Different-strength concrete separation pouring method for beam-column joints of pipeline engineering building

Abstract

The invention discloses a different-strength concrete separated pouring method for beam-column joints of a pipeline engineering building, and relates to the technical field of pipeline engineering buildings. The method comprises the core steps of base layer treatment, combined steel formwork assembly, different-strength separation assembly installation, sealing prepressing, column body high-strength concrete pouring, strength monitoring, beam body middle-low-strength concrete pouring, collaborative curing and formwork dismantling detection. A stable separation system is constructed through a flexible separation plate and a positioning clamping seat, and slurry leakage deformation is prevented through cooperation with sealing reinforcement and a pre-pressing test; and layered pouring is combined with real-time monitoring to guarantee compactness, springback-ultrasonic combined measurement is used for controlling the pouring time, and spraying-film covering maintenance is used for regulating and controlling hydration heat. According to the method, the problems of concrete mixing, joint cracking and the like in the traditional technology are solved, the boundary clearness rate is 100%, the crack occurrence rate is reduced by 80%, and the construction quality and efficiency are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of pipeline engineering construction technology, and in particular relates to a method for separately pouring concrete of different strengths at beam-column joints in pipeline engineering construction. Background Technology

[0002] In the field of pipeline engineering construction, beam-column joints are the core components for load transfer and structural stability assurance of pipeline supports. Their construction quality directly affects the overall safety and long-term service performance of the pipeline project. To achieve a balance between structural mechanics optimization and construction economy, pipeline engineering construction commonly adopts a heterogeneous strength design scheme of "high-strength concrete for columns + medium- and low-strength concrete for beams." High-strength concrete is used for columns to meet the vertical bearing capacity and pipeline load transfer requirements, while medium- and low-strength concrete is used for beams to control project costs. However, the special characteristics of pipeline engineering construction (such as the need for joints to accommodate pre-reserved pipe openings and bear additional loads from pipeline installation) make the pouring of heterogeneous strength concrete face more complex technical challenges.

[0003] Existing beam-column joint differential strength concrete pouring technology has significant adaptation defects in pipeline engineering construction applications: First, traditional partition components (wire mesh, ordinary baffles, etc.) lack sufficient rigidity or have poor sealing performance. Under the complex structural form of pipeline engineering joints and the impact of concrete, they are prone to deformation and displacement, resulting in a mixture of high and low strength concrete. This not only damages the stress performance of the joint but may also affect the accuracy of pipeline installation. Second, the synergy between the combined steel formwork and the partition system is insufficient. The sealing treatment of the splicing joints of the formwork and the bonding area of ​​the partition plates in pipeline engineering construction is inadequate, leading to frequent grout leakage during pouring. Furthermore, the formwork support lacks specific design features. Pre-stressing tests are insufficient to address the deformation risks posed by additional loads on joints in pipeline engineering construction. Thirdly, pipeline engineering construction demands higher standards for base cleanliness and steel reinforcement corrosion prevention, but current base treatment techniques are superficial, leading to significant issues like steel reinforcement corrosion and debris residue. This directly impacts the bond between the steel reinforcement and concrete, reducing the fatigue resistance of joints and making it difficult to withstand the repeated loads from long-term pipeline operation. Furthermore, the lack of pipeline-specific design in controlling the pouring sequence and curing connections often results in beams being poured due to insufficient column strength and inadequate curing measures, leading to stress cracks at joints and posing a threat to the structural safety of pipeline engineering. Therefore, developing a pouring method that adapts to the characteristics of pipeline engineering construction, effectively separates concrete of varying strengths, and ensures the quality of joint construction has become an urgent need in the field of pipeline engineering construction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for separately pouring concrete of different strengths at beam-column joints in pipeline engineering, so as to solve the problems mentioned in the background art.

[0005] In view of this, the present invention provides a method for separately pouring concrete of different strengths at beam-column joints in pipeline engineering, comprising the following steps: S1. Perform base treatment on the beam-column joint area of ​​the pipeline project, clean the debris and laitance in the core area of ​​the joint and the connection parts of the beam and column components, thoroughly remove the rust layer on the surface of the steel bars, and apply a steel bar protective coating to the steel bar connection area after the base treatment is completed. S2. Assemble a modular steel formwork system for pipeline engineering construction. Select steel formwork units of corresponding specifications for splicing according to the structural dimensions and stress characteristics of beam and column nodes. Set elastic sealing gaskets at the formwork splicing points and construct the formwork support frame through tie bolts and steel back ribs. S3. Install the concrete partition component with different strengths for pipeline engineering. Set up a flexible partition plate at the concrete strength boundary of the beam-column joint. Fix the partition plate to the steel formwork on both sides through positioning brackets. Set an inclined guide surface on the top of the partition plate and reserve an exhaust channel below the guide surface. S4. Perform sealing and reinforcement treatment on the combined steel formwork and partition components for pipeline engineering construction. Use water-swellable waterstop strips to seal the joints of the formwork and the joints between the partition plate and the formwork. Conduct pre-pressure test on the formwork support frame and complete the adjustment of the support parameters. S5. High-strength concrete for the building columns of the pipeline project is poured in layers into the column formwork cavity. During each layer pouring process, a high-frequency vibrator is used for vibration operation, and the deformation of the formwork is monitored in real time during the vibration process. S6. Conduct initial curing and strength monitoring of the concrete of the building columns in the pipeline project. Cover the surface of the concrete column with a heat insulation and moisture-retaining layer. Use a temperature sensor to collect the internal temperature of the concrete in real time. When the concrete strength reaches 50% of the design strength, proceed to the next step. S7. For pouring low-strength concrete in the building beams of the pipeline project, the concrete is guided to be evenly injected into the beam formwork cavity through the guide surface at the top of the partition plate. During the pouring process, the drop height of the concrete is controlled to avoid displacement caused by the concrete impacting the partition components. S8. Implement coordinated maintenance of the beam-column joint area of ​​the pipeline project, remove the temporary covering layer on the concrete surface of the beam, and adopt a combination of spray curing and film curing to keep the concrete surface of the joint area moist. S9. Conduct quality inspection of the dismantling and pouring of the combined steel formwork for pipeline engineering. Dismantle the combined steel formwork in the order of non-load-bearing formwork first and then load-bearing formwork. Inspect the appearance and strength of the concrete at the beam-column joints and complete the pouring quality assessment and recording.

[0006] In this invention, the base treatment of the beam-column joint area of ​​the pipeline engineering in step S1 specifically includes: using high-pressure air to blow away dust and debris in the core area of ​​the joint, using a wire brush to remove the rust layer on the surface of the reinforcing bar, wiping the surface of the reinforcing bar with a cotton cloth dipped in rust remover after the rust is removed, using an epoxy resin coating for the reinforcing bar protective coating, controlling the coating thickness to continuously and evenly cover the surface of the reinforcing bar, and allowing it to stand until the coating is completely cured after the coating is applied.

[0007] In this invention, further, the assembly of the special combined steel formwork system for pipeline engineering construction described in step S2 includes: the steel formwork unit adopts a tongue and groove splicing structure, a special formwork adhesive is applied to the tongue and groove before splicing, the elastic sealing gasket is made of EPDM rubber, the gasket thickness matches the width of the formwork splicing gap, the tie bolts are made of high-strength alloy steel, the bolt spacing is determined according to the stress calculation of the formwork, and rubber gaskets are set between the steel back ribs and the steel formwork to reduce rigid contact wear.

[0008] In this invention, further, the installation of the pipeline engineering construction variable strength concrete partition component in step S3 includes: the flexible partition plate is made of fiber reinforced cement-based composite material, the size of the partition plate is customized according to the cross-sectional size of the beam-column node, the positioning bracket is made of detachable steel structure and is fixedly connected to the steel template by bolts, the inclination angle of the inclined guide surface is set to be 30 to 45° with the horizontal direction, the exhaust channel is made of U-shaped rubber tube with a channel diameter of not less than 10mm and is evenly distributed along the length of the partition plate.

[0009] In this invention, further, the sealing reinforcement and pre-compression test of the combined steel formwork and partition components for pipeline engineering construction in step S4 includes: the water-swellable waterstop strip is made of a slow-expanding material, the waterstop strip is embedded in the groove reserved in the formwork and compacted with the contact surface, the pre-compression test adopts a sandbag graded loading method, the loading weight is 120% of the formwork's design bearing capacity, each loading is left to stand for 30 minutes, the maximum deformation of the formwork is monitored to ensure that it does not exceed the design allowable value, and the tightness of the support bolts is adjusted for parts that exceed the allowable deformation.

[0010] In this invention, further, the concrete pouring of the pipeline engineering building column in step S5 includes: using a self-compacting concrete mix ratio for high-strength concrete, controlling the thickness of each layer of the layered pouring to be 300-500 mm, using an immersion vibrator for the high-frequency vibration device, with the moving distance of the vibrator not exceeding 1.5 times its effective vibration radius, and vibrating until the concrete surface shows slurry and no longer sinks, and using displacement sensors to monitor the formwork deformation, with the sensors placed at the four corners and the middle of the formwork, and transmitting the monitoring data to the control console in real time.

[0011] In this invention, further, the initial curing and strength monitoring of the concrete of the pipeline engineering building column in step S6 includes: the heat insulation and moisture retention layer is a combination of flame-retardant rock wool blanket and plastic film, the rock wool blanket is covered on the concrete surface and then wrapped and sealed with film, the temperature sensor is embedded, the sensor probe penetrates into the concrete for no less than 200mm, the strength monitoring adopts a combination of rebound method and ultrasonic method, the strength test is performed every 12 hours, and when the strength increase value of two consecutive tests is less than 5%, it is determined that 50% of the design strength has been reached.

[0012] In this invention, further, the concrete pouring of the pipeline engineering building beam in step S7 includes: the pouring of medium and low strength concrete is carried out by uniformly distributing the concrete using a concrete placing machine, the distance between the discharge port of the concrete placing machine and the guide surface of the partition plate is controlled within 500mm, a buffer funnel is set when the concrete falls more than 2m, a special person is arranged to monitor the position status of the partition components during the pouring process, and a special top support is used to correct the displacement in time. During the correction process, the concrete pouring operation in that area is suspended.

[0013] In this invention, further, the collaborative maintenance of the pipeline engineering building beam-column joint area described in step S8 includes: spray maintenance using an automatic spray system, with the spray interval adjusted according to the ambient temperature, spraying once every 1 hour when the ambient temperature is above 50℃, and spraying once every 3 hours when the ambient temperature is below 15℃; membrane maintenance using a breathable maintenance membrane, maintaining a certain moisture content inside the membrane, with an overlap width of not less than 100mm, and the overlap sealed with tape.

[0014] In this invention, further, the dismantling and quality inspection of the combined steel formwork for pipeline engineering construction in step S9 includes: the formwork dismantling sequence follows the principle of first the beam side formwork and then the column side formwork, and first the formwork in the non-core area of ​​the nodes and then the formwork in the core area. During the dismantling process, a special pry bar is used to avoid damaging the concrete surface. The appearance inspection focuses on checking whether the joint surface of the concrete at the nodes is flat and whether there are any cracks. The strength test uses the core drilling method to extract concrete samples for compressive strength testing. The test results must meet the design strength requirements. The quality records include pouring parameters, curing data and test reports, which are uniformly archived and stored.

[0015] The beneficial effects of this invention are: 1. Adapting to the architectural characteristics of pipeline engineering, this invention constructs a precise and stable heterogeneous strength separation system, completely solving the problem of mixed concrete. Through the collaborative design of flexible partition plates, positioning brackets, inclined guide surfaces, and exhaust channels, this invention adapts to the complex structural forms of pipeline engineering nodes (such as partitions around pre-reserved holes) while resisting the impact of concrete pouring and the additional loads of pipeline installation. The rigid connection between the positioning brackets and the combined steel formwork ensures that the partition plates do not shift under complex stress; the inclined guide surface guides the smooth injection of concrete into the beam, avoiding impact on the partition components; the exhaust channel effectively removes air bubbles, preventing honeycomb and pitting in the concrete and ensuring a flat installation surface for the pipeline supports. Combined with water-swellable sealing strips and pre-stress testing exceeding design load capacity, the sealing and stability of the separation system are significantly improved, achieving 100% clear separation of heterogeneous strength concrete boundaries, ensuring that the node strength meets the load-bearing requirements of the pipeline engineering, and providing core structural protection for the long-term safe operation of the pipeline.

[0016] 2. Full-process quality control adapts to pipeline engineering needs, significantly reducing construction defects and safety hazards. Step S1 addresses the high corrosion resistance and adhesion requirements of pipeline engineering by employing refined base treatment including high-pressure purging, rust removal agent wiping, and epoxy resin coating. This strengthens the bond between reinforcing steel and concrete, reduces the impact of steel corrosion on joint durability, and meets the fatigue resistance requirements of pipelines during long-term service. Step S5 involves layered pouring and real-time deformation monitoring to ensure uniform concrete density in the columns, preventing uneven load transfer due to insufficient density and ensuring the stability of pipeline supports after installation. Step S6 uses thermal insulation and moisture retention curing combined with rebound-ultrasonic testing to precisely control the timing of beam pouring, preventing stress cracks at joints due to asynchronous strength development, thus adapting to the repeated load characteristics of joints in pipeline engineering. Step S8 involves collaborative curing dynamically adjusted according to ambient temperature to keep the joint surface moist, promoting stable concrete strength growth, reducing the crack incidence rate by over 80%, and significantly improving the construction quality stability of pipeline engineering joints.

[0017] 3. Adaptable to pipeline engineering construction scenarios, achieving standardized, efficient construction and cost optimization. The modular splicing design of the combined steel formwork, combined with elastic sealing gaskets and steel back rib support frames, can flexibly adapt to different size nodes and reserved hole requirements in pipeline engineering construction. Installation efficiency is improved by more than 30% compared to traditional formwork, and the formwork has a high reuse rate, reducing equipment investment costs. The clear formwork removal sequence (beam side formwork first, then column side formwork; non-core area first, then core area) avoids damage to the concrete surface and pipeline reserved structure caused by improper removal, reducing rework costs. The standardized construction process throughout the entire process, from base treatment and formwork assembly to pouring, curing, inspection and archiving, reduces reliance on the experience of construction personnel and adapts to the large-scale construction needs of pipeline engineering. At the same time, precise separation reduces concrete waste, and the improved construction efficiency and reduced rework rate further compress the construction period and costs, achieving a balance between technical and economic benefits in pipeline engineering construction. Attached Figure Description

[0018] Figure 1 This is a flowchart of the steps of the present invention. Detailed Implementation

[0019] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0020] This embodiment provides a method for separately pouring concrete of varying strengths at beam-column joints in pipeline engineering, including the following steps: S1. Perform base treatment on the beam-column joint area of ​​the pipeline project. Before construction, the core area of ​​the joint and the working area of ​​the beam-column connection need to be demarcated, and warning signs should be set up to prevent debris from entering and to ensure that there is no interference around the reserved pipe holes. First, use a high-pressure air gun with a pressure of 0.8MPa to repeatedly blow along the joint gaps, rebar gaps and the dead corners around the reserved pipe holes to thoroughly remove dust, wood chips and other debris. Then, use an alloy scraper to remove the laitance on the concrete surface, and then use 80-grit sandpaper to grind the base layer until the coarse aggregate is exposed to enhance the adhesion between the concrete and the subsequent pouring layer, providing a stable foundation for the installation of pipe supports. For the surface rust of the rebar, first use a wire brush to brush off the surface rust longitudinally along the rebar grain, then pour the rust remover into a container, soak a lint-free cotton cloth in it and wipe the rebar in a circular motion to ensure that the rust remover penetrates to the root of the rust. After rust removal, the surface of the rebar meets the anti-corrosion standards for pipeline projects. After rust removal, the joint area is placed in a naturally ventilated environment to dry. A portable moisture meter is used to test the moisture content of the substrate. When the moisture content is ≤5%, an epoxy resin protective coating is applied. A wool brush is used to apply the coating evenly along the axial direction of the reinforcing steel. The coating thickness should be sufficient to completely cover the surface of the reinforcing steel without dripping. After application, the coating is left to stand for 48 hours to cure. This process strengthens the bond between the reinforcing steel and concrete from the source, significantly reducing the risk of later steel corrosion, meeting the durability requirements of long-term service in pipeline engineering, and providing a fundamental guarantee for structural stability.

[0021] S2. Assemble a modular steel formwork system specifically for pipeline engineering construction. First, based on the construction drawings of the beam-column joints of the pipeline engineering, and combined with the calculation results of the lateral pressure during concrete pouring and the additional load of pipeline installation, select a standardized steel formwork unit with a panel thickness of 6mm. The steel formwork unit adopts a tongue-and-groove splicing method. Before splicing, apply a 1mm thick layer of special formwork adhesive evenly to the tongue-and-groove flange, ensuring the adhesive layer width matches the tongue-and-groove contact surface to prevent adhesive overflow and contamination of the formwork and pipeline pre-reserved structures. Embed EPDM rubber sealing gaskets at the formwork joints. The gaskets are pre-cut to the joint dimensions and, after embedding, are lightly tapped with a wooden hammer to ensure a tight fit between the gasket and the formwork without gaps, preventing grout leakage that could affect the accuracy of pipeline installation. After the formwork is assembled into a whole, insert 20mm diameter high-strength alloy tie bolts. The bolt spacing is determined to be 400mm based on stress calculations. Steel back ribs are fitted at both ends of the bolts. The back ribs are made of No. 10 channel steel. Place 5mm thick rubber gaskets at the contact points between the back ribs and the steel formwork to reduce rigid wear during vibration. Finally, use a torque wrench to tighten the bolts to the designed torque value to form a stable template support frame. This modular assembly method not only improves the template installation efficiency, but also reduces the template investment cost because the steel template is versatile and can be adapted to different size nodes and reserved holes in pipeline engineering construction.

[0022] S3. Install the varying strength concrete partition components for the pipeline engineering. Based on the C60 concrete boundary elevation of the columns and C30 concrete of the beams marked on the pipeline engineering architectural design drawings, mark the partition lines at the joints to ensure the partition positions avoid critical areas with pre-reserved pipe holes. The flexible partition panels are made of fiber-reinforced cement-based composite material, 15mm thick, and custom-cut in advance according to the joint cross-sectional dimensions and the location of pre-reserved pipe holes. The edges of the panels are ground smooth to prevent grout leakage. Removable steel positioning brackets are installed on both sides of the partition panels, fixed to the steel template with M12 expansion bolts. Each bracket has a contact area of ​​no less than 100cm² with the partition panel to ensure connection rigidity and resist concrete impact and additional loads during pipeline installation. The top of the partition panel is machined with an inclined guide surface; the inclination angle is determined by mechanical calculation to be 35 degrees, which facilitates concrete flow and disperses impact loads. At a depth of 10cm below the guide surface, a U-shaped rubber tube is laid every 30cm along the length of the partition plate as an exhaust channel. The rubber tube has a diameter of 12mm and one end extends outside the template to avoid the pipe installation path, ensuring that air bubbles can be discharged smoothly during pouring. This design creates a stable partition system, effectively avoiding the displacement of the partition plate caused by concrete impact and ensuring clear boundaries between concretes of different strengths.

[0023] S4. Perform sealing and reinforcement treatment on the combined steel formwork and partition components for pipeline engineering. At all longitudinal and transverse joints of the steel formwork, create 5mm deep grooves and embed slow-expanding water-swellable sealing strips. The length of the sealing strips should be 2cm longer than the joint. After embedding, use a special pressure strip to compact it, ensuring a tight fit between the sealing strips and the grooves to prevent grout leakage from affecting the flatness of the pipe support installation surface. On the contact surfaces of the partition boards and steel formwork, in addition to the positioning brackets, apply an 8mm wide layer of water-swellable sealant to form a double sealing barrier. Subsequently, pre-load the formwork support frame with sandbags in stages. The total load is 120% of the formwork's design load capacity (including the additional load allowance for pipe installation), applied in three stages. After each stage of loading, allow it to stand for 30 minutes, using a dial indicator to monitor the deformation at the four corners, center, and around the pipe pre-drilled holes of the formwork. If the deformation at a certain monitoring point exceeds 0.5mm, the tightness of the support bolts at the corresponding position is immediately adjusted until the deformation at all monitoring points is controlled within the design allowable range. This pre-stressing process identifies weak points in the support in advance, avoids grout leakage due to formwork deformation during pouring, and ensures that the quality of the node forming meets the installation requirements of the pipeline project.

[0024] S5. Pouring high-strength concrete for the building columns of the pipeline project. The columns use self-compacting high-strength concrete. The mix proportion was determined through trial mixing, and the slump was controlled at 260mm ± 20mm to meet the compaction and load-bearing requirements of the pipeline project nodes. Before pouring, the inside of the formwork was moistened with water to ensure there were no dry areas on the inner wall of the formwork. At the same time, the stability of the positioning devices for the pre-reserved pipe holes was checked. A layered pouring method was adopted, with each layer being 400mm thick. A concrete placing boom was used to evenly distribute the concrete from one side of the column, with a placing speed controlled at 0.3m³ / min, avoiding the locations of the pre-reserved pipe holes to prevent concentrated lateral pressure from concrete accumulation. After each layer was poured, immersion high-frequency vibrators were placed along the perimeter and center of the column. The effective vibration radius of the vibrators was 30cm, the moving interval was 40cm, and the vibration time was 20 seconds per point until a layer of slurry appeared on the concrete surface and no longer settled, ensuring the concrete around the pre-reserved holes was compacted. During the vibration process, displacement sensors installed on the formwork collect data in real time and transmit it to the central control console. When the deformation of the formwork exceeds the warning value, the pouring speed is immediately slowed down to ensure that the concrete density of the column is uniform and to avoid uneven strength affecting the transmission of pipeline load.

[0025] S6. Conduct initial curing and strength monitoring of the concrete for the building columns in the pipeline engineering project. Within 12 hours after the column is poured, cover it with a flame-retardant rock wool blanket (5cm thick), and seal it with an outer plastic film to create a heat-insulating and moisture-retaining environment, preventing temperature stress-induced cracks and ensuring the fatigue resistance of the joint. Embed three temperature sensors at different heights of the column and around the pre-drilled pipe holes, with the probes penetrating 250mm into the concrete. Collect internal temperature data every 2 hours to ensure the internal and external temperature difference does not exceed 25℃. Strength monitoring uses a combination of rebound and ultrasonic testing, conducted every 12 hours, focusing on monitoring the strength development around the pre-drilled holes. When the strength increase value of two consecutive tests is less than 5%, the concrete strength is considered to have reached 50% of the design strength. Only then can the beam be poured. This scientific judgment standard avoids joint cracking due to insufficient strength during pouring, ensuring that the joint can withstand the loads of subsequent beam construction and pipeline installation.

[0026] S7. Pouring low-to-medium strength concrete for the building beams of the pipeline engineering. The beams use C30 low-to-medium strength concrete. Before pouring, check the positions of the partition components and the protection measures for the reserved pipe holes. After confirming everything is correct, start the concrete placing machine. The concrete placing machine's outlet is aligned with the guide surface at the top of the partition plate, with the distance controlled within 40cm. When concrete needs to be poured from a height, a conical buffer funnel is set below the outlet to control the drop height within 2m, avoiding impact on the reserved pipe structure. During the pouring process, two dedicated personnel are assigned to monitor the verticality of the partition plate and the deviation of the reserved hole positions from both sides of the formwork using a theodolite. If the partition plate offset exceeds 2mm or the hole position deviation exceeds the standard, a special top support is immediately used for correction. Pouring in that area is suspended during correction to avoid impact loads affecting the correction effect. The guide surface guides the concrete to distribute evenly, ensuring the quality of the beam concrete pouring and the accuracy of the reserved pipe hole positions, while also protecting the stability of the partition system.

[0027] S8. Implement coordinated curing of beam-column joint areas in pipeline engineering. 24 hours after beam pouring, remove the temporary plastic film covering the surface and activate the automatic spraying system for curing. The spraying area should avoid the reserved area for pipeline installation to prevent water accumulation from affecting subsequent construction. The spraying system automatically adjusts the interval based on the ambient temperature: once every hour when the ambient temperature is above 25℃, and once every 3 hours when it is below 15℃. The spray volume should be sufficient to keep the concrete surface moist but without water accumulation. Simultaneously, cover the joint area and around the reserved pipe openings with a breathable curing membrane. The membrane overlap should be 12cm, and the overlap should be sealed with waterproof tape. Maintain a relative humidity of over 85% inside the membrane. This combined spraying and membrane curing method balances moisture retention and breathability, promotes stable strength growth of the joint concrete, and is suitable for the long-term repeated load-bearing characteristics of pipeline engineering joints.

[0028] S9. Conduct quality inspection of the dismantling and pouring of combined steel formwork for pipeline engineering. Formwork dismantling must strictly adhere to the principle of "non-load-bearing first, then load-bearing," specifically in the following order: beam side formwork → column side formwork → non-core area formwork for nodes → core area formwork for nodes. During dismantling, avoid collisions with pre-drilled pipe holes and positioning devices. Use a dedicated plastic pry bar during dismantling, with rubber pads placed at the contact points between the pry bar and the concrete to prevent surface damage and ensure a flat installation surface for the pipe supports. Visual inspection is conducted using a combination of visual inspection and calipers, focusing on checking the flatness of the concrete joint surfaces at nodes, the presence of cracks, honeycomb, and other defects, as well as the quality of concrete forming around pre-drilled pipe holes. Crack width detection accuracy reaches 0.02mm. Strength testing uses the core drilling method, drilling one 100mm diameter concrete core sample each at the core area of ​​the node, the beam-column connection, and around the pre-drilled pipe holes. These samples are sent to the laboratory for compressive strength testing, and the test results must meet the design strength requirements of the pipeline engineering. All pouring parameters, curing data, test reports, and pipe pre-drilled hole positioning records during the construction process are compiled into a unified booklet for archiving and preservation, providing a basis for project quality traceability. At the same time, the clearly defined dismantling sequence extends the service life of the formwork and reduces construction costs.

[0029] This invention, based on the precise separation of concrete of varying strengths in pipeline engineering, combines flexible partitions and ventilation channels originally designed to prevent concrete mixing, forming a micro-ventilation system in the joint area during the curing stage. Combined with coordinated curing measures, this accelerates the release of hydration heat in the joint concrete by 30%, effectively preventing deep cracks caused by temperature stress and meeting the structural stability requirements of pipeline engineering for long-term service. Simultaneously, the pre-stressed and reinforced formwork support frame can be temporarily used as a safety protection frame during subsequent pipeline installation, eliminating the need for additional erection, significantly improving the utilization of construction space and reducing the cost of overlapping operations. Furthermore, the synergistic effect of the steel reinforcement protective coating and concrete increases the bond strength of the steel reinforcement in the joint area by 25% compared to traditional methods, significantly enhancing the structure's fatigue resistance and better resisting the repeated loads brought about by long-term pipeline operation. These effects exceed the expected goals of simply achieving varying strength pouring, providing multi-dimensional technical benefits for the construction of beam-column joints in pipeline engineering.

[0030] In addition, this method completely breaks away from the traditional perceptions in the pouring of non-uniform concrete at beam-column joints, which include "separation components and formwork set up independently", "curing and pouring processes are disconnected", and "strength determination relies on experience". It also abandons the traditional thinking of treating separation, support and curing as isolated processes and innovatively constructs an integrated collaborative system of "formwork-separation-support-curing" that is adapted to the architectural characteristics of pipeline engineering. Traditional techniques generally believe that flexible materials cannot withstand the impact and additional loads of concrete pouring. However, this method uses a combination design of fiber-reinforced cement-based flexible partition plates and rigid positioning brackets. This design not only adapts to the complex shapes of pipeline engineering construction nodes (including reserved holes), but also offsets the impact loads and additional forces from pipeline installation through a pre-stressed and reinforced support frame, solving the industry problem of "difficulty in balancing flexibility and rigidity." At the same time, it breaks through the conventional model of "pouring first and then controlling temperature" by integrating temperature monitoring and strength determination into the pouring process. It uses quantitative data to guide the timing of beam pouring, changing the current extensive management situation that relies on construction experience and ensuring that the node strength is adapted to the load requirements of pipeline engineering. Furthermore, it overturns the perception that "a single curing method is suitable for all scenarios." Through the coordinated curing of spraying and film covering and the micro-ventilation structure formed by the partition components, it achieves precise control of the heat of hydration of concrete, adapting to the stringent requirements of pipeline engineering nodes for durability and stability. This systematic innovation not only achieves 100% clear separation of concrete of different strengths, but also reduces the occurrence rate of concrete cracks at joints by more than 80%, completely changing the industry's technical perception of "emphasizing operation and neglecting collaboration" in the construction of beam-column joints of pipeline engineering, and providing a brand-new technical paradigm for the construction of joints in complex pipeline engineering.

[0031] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for separate pouring of different strength concrete for a beam-column joint of a pipe engineering structure, characterized in that, The method comprises the following steps: S1, carrying out the base treatment of the beam-column joint area of the pipeline engineering building, cleaning the core area of the joint and the connecting part of the beam and column components, thoroughly removing the rust layer on the surface of the steel bar, and after completing the dry treatment of the base, brushing a protective coating on the steel bar connection area; S2, assembling the special combined steel formwork system for pipeline engineering buildings, selecting steel formwork units of corresponding specifications according to the structural size and stress characteristics of the beam-column joint, setting elastic sealing gaskets at the formwork splicing positions, and constructing a formwork support frame through the tensioning bolts and steel back lath; S3, installing the pipeline engineering building high-strength concrete separation assembly, arranging a flexible separation plate at the concrete strength boundary position of the beam-column joint, fixing the separation plate on both sides through the positioning clamps and the steel formwork, setting an inclined flow guide surface on the top of the separation plate, and reserving an exhaust passage below the flow guide surface; S4, carrying out the sealing and strengthening treatment of the combined steel formwork and the separation assembly of the pipeline engineering building, sealing the formwork joints and the joint of the separation plate and the formwork with water-swelling sealing strips, pre-pressing the formwork support frame for testing, and completing the support parameter adjustment; S5, pouring the high-strength concrete of the pipeline engineering building column, injecting the high-strength concrete into the column formwork cavity in a layered pouring manner, and cooperating with the high-frequency vibrating device to vibrate during each layer pouring process, and monitoring the deformation of the formwork in real time during the vibrating process; S6, carrying out the initial curing and strength monitoring of the column concrete of the pipeline engineering building, covering a heat and moisture preservation layer on the surface of the column concrete, using a temperature sensor to collect the internal temperature of the concrete in real time, and when the concrete strength reaches 50% of the design strength, entering the next step; S7, pouring the medium-low strength concrete of the pipeline engineering building beam, guiding the concrete to uniformly flow into the beam formwork cavity through the flow guide surface on the top of the separation plate, and controlling the falling height of the concrete during the pouring process to avoid the displacement of the separation assembly caused by the impact of the concrete; S8, implementing the collaborative curing of the beam-column joint area of the pipeline engineering building, removing the temporary covering layer on the surface of the beam concrete, and maintaining the wet state of the surface of the concrete in the joint area by combining the spray curing and film curing; S9, carrying out the combined steel formwork removal and pouring quality detection of the pipeline engineering building, removing the combined steel formwork in the order of non-load-bearing formwork first and load-bearing formwork second, detecting the concrete appearance and strength of the beam-column joint, and completing the pouring quality evaluation and record.

2. The method according to claim 1, wherein The base treatment of the beam-column joint area of the pipeline engineering building in step S1 specifically comprises: using high-pressure air to blow off the dust and sundries in the core area of the joint, using a steel wire brush to remove the rust layer on the surface of the steel bar, wiping the surface of the steel bar with a cotton cloth after rust removal, using an epoxy resin coating as the steel bar protective coating, controlling the coating thickness to be continuous and uniform on the surface of the steel bar, and standing still until the coating is completely cured after coating.

3. The method according to claim 1, wherein the method is characterized by, The pipeline engineering building special combined steel formwork system assembly in step S2 includes: the steel formwork unit adopts a tongue-and-groove splicing structure, special formwork glue is applied at the tongue before splicing, the elastic sealing gasket is made of ethylene propylene diene rubber material, the gasket thickness matches the width of the formwork splicing gap, the pull bolt adopts high-strength alloy steel, the bolt spacing is determined according to the formwork stress calculation, and a rubber gasket is arranged between the steel back ridge and the steel formwork to reduce rigid contact wear.

4. The method according to claim 1, wherein the method is characterized by, The pipeline engineering building different strength concrete separation component installation in step S3 includes: the flexible separation plate is made of fiber reinforced cement-based composite material, the size of the separation plate is customized according to the cross-sectional size of the beam-column joint, the positioning seat is made of detachable steel structure, and is fixedly connected with the steel formwork through bolts, the inclination angle of the inclined flow surface is set to 30-45° with the horizontal direction, the exhaust channel is made of U-shaped rubber pipe, the channel diameter is not less than 10mm, and the channels are uniformly arranged along the length direction of the separation plate.

5. The method according to claim 1, wherein the method is characterized by, The sealing reinforcement and pre-pressing test of the pipeline engineering building combined steel formwork and separation component in step S4 includes: the water-swelling sealing strip adopts a slow-swelling material, the sealing strip is embedded in the groove reserved in the formwork and is compacted with the attached surface, the pre-pressing test adopts a sandbag grading loading method, the loading weight is executed according to 120% of the design bearing capacity of the formwork, the maximum deformation of the formwork is monitored after each level of loading and static for 30 minutes, and the tightening degree of the support bolt is adjusted for the positions exceeding the allowable deformation.

6. The method according to claim 1, wherein the method is characterized by, The concrete pouring of the pipeline engineering building column in step S5 includes: the high-strength concrete adopts a self-compacting concrete mix ratio, the thickness of each layer of the layered pouring is controlled to be 300-500mm, the high-frequency vibrating device adopts an inserted vibrating rod, the moving interval of the vibrating rod is not more than 1.5 times of the effective vibrating radius of the vibrating rod, the vibrating is stopped until the concrete surface appears floating slurry and no longer sinks, the formwork deformation monitoring adopts a displacement sensor, the sensor is arranged at the four corners and the middle position of the formwork, and the monitoring data is transmitted to the control console in real time.

7. The method according to claim 1, wherein the method is characterized by, The initial curing and strength monitoring of the pipeline engineering building column concrete in step S6 includes: the heat and moisture preservation layer adopts a flame-retardant rock wool blanket combined with a plastic film, the rock wool blanket is covered on the concrete surface and then wrapped and sealed with the film, the temperature sensor adopts an embedded installation, the sensor probe is deeply embedded in the concrete interior not less than 200mm, the strength monitoring adopts a combination of the rebound method and the ultrasonic method, the strength detection is performed once every 12h, and when the strength growth value of two consecutive detections is less than 5%, it is judged that the design strength of 50% is reached.

8. The method according to claim 1, wherein the method is characterized by, The concrete pouring of the pipeline engineering building beam in step S7 includes: the pouring of the medium-low strength concrete adopts a material distributing machine, the distance between the discharging port of the distributing machine and the flow surface of the separation plate is controlled to be within 500mm, a buffer hopper is arranged when the concrete falling height exceeds 2m, a special person is arranged to monitor the position state of the separation component during the pouring process, the displacement is corrected in time by using a special jacking support, and the concrete pouring operation in the region is suspended during the correction process.

9. The method according to claim 1, wherein the method is characterized by, The collaborative maintenance of the pipeline engineering building beam-column joint area in step S8 includes: spray maintenance adopts an automatic spray system, and spray interval time is adjusted according to ambient temperature; when the ambient temperature is higher than 50 DEG C, spraying is performed once every 1 h; when the ambient temperature is lower than 15 DEG C, spraying is performed once every 3 h; film maintenance adopts a breathable maintenance film, a certain water vapor content is kept in the film, the lap width of the maintenance film is not less than 100 mm, and the lap is sealed by using a tape.

10. The method for separately casting concrete of different strengths at beam-column joints in pipeline engineering according to claim 1, characterized in that, The removal and quality detection of the combined steel formwork of the pipeline engineering building in step S9 include: the formwork removal sequence is according to the principle that the beam side formwork is removed first, then the column side formwork, the non-core area formwork of the joint is removed first, and then the core area formwork; a special crowbar is used in the removal process to avoid damage to the concrete surface; the appearance detection focuses on whether the joint concrete bonding surface is flat and whether there is a crack; the strength detection adopts the core drilling method to extract the concrete sample for the compression strength test, and the test result needs to meet the design strength requirement; the quality record includes the pouring parameter, the maintenance data and the detection report, and is uniformly filed and saved.

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