Structure, design and construction method for reinforcing PCCP (Prestressed Concrete Cylinder Pipe) by internally-wound steel bar composite flexible impermeable layer

Abstract

The invention discloses a structure, a design and a construction method for reinforcing a PCCP (prestressed concrete cylinder pipe) by an internally-wound steel bar composite flexible impermeable layer, a bearing main body of the composite structure is a spiral steel bar on the inner wall of the PCCP, and an impermeable system comprises quick-setting elastic putty between the steel bars and a high-strength flexible impermeable coating on the surface of the quick-setting elastic putty. The design method is based on elastic mechanics, a nonlinear analysis model is constructed, and the design of the steel bar diameter and the screw pitch is achieved. The reinforcing process comprises the steps of spirally winding the steel bars, coating the adhesive, filling the quick-setting elastic putty and blade-coating the high-strength flexible anti-seepage coating, so that a composite anti-seepage reinforcing system with structural strength and deformation adaptability can be formed. The problem that the device enters a narrow space is solved through disassembly and on-site assembly of the steel bar winding device, the technology has the advantages of being good in reinforcing effect, short in construction period and low in manufacturing cost, earth surface excavation is avoided, and the method is suitable for permanent repair of the large-diameter and high-internal-pressure PCCP.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water pipeline repair and reinforcement, in particular to a structure, design and construction method of a PCCP reinforced by a composite flexible anti-seepage layer with inner steel reinforcement. BACKGROUND

[0002] The mileage of PCCP pipelines in China is close to 30,000 km, with large diameter and high working pressure characteristics. At present, PCCP pipelines are in the stage of both new construction and operation and maintenance, and it is urgent to reserve efficient repair and reinforcement technology to deal with the potential threat of pipe explosion.

[0003] Existing repair technologies can be divided into two categories according to excavation requirements: excavation type (such as removal and replacement, steel wire reinforcement, necked steel cylinder lining and steel pipe insertion) which needs to destroy the ground and has high cost; and non-excavation type mainly using carbon fiber reinforced composite material, which shortens the construction period but still has essential defects. Specifically, the thickness of the reinforcement layer is insufficient due to the process limitation of CFRP, and the anti-seepage layer is easily torn and invalid due to pipe core cracking; the steel cylinder lining and steel pipe insertion significantly reduce the flow section; and the steel wire technology still needs local excavation and cannot solve the problem of pipe internal micro-crack leakage.

[0004] In summary, the current PCCP pipeline reinforcement technology faces three major problems: first, the size of the pipeline inlet and outlet restricts the entry and exit of large equipment; second, the thickness and bearing capacity of the reinforcement layer are difficult to balance; and third, the existing anti-seepage layer cannot adapt to pipe core cracking and deformation. Especially for non-excavation repair scenarios, an innovative solution is needed that can simultaneously improve structural strength, anti-seepage reliability and construction adaptability. SUMMARY

[0005] In view of the above technical problems in the existing PCCP pipeline reinforcement related technology, the present application proposes a structure, design and construction method of a PCCP reinforced by a composite flexible anti-seepage layer with inner steel reinforcement, which can overcome the above shortcomings of the prior art.

[0006] To achieve the above technical purposes, the technical solution of the present application is as follows:

[0007] A structure of a PCCP reinforced by a composite flexible anti-seepage layer with inner steel reinforcement;

[0008] The structure of the inner steel bar winding composite flexible anti-seepage layer reinforcing PCCP comprises a PCCP pipe body, a spiral steel bar layer, a quick-setting elastic putty layer and a flexible anti-seepage layer; the spiral steel bar layer comprises a plurality of steel bars spirally wound on the inner surface of the PCCP pipe body at a corresponding pitch; the quick-setting elastic putty layer is filled in the gap of the spiral steel bar layer and is bonded with the steel bar and the inner surface of the PCCP pipe body to form a first water stop barrier; the flexible anti-seepage layer covers the outer surface of the quick-setting elastic putty layer to form a second water stop barrier; and the adhesive is applied on the inner surface of the PCCP pipe body and the surface of the spiral steel bar layer to enhance the bonding strength of the steel bar, the PCCP pipe body and the quick-setting elastic putty layer.

[0009] Further, the adhesive is a two-component material, the surface drying time of the adhesive is less than 6 hours, the bonding strength of the adhesive with the PCCP pipe body is greater than 2.5 MPa, and the bonding strength of the adhesive with the steel bar is greater than 5 MPa.

[0010] Further, the quick-setting elastic putty layer is a three-component material, the tensile strength of the quick-setting elastic putty layer is greater than or equal to 2.5 MPa, the compressive strength is greater than or equal to 15 MPa, the adhesion is greater than or equal to 2.5 MPa, and the elongation is greater than or equal to 6%, and the one-time scraping thickness is 8 mm without falling.

[0011] Further, the flexible anti-seepage layer is a single-component high-strength flexible anti-seepage material, the tensile strength of the flexible anti-seepage layer is greater than or equal to 20 MPa, the elongation at break is greater than or equal to 200%, the tear strength is greater than or equal to 70 kN / m, the Shore hardness is greater than or equal to 80, the adhesion is greater than or equal to 2.5 MPa, and the water absorption rate is less than 4%.

[0012] Further, the pitch of the plurality of steel bars of the spiral steel bar layer is adjustable, and the reinforcing layer thickness and pressure bearing capacity are increased by reducing the pitch or increasing the diameter of the steel bar.

[0013] According to a second aspect of the present application, a design method of an inner steel bar winding composite flexible anti-seepage layer reinforcing PCCP is provided.

[0014] The design method comprises the following steps:

[0015] S1. Spiral steel bar equivalent modeling: based on the volume conservation law, the spiral steel bar is equivalent to a continuous steel cylinder, and the equivalent thickness thereof is calculated as follows:

[0016]

[0017] In the formula, t is the equivalent thickness of the steel bar, d is the diameter of the steel bar, and h is the pitch of the steel bar. d d

[0018] ​​S2. Multi-layer structure homogenization treatment: The four-layer structure, including the equivalent steel cylinder, inner core, steel cylinder and outer core, is simplified into a single homogeneous thick-walled cylinder by volume-weighted average elastic parameters:

[0019]

[0020] In the formula, u r Let E be the radial displacement, E be the elastic modulus, υ be Poisson's ratio, and r be the elastic modulus. n r is the inner diameter of the cylinder. w p is the outer diameter of the cylinder. n For the internal pressure of the cylinder, p w External pressure on the cylinder;

[0021] S3. Plane strain parameter correction: Adjusting the elastic modulus E of the homogeneous material... r And Poisson ratio υ s Converted to plane strain equivalent values:

[0022]

[0023] S4. Solution of interlayer displacement compatibility: Establish the radial displacement continuity equation of each layer contact surface;

[0024]

[0025] In the formula, u r1 u r2 u r3 and u r4 These are the radial displacements of the contact surfaces of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively.

[0026] S5. Calculate the circumferential stress of each layer of the reinforced structure according to the following formula:

[0027]

[0028] In the formula, σ θ1 σ θ2 σ θ3 and σ θ4 These are the circumferential stresses of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively.

[0029] S6. Load reconstruction after concrete cracking: The circumferential elastic modulus of the cracked concrete is corrected as follows:

[0030]

[0031] In the formula, E con This refers to the elastic modulus of concrete. This is the assumed circumferential modulus of elasticity after concrete cracking.

[0032] S7. Recalculate the circumferential stress of the steel cylinder, and complete the limit bearing capacity check.

[0033] According to a third aspect of the present application, a construction method for reinforcing PCCP by using a steel bar composite flexible anti-seepage layer is provided.

[0034] The construction method comprises the following steps:

[0035] Step 1. Equipment transportation: the steel bar winding device and materials in the pipe are transported to the pipe section to be repaired through the inspection valve well mouth and the branch pipe; the maximum size of the steel bar winding device is smaller than the minimum aperture of the inspection valve well mouth and the branch pipe.

[0036] Step 2. Steel bar winding: positioning steel plates are welded at the starting point and the ending point of the inner surface of the pipe section to be repaired, and the steel bar is spirally wound by the steel bar winding device according to the pitch.

[0037] Step 3. Anti-seepage treatment: adhesive is brushed between the steel bars and on the surface, and fast-setting elastic putty is filled to be flush with the top surface of the steel bar after the surface is dry, and a flexible anti-seepage layer is formed by scraping 1.5-3 mm thick high-strength flexible anti-seepage material after solidification.

[0038] Further, in the above step 1, the disassembled steel bar winding device is sent into the PCCP pipe body to be reinforced through the branch pipe of the valve well by using the lifting equipment, hinges and manual cooperation, and is assembled in the PCCP pipe body to be reinforced.

[0039] The present application has the following beneficial effects: the non-excavation construction is realized by using the disassembled equipment to be transported through the valve well, so that the ground surface is not damaged and the construction period is shortened; the thickness and bearing capacity of the reinforced layer are enhanced by adjusting the diameter and pitch of the steel bar, so that the internal pressure resistance of the pipeline is significantly improved; the composite structure design of the fast-setting elastic putty filling and the high-strength flexible anti-seepage coating layer makes the reinforced layer still maintain the complete anti-seepage function when the pipe core cracks. Finally, the effects of preventing pipe explosion risk, adapting to pipeline deformation and reducing comprehensive cost are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0041] Figure 1 is a transportation schematic diagram of the steel bar winding device of the structure of the steel bar composite flexible anti-seepage layer for reinforcing PCCP according to the embodiment of the present application;

[0042] Figure 2is a schematic diagram of a pipe inner spiral winding steel bar of a structure of a PCCP reinforced by a composite flexible impervious layer with inner winding steel bars according to an embodiment of the present application;

[0043] Figure 3 is a schematic diagram of a cross-sectional structure of a structure of a PCCP reinforced by a composite flexible impervious layer with inner winding steel bars according to an embodiment of the present application;

[0044] Figure 4 is a schematic diagram of a cross-sectional structure of a pipe wall unfolded state of a structure of a PCCP reinforced by a composite flexible impervious layer with inner winding steel bars according to an embodiment of the present application;

[0045] In the figure: 1, PCCP pipe body; 2, spiral steel bar layer; 3, quick-setting elastic putty layer; 4, flexible impervious layer; 5, adhesive; 6, manhole well mouth of an inspection valve; 7, inspection valve well; 8, branch pipe; 9, pipe inner steel bar winding device; 10, steel bar. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application belong to the scope of protection of the present application.

[0047] It should be understood that, in the description of the embodiments of the present application, the orientations or positional relationships indicated by the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms “first” and “second” are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of “several” is two or more, unless otherwise explicitly and specifically limited.

[0048] As Figures 2 to 4As shown, the structure of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application comprises a PCCP pipe body 1, a spiral steel bar layer 2, a fast-setting elastic putty layer 3 and a flexible anti-seepage layer 4. The spiral steel bar layer 2 comprises a plurality of turns of steel bars 10 spirally wound on the inner surface of the PCCP pipe body 1 according to a corresponding pitch. The fast-setting elastic putty layer 3 is filled in the gaps of the spiral steel bar layer 2 and is bonded to the steel bars 10 and the inner surface of the PCCP pipe body 1, forming a first water-stopping barrier. The flexible anti-seepage layer 4 covers the outer surface of the fast-setting elastic putty layer 3, forming a second water-stopping barrier. The adhesive 5 is applied to the inner surface of the PCCP pipe body 1 and the surface of the spiral steel bar layer 2, used to enhance the bonding strength of the steel bars 10, the PCCP pipe body 1 and the fast-setting elastic putty layer 3.

[0049] In a specific embodiment of the structure of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application, the adhesive 5 is a two-component material, the surface drying time of the adhesive 5 is less than 6 hours, and the bonding strength of the adhesive 5 to the PCCP pipe body 1 is greater than 2.5 MPa and to the steel bars 10 is greater than 5 MPa.

[0050] In a specific embodiment of the structure of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application, the fast-setting elastic putty layer 3 is a three-component material, the tensile strength of the fast-setting elastic putty layer 3 is ≥2.5 MPa, the compressive strength is ≥15 MPa, the adhesion is ≥2.5 MPa, and the elongation is ≥6%, and the one-time squeegee coating thickness is 8 mm without sagging.

[0051] In a specific embodiment of the structure of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application, the flexible anti-seepage layer 4 is a single-component high-strength flexible anti-seepage material, the tensile strength of the flexible anti-seepage layer 4 is ≥20 MPa, the elongation at break is ≥200%, the tear strength is ≥70 kN / m, the Shore hardness is ≥80, the adhesion is ≥2.5 MPa, and the water absorption is <4%.

[0052] In a specific embodiment of the structure of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application, the pitch of the plurality of turns of steel bars 10 of the spiral steel bar layer 2 is adjustable, and the reinforcement layer thickness and pressure-bearing capacity can be improved by reducing the pitch or increasing the diameter of the steel bars 10.

[0053] In a second aspect, the design method of the inner-wound steel bar composite flexible anti-seepage layer reinforced PCCP according to the embodiment of the present application comprises the following steps:

[0054] S1. Spiral steel bar equivalent modeling: based on the volume conservation law, the spiral steel bar is equivalent to a continuous steel cylinder, and the equivalent thickness is calculated.

[0055] That is: the inner winding steel reinforcement simplification method and nonlinear analysis model. The inner winding steel reinforcement simplification method is to convert the steel reinforcement into a uniform steel cylinder with the same area, that is, to convert the inner winding steel reinforcement into a uniform steel cylinder with the same area:

[0056]

[0057] In the formula, t d is the equivalent thickness of the steel reinforcement, d is the diameter of the steel reinforcement, h d is the pitch of the steel reinforcement;

[0058] S2. Homogenization treatment of the multi-layer structure: the four-layer structure including the equivalent steel cylinder, the inner layer pipe core, the steel cylinder and the outer layer pipe core is simplified into a single homogenized thick-walled cylinder through volume-weighted average elastic parameters;

[0059] Specifically, in the nonlinear analysis model, the most unfavorable condition is assumed, that is, the PCCP does not consider the mortar protection layer and the prestressed steel wire, the reinforcing layer does not consider, and the reinforcing structure from inside to outside is in turn: the spiral steel reinforcement equivalent to the thin steel cylinder, the inner layer pipe core, the steel cylinder, the outer layer pipe core. According to the principle of elasticity, the reinforcing structure is simplified into a uniform thick-walled cylinder under pressure, and the radial displacement solution of the Lame formula is as follows:

[0060]

[0061] In the formula, u r is the radial displacement, E is the elastic modulus, υ is the Poisson's ratio, r n is the inner diameter of the cylinder, r w is the outer diameter of the cylinder, p n is the internal pressure of the cylinder, p w is the external pressure of the cylinder;

[0062] S3. Plane strain parameter correction: the elastic modulus E r and the Poisson's ratio υ s of the homogenized material are converted into plane strain equivalent values:

[0063]

[0064] S4. Interlayer displacement coordination solution: the radial displacement continuity equation of the contact surface of each layer is established;

[0065] Specifically, the load on the inner surface of the reinforcing structure is the given internal water pressure; the outer surface of the reinforcing structure is assumed to not bear the external soil pressure, and the radial displacement coordination condition between layers is calculated by the following formula:

[0066]

[0067] In the formula, u r1 , u r2 , u r3 and u r4These are the radial displacements of the contact surfaces of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively.

[0068] S5. Calculate the circumferential stress of each layer of the reinforced structure according to the following formula:

[0069]

[0070] In the formula, σ θ1 σ θ2 σ θ3 and σ θ4 These are the circumferential stresses of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively.

[0071] S6. Load reconstruction after concrete cracking, correcting the circumferential elastic modulus of cracked concrete;

[0072] Specifically, it is assumed that before the concrete cracks, the deformation of each layer of the reinforced structure is coordinated; after the concrete cracks, the inner core only transmits radial loads, and circumferential stress is ignored:

[0073]

[0074] In the formula, E con This refers to the elastic modulus of concrete. This is the assumed circumferential modulus of elasticity after concrete cracking.

[0075] S7. Recalculate the circumferential stress of the steel cylinder and complete the ultimate bearing capacity check.

[0076] As the water pressure inside the pipe increases, this method can obtain the stress of the reinforcing steel bars inside the pipe before, during, and after the core concrete cracks. By setting the allowable stress of the reinforcing steel bars inside the pipe, the diameter and spacing of the reinforcing steel bars can be designed, and it can also be used to evaluate the reinforcement effect of PCCP pipes in reinforcement tests.

[0077] Thirdly, the construction method for reinforcing PCCP with an internally wound steel reinforced composite flexible seepage-proof layer according to an embodiment of the present invention includes the following steps:

[0078] Step 1: Equipment transfer within the pipeline: such as Figure 1 The diagram illustrates a method for transporting materials and equipment required for reinforcing a PCCP pipe from the surface to the section requiring repair. Specifically, materials and equipment are transported to the nearest valve well. Using a combination of lifting equipment, hinges, and manual labor, the materials and equipment are first passed through the surface-level maintenance valve well, then through the branch pipe connected to the PCCP, and finally transported to the section requiring repair using a combination of transport vehicles and manual labor. The maximum size of the transported materials and equipment must be smaller than the minimum size of the valve well opening and the branch pipe. If necessary, the entire equipment may need to be disassembled into parts, transported into the pipeline, and then reassembled.

[0079] Step two: spiral steel reinforcement in pipe winding: as shown, according to the design results of PCCP inner steel reinforcement, first weld a circle of steel plate at the starting point and the end point of the steel winding, then assemble the equipment and materials required for the inner winding steel, weld the starting point of the steel with the steel plate, set the pitch of the spiral steel, move the equipment along the length direction of the pipe during the spiral winding of the steel, form the spiral winding effect of the steel, and finally weld the end point of the steel with the end steel plate. Figure 2

[0080] Step three: flexible impermeable layer treatment: after the steel winding in the pipe is completed, the spacing of the steel is adjusted uniformly, and the adhesive is uniformly brushed on the gap between the steels and the surface of the steel; after the adhesive is dry, the gap between the spiral steels is filled with quick-setting elastic putty, and the quick-setting elastic putty, the steel and the inner surface of the pipe core are fully contacted and bonded by using a scraper and a pressing tool. Among them, the quick-setting elastic putty is filled to be flush with the top surface of the steel, and after the quick-setting elastic putty is solidified, a 1.5-3mm thick high-strength flexible impermeable material is scraped on the surface.

[0081] In summary, by means of the above technical solutions of the present application, the non-excavation construction is realized by using the detachable equipment through the valve well, so as to avoid surface damage and shorten the construction period; the thickness and bearing capacity of the reinforcement layer are enhanced by adjusting the diameter and pitch of the steel, so as to significantly improve the anti-internal pressure capacity of the pipeline; the composite structure design of the quick-setting elastic putty filling and the high-strength flexible impermeable coating is adopted, so that the reinforcement layer still maintains the complete impermeable function when the pipe core cracks. Finally, the effects of preventing pipe explosion risk, adapting to pipeline deformation and reducing comprehensive cost are achieved.

[0082] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.​

Claims

1. A structure for reinforcing PCCP with an internally wrapped steel reinforcement composite flexible waterproof layer, characterized in that, The system includes a PCCP pipe body (1), a spiral steel bar layer (2), a quick-setting elastic putty layer (3), and a flexible waterproof layer (4). The spiral steel bar layer (2) includes several turns of steel bars (10) spirally wound around the inner surface of the PCCP pipe body (1) with corresponding pitches. The quick-setting elastic putty layer (3) fills the gaps in the spiral steel bar layer (2) and bonds to the steel bars (10) and the inner surface of the PCCP pipe body (1) to form a first waterproof barrier. The flexible waterproof layer (4) covers the outer surface of the quick-setting elastic putty layer (3) to form a second waterproof barrier. The adhesive (5) is applied to the inner surface of the PCCP pipe body (1) and the surface of the spiral steel bar layer (2) to enhance the bonding strength between the steel bars (10), the PCCP pipe body (1), and the quick-setting elastic putty layer (3).

2. The structure of PCCP reinforced with an internally wrapped steel reinforcement composite flexible waterproof layer according to claim 1, characterized in that, The adhesive (5) is a two-component material. The surface drying time of the adhesive (5) is less than 6 hours. The bonding strength of the adhesive (5) with the PCCP pipe body (1) is greater than 2.5 MPa and the bonding strength with the reinforcing bar (10) is greater than 5 MPa.

3. The structure of PCCP reinforced with an internally wrapped steel reinforcement composite flexible waterproof layer according to claim 1, characterized in that, The quick-setting elastic putty layer (3) is a three-component material. The quick-setting elastic putty layer (3) has a tensile strength ≥2.5MPa, a compressive strength ≥15MPa, an adhesion ≥2.5MPa, an elongation ≥6%, and a single application thickness of 8mm without dripping.

4. The structure of PCCP reinforced with an internally wrapped steel reinforcement composite flexible waterproof layer according to claim 1, characterized in that, The flexible impermeable layer (4) is a single-component high-strength flexible impermeable material. The flexible impermeable layer (4) has a tensile strength ≥20MPa, an elongation at break ≥200%, a tear strength ≥70kN / m, a Shore hardness ≥80, an adhesion ≥2.5MPa, and a water absorption rate <4%.

5. The structure of PCCP reinforced with an internally wrapped steel reinforcement composite flexible seepage-proof layer according to claim 1, characterized in that, The pitch of several rings of steel bars (10) in the spiral steel bar layer (2) is adjustable. By reducing the pitch or increasing the diameter of the steel bars (10), the thickness of the reinforcement layer and the bearing capacity can be improved.

6. The design method for reinforcing PCCP with an internally wrapped steel reinforcement composite flexible waterproofing layer according to any one of claims 1-5, comprising the following steps: S1. Equivalent Modeling of Spiral Reinforcing Bars: Based on the law of volume conservation, spiral reinforcing bars are equivalent to continuous steel cylinders, and their equivalent thickness is calculated: In the formula, t d where d is the equivalent thickness of the reinforcing bar, h is the diameter of the reinforcing bar, and d is the equivalent d The pitch of the reinforcing bar; S2. Multi-layer structure homogenization treatment: The four-layer structure, including the equivalent steel cylinder, inner core, steel cylinder and outer core, is simplified into a single homogeneous thick-walled cylinder by volume-weighted average elastic parameters: In the formula, u r Let E be the radial displacement, E be the elastic modulus, υ be Poisson's ratio, and r be the elastic modulus. n r is the inner diameter of the cylinder. w p is the outer diameter of the cylinder. n For the internal pressure of the cylinder, p w External pressure on the cylinder; S3. Plane strain parameter correction: Adjusting the elastic modulus E of the homogeneous material... r And Poisson ratio υ s Converted to plane strain equivalent values: S4. Solution of interlayer displacement compatibility: Establish the radial displacement continuity equation of each layer contact surface; In the formula, u r1 u r2 u r3 and u r4 These are the radial displacements of the contact surfaces of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively. S5. Calculate the circumferential stress of each layer of the reinforced structure according to the following formula: In the formula, σ θ1 σ θ2 σ θ3 and σ θ4 These are the circumferential stresses of the spiral reinforcing bar, the inner core, the steel cylinder, and the outer core, respectively. S6. Load reconstruction after concrete cracking: The circumferential elastic modulus of the cracked concrete is corrected as follows: In the formula, E con This refers to the elastic modulus of concrete. This is the assumed circumferential modulus of elasticity after concrete cracking. S7. Recalculate the circumferential stress of the steel cylinder and complete the ultimate bearing capacity check.

7. The construction method for reinforcing PCCP with an internally wrapped steel reinforcement composite flexible seepage barrier layer according to any one of claims 1-5, characterized in that, It also includes the following steps: Step 1. Equipment Transportation: Transport the reinforcing steel bar winding device (9) and materials inside the reinforced equipment pipe to the pipe section to be repaired through the wellhead (6) and branch pipe (8) of the maintenance valve well; the maximum size of the reinforcing steel bar winding device (9) inside the pipe is smaller than the minimum diameter of the surface valve well (6) and branch pipe (8). Step 2. Rebar winding: Weld positioning steel plates at the start and end points of the inner surface of the pipe section to be repaired, and spirally wind the reinforcing bars (10) according to the pitch using the pipe reinforcing bar winding device (9). Step 3. Anti-seepage treatment: Apply adhesive (5) to the gaps and surface of the steel bars (10), and after the surface is dry, fill with quick-setting elastic putty until it is flush with the top surface of the steel bars. After curing, apply a 1.5-3mm thick high-strength flexible anti-seepage material to form a flexible anti-seepage layer (4).

8. The construction method for reinforcing PCCP with an internally wrapped steel reinforcement composite flexible seepage barrier layer according to claim 7, characterized in that, In step one, a lifting device, hinges and manual labor are used to send the disassembled steel bar winding device (9) into the PCCP pipe body (1) to be reinforced through the wellhead (6), the wellhead (7) and the branch pipe (8), and then assemble it in the PCCP pipe body (1) to be reinforced.

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