Lightweight corrosion-resistant prestressed concrete cylinder pipe and preparation method thereof

Abstract

The invention discloses a light-weight corrosion-resistant prestressed concrete cylinder pipe which comprises a steel cylinder, a UHPC pipe core, a BFRP prestressed tendon layer and a mortar protection layer. The two layers of UHPC pipe cores are respectively positioned on the two sides of the steel cylinder; the BFRP prestressed tendon layer is fixed through a split type basalt anchoring device, and the anchoring device comprises an inner layer BFRP-RPM embedded part and an outer layer epoxy resin grouting layer. Variable cross-section thickness distribution is designed in the axial direction of the UHPC pipe core, the end thickness # imgabs0 # of a bell and spigot is 60-80 mm, and the middle thickness # imgabs1 # of the bell and spigot is 40-50 mm; bFRP prestressed tendons are adopted to replace traditional high-strength prestressed steel wires. The BFRP material has excellent corrosion resistance and can keep stable performance in a chloride ion corrosion environment, so that the problem of wire breakage caused by corrosion is avoided, the corrosion resistance of the pipeline is remarkably improved, and the service life of the pipeline is prolonged.

Description

Technical Field

[0001] The present invention relates to a concrete pipe, and in particular to a lightweight and corrosion-resistant prestressed concrete cylinder pipe and a preparation method thereof. Background Art

[0002] As an important pipeline structure form, traditional prestressed concrete cylinder pipes (PCCP) are widely used in water conveyance and gas transmission projects in the fields of water conservancy, municipal engineering, industry, etc. It combines the advantages of steel and concrete, and enhances the bearing capacity and durability of the pipeline through prestress technology. However, with the increasingly complex engineering application environment and the continuous improvement of engineering requirements, some problems have gradually emerged in the corrosion resistance, lightweight and long-term performance stability of traditional PCCP pipes, restricting their wider application.

[0003] In harsh environments such as chloride ion erosion, the high-strength prestressed steel wires in traditional PCCP pipes are prone to corrosion, resulting in a decrease in the structural strength of the pipeline, and even causing wire breakage accidents, seriously affecting the safe operation and service life of the pipeline.

[0004] Moreover, due to the use of a thick-wall concrete structure, the self-weight of traditional PCCP pipes is relatively large, which not only increases the energy consumption in the production, transportation and installation processes, but also restricts their application in some special projects, such as high-altitude erection and deep-sea laying. At the same time, during the long-term use of traditional PCCP pipes, due to factors such as material aging and environmental erosion, their structural performance will gradually decline, making it difficult to meet the engineering requirements for long-term safety and reliability.

[0005] Therefore, there is an urgent need for a lightweight and corrosion-resistant prestressed concrete cylinder pipe and a preparation method thereof to solve the technical problems existing in the above-mentioned prior art. Summary of the Invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a lightweight and corrosion-resistant prestressed concrete cylinder pipe and a preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a lightweight and corrosion-resistant prestressed concrete cylinder pipe, comprising: a steel cylinder, a UHPC pipe core, a BFRP prestressed tendon layer and a mortar protective layer; the UHPC pipe core has two layers, which are respectively located on both sides of the steel cylinder; The BFRP prestressed tendon layer is fixed by a split basalt anchoring device, and the anchoring device comprises an inner BFRP-RPM embedded kit and an outer epoxy resin grouting layer;

[0008] The UHPC pipe core is designed with a variable cross-section thickness distribution along the axial direction, and the thickness of the socket and spigot ends = 60 - 80 mm, and the thickness of the middle part = 40 - 50 mm.

[0009] In a preferred embodiment of the present invention, the surface of the BFRP prestressed tendon is treated by plasma etching to form a micro-nano rough structure with a size of 3.5-5.0 μm, and a nano-SiO2 coating containing 0.5%-1.0% -aminopropyltriethoxysilane is coated.

[0010] In a preferred embodiment of the present invention, the contact surface between the BFRP-RPM insert kit of the split basalt anchoring device and the reinforcing material is provided with a 30° taper self-locking structure, and the anchoring efficiency coefficient is ≥0.95.

[0011] In a preferred embodiment of the present invention, the mortar protective layer adopts a composite mortar added with polypropylene fiber and nano-titanium dioxide, wherein the volume fraction of the polypropylene fiber is 0.1%-0.3%, and the mass fraction of the nano-titanium dioxide is 1%-3%.

[0012] In a preferred embodiment of the present invention, a preparation method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe is provided. Based on the above-mentioned lightweight and corrosion-resistant prestressed concrete cylinder pipe, the method includes the following steps: S1. Use a six-degree-of-freedom robot for intelligent winding, and real-time monitor the tension, angle and spacing parameters; S2. Implement gradient prestress tension control through fiber Bragg grating sensors and load in three stages; S3. When pouring the UHPC pipe core, adopt a variable cross-section formwork system, and determine the thickness transition curve through finite element topology optimization.

[0013] In a preferred embodiment of the present invention, the three-stage loading includes: the loading rate in the 0-30%σ_con stage is 0.1MPa / s; the loading rate in the 30%-80%σ_con stage is 0.5MPa / s; the stress relaxation compensation algorithm is enabled in the 80%-100%σ_con stage.

[0014] In a preferred embodiment of the present invention, in step S1, an infrared thermal imaging wire break detection module is integrated during the intelligent winding process, and the wire break rate is ≤0.05%.

[0015] In a preferred embodiment of the present invention, the 28-day compressive strength of the UHPC pipe core is ≥150MPa, the tensile strength is ≥12MPa, and the electric flux is ≤500C.

[0016] In a preferred embodiment of the present invention, in step S3, before pouring the UHPC pipe core, the inner surface of the formwork is treated with superhydrophobic treatment, and the contact angle between the treated formwork and the UHPC pipe core is ≥150°.

[0017] The present invention solves the defects existing in the background art and has the following beneficial effects:

[0018] (1) Replace the traditional high-strength prestressed steel wire with BFRP prestressed tendons. The BFRP material has excellent corrosion resistance and can maintain stable performance in an environment eroded by chloride ions, thus avoiding the problem of wire breakage caused by corrosion, significantly improving the corrosion resistance of the pipeline, and extending the service life of the pipeline.

[0019] (2) Replace the traditional core concrete with UHPC. UHPC has higher compressive strength and tensile strength, can reduce the wall thickness of the core concrete while ensuring the performance of the pipeline, thereby reducing the self-weight of the pipeline, realizing the lightweight design of the pipeline, and reducing the energy consumption and cost in the production, transportation and installation processes.

[0020] (3) By optimizing the structural design and preparation process of the pipeline, such as adopting intelligent wire winding technology, gradient prestress tension control and variable cross-section formwork system, etc., ensure that the pipeline maintains stable performance during long-term use, thus significantly improving the durability of the pipeline and meeting the requirements of long-term stable operation.

[0021] (4) Replace traditional high-energy-consuming materials with green and low-carbon materials such as UHPC, and optimize the preparation process to reduce energy consumption during production, thereby significantly reducing the carbon emissions during the production and transportation of the pipeline, meeting the development trend of green and low-carbon.

[0022] (5) By adopting new materials such as BFRP prestressed tendons and UHPC and optimizing the preparation process, the present invention effectively solves the technical problems such as corrosion, weight, durability and carbon emissions encountered in the application of traditional prestressed concrete cylinder pipes, achieving the improvement of pipeline performance, extension of service life, reduction of energy consumption and cost, and meeting the development trend of green and low-carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts;

[0024] Figure 1 is the flowchart of the preparation method of the lightweight and corrosion-resistant prestressed concrete cylinder pipe of the preferred embodiment of the present invention;

[0025] Figure 2 is the structural schematic diagram of the lightweight and corrosion-resistant prestressed concrete cylinder pipe of the preferred embodiment of the present invention.

[0026] In the figure, 1 is a steel cylinder; 2 is a UHPC pipe core; 3 is a BFRP prestressed tendon layer; 4 is a mortar protective layer. Detailed implementation mode

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0028] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0029] As Figure 1 shown, a preparation method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe includes the following steps: S1: Use a six-degree-of-freedom robot for intelligent wire winding. The robot conducts trajectory planning through joint space or Cartesian space to ensure the accuracy and efficiency of wire winding. Joint space planning plans the spatial motion trajectory of the end of the robotic arm by determining the change sequence of each joint angle, while Cartesian space planning directly plans the pose change of the end of the robotic arm to meet different wire winding requirements.

[0030] During the wire winding process, the tension, angle, and spacing parameters are monitored in real time to ensure the quality of wire winding. Through sensor data acquisition and processing algorithms, such as weighted smoothing, extraction of mutations, and simple moving average methods, the sensor data is processed to ensure the accuracy and stability of the data.

[0031] It should be further supplemented here that the six-degree-of-freedom robot realizes precise control of angle and trajectory through dual-mode trajectory planning: In the joint space mode, the controller calculates the rotation angle sequence of J1-J6 axes to make the wire winding head move along the space curve of the variable cross-section pipe body. For example, in the socket and spigot area, by adjusting the linear displacement rate of J4-J6 axes, the dynamic switching of the winding angle from 90° to 85° / 95° is realized, and the error ≤ ±0.5°; the Cartesian space mode is used for the straight pipe section. The spiral trajectory is generated by CAM software, and the surface of the pipe body is scanned in real time by the KEYENCE LK-G80 laser distance sensor to dynamically correct the trajectory deviation, and the pitch error ≤ ±1mm. The combination of the two modes ensures the angle accuracy and trajectory smoothness in different sections.

[0032] The monitoring system realizes multi-functional real-time monitoring through multi-sensor integration: the strain-type tension sensor collects the tension of the reinforcing bars in real time with an accuracy of ±1% FS, and is linked with the Yaskawa Sigma-7 servo motor to dynamically compensate for tension fluctuations; the line laser displacement sensor scans the spacing between adjacent reinforcing bars with an accuracy of ±0.2 mm, and adjusts the moving speed of the robot through the PID algorithm; the FLIR A315 infrared thermal imaging module detects broken wires at a frequency of 50 Hz, triggers an alarm and locates within 0.1 s when the temperature difference ≥ 2°C, with an accuracy of ±5 mm. The data is fused and processed by the Siemens S7-1500 PLC, and after being filtered by the weighted smoothing and mutation extraction algorithms, it is displayed and traced in real time through the Weinview MT8102iE touch screen.

[0033] Integrate an infrared thermal imaging broken wire detection module, which uses infrared thermal imaging technology to detect broken wires. When a broken wire is detected, the module will trigger an alarm mechanism to timely handle the broken wire problem and ensure the continuity and quality of the wire winding, with a broken wire rate ≤ 0.05%.

[0034] S2: Monitor the change of prestress through fiber Bragg grating sensors. The sensors are installed on the surface of the structure or the fixed screws of the structure to monitor the deformation of the structure or the interaction between the surrounding rock and the structure. Through the finite element analysis method, the strain of each part can be analyzed, so as to realize the accurate monitoring of prestress.

[0035] The loading method is divided into three stages of loading, and the stress value is corrected through the stress relaxation compensation algorithm to ensure the accuracy of prestress tensioning.

[0036] The first stage: 0~30%σ_con, the loading rate is 0.1 MPa / s, and the loading is slow to avoid impacting the structure.

[0037] The second stage: 30%~80%σ_con, the loading rate is 0.5 MPa / s, and the prestress is gradually increased to 80% of the design value.

[0038] The third stage: 80%~100%σ_con, enable the stress relaxation compensation algorithm to precisely control the prestress and ensure the accuracy of prestress tensioning.

[0039] S3: Use a variable cross-section formwork system, determine the thickness transition curve through finite element topology optimization to optimize the structural design of the formwork. The formwork design takes into account factors such as stiffness, strength, stability, as well as long-distance transportation and assembly accuracy, etc., to ensure the stability and accuracy of the formwork during the pouring process. At the same time, set the demoulding hydraulic cylinder according to the demoulding load to reduce the construction intensity of workers.

[0040] Before pouring the UHPC core, the inner surface of the formwork is treated with superhydrophobic treatment. The contact angle between the treated formwork and the UHPC core is ≥150°, so as to improve the anti-fouling and self-cleaning capabilities of the formwork, facilitate demoulding and extend the service life of the formwork. The superhydrophobic treatment is achieved by methods such as electrochemical etching, layer-by-layer self-assembly, sol-gel method or electrodeposition method.

[0041] The 28-day compressive strength of the UHPC core is ≥150 MPa, the tensile strength is ≥12 MPa, and the electric flux is ≤500 C, ensuring the high performance and durability of the core and meeting the use requirements of lightweight and corrosion-resistant prestressed concrete cylinder pipes.

[0042] A lightweight and corrosion-resistant prestressed concrete cylinder pipe includes: a steel cylinder 1, a UHPC core 2, a BFRP prestressed tendon layer 3 and a mortar protective layer 4; the UHPC core 2 has two layers, which are respectively located on both sides of the steel cylinder 1.

[0043] The fixation of the BFRP prestressed tendon layer 3 is fixed by a split basalt anchoring device, which includes an inner BFRP-RPM inlay kit and an outer epoxy resin grouting layer. The BFRP-RPM inlay kit is provided with a 30° taper self-locking structure on the contact surface with the tendon, and the anchoring efficiency coefficient is ≥0.95, ensuring the stable anchoring of the prestressed tendon.

[0044] The surface of the BFRP prestressed tendon layer 3 is treated to enhance the bonding performance between the prestressed tendon and the concrete. The surface of the BFRP prestressed tendon is treated by plasma etching to form a micro-nano rough structure of 3.5 - 5.0 μm, and a nano-SiO2 coating containing 0.5% - 1.0% aminopropyltriethoxysilane is coated to improve the corrosion resistance and interfacial bonding strength of the tendon.

[0045] The UHPC core 2 is designed with a variable cross-sectional thickness distribution along the axial direction. The thickness of the socket and spigot ends is 60 - 80 mm, and the thickness in the middle is 40 - 50 mm to achieve the lightweight design of the pipe body. At the same time, the 28-day compressive strength of the UHPC core is ≥150 MPa, the tensile strength is ≥12 MPa, and the electric flux is ≤500 C, ensuring the high performance and durability of the core.

[0046] The mortar protective layer 4 uses a composite mortar added with polypropylene fiber and nano-titanium dioxide. The volume fraction of polypropylene fiber is 0.1% - 0.3% to improve the crack resistance of the mortar; the mass fraction of nano-titanium dioxide is 1% - 3% to endow the mortar with self-cleaning ability and extend the service life of the pipeline.

[0047] Example 1

[0048] Raw material preparation

[0049] The steel cylinder is made of Q345B steel, with an outer diameter of 1000 mm, a wall thickness of 10 mm, and a length of 6000 mm. The BFRP prestressing tendons have a diameter of 8 mm, and their surfaces are treated by plasma etching to form a micro-nano rough structure with a size of 4.0 μm, and are coated with a nano-SiO2 coating containing 0.8% aminopropyltriethoxysilane.

[0050] The UHPC material consists of cement, silica fume, quartz sand, high-range water reducer and water. After being mixed in proportion, its 28-day compressive strength reaches 180 MPa, its tensile strength reaches 15 MPa, and its electric flux is 400 C.

[0051] The mortar protective layer material is selected as ordinary Portland cement and polypropylene fiber with a volume fraction of 0.2% and nano-titanium dioxide with a mass fraction of 2%.

[0052] A six-degree-of-freedom robot is adopted, equipped with a tension sensor, an angle sensor and a spacing sensor. The robot precisely controls the winding trajectory through Cartesian space planning to ensure that the BFRP prestressing tendons are evenly wound on the outer surface of the steel cylinder. The tension is monitored in real time and controlled within 500 N ± 5%, the angle is maintained at 90°, the spacing is controlled within 50 mm ± 2%, and the sensor data is processed by a weighted smoothing algorithm to ensure the winding quality. An integrated infrared thermal imaging broken wire detection module is adopted, and the broken wire rate is controlled within 0.03%.

[0053] Fiber Bragg grating sensors are arranged on the surface of the BFRP prestressing tendons. The loading is carried out in three stages: The first stage: 0 - 30%σ_con, where σ_con is the designed prestress value, and the loading rate is 0.1 MPa / s. The second stage: 30% - 80%σ_con, and the loading rate is 0.5 MPa / s. The third stage: 80% - 100%σ_con, and a stress relaxation compensation algorithm is enabled to ensure accurate application of the prestress. The change of the prestress is monitored in real time through the fiber Bragg grating sensors to ensure that the tensioning process is controllable.

[0054] A variable cross-section formwork system is adopted. The thickness transition curve is determined by finite element topology optimization. The thickness at the socket and spigot ends is 70 mm, and the thickness in the middle is 45 mm. The inner surface of the formwork is treated with superhydrophobic treatment, and the contact angle after treatment reaches 160°. The UHPC material is poured, vibrated thoroughly, and cured for 28 days to ensure that the performance of the UHPC pipe core meets the standards.

[0055] A composite mortar is smeared on the outer surface of the UHPC pipe core with a thickness of 5 mm. It is cured for 7 days to ensure the tight bonding between the mortar protective layer and the UHPC pipe core.

[0056] In a preferred embodiment, the lightweight corrosion-resistant prestressed steel cylinder concrete pipe further includes: a graphene-nano-SiO2 composite coating, which is attached to the inner side of the UHPC pipe core by chemical vapor deposition, with a thickness of 0.1 - 0.5 mm, and the chloride ion diffusion coefficient.

[0057] The UHPC core is a basalt fiber-carbon nanotube hybrid UHPC core. The fiber volume fraction shows a gradient distribution of 8% - 5% from the inside to the outside, and is internally provided with segmented stepped basalt composite bars. The diameters of both ends of the basalt composite bars are 15% - 20% larger than the middle section, and the tensile stress is sinusoidally distributed along the basalt fiber-carbon nanotube hybrid UHPC core.

[0058] It is further supplemented here that the variable-diameter BFRP prestressed bars are prefabricated by a customized pultrusion process. A segmented heating furnace is used with a temperature error of ±2°C to control the mold temperature field, producing tapered transition bars composed of standard sections and thickened sections to ensure continuous fibers without breakage. The robotic winding system is configured with a three-station reel bracket. Each reel independently controls the tension through a magnetic powder brake, and is driven by a Panasonic MINAS A6 servo motor through a synchronous belt to achieve a quick switch within 10s, compatible with the continuous winding of bars with different diameters.

[0059] Variable-diameter winding uses a Raytek 3i2ML laser diameter gauge to accurately identify the bar diameter in real time with an accuracy of ±0.02mm, and automatically calls the corresponding process parameters: for the small-diameter bars in the standard section, a tension of 500 - 600N and a winding angle of 85° - 95° are used; for the large-diameter bars in the thickened section, the tension is increased to 700 - 800N, and the spacing is expanded to 60 - 70mm to avoid overlap. The gradient mode is started 500mm before the diameter switching point. By linearly adjusting the robot moving speed at 50 - 30mm / s and the pipe body rotation speed at 1 - 1.5rpm, and cooperating with a Basler vision sensor to monitor the quality of the transition section, a smooth transition of the helix angle is ensured. Furthermore, the cross-sectional area of the bars at the socket and spigot ends is increased by 44%, and the tensile stiffness is increased by more than 50%, effectively reducing the stress concentration at the interface, and multi-specification production can be adapted through software parameters without hardware modification.

[0060] The microbial mineralization repair mortar layer contains Bacillus pasteurii and calcium carbonate precursors, and is used to repair the cracks generated on the surface of the mortar protective layer.

[0061] Example 2

[0062] Raw material preparation

[0063] The steel cylinder is made of Q390B steel, with an outer diameter of 1200mm, a wall thickness of 12mm, and a length of 8000mm. The diameter of the BFRP prestressed bar is 10mm, and the surface is treated by plasma etching to form a micro-nano rough structure of 4.5μm, and coated with a nano-SiO2 coating containing 1.0% aminopropyltriethoxysilane.

[0064] The optimized mix ratio of the UHPC material has a 28-day compressive strength of 200MPa, a tensile strength of 18MPa, and an electric flux of 350C. The mortar protective layer material is based on ordinary Portland cement and is added with 0.1% steel fiber to improve the crack resistance.

[0065] A six-degree-of-freedom robot is adopted, equipped with high-precision tension sensors and angle sensors. The robot searches for the optimal winding path through joint space planning and in combination with the particle swarm optimization algorithm.

[0066] The tension is monitored in real time and controlled within 600N ± 3%, the angle is maintained at 85° - 95°, and the spacing is controlled within 45mm ± 1%. The sensor data is processed through the extraction mutation algorithm to improve the winding accuracy. An integrated infrared thermal imaging broken wire detection module is used, and the broken wire rate is controlled within 0.02%.

[0067] Fiber Bragg grating sensors are arranged at the connection between the BFRP prestressed tendon and the steel cylinder. The loading is carried out in three stages, and the loading rate is optimized as follows: The first stage: 0 - 30%σ_con, the loading rate is 0.15MPa / s. The second stage: 30% - 80%σ_con, the loading rate is 0.6MPa / s. The third stage: 80% - 100%σ_con, the improved stress relaxation compensation algorithm is enabled to improve the prestress control accuracy. Through the fiber Bragg grating sensors and finite element analysis, the prestress distribution and structural deformation are monitored in real time.

[0068] A variable cross-section formwork system is adopted. Through topology optimization and 3D printing technology, a complex thickness transition curve is realized, with the thickness of the socket end being 80mm and the middle thickness being 40mm. The inner surface of the formwork is treated with superhydrophobic treatment, and the contact angle after treatment reaches 165°. The optimized UHPC material is poured, and the vacuum-assisted pouring technology is adopted to improve the density, and it is cured for 28 days.

[0069] A composite mortar added with steel fibers is smeared on the outer surface of the UHPC tube core, with a thickness of 6mm. It is cured for 14 days to ensure that the mortar protective layer has excellent crack resistance and durability.

[0070] The following is the performance comparison and conclusion between Example 1 and Example 2.

[0071] Table 1 Performance indicators Example 1 Example 2 Comparative description Steel cylinder Q345B, outer diameter 1000mm, wall thickness 10mm, length 6000mm Q390B, outer diameter 1200mm, wall thickness 12mm, length 8000mm The steel cylinder material of Example 2 has higher strength and larger specifications BFRP prestressed tendon Diameter 8mm, plasma etching (4.0μm), nano-SiO2 coating (0.8% aminopropyltriethoxysilane) Diameter 10mm, plasma etching (4.5μm), nano-SiO2 coating (1.0% aminopropyltriethoxysilane) The prestressed tendon of Example 2 has a larger diameter, higher surface roughness, and a more optimal coating composition ratio UHPC core 28-day compressive strength 180MPa, tensile strength 15MPa, electric flux 400C 28-day compressive strength 200MPa, tensile strength 18MPa, electric flux 350C The UHPC material of Example 2 has better performance, higher strength, and better durability Mortar protective layer Ordinary Portland cement + polypropylene fiber (0.2%) + nano-titanium dioxide (2%), thickness 5mm Ordinary Portland cement + steel fiber (0.1%) + nano-titanium dioxide (2%), thickness 6mm The mortar protective layer of Example 2 adds steel fiber, has a slightly thicker thickness, and better crack resistance

[0072] Table 2 Preparation process Example 1 Example 2 Comparative description Intelligent wire winding Six-degree-of-freedom robot, Cartesian space planning, tension 500N±5%, angle 90°, spacing 50mm±2%, wire breakage rate 0.03% Six-degree-of-freedom robot, joint space planning + particle swarm optimization algorithm, tension 600N±3%, angle 85°~95°, spacing 45mm±1%, wire breakage rate 0.02% The wire winding accuracy of Example 2 is higher and the wire breakage rate is lower Prestressed tensioning Fiber Bragg grating sensor, three-stage loading (0.1MPa / s, 0.5MPa / s, stress relaxation compensation algorithm) Fiber Bragg grating sensor, three-stage loading (0.15MPa / s, 0.6MPa / s, improved stress relaxation compensation algorithm) The loading rate of Example 2 is faster and the stress control is more accurate UHPC pouring Variable cross-section formwork system, superhydrophobic treatment (contact angle 160°), curing for 28 days Variable cross-section formwork system (3D printing), superhydrophobic treatment (contact angle 165°), vacuum-assisted pouring, curing for 28 days The formwork system of Example 2 is more advanced and the pouring process is more optimized Mortar construction Applying composite mortar, thickness 5mm, curing for 7 days Applying composite mortar with added steel fiber, thickness 6mm, curing for 14 days The mortar layer of Example 2 is thicker and the curing is more sufficient Table 3 Expected performance Example 1 Example 2 Comparative description Lightweight effect Core thickness 70mm (end) / 45mm (middle) Core thickness 80mm (end) / 40mm (middle) The core thickness change of Example 2 is smoother, and the overall lightweight effect may be better (specific calculation is required) Corrosion resistance BFRP surface treatment + nano-coating + mortar protective layer Optimized BFRP surface treatment + nano-coating + steel fiber mortar protective layer Example 2 has better corrosion resistance due to the improved proportion of coating components and the crack resistance of the mortar protective layer Structural performance High-strength UHPC + precise prestress control Higher-strength UHPC + more precise prestress control + optimized structural design The structural performance of Example 2 is better, with higher load-bearing capacity and durability

[0073] Conclusion: Example 2 is superior to Example 1 in terms of performance in many aspects.

[0074] In Example 2, higher-strength steel cylinders and BFRP prestressed tendons are selected, and the mix ratios of UHPC and the mortar protective layer are optimized, improving the overall performance of the materials.

[0075] Example 2 adopted a more advanced winding trajectory planning method, a faster prestress loading rate, and a more precise stress control algorithm. Meanwhile, the UHPC pouring and mortar construction processes were optimized.

[0076] Example 2 showed excellent performance in terms of lightweight effect, corrosion resistance, and structural performance. In particular, the improvement in structural performance was significant, capable of meeting the higher requirements of engineering applications.

[0077] It should be emphasized that Example 1 already had good performance and was suitable for general engineering requirements: The preparation method and material selection of Example 1 were already able to meet the application scenarios of most lightweight and corrosion-resistant prestressed concrete cylinder pipes, with the advantages of cost-effectiveness and process maturity.

[0078] Example 2 was more suitable for high-end or special engineering requirements: The optimized design and advanced process of Example 2 made it more suitable for projects with extremely high requirements for pipeline performance, such as water conveyance, gas transmission, etc. in harsh environments like high pressure, large flow rate, and strong corrosion.

[0079] For the concrete pipes prepared by the above preparation method, in areas with medium to high corrosion environments, basalt fiber, as a green and low-carbon emission industrial raw material that is pollution-free and reusable, the basalt fiber composite bars produced using it have excellent properties such as light weight, high tensile strength, and corrosion resistance. Replacing the high-strength prestressed steel wires in PCCP pipes with them can effectively solve the problem of corrosion and wire breakage of high-strength prestressed steel wires in the chloride ion erosion environment. Replacing the traditional core concrete with ultra-high performance concrete (UHPC) can reduce the wall thickness, significantly reduce the amount of concrete used, and reduce the self-weight, thereby reducing the energy consumption during production, transportation, and installation. This lightweight and corrosion-resistant prestressed concrete cylinder pipe (PCCP) based on basalt fiber composite bars (BFRP) and ultra-high performance concrete (UHPC) has a significantly improved service life and a significantly reduced carbon emission compared to traditional PCCP pipes.

[0080] Based on the inspiration of the ideal embodiments of the present invention as above, through the above description, relevant personnel can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A lightweight and corrosion-resistant prestressed concrete cylinder pipe, characterized in that, Including: A steel cylinder, a UHPC core, a BFRP prestressed tendon layer and a mortar protective layer; the UHPC core has two layers, which are respectively located on both sides of the steel cylinder; The BFRP prestressed tendon layer is fixed by a split basalt anchoring device, and the anchoring device includes an inner BFRP-RPM embedded kit and an outer epoxy resin grouting layer; The UHPC core is designed with a variable cross-sectional thickness distribution along the axial direction, and the thickness of the socket and spigot ends = 60 - 80 mm, and the thickness in the middle = 40 - 50 mm.

2. A lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 1, characterized in that: The surface of the BFRP prestressed tendon is treated by plasma etching to form a micro-nano rough structure with a size of 3.5 - 5.0 μm, and a nano-SiO2 coating containing 0.5% - 1.0% -aminopropyltriethoxysilane is coated.

3. A lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 1, characterized in that: The BFRP-RPM embedded kit of the split basalt anchoring device is provided with a 30° taper self-locking structure on the contact surface with the tendon, and the anchoring efficiency coefficient ≥ 0.

95.

4. A lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 1, characterized in that: The mortar protective layer adopts a composite mortar added with polypropylene fiber and nano-titanium dioxide, wherein the volume content of polypropylene fiber is 0.1% - 0.3%, and the mass content of nano-titanium dioxide is 1% - 3%.

5. A preparation method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe, based on the lightweight and corrosion-resistant prestressed concrete cylinder pipe according to any one of claims 1-4, characterized in that, Including the following steps: S1. Use a six-degree-of-freedom robot for intelligent winding, and real-time monitor the tension, angle and spacing parameters; S2. Implement gradient prestress tension control through fiber Bragg grating sensors and load in three stages; S3. When pouring the UHPC core, use a variable cross-section formwork system, and determine the thickness transition curve through finite element topology optimization.

6. The preparation method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 5, characterized in that: The three-stage loading includes: the loading rate in the 0 - 30%σ_con stage is 0.1MPa / s; the loading rate in the 30% - 80%σ_con stage is 0.5MPa / s; the stress relaxation compensation algorithm is enabled in the 80% - 100%σ_con stage.

7. The manufacturing method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 5, characterized in that: In step S1, an infrared thermal imaging wire break detection module is integrated during the intelligent winding process, and the wire break rate ≤ 0.05%.

8. The preparation method of a lightweight and corrosion-resistant prestressed concrete cylinder pipe according to claim 5, characterized in that: The 28d compressive strength of the UHPC core ≥ 150MPa, the tensile strength ≥ 12MPa, and the electric flux ≤ 500C.

9. The preparation method of a lightweight and corrosion-resistant pre-stressed concrete cylinder pipe according to claim 5, characterized in that: In step S3, before pouring the UHPC core, the inner surface of the formwork is treated with superhydrophobic treatment, and the contact angle between the treated formwork and the UHPC core ≥ 150°.

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