences are the main climatic hazards. In the edge areas of the Hexi Corridor-Alashan desert salinization zone, the formation of two different types of saline soil—alluvial saline soil and lacustrine saline soil—is mainly controlled by stratigraphic lithology, climatic factors, hydrological conditions, and the influence of different geomorphic units and groundwater conditions. These environmental conditions present significant challenges to structural construction. Culverts are a crucial component of highways. Culvert construction typically involves on-site steel reinforcement binding, formwork erection, and concrete pouring. This process is time-consuming, labor-intensive, and highly susceptible to climatic influences, making quality control difficult and posing significant safety risks to people and property. Ensuring high-quality culvert construction under the harsh conditions of cold, arid, windy, and highly variable temperatures is a critical challenge that urgently needs to be addressed in highway construction in the Hexi Corridor. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a method for constructing precast box culverts.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A precast box culvert construction method, suitable for harsh climatic environments with cold, drought, strong winds, and large temperature differences, is characterized by the following steps: S1. Construction preparation: Level and harden the prefabrication site, and build a fully enclosed color steel shed; set up fixed platforms according to the type, quantity and construction period of the culvert sections, install grout-stop strips on both sides of the platform top, and improve the site drainage system; S2. Reinforcing bar processing and binding: Inspected and qualified reinforcing bars are centrally cut and processed, and the main bars are connected by sleeve connection; the processed semi-finished reinforcing bars are bound and shaped on an adjustable reinforcing bar binding platform, which can be adjusted in length according to different span or height dimensions of the culvert section to accommodate various sizes and types of culvert sections; S3. Template Installation: Standard steel templates are used. Before installation, they are inspected, trial-assembled, and release agent is applied. During installation, the inner template is first fixed to the platform, then the steel reinforcement cage is hoisted into the template and the protective layer is adjusted. Finally, the outer template is installed, and special sealing rubber gaskets, tie rods, and limiting devices are used to ensure that the template is installed firmly and tightly. S4. Concrete pouring: Concrete pouring is carried out in an enclosed greenhouse at the optimal time of day based on temperature observation data; horizontal, layered, and continuous pouring is adopted, with each layer thickness controlled to be no more than 30cm; an immersion vibrator is used for compaction, and a dedicated person is assigned to monitor the formwork status; after pouring, a finishing and secondary finishing are carried out. S5. Concrete Curing: After the concrete is poured, the culvert section is immediately covered with a mobile special curing shed and sealed with insulation cloth; connect a biomass and / or electric heating boiler to introduce hot steam into the curing shed for curing; monitor the environment inside the shed in real time with a temperature and humidity monitor to maintain the temperature at 20±2℃ and the humidity at above 95% for continuous constant temperature and humidity curing until the concrete strength reaches the design requirements; S6. Culvert Section Storage: After curing, the culvert sections are inspected for quality and tested for concrete strength. Once the strength reaches 100% of the design strength, they are stored flat according to their number and installation sequence. S7. Transportation and Installation: Flatbed trucks are used to transport culvert sections, and binding and securing measures are taken. After arriving at the site, the culvert sections are turned into a vertical position using pre-embedded lifting rings and a crane. "C" type lifting tools equipped with rubber pads are used for lifting, with the lifting port of the lifting tool embedded in the culvert section, and the sections are installed in place in sequence from one side to the other. S8. Joint and Waterproofing Treatment: After installation, clean and moisten the joints and settlement joints, and fill them with polymer mortar and asphalt hemp rope; apply waterproof asphalt to the outside of the culvert, and wrap rubber waterstops around the joints and settlement joints to complete the waterproofing layer construction.

[0005] Preferably, in step S2, the adjustable rebar tying platform is used for culvert types with the same span but different heights or different spans but the same height. By setting adjustment buckles or making the platform according to the maximum size, it can achieve multiple uses, saving costs and space.

[0006] Preferably, in step S5, the health maintenance process is monitored by a dedicated person, and the temperature and humidity conditions are observed and adjusted every 2 hours during the day and every 1 hour at night during the initial stage of maintenance.

[0007] Preferably, in step S7, when the "C" type lifting tool is used for lifting, the culvert section is first lifted 2-3 cm away from the support surface and then paused to check the stress points and confirm that there are no problems before continuing the lifting; during installation, the culvert section is aligned with the installation control line that pops out on the foundation.

[0008] This also includes using fully enclosed corrugated steel sheds at concrete mixing plants and installing water purification equipment to ensure the quality of raw materials and mixing water.

[0009] The present invention has the following beneficial effects: 1. This invention adopts centralized prefabrication in a closed greenhouse, which effectively avoids the impact of severe weather such as strong winds, rain, and snow on the construction of culvert sections.

[0010] 2. The culvert section of this invention adopts a horizontal prefabrication method, which reduces the construction difficulty.

[0011] 3. This invention uses a sleeve to connect the main reinforcing bars, which avoids the adverse effects of strong winds on welding quality during arc welding. Furthermore, the adjustable rebar tying platform enables rapid and precise rebar tying, ensuring the quality of the tying spacing and protective layer. This effectively solves the tying difficulties caused by the diverse types of rebars and limited space in culvert sections.

[0012] 4. This invention utilizes statistical analysis of temperature variations to flexibly determine the optimal time for concrete pouring, ensuring ideal pouring conditions. Simultaneously, a dedicated curing shed is constructed, employing biomass and electrically heated curing boilers for steam curing. Temperature and humidity are monitored regularly to ensure the curing environment is unaffected by adverse weather conditions, thereby improving construction quality.

[0013] 5. This invention, by using a "C"-shaped lifting tool for culvert section installation, can significantly improve installation efficiency, reduce construction costs, and accelerate construction progress. Attached Figure Description

[0014] Figure 1 A flowchart illustrating the construction method for the invention; Figure 2 This is a first-view three-dimensional structural diagram of the present invention.

[0015] Figure 3 This is a schematic diagram of the second perspective three-dimensional structure of the present invention.

[0016] Figure 4 This is a schematic diagram of the third-view three-dimensional structure of the present invention.

[0017] Figure 5 For the present invention Figure 2 Enlarged schematic diagram of the structure at point A in the middle.

[0018] In the attached diagram: 1. Base; 2. Mold assembly; 200. Inner mold; 201. Outer mold; 202. Connecting plate; 203. Triangular plate; 204. Limiting plate; 205. Stop block; 206. Screw; 207. Bolt; 3. Mounting assembly; 300. Positioning plate; 301. Mounting plate; 4. Limiting assembly; 400. Tie rod; 401. Nut; 402. Threaded pipe; 5. Reinforcing steel cage; 6. Lifting ring. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1

[0021] S1. Construction Preparation First, the site is leveled to ensure its flatness and elevation. The ground is hardened and the entire prefabrication area is fully enclosed with a color steel shed. The number of piers is set according to the type and quantity of culvert sections and the construction period. Grouting strips are installed on both sides and top of the piers to prevent grout leakage. Drainage facilities are also installed to ensure that the drainage system is unobstructed.

[0022] S2, Reinforcing bar processing and binding (1) All steel bars are stacked in the raw material storage area after passing inspection. During the cutting and processing, the steel bars are placed in the semi-finished product storage area according to the drawings and specifications. During processing, all main steel bar connections are made using sleeve connections to avoid the use of arc welding, which may affect the welding quality due to strong winds.

[0023] (2) The processed semi-finished steel bars are placed on an adjustable platform for binding. The advantage is that for culvert steel bars of the same span or height, the binding can be carried out by simply adjusting the length of the platform according to the size type. (This project is designed with five sizes of culverts: 2*1.5, 2*2, 3*2, 4*2, and 4*3. Among them, 2*1.5 and 2*2 and 4*2 and 4*3 are different heights of the same span. The platform can be made at the higher size to meet the binding requirements of the two types of culverts. 2*2, 3*2, and 4*2 are different spans of the same height. The platform can be made at the wider size and adjustable buckles can be set up for binding as needed. This is convenient and quick.) This not only saves costs in platform manufacturing but also saves the effective usable area of ​​the prefabrication yard.

[0024] (3) The dimensions, quantity, spacing, and position of the reinforcing bars shall meet the design and specification requirements. The intersections of the reinforcing bars shall be firmly tied with wire, and spot welding shall be used if necessary. The wire ends used for tying shall be bent inward and shall not extend into the concrete cover. Precast quincunx-shaped concrete spacers shall be tied between the reinforcing bars and the formwork as required by the design, with one spacer every 0.5m, and the spacers shall be arranged in a quincunx pattern to ensure the thickness of the concrete cover. After the reinforcing bars are tied, the type and spacing of the reinforcing bars and the thickness of the cover shall be carefully checked, and any problems shall be adjusted in a timely manner to meet the design requirements.

[0025] S3, Template Installation The precast formwork for the box culvert uses standardized steel formwork, which has sufficient strength, rigidity and stability; ensuring the accurate shape, size and position of the embedded parts of the box culvert wall formwork.

[0026] (1) Template installation preparation work ① After the template arrives on site, a thorough and comprehensive inspection should be carried out on the template, and a trial assembly should be conducted. The assembly sequence of the template is basically inner mold → outer mold.

[0027] ② A special release agent should be applied to the surface of the formwork that comes into contact with the concrete. First, grind the formwork to remove oil and rust, and clean it thoroughly. Then, apply the release agent evenly to the formwork. After the release agent dries, you can proceed with tasks such as hoisting steel bars.

[0028] ③ The mounting base should be kept flat, with an error not exceeding the design allowable value and not greater than 5mm.

[0029] (2) Template Installation During installation, the inner formwork is first fixed to the pedestal with bolts and secured with support brackets to ensure stability. Then, the reinforcing cage is hoisted, with strict control over the protective layer during hoisting; any defects must be adjusted promptly. Finally, the outer formwork is installed. A specially designed sealing rubber gasket is used at the connection between the outer formwork and the pedestal. The rubber gasket is cut to match the shape of the connection edge, offering good elasticity, acid and alkali resistance, and ensuring a tight, leak-proof seal after installation, while also facilitating demolding. After the outer formwork is installed, the dimensions of each part are checked. Once the requirements are met, a limiting device is used for support and fixation, ensuring the outer formwork is stable and secure.

[0030] S4, Concrete Pouring Because of the use of horizontal casting, it is much more efficient and convenient than vertical casting. Its advantages are that the casting height is greatly reduced, with the highest being only 2 meters, and there are fewer transverse steel bars, which gives more space for the vibrator and greatly improves the construction quality of the beam concrete.

[0031] Concrete pouring is carried out in a closed shed, which effectively avoids the impact of severe weather such as strong winds, rain, and snow on the concrete pouring process. Based on temperature observation and statistics, the concrete pouring time is adjusted to the best time of day when the temperature is optimal, so as to ensure that the concrete pouring conditions are in the best condition.

[0032] Concrete is centrally mixed at a batching plant, which is fully enclosed with a corrugated steel shed to ensure the quality of raw materials under adverse weather conditions such as strong winds, rain, and snow. Concrete is transported by tanker trucks. During transportation, it should be stirred at a slow speed of 2-4 r / min, and then stirred at a normal speed before unloading. Concrete pouring is continuous and done in one go, with a pouring time not exceeding 3 hours. The layer thickness should be controlled to not exceed 30cm. An immersion vibrator is used for concrete vibration, employing a "quick insertion, slow withdrawal" technique. The vibrator should be inserted quickly to ensure equal vibration of the upper and lower layers, and withdrawn slowly; otherwise, the vibrator's position will not be properly compacted by the concrete mix. The movement distance should not exceed 50cm. The vibration time at each vibration point should be 20-30 seconds, until the concrete surface no longer shows significant subsidence, no more air bubbles appear, and the surface is flat with a layer of slurry. Vibration should be performed at a distance of 5-10 cm from the formwork, and collisions with the reinforcing bars should be avoided as much as possible. During concrete pouring, a designated person should monitor the formwork. If bolts become loose, the formwork shifts, or slurry leaks, measures should be taken promptly to address the issue. The top surface should be smoothed as required after pouring, and a second smoothing should be performed before initial setting.

[0033] S5, Concrete Curing Because the project site is located in the Hexi region, characterized by strong winds and large temperature differences, with dry summers and cold winters, proper concrete curing is a crucial task. This involves preventing the concrete from drying out too quickly in windy conditions and causing cracks, avoiding quality defects due to large temperature differences, and preventing rapid moisture evaporation under dry conditions. Ultimately, the project team adopted a "mobile curing shed" combined with a biomass and electric heating boiler for steam curing. Temperature and humidity meters were used to dynamically control the curing environment, ensuring the entire curing process was unaffected by harsh weather conditions until the culvert strength met design requirements upon completion.

[0034] The mobile curing shed is a dedicated curing shed that is calculated and processed according to the structural type and curing cycle before the curing of culvert sections. Since the culvert section base is a fixed base, the curing shed can be moved to the culvert section with matching size and sealed for curing according to the type of culvert section prefabricated each day. After curing, it can be reused, which improves efficiency and saves costs.

[0035] After the concrete is poured, a curing shed is sealed and covered with insulation cloth. Steam is then introduced to control the humidity and temperature inside the shed. Curing conditions are monitored using temperature and humidity meters to ensure that the temperature inside the shed is maintained at 20±2℃. The formwork is removed the next day when the ambient temperature is high and the concrete has reached the required strength for demolding. After the formwork is removed, the curing shed is sealed again and covered with insulation cloth. The humidity and temperature inside the shed are controlled using biomass and electric heating boilers. A dedicated person monitors and adjusts the curing conditions using temperature and humidity meters every 2 hours during the day and every hour at night to ensure that the temperature inside the shed is maintained at 20±2℃ and the humidity is maintained above 95%. Curing continues for 7 days until the concrete strength reaches the design requirements.

[0036] S6, Storage (1) Before storing the culvert sections, the quality of the culvert sections shall be inspected and accepted at the prefabrication site. Check whether the inner and outer diameters and thicknesses are consistent with the design drawings, and whether the overall deformation, shape and defect repair of the culvert sections are within the specified range.

[0037] (2) Concrete strength testing. The laboratory conducts rebound tests on box culverts that have not yet reached the required age. They can only be moved and stored when the concrete strength reaches 100% of the design strength.

[0038] (3) Mark the dimensions, specifications, pouring date, culvert pile number and box culvert number on the culvert section.

[0039] (4) Once the concrete strength reaches 100% of the design strength, store the precast box culverts according to their number and installation sequence. When storing precast box culverts, ensure the ground is flat and that they are laid flat; do not turn them over arbitrarily.

[0040] S7, Transportation and Installation (1) The precast box culvert sections are loaded onto the truck using one crane. First, the flatbed truck is driven to the designated loading position, and then the crane is used to lift the numbered precast box culvert sections to be erected from the storage area and slowly place them onto the flatbed truck. During the placement process, the culvert sections are protected, and square timbers are used to support the precast box culvert sections and the truck body.

[0041] (2) A flatbed truck shall be used for transportation, transporting 2-3 sections at a time. During transportation, the precast box culvert sections shall be securely tied to the flatbed truck with a chain guide and safely transported to the construction site. During transportation, the flatbed truck shall drive as close to the right side of the road as possible, and personnel shall be assigned to guide traffic and monitor the beams and culverts during transportation. If the beams and culverts become loose due to road bumps, the truck shall be stopped immediately for handling.

[0042] (3) When the culvert section is transported to the hoisting position, the hoisting rings embedded on the side of the culvert section are used in conjunction with the large and small hooks of the crane to lift the culvert section from the flatbed truck to a relatively flat place near the culvert foundation and flip it over, changing it from a horizontal position to a vertical position. Then the hoisting rings are cut to prepare for the installation of the culvert section in advance.

[0043] (4) Since the installation method used in this project is a "C" type lifting tool, the lifting port of the "C" type lifting tool can be quickly inserted into the culvert section for installation. Compared with the previous method, it is faster and simpler to operate, saving time and improving efficiency. During installation, the culvert section is lifted about 2-3cm away from the support surface and then paused to carefully check the stress points. Only after confirming that there are no errors can the support pads be removed and the lifting can continue. During the descent, in order to ensure accurate descent, the installation control edge line is marked on the foundation and is aligned with the installation edge line during placement. Rubber pads are set on the contact surface of the "C" type lifting tool with the culvert section to avoid damage to the culvert section by the lifting tool itself during the lifting of the culvert section.

[0044] (5) The prefabricated box culvert sections shall be installed in order from one side to the other. It is strictly forbidden to install the two sides first and then the middle, so as to avoid collision and scratching between the culvert sections.

[0045] S8. Installation complete. After the culvert section is installed, its joints, settlement joints and waterproof layer are constructed.

[0046] (1) Joint When assembling precast reinforced concrete box culvert segments, the concrete surfaces on both sides of the joint should be thoroughly rinsed with clean water and moistened. Then, the joint should be filled with polymer M15 mortar 15cm outward from the inside of the culvert, and the remaining gaps should be filled with asphalt hemp rope.

[0047] (2) Settlement joint Settlement joints are typically installed every 4-6 meters along the length of the culvert abutment. These joints must penetrate the entire culvert cross-section (including the foundation) and are 2 cm wide. Settlement joints are only installed in concealed culverts; open culverts do not have them. The inner side of the culvert body is filled with polymer M15 mortar for a 15 cm gap outwards, with any remaining voids filled with asphalt-impregnated hemp fiber.

[0048] (3) Waterproof layer The waterproofing measures on the outside of the culvert involve applying two coats of waterproof asphalt, each 1.5mm thick, to the area where the culvert contacts the backfill. No additional mortar is applied after this. Finally, the joints and settlement joints are wrapped circumferentially with MG-1 type rubber-backed waterstops (3mm thick). The next construction step can only proceed after the outer waterproofing layer of the culvert is completed.

[0049] Example 2

[0050] Reference Figures 2-5 A precast box culvert construction structure includes a platform 1, a mold assembly 2 is provided on the upper surface of the platform 1, a limit assembly 4 is provided on the mold assembly 2, and an installation assembly 3 is provided on the bottom of the platform 1.

[0051] Mold assembly 2 includes an inner mold 200 and an outer mold 201 mounted on a base 1. The bottom of the inner mold 200 penetrates the base 1 and extends to the outside of the base 1. A connecting plate 202 is fixedly mounted on the surface of the outer mold 201, and a triangular plate 203 is fixedly mounted on the top of the connecting plate 202. One side of the triangular plate 203 is fixedly connected to one side of the outer mold 201. A limiting plate 204 is inserted into the inner mold 200, and a stop block 205 is fixedly mounted on one end of the limiting plate 204. A screw 206 is inserted into the limiting plate 204, and one end of the screw 206 is threadedly connected to the bottom of the base 1. A screw 206 is provided on the limiting plate 204 for screws. The base 1 has a threaded hole at the bottom for screw 206 to be threaded into it, and the screw 206 is threaded into the threaded hole. A bolt 207 is inserted into the connecting plate 202, and the bottom of the bolt 207 is threaded into the upper surface of the base 1. The connecting plate 202 has a round hole for the bolt 207 to pass through. The mold assembly 2 and the mounting assembly 3 are set up to facilitate positioning and installation during use, thereby improving the ease of use of the structure and making it more convenient for subsequent use and for staff to operate.

[0052] The limiting component 4 includes a pull rod 400 inserted into the outer mold 201 and the inner mold 200. A nut 401 is threaded onto the surface of the pull rod 400, with one side of the nut 401 fitting against one side of the inner mold 200. A threaded tube 402 is fitted onto the surface of the pull rod 400, with one side of the threaded tube 402 fitting against one side of the outer mold 201. Both the outer mold 201 and the inner mold 200 have rod holes for the pull rod 400 to pass through. The inner wall of the rod hole is slidably connected to the surface of the pull rod 400. A wrench is fixedly installed at one end of the threaded tube 402, and the surface of the wrench has anti-slip textures. A steel reinforcement cage 5 is provided between the inner mold 200 and the outer mold 201, and a lifting ring 6 is fixedly installed on the steel reinforcement cage 5. The limiting component 4 facilitates limiting operations during use and also facilitates limiting installation during subsequent use, thereby improving the ease of use of the structure.

[0053] Reference Figure 2 In a preferred embodiment, the mounting assembly 3 includes positioning plates 300 fixedly mounted on both sides of the bottom of the base 1, and mounting plate 301 fixedly mounted on the bottom of the positioning plate 300. The mounting plate 301 has mounting holes, which are oblong holes, and the lower surface of the mounting plate 301 has anti-slip texture.

[0054] Working principle: First, the site is leveled to ensure flatness and elevation. The ground is hardened and the entire prefabrication area is fully enclosed with a color steel shed. The number of piers is set according to the type and quantity of culvert sections and the construction period. Grouting strips are installed on both sides and top of the piers to prevent grout leakage. Drainage facilities are also installed to ensure that the drainage system is unobstructed.

[0055] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A construction method for precast box culverts, suitable for harsh climatic environments with cold, drought, strong winds, and large temperature differences, characterized in that... Includes the following steps: S1. Construction preparation: Level and harden the prefabrication site, and build a fully enclosed color steel shed; set up fixed platforms according to the type, quantity and construction period of the culvert sections, install grout-stop strips on both sides of the platform top, and improve the site drainage system; S2. Reinforcing bar processing and binding: Inspected and qualified reinforcing bars are centrally cut and processed, and the main bars are connected by sleeve connection; the processed semi-finished reinforcing bars are bound and shaped on an adjustable reinforcing bar binding platform, which can be adjusted in length according to different span or height dimensions of the culvert section to accommodate various sizes and types of culvert sections; S3. Template Installation: Standard steel templates are used. Before installation, they are inspected, trial-assembled, and release agent is applied. During installation, the inner template is first fixed to the platform, then the steel reinforcement cage is hoisted into the template and the protective layer is adjusted. Finally, the outer template is installed, and special sealing rubber gaskets, tie rods, and limiting devices are used to ensure that the template is installed firmly and tightly. S4. Concrete pouring: Concrete pouring is carried out in an enclosed greenhouse at the optimal time of day based on temperature observation data; horizontal, layered, and continuous pouring is adopted, with each layer thickness controlled to be no more than 30cm; an immersion vibrator is used for compaction, and a dedicated person is assigned to monitor the formwork status; after pouring, a finishing and secondary finishing are carried out. S5. Concrete Curing: After the concrete is poured, the culvert section is immediately covered with a mobile special curing shed and sealed with insulation cloth; connect a biomass and / or electric heating boiler to introduce hot steam into the curing shed for curing; monitor the environment inside the shed in real time with a temperature and humidity monitor to maintain the temperature at 20±2℃ and the humidity at above 95% for continuous constant temperature and humidity curing until the concrete strength reaches the design requirements; S6. Culvert Section Storage: After curing, the culvert sections are inspected for quality and tested for concrete strength. Once the strength reaches 100% of the design strength, they are stored flat according to their number and installation sequence. S7. Transportation and Installation: Flatbed trucks are used to transport culvert sections, and binding and securing measures are taken. After arriving at the site, the culvert sections are turned into a vertical position using pre-embedded lifting rings and a crane. "C" type lifting tools equipped with rubber pads are used for lifting, with the lifting tool's lifting port embedded in the culvert section, and the sections are installed in place in sequence from one side to the other. S8. Joint and Waterproofing Treatment: After installation, clean and moisten the joints and settlement joints, and fill them with polymer mortar and asphalt hemp rope; apply waterproof asphalt to the outside of the culvert, and wrap rubber waterstops around the joints and settlement joints to complete the waterproofing layer construction.

2. The precast box culvert construction method according to claim 1, characterized in that, In S2, the adjustable rebar tying platform is designed for culvert types with the same span but different heights or different spans but the same height. By setting adjustment buckles or making the platform according to the maximum size, it can achieve multiple uses with one machine, saving costs and space.

3. The precast box culvert construction method according to claim 1, characterized in that, In S5, the health maintenance process is monitored by a dedicated person. During the initial stage of maintenance, the temperature and humidity conditions are observed and adjusted every 2 hours during the day and every 1 hour at night.

4. The precast box culvert construction method according to claim 1, characterized in that, In S7, when the "C" type lifting tool is used for hoisting, the culvert section is first lifted 2-3cm away from the support surface and then paused. The force-bearing parts are checked and confirmed to be correct before continuing the hoisting. During installation, the culvert section is aligned with the installation control line that pops out on the foundation.

5. A precast box culvert construction method according to claim 1, characterized in that, This also includes using fully enclosed corrugated steel sheds at concrete mixing plants and installing water purification equipment to ensure the quality of raw materials and mixing water.

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