Prestressed composite pipes and pipe assemblies

Abstract

This utility model provides a prestressed composite pipe and pipe assembly. The prestressed composite pipe includes a concrete liner, a steel pipe, and an intermediate interlayer. The steel pipe is coaxially sleeved outside the concrete liner, with a pre-existing gap between the inner wall of the steel pipe and the outer wall of the concrete liner. The intermediate interlayer is sandwiched between the inner wall of the steel pipe and the outer wall of the concrete liner, and includes an inner wall that adheres to the outer wall of the concrete liner and an outer wall that adheres to the inner wall of the steel pipe. The inner wall of the intermediate interlayer presses against the outer wall of the concrete liner to create tangential prestress in the concrete liner, and the outer wall of the intermediate interlayer presses against the inner wall of the steel pipe to create tangential tensile prestress in the steel pipe. This prestressed composite pipe fully utilizes the respective performance advantages of concrete and steel, possessing strong resistance to internal pressure and good ring stiffness.

Description

Technical Field

[0001] This utility model belongs to the field of fluid transportation pipeline technology, and in particular relates to a prestressed composite pipeline and pipeline combination. Background Technology

[0002] In fluid transport pipelines, the main types of pipes available on the market include steel pipes, cast iron pipes, concrete pipes (including box culverts of various shapes), prestressed concrete pipes with steel sleeves (PCCP), fiberglass pipes, and HDPE plastic pipes. In practical engineering applications, PCCP pipes and steel pipes are the primary choices for large-diameter pressure-bearing pipelines.

[0003] PCCP (Precast Concrete Pipeline) pipes have been around for about a century, and their structural form has not fundamentally changed. This type of pipe primarily utilizes the tensile strength of prestressed steel wires, which are wound around the outside of a concrete pipe to resist internal water pressure. The thicker pipe wall and prestressing provide greater ring stiffness. A PCCP pipe consists of an inner concrete lining, a thin-walled steel sleeve, an outer concrete layer, spiral prestressed steel wires, and an outer shotcrete protective layer. The production of this type of pipe involves many stages, strict quality control requirements, and high production costs. In practical applications, the structural reliability of this type of pipe is not high. The loose outer shotcrete layer provides limited corrosion protection for the steel wires; if even one prestressed steel wire breaks, the entire pipe section will collapse. Furthermore, this type of pipe has insufficient axial bending resistance and cannot adapt well to uneven foundation settlement. Research shows that currently used PCCP pipes suffer from numerous wire breakage problems, and the risk of pipe bursts and water inrush continues to threaten project safety. In many regions, PCCP pipes are considered obsolete.

[0004] Steel pipes are well-suited for applications with high internal water pressure, but not for large diameters. While steel's high tensile strength generally allows it to withstand internal water pressure without requiring a large wall thickness, unbalanced loads such as soil compression, top moving loads, and the weight of the pipe and the internal / external liquids necessitate a high ring stiffness. Therefore, larger diameter steel pipes must meet certain wall thickness requirements (generally not less than 1 / 100 to 1 / 150 of the pipe diameter; the larger the diameter, the thicker the wall). This characteristic allows steel pipes to meet economic requirements for diameters below 1.0 meter, but beyond that, the ring stiffness decreases rapidly with increasing diameter. To achieve sufficient ring stiffness, steel consumption surges, making steel pipes unsuitable for large-diameter pressure pipeline projects.

[0005] In the selection of pipelines for high-flow-rate, high-pressure water transmission projects, steel pipes with thicker walls are generally preferred due to the low reliability, difficult installation, and maintenance of PCCP pipes. However, for applications involving extra-large diameter pipelines, steel pipes are no longer suitable, and PCCP pipes must be selected. For example, the Beijing section of the South-to-North Water Diversion Project uses PCCP pipes with a diameter of 4 meters.

[0006] The traditional types of pipes mentioned above cannot well coordinate the performance requirements of large pipe diameter, high internal water pressure, large unbalanced load and safety and reliability in terms of structure. Traditional types of pipes also lead to material waste, high cost and high maintenance cost because they fail to make full use of the excellent performance of materials.

[0007] In the construction of high-flow-rate, high-pressure water transmission projects, there is an urgent need for pipelines that can reliably withstand internal water pressure and effectively resist unbalanced loads, while also being cost-effective. Addressing this need has become one of the most pressing issues in engineering applications. Utility Model Content

[0008] To address the shortcomings of related technologies, this application provides a prestressed composite pipe and pipe assembly, which allows the performance advantages of steel and concrete to be fully utilized, while achieving the characteristics of being able to withstand internal pressure and unbalanced loads, making it suitable for applications in high-flow-rate pressure water transmission pipelines.

[0009] This application provides a prestressed composite pipe, comprising:

[0010] Concrete lining pipe;

[0011] A steel pipe is coaxially fitted around a concrete liner, with a pre-existing gap between the inner wall of the steel pipe and the outer wall of the concrete liner; and

[0012] An intermediate interlayer is sandwiched between the inner wall of the steel pipe and the outer wall of the concrete liner. The intermediate interlayer includes an inner wall that is attached to the outer wall of the concrete liner and an outer wall that is attached to the inner wall of the steel pipe.

[0013] The inner wall of the intermediate interlayer presses against the outer wall of the concrete liner to form tangential prestress in the concrete liner, and the outer wall of the intermediate interlayer presses against the inner wall of the steel pipe to form tangential pretension in the steel pipe.

[0014] In some embodiments, multiple end connectors are pre-embedded at both ends of the concrete liner in the axial direction, and the multiple end connectors are distributed at intervals along the circumference of the concrete liner. The end connectors extend from the end face of the concrete liner into the interior of the concrete liner. The end connectors include an inner cavity. The end of the end connector near the end face of the concrete liner is an open end, so that fasteners can be inserted into the inner cavity for connection. The end of the end connector inside the concrete liner is a closed end, so as to prevent concrete from entering the inner cavity of the end connector during the pouring process.

[0015] In some embodiments, the axial length of the steel pipe is greater than the axial length of the concrete liner, and the two ends of the steel pipe extend out of the end face of the concrete liner to form an extension section, which is used to connect with adjacent pipes to form a pipe assembly.

[0016] In some embodiments, end rings are respectively provided at both ends of the intermediate interlayer in the axial direction. The outer peripheral side of the end ring is fixedly connected to the inner wall of the steel pipe, and the inner peripheral side of the end ring is located close to the concrete lining pipe.

[0017] In some embodiments, the end ring is recessed axially relative to the end face of the concrete liner to form a recess between the end ring, the concrete liner, and the steel pipe, the recess being used to install a seal during pipe forming.

[0018] In some embodiments, multiple axial reinforcing bars are anchored within the concrete liner, and the multiple axial reinforcing bars are spaced apart in the circumferential direction of the concrete liner.

[0019] Along the axial direction of the concrete lining pipe, each axial reinforcing bar is correspondingly provided with two end connectors, and the two ends of the axial reinforcing bar are respectively fixedly connected to the corresponding end connectors.

[0020] In some embodiments, an uneven structure is formed on the inner wall of the steel pipe and / or the outer wall of the concrete liner, and the outer wall of the intermediate interlayer is embedded in the uneven structure.

[0021] This application also provides a prestressed composite pipe assembly, comprising multiple prestressed composite pipe sections connected in sequence as described above; wherein the ends of adjacent prestressed composite pipe sections face each other, and a connection space is formed between the inner sides of two extension sections of adjacent prestressed composite pipe sections and the end faces of two concrete liner pipes.

[0022] In some embodiments, two water-stop pressure plates and an elastic water-stop ring are provided in each connection space; the two water-stop pressure plates are respectively provided for two adjacent prestressed composite pipe sections, each water-stop pressure plate includes a first pressure plate and a second pressure plate fixedly connected, the first pressure plate is opposite to and tightly connected to the end face of the concrete liner in the corresponding prestressed composite pipe, and the second pressure plate is opposite to the extension section of the steel pipe in the corresponding prestressed composite pipe; the elastic water-stop ring includes two oppositely arranged annular surfaces and a sidewall connecting the outer periphery of the two annular surfaces, the annular surfaces are sandwiched between the first pressure plate and the end face of the concrete liner, and the sidewall is sandwiched between the second pressure plate and the two extension sections.

[0023] In some embodiments, a water-stop seat ring is provided in the connection space, the water-stop seat ring connects two adjacent extension sections, there is a gap between the two ends of the water-stop seat ring in the axial direction and the end face of the concrete liner, and an annular sealing strip is installed between the water-stop seat ring and the extension section.

[0024] Based on the above technical solution, the prestressed composite pipe in this embodiment has an intermediate interlayer sandwiched between the concrete liner and the steel pipe. The intermediate interlayer forms pressure contact with the inner concrete liner, generating tangential prestress in the concrete liner and tangential pretensile stress in the steel pipe. This eliminates the cross-sectional profile defects of the steel pipe, fully utilizes the respective performance advantages of steel and concrete, and also possesses the characteristics of withstanding large internal pressure and unbalanced loads. Compared with ordinary steel pipes, the thickness of the steel plate used in this prestressed composite pipe can be significantly reduced, thereby saving a large amount of steel. It demonstrates advantages in performance, manufacturing, cost, safety, reliability, corrosion resistance, and connection. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the prestressed composite pipe in the embodiments of this application;

[0026] Figure 2 Cross-sectional view of the prestressed composite pipe in the embodiments of this application;

[0027] Figure 3 for Figure 2 A magnified view of part A in the middle;

[0028] Figure 4 This is a longitudinal section view of the prestressed composite duct in an embodiment of this application;

[0029] Figure 5 for Figure 4 A magnified view of part B in the middle;

[0030] Figure 6 for Figure 4 A magnified view of part C in the middle;

[0031] Figure 7This is a schematic diagram of the first connection scheme of the prestressed composite pipe assembly in the embodiments of this application;

[0032] Figure 8 This is a schematic diagram of a second connection scheme for the prestressed composite pipe assembly in an embodiment of this application;

[0033] Figure 9 This is a schematic diagram of a third connection scheme for the prestressed composite pipe assembly in the embodiments of this application;

[0034] Figure 10 This is a longitudinal section view of the intermediate state of the composite pipeline during the pipeline forming process.

[0035] Figure 11 for Figure 10 A magnified view of part D in the middle. Figure 11 In this state, some of the grouting material is discharged through the vent pipe;

[0036] Figure 12 for Figure 10 A magnified view of part E in the middle section, showing the grout entering through the grouting pipe.

[0037] In the picture:

[0038] 1. Concrete lining pipe; 11. End connector; 111. Inner cavity; 112. Open end; 113. Closed end; 12. Axial reinforcement; 13. Circumferential reinforcement; 2. Steel pipe; 21. Extension section; 22. End ring; 23. Connection space; 3. Intermediate layer; 31. Grouting space; 32. Recess; 33. Sealing element; 401. Groove hole; 41. Base flange; 42. Top flange; 51. Fastener; 52. Gasket; 61. Grouting pipe; 62. Grouting control valve; 71. Exhaust pipe; 72. Exhaust control valve; 81. Water-stop pressure plate; 811. First pressure plate; 812. Second pressure plate; 82. Elastic water-stop ring; 821. Annular surface; 822. Side wall; 91. Water-stop seat ring; 92. Annular sealing strip; 101. Annular weld; 102. Filler. Detailed Implementation

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0041] In the description of this application, it should be understood that the terms "inner", "outer", "axial", "radial", "circumferential", "tangential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. The term "multiple" in this application refers to two or more.

[0043] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0044] It is to be understood that although the accompanying drawings may show a specific order of method steps, the order of steps may differ from the depicted order. Furthermore, two or more steps may be performed simultaneously or partially simultaneously. All such variations are within the scope of this disclosure.

[0045] For a long time, in the field of pipeline engineering applications, the selection of pipelines has mainly relied on the specific types of pipes supplied by manufacturers. This method of selecting pipelines has, to some extent, severed the close relationship between pipeline performance and application conditions, especially for large-diameter pressure-bearing pipelines.

[0046] Large-section reinforced concrete pressure pipelines typically have an inner steel lining. This lining is used only for internal seepage prevention and as an internal formwork for concrete pouring, resulting in a significant waste of steel properties. During pipeline manufacturing and construction, the inner steel lining undergoes numerous processes, including plate rolling, welding, internal reinforcement, pipe installation, rebar tying, and concrete pouring. After these processing steps, it is difficult to maintain a standard circular shape for the pipe wall, leading to cross-sectional profile defects.

[0047] For pressurized pipelines, such cross-sectional profile defects significantly weaken their pressure-bearing capacity. When a pipeline with cross-sectional profile defects is subjected to internal pressure, the cross-sectional profile will inevitably deform first, tending towards a standard circle to achieve an effective circular cross-section. Before the cross-sectional profile reaches an effective circle, the pipe wall cannot form effective tangential (circumferential) tension. At this time, the internal pressure is mainly balanced by the bending and tensile properties of the reinforced concrete. However, because the tensile strength of reinforced concrete is inherently weak, it is prone to cracking and damage under large internal pressure. Therefore, such pipelines cannot withstand large internal pressures and cannot meet the engineering requirements of high internal pressure scenarios.

[0048] The same problems exist for steel pipes with concrete linings. Because the walls of the concrete lining are generally thin, its bending resistance is very limited. Concrete shrinkage often causes the concrete lining to detach from the outer steel pipe, resulting in poor joint stress distribution and significant corrosion on the inner surface of the steel pipe. Furthermore, the outer steel pipe also has cross-sectional profile defects, which significantly affect the tensile strength of the steel. Under large bending moment loads, the concrete is prone to cracking, damage, and loss of its structural resistance. Based on these problems, steel pipe structures with concrete linings still cannot meet the engineering requirements of high internal pressure scenarios.

[0049] To address the aforementioned issues, this application proposes a prestressed composite pipe and pipe assembly that eliminates the cross-sectional profile defects of steel pipes, fully utilizes the respective performance advantages of steel and concrete, and possesses the ability to withstand significant internal pressure and unbalanced loads. Compared to ordinary steel pipes, the thickness of the steel plate used in this prestressed composite pipe can be significantly reduced, thereby saving a substantial amount of steel. It demonstrates advantages in performance, manufacturing, cost, safety, reliability, corrosion resistance, and connection. The pipe provided in this application is suitable for applications in water, oil, or gas transportation.

[0050] The first aspect of this application provides a prestressed composite pipe, such as Figures 1-6As shown, the prestressed composite pipe includes: a concrete liner 1, a steel pipe 2, and an intermediate interlayer 3; the steel pipe 2 is coaxially sleeved outside the concrete liner 1, and a gap is reserved between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1; the intermediate interlayer 3 is sandwiched between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1, and the intermediate interlayer 3 includes an inner side wall that is attached to the outer wall of the concrete liner 1 and an outer side wall that is attached to the inner wall of the steel pipe 2.

[0051] The inner wall of the intermediate interlayer 3 presses against the outer wall of the concrete liner 1 to form tangential prestress in the concrete liner 1; and the outer wall of the intermediate interlayer 3 presses against the inner wall of the steel pipe 2 to form tangential pretension in the steel pipe 2.

[0052] The aforementioned prestressed composite duct has an inner concrete liner 1 and an outer steel pipe 2, with an intermediate interlayer 3 sandwiched between them. The intermediate interlayer 3 forms pressure contact with the inner concrete liner 1, causing the liner 1 to tend to retract inwards, creating tangential (circumferential) prestress within it to compensate for the concrete's extremely low tensile strength. Simultaneously, the intermediate interlayer 3 also forms pressure contact with the outer steel pipe 2, causing it to tend to expand outwards, creating tangential (circumferential) prestress within it, and eliminating cross-sectional profile defects. Through these stress effects, the concrete liner 1, intermediate interlayer 3, and steel pipe 2 form a tight bond, allowing them to share the load and fully utilize the respective performance advantages of concrete and steel. This circumferential prestressed composite duct possesses strong resistance to internal pressure and good ring stiffness.

[0053] In engineering applications, the aforementioned prestressed composite pipeline is buried underground. When there is no internal pressure or the internal pressure is low, the properties of prestressed concrete resist unbalanced loads, and the concrete liner 1 generally does not experience tensile stress and cracking. After bearing internal pressure, the increase in internal pressure gradually reduces the prestress on the concrete liner 1 and the intermediate interlayer 3. The reduced prestress on the intermediate interlayer 3 and the concrete liner 1 is transferred to the outer steel pipe 2, increasing the prestress on the outer steel pipe 2. As the internal pressure increases, the overall ring stiffness of the pipeline also continuously increases, and its ability to resist unbalanced loads is continuously enhanced. During the above-mentioned stress process, the performance advantages of the steel pipe 2 and the concrete liner 1 are brought into play, simultaneously achieving the characteristics of bearing both internal pressure and unbalanced loads, meeting the engineering requirements under high internal pressure scenarios.

[0054] It should be noted that, in the description of this application, "fitting" means that the surface shape of one component matches and is in contact with another component, and does not mean that adhesives or other media are used for bonding.

[0055] In some embodiments, the intermediate interlayer 3 is formed by pressurized grouting and hardening between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1. This application does not limit the specific composition of the grouting material; those skilled in the art can select from existing grouting materials according to actual needs.

[0056] In some embodiments, the thickness of the intermediate interlayer 3 is 1 to 50 mm, that is, the radial distance between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1 is 1 to 50 mm.

[0057] In the molding process of prestressed composite pipe, steel pipe 2 and concrete liner 1 are first installed. The inner diameter of steel pipe 2 is larger than the outer diameter of concrete liner 1. An annular space is formed between concrete liner 1 and steel pipe 2. The two ends of the annular space are sealed, and grout is injected into the annular space under pressure. The pressure is applied to the pipe walls of concrete liner 1 and steel pipe 2 on both sides through the grout. After the grout hardens, the pressure state is maintained to form prestress in the composite pipe.

[0058] The radial distance between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1 is 1–50 mm, resulting in a moderate volume of the annular space formed between them. This facilitates pressurized grouting operations while avoiding safety hazards caused by the formation of a large-volume pressure vessel, thus improving the constructability of the prestressed composite pipeline. The radial distance between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1, i.e., the thickness of the intermediate interlayer 3, can be selected within the above range according to the specifications and design requirements of the prestressed composite pipeline. For example, it can be 10 mm, 20 mm, 30 mm, 40 mm, or any value within the above range. It is understood that the range of 1–50 mm described herein is merely an optional embodiment and does not constitute a limitation on the scope of protection of this application.

[0059] In some embodiments, such as Figures 4-6 As shown, the axial length of the steel pipe 2 is greater than the axial length of the concrete liner 1, and the two ends of the steel pipe 2 extend out of the end face of the concrete liner 1 in the axial direction to form an extension section 21. The extension section 21 is used to connect with adjacent pipes to form a pipe assembly.

[0060] In some embodiments, the axial length of the steel pipe 2 is 10-30 cm longer than the axial length of the concrete liner 1, and the length of the extension sections 21 extending from both ends of the steel pipe 2 beyond the end faces of the concrete liner 1 is 2-15 cm. Extension sections 21 within this length range facilitate installation and sealing operations during pipe forming, and also facilitate connection and sealing between adjacent pipe ends during pipe connection. It is understood that the 10-30 cm range described herein is merely an optional embodiment and does not constitute a limitation on the scope of protection of this application. Furthermore, the extension sections 21 reserved at both ends of the same prestressed composite pipe section can have different lengths; for example, one end's extension section 21 is 2 cm, and the other end's extension section 21 is 14 cm; those skilled in the art can set these lengths as needed.

[0061] In some embodiments, such as Figure 5 and Figure 6 As shown, end rings 22 are respectively provided at both ends of the intermediate interlayer 3 in the axial direction. The outer circumference of the end rings 22 is fixedly connected to the inner wall of the steel pipe 2, and the inner circumference of the end rings 22 is located close to the concrete liner 1. The end rings 22 are provided at both ends of the intermediate interlayer 3 to seal the annular space between the concrete liner 1 and the steel pipe 2 during the pipe forming process. Optionally, the outer circumference of the end rings 22 is welded to the inner wall of the steel pipe 2 to achieve a stable connection and prevent the end rings 22 from loosening or shifting under pressure.

[0062] In some embodiments, such as Figure 5 and Figure 6 As shown, the end ring 22 is recessed axially relative to the end face of the concrete liner 1 to form a recess 32 between the end ring 22, the concrete liner 1, and the steel pipe 2. The recess 32 is used to install the seal 33 during the pipe forming process. During the pipe forming process, since the intermediate interlayer 3 is achieved by pressurized grouting, it is necessary to ensure the sealing of the grouting space 31 (i.e., the annular space between the concrete liner 1 and the steel pipe 2) to prevent grout overflow. Therefore, the annular space needs to be sealed before grouting. The recess 32 formed in this embodiment can provide installation space for the seal 33, facilitating the sealing operation.

[0063] In some embodiments, such as Figures 4-6As shown, multiple end connectors 11 are pre-embedded at both ends of the concrete liner 1 along its axial direction. The multiple end connectors 11 are distributed at intervals along the circumference of the concrete liner 1. The end connectors 11 extend from the end face of the concrete liner 1 into the interior of the concrete liner 1. The end connector 11 includes an inner cavity 111. The end of the end connector 11 near the end face of the concrete liner 1 is an open end 112 for fasteners to be inserted into the inner cavity 111 for connection. The end of the end connector 11 located inside the concrete liner 1 is a closed end 113 to prevent concrete from entering the inner cavity 111 of the end connector 11 during the pouring process.

[0064] In the above embodiment, multiple end connectors 11 are pre-embedded circumferentially at both ends of the concrete liner 1. The end connectors 11 can be connected to the fasteners 51, facilitating the installation of the concrete liner 1 during pipe forming and also facilitating connection with water-stopping components or adjacent pipes during the formation of the pipe assembly. It is understood that the length of the end connectors 11 should meet the anchorage length requirements of the steel bar in the concrete as specified in the standard to ensure the stability of the connection.

[0065] Optionally, the inner surface of the inner cavity 111 of the end connector 11 is formed with an internal thread, and the fastener 51 is specifically a bolt. The bolt is screwed into the inner cavity 111 of the end connector 11 to achieve connection.

[0066] In some embodiments, a plurality of axial reinforcing bars 12 are anchored and connected inside the concrete liner 1, and the plurality of axial reinforcing bars 12 are arranged at intervals in the circumferential direction of the concrete liner 1.

[0067] In some embodiments, a circumferential steel bar 13 is also anchored inside the concrete liner 1, and the circumferential steel bar 13 is fixedly connected to a plurality of axial steel bars 12.

[0068] By setting the axial reinforcement 12 and the circumferential reinforcement 13, a reinforcement network structure is formed in the concrete lining, giving the concrete lining a good ability to withstand external loads in both the axial and circumferential directions. Optionally, the circumferential reinforcement 13 can be multiple ring reinforcements, which are arranged axially along the steel pipe 2 and interconnected with the multiple axial reinforcements 12; the circumferential reinforcement 13 can also be a continuous spiral reinforcement, which extends spirally along the axial direction of the steel pipe 2 and interconnects with the multiple axial reinforcements 12.

[0069] In some embodiments, each axial reinforcing bar 12 is correspondingly provided with two end connectors 11 along the axial direction of the concrete liner 1, and the two ends of the axial reinforcing bar 12 are respectively fixedly connected to the corresponding end connectors 11. Optionally, the axial reinforcing bars 12 and the end connectors 11 at both ends are welded together by lap or butt joint; the circumferential reinforcing bars 13 located within the axial length range of the end connectors 11 are welded to the outer wall of the end connectors 11. In the above manner, the axial reinforcing bars 12, circumferential reinforcing bars 13 and end connectors 11 in the reinforced concrete liner 1 are connected to form an integral whole, so that the concrete liner 1 has a more stable skeleton structure and improves its ability to withstand external loads. During the fabrication of the concrete liner 1, it is possible to apply tensile force to the end connectors 11 at both ends, and use the axial reinforcing bars 12 as axial prestressing reinforcing bars according to the construction process of prestressed concrete to improve the axial mechanical properties of the composite pipe.

[0070] In some embodiments, an uneven structure (not shown in the figure) is formed on the inner wall of the steel pipe 2, and the outer wall of the intermediate interlayer 3 is embedded in the uneven structure. In this embodiment, in order to increase the mutual constraint between the intermediate interlayer 3 and the steel pipe 2, the steel pipe 2 can be made of steel plate with inner surface embossed, so that the inner wall of the steel pipe 2 has an uneven structure (pattern). During the grouting process of the intermediate interlayer 3, the grout can enter the uneven structure, so that the outer wall of the hardened intermediate interlayer 3 is embedded in the uneven structure, thereby increasing the shear resistance of the interface between the intermediate interlayer 3 and the steel pipe 2.

[0071] In some embodiments, an uneven structure (not shown in the figure) is formed on the outer wall of the concrete liner 1, and the inner wall of the intermediate interlayer 3 is embedded in the uneven structure. In this embodiment, in order to increase the mutual constraint between the intermediate interlayer 3 and the concrete liner 1, the outer template of the concrete liner 1 can be made of patterned steel plate with an inner embossed surface, so that the outer wall of the concrete liner 1 has an uneven structure (pattern). During the grouting process of the intermediate interlayer 3, the grout can enter the uneven structure, so that the inner wall of the hardened intermediate interlayer 3 is embedded in the uneven structure, thereby increasing the shear resistance of the interface between the intermediate interlayer 3 and the concrete liner 1.

[0072] In some embodiments, an uneven structure (not shown in the figure) is formed on the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1, and the outer and inner walls of the intermediate interlayer 3 are respectively embedded and connected to the uneven structures on both sides.

[0073] The second aspect of this application also provides a prestressed composite pipe assembly, comprising multiple prestressed composite pipe sections as described in the embodiments of the first aspect above, connected in sequence; wherein the ends of adjacent prestressed composite pipe sections are opposite each other, and a connecting space 23 is formed between the inner sides of the two extension sections 21 of the adjacent prestressed composite pipe sections and the end faces of the two concrete liner pipes 1.

[0074] The above-mentioned prestressed composite pipe assembly has a connection space 23 that can accommodate various required connection components, and an extension section 21 that can protect the connection components from external damage, significantly improving the reliability of the pipe connection and ensuring the long-term stable operation of the prestressed composite pipe assembly under complex working conditions.

[0075] Based on the above-mentioned prestressed composite pipe combination, this application provides three connection schemes.

[0076] In the first connection scheme, such as Figure 7 As shown, two water-stop pressure plates 81 and an elastic water-stop ring 82 are provided in each connection space 23. The two water-stop pressure plates 81 are respectively set for two adjacent prestressed composite pipe sections. The longitudinal section of each water-stop pressure plate 81 is L-shaped, including a first pressure plate 811 and a second pressure plate 812 that are fixedly connected. The first pressure plate 811 is opposite to and tightly connected to the end face of the concrete liner 1 in the corresponding prestressed composite pipe. The second pressure plate 812 is opposite to the extension section 21 of the steel pipe 2 in the corresponding prestressed composite pipe. The longitudinal section of the elastic water-stop ring 82 is U-shaped, including two oppositely arranged annular surfaces 821 and a side wall 822 connecting the outer periphery of the two annular surfaces 821. The annular surfaces 821 are sandwiched between the first pressure plate 811 and the end face of the concrete liner 1. The side wall 822 is sandwiched between the second pressure plate 812 and the two extension sections 21.

[0077] The connection scheme provided in the above embodiments can ensure flexible connection and sealing of pipe joints, guarantee the independent stress of each pipe section, adapt to various deformations, cope with changes in conditions such as uneven foundation settlement and axial expansion and contraction due to temperature, and facilitate connection with other structures or other types of pipelines. It also facilitates subsequent maintenance, repair, and pipeline upgrading of the water supply structure, and makes connection with water conveyance structures, other types of pipelines, and pipeline equipment easier. Furthermore, the extension section 21 can protect the inner elastic water-stop ring 82, preventing damage to the water-stop ring from affecting the water-stopping effect.

[0078] In some embodiments, since the extension sections 21 at both ends of the same prestressed composite pipe have different lengths, the length of the second pressure plate 812 is set to correspond to the length of its opposite extension section 21. In one embodiment, the extension section 21 at one end of the pipe is only 3cm long, and its water-stop pressure plate 81 may only include the first water-stop pressure plate 811, without the second pressure plate 812.

[0079] The elastic water-stop ring 82 can be a U-shaped water-stop rubber ring. The water-stop pressure plate 81 is fastened to the end connector 11 using fasteners 51; optionally, the fasteners 51 are bolts.

[0080] In the first connection method mentioned above, the two adjacent prestressed composite pipe sections achieve a flexible connection, which can maintain a suitable connection gap between adjacent pipes and adapt to uneven settlement of the foundation and axial expansion and contraction deformation of the pipes.

[0081] In the second connection scheme, such as Figure 8 As shown, a water-stop seat ring 91 is provided in the connecting space 23. The water-stop seat ring 91 connects two adjacent extension sections 21. There is a gap between the two ends of the water-stop seat ring 91 in the axial direction and the end face of the concrete liner 1. An annular sealing strip 92 is installed between the water-stop seat ring 91 and the extension section 21.

[0082] In the connection scheme provided in the above embodiment, the water-stop ring 91 and the annular sealing strip 92 are installed on the inner side of the ends of two adjacent prestressed composite pipe sections, and the annular sealing strip 92 is installed in the groove of the water-stop ring 91. This connection method is suitable for situations where the pipe foundation is relatively stable, and is also suitable for connection with pipes such as PCCP.

[0083] In the third connection scheme, such as Figure 9 As shown, the ends of every two adjacent extensions 21 of the prestressed composite pipe are connected by welding, achieving a rigid connection with a circumferential weld 101. This connection method is equivalent to the welding connection of ordinary steel pipes and is suitable for situations where temperature differences do not cause large axial expansion or contraction, or where the pipe needs to transmit axial force. The extensions 21 of the steel pipe 2 ensure that the welding temperature will not adversely affect the concrete liner 1 during welding.

[0084] In some embodiments, the connection space 23 between two adjacent composite pipe sections may be left untreated. In other embodiments, for cases where the water flow velocity inside the pipe is high, the connection space 23 may be filled with filler 102; for example, flexible or rigid filler 102 may be selected to fill the connection space 23 as needed.

[0085] In addition, the exposed surface of steel pipe 2 can be treated with different anti-corrosion measures depending on environmental conditions, such as coating with polymer coatings, thermal spraying zinc anti-corrosion, cathodic protection, etc. The inner surface of concrete lining pipe 1 can be left untreated, or it can be sprayed with a highly elastic polymer sealing coating to enhance the protection of steel pipe, concrete and internal reinforcing steel.

[0086] To aid in understanding the prestressed composite pipe in this application, a forming process for the prestressed composite pipe is provided below.

[0087] A concrete liner 1 is manufactured using centrifugal casting or conventional casting with internal and external formwork. End connectors 11 are pre-embedded at both ends of the concrete liner 1, and axial steel bars 12 and circumferential steel bars 13 are pre-embedded inside the concrete liner 1 to form a steel reinforcement network.

[0088] Before the concrete liner 1 is poured, tension is applied to the end connectors 11 at both ends by fasteners 51. After the concrete liner 1 is poured and hardened, a pre-tensioned axially prestressed concrete member with axial steel bars 12 as prestressed steel bars can be obtained.

[0089] Manufacture steel pipe 2, the inner diameter of steel pipe 2 is 40mm larger than the outer diameter of concrete liner pipe 1; end rings 22 are welded to the inner wall of steel pipe 2 near both ends, the distance between the two end rings 22 is 50mm shorter than the axial length of concrete liner pipe 1, and the end ring 22 at each end is recessed 25mm inward relative to the end face of concrete liner pipe 1.

[0090] Before grouting, the concrete liner 1 is installed on the top surface of the base flange 41, and simultaneously connected to the end connector 11 (extended nut) at the bottom of the concrete liner 1 using fasteners 51 (bolts) through the slotted hole 401 and washer 52 on the base flange 41. After the concrete liner 1 is in place, the bottom sealing element 33 (air-filled sealing ring) is installed, and the steel pipe 2 is coaxially installed on the top surface of the base flange 41 on the outside of the concrete liner 1. There is a gap between the inner wall of the steel pipe 2 and the outer wall of the concrete liner 1. The end rings 22 set near both ends of the steel pipe 2 close the two ends of the gap, forming the grouting space 31.

[0091] An upper sealing element 33 (air-filled sealing ring) is installed on the top surface of the top end ring 22. A top flange 42 is installed on the top of the concrete liner 1, and then fasteners 51 (bolts) are used to connect it to the end connector 11 at the top of the concrete liner 1 through the slotted hole 401 and the washer 52 on the top flange 42. The function of the slotted hole 401 is to provide radial deformation freedom at both ends of the concrete liner 1, allowing the ends of the concrete liner 1 to undergo inward displacement under the action of grouting pressure.

[0092] A grouting pipe 61 is welded to the bottom of the steel pipe 2, and an exhaust pipe 71 is welded to the top of the steel pipe 2. The grouting pipe 61 and the exhaust pipe 71 are connected to the grouting space 31. A grouting control valve 62 and an exhaust control valve are respectively connected to the bottom grouting pipe 61 and the top exhaust pipe 71 for grouting, venting and maintaining grouting pressure.

[0093] Grout is injected into the grouting space 31 between the concrete liner 1 and the steel pipe 2 through the bottom grouting pipe 61 and the grouting control valve. After the top vent pipe 71 begins to discharge grout, the vent control valve is closed, and the grout is injected under pressure until the grouting pressure reaches the predetermined design value. Then, the grouting control valve is closed, and the grout is allowed to harden completely. After the grouting operation is completed and the grout has hardened completely, the bottom grouting pipe 61 and the top vent pipe 71 are cut off, and the corresponding gaps on the steel pipe 2 are sealed.

[0094] The aforementioned prestressed composite pipe can completely correct the cross-sectional profile defects of the steel pipe 2 by injecting grout, forming circumferential pretension on the pipe wall of the steel pipe 2 and circumferential precompression on the pipe wall of the concrete liner 1. After the grout hardens, a composite pipe with stable circumferential pretension can be obtained.

Claims

1. A prestressed composite pipe, characterized in that, include: Concrete lining pipe; A steel pipe is coaxially fitted around the concrete liner, with a gap reserved between the inner wall of the steel pipe and the outer wall of the concrete liner; and An intermediate interlayer is sandwiched between the inner wall of the steel pipe and the outer wall of the concrete liner. The intermediate interlayer includes an inner sidewall that is in contact with the outer wall of the concrete liner and an outer sidewall that is in contact with the inner wall of the steel pipe. The inner wall of the intermediate interlayer presses against the outer wall of the concrete liner to form a tangential prestress in the concrete liner, and the outer wall of the intermediate interlayer presses against the inner wall of the steel pipe to form a tangential pretension in the steel pipe.

2. The prestressed composite pipe according to claim 1, characterized in that, Multiple end connectors are pre-embedded at both ends of the concrete liner in the axial direction, and the multiple end connectors are distributed at intervals along the circumference of the concrete liner. The end connector extends from the end face of the concrete liner into the interior of the concrete liner. The end connector includes an inner cavity. The end of the end connector near the end face of the concrete liner is an open end for fasteners to be inserted into the inner cavity for connection. The end of the end connector inside the concrete liner is a closed end to prevent concrete from entering the inner cavity of the end connector during the pouring process.

3. The prestressed composite pipe according to claim 1, characterized in that, The axial length of the steel pipe is greater than the axial length of the concrete liner, and both ends of the steel pipe extend out of the end face of the concrete liner to form an extension section. The extension section is used to connect with adjacent pipes to form a pipe assembly.

4. The prestressed composite pipe according to claim 3, characterized in that, End rings are provided at both ends of the intermediate interlayer along the axial direction. The outer circumference of the end rings is fixedly connected to the inner wall of the steel pipe, and the inner circumference of the end rings is located close to the concrete lining pipe.

5. The prestressed composite pipe according to claim 4, characterized in that, The end ring is recessed inward relative to the end face of the concrete liner in the axial direction to form a recess between the end ring, the concrete liner and the steel pipe. The recess is used to install a seal during the pipe forming process.

6. The prestressed composite pipe according to claim 2, characterized in that, Multiple axial steel bars are anchored inside the concrete liner, and the multiple axial steel bars are arranged at intervals in the circumferential direction of the concrete liner. Along the axial direction of the concrete liner, each axial reinforcing bar is correspondingly provided with two end connectors, and the two ends of the axial reinforcing bar are respectively fixedly connected to the corresponding end connectors.

7. The prestressed composite pipe according to claim 1, characterized in that, An uneven structure is formed on the inner wall of the steel pipe and / or the outer wall of the concrete liner, and the outer wall of the intermediate interlayer is embedded and fixedly connected to the uneven structure.

8. A prestressed composite pipe assembly, characterized in that, The device comprises multiple prestressed composite pipe sections as described in any one of claims 3-5, connected sequentially; wherein the ends of two adjacent prestressed composite pipe sections face each other, and a connecting space is formed between the inner sides of the two extension sections of the two adjacent prestressed composite pipe sections and the end faces of the two concrete lining pipes.

9. The prestressed composite pipe assembly according to claim 8, characterized in that, Two water-stop pressure plates and an elastic water-stop ring are provided in each of the connection spaces; The two water-stop pressure plates are respectively set for two adjacent sections of the prestressed composite pipe. Each water-stop pressure plate includes a first pressure plate and a second pressure plate that are fixedly connected. The first pressure plate is opposite to and fastened to the end face of the concrete liner in the corresponding prestressed composite pipe. The second pressure plate is opposite to the extension section of the steel pipe in the corresponding prestressed composite pipe. The elastic waterstop ring includes two opposing annular surfaces and a sidewall connecting the outer peripheries of the two annular surfaces. The annular surfaces are sandwiched between the first pressure plate and the end face of the concrete liner, and the sidewall is sandwiched between the second pressure plate and the two extension sections.

10. The prestressed composite pipe assembly according to claim 8, characterized in that, A water-stop seat ring is provided in the connection space, the water-stop seat ring connects two adjacent extension sections, there is a gap between the two ends of the water-stop seat ring in the axial direction and the end face of the concrete liner, and an annular sealing strip is installed between the water-stop seat ring and the extension section.

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