A PCCP prestress loss testing device and method

Abstract

The present invention discloses a PCCP prestress loss test device and method, which relate to the technical field of PCCP prestress loss test, and include the following steps: S1: determining an equivalent bending curvature radius according to a target pipe diameter, selecting a test section bending baffle that matches the equivalent bending curvature radius, pouring concrete with the same strength as the target pipe core concrete at the test section bending baffle based on the equivalent bending curvature radius, and curving until the test reaches a preset strength to obtain a concrete contact template with curvature. The present invention establishes independent variable control capabilities and provides accurate and stable loss rate data. The host can separate the specific influence of each single factor on the prestress loss rate, realize true decoupling analysis, and replace the prototype pipe test through modular combination. While truly simulating the working state of the PCCP prestressed steel wire, it effectively shortens the test cycle and reduces the test cost.

Description

Technical Field

[0001] The present invention relates to the technical field of PCCP prestress loss testing, and in particular to a PCCP prestress loss testing device and method. Background Art

[0002] Existing methods for testing prestress loss in PCCP involve attaching sensors to prestressed high-strength steel wire attached to finished pipes and conducting static loss tests. This results in high material consumption (requiring an entire finished pipe), long testing cycles (the pipes must be maintained until in-service), a limited number of tests, and multiple interference factors. The present invention uses a scaled model to simulate the actual working conditions of PCCP and conducts prestress loss tests using a data integration device. This can be reused in parallel, significantly reducing testing costs and shortening testing cycles. During the actual test, multiple parameters, including prestressed tendon diameter (5-9mm), initial tensile stress (800-1500MPa), concrete strength (C30-C60), mortar cover strength (20-50MPa), and pipe diameter (DN2200-DN4000), interact with each other. Conventional methods cannot independently control a single test variable, while the present invention allows for repeated testing to independently control each parameter and achieve more accurate results. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides a PCCP prestress loss testing device and method.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] A PCCP prestress loss testing device and method includes the following steps:

[0006] S1: Determine the equivalent bending curvature radius based on the target pipe diameter, select a test section bending baffle that matches the equivalent bending curvature radius, pour concrete with the same strength as the target pipe core concrete at the test section bending baffle based on the equivalent bending curvature radius, and cure until the test reaches the preset strength to obtain a concrete contact formwork with curvature;

[0007] S2: Pass the anchorage section of the test reinforcement through the anchorage section baffle and tighten the nut. Place a stress sensor between the nut and the anchorage section baffle to monitor the stress changes of the test reinforcement in real time.

[0008] S3: bend the measuring section of the test reinforcement along the curvature of the concrete contact formwork and attach it to the contact interface of the concrete contact formwork;

[0009] S4: The tensioning section of the test reinforcement passes through the tensioning section baffle and applies a preset initial tensioning stress. After reaching the preset value, tighten the nut, remove the temporary loading device and let it stand for a preset time to eliminate residual stress.

[0010] S5: Attach grating strain sensors to the maximum bending moment point and inflection point of the measuring section of the test reinforcement. After the load is stabilized for a specified time, synchronously collect data from the stress sensor in the anchoring section and the grating strain sensor in the measuring section, and calculate the prestress loss rate through the host computer.

[0011] The independent control of the bending radius and concrete strength of S1 and the stress stabilization process of S4 are used to calculate and analyze the collected data, achieving decoupling analysis of the following parameters:

[0012] The influence of reinforcement diameter on prestress loss rate;

[0013] The influence of reinforcement bending curvature on prestress loss rate;

[0014] Effect of concrete strength on prestress loss rate.

[0015] Preferably, in S5, one end of the measuring section of the test reinforcement close to the tensioning section is used as the starting point, the maximum bending moment point is the midpoint of the measuring section of the test reinforcement, and the inflection point is one-quarter of the measuring section of the test reinforcement.

[0016] Preferably, grating strain sensors are pasted on the top and outer sides of the maximum bending moment point and the inflection point.

[0017] Preferably, the prestress loss rate in S5 is The calculation formula is:

[0018] ;

[0019] in, is the slip at the reinforcement-concrete interface, =80-120GPa / mm is the slip influence coefficient, To preset the initial tensile stress, is the elastic modulus of the reinforcement, is the cross-sectional area of ​​the reinforcement, are the coordinates of the point with maximum bending moment.

[0020] Preferably, the curvature radius of the curved baffle in the test section in S1 is satisfy: ;

[0021] in, The target diameter is 2200mm≤ ≤4000mm, is the pipe wall thickness compensation coefficient, and the range of the pipe wall thickness compensation coefficient is 50mm≤ ≤100mm.

[0022] Preferably, the diameter of the tested reinforcement in S1 is in the range of 5-9 mm, and the concrete strength is in the range of C30-C60.

[0023] Preferably, the standing time in S4 is satisfy: ;

[0024] in, is the stress relaxation factor, and its value range is .

[0025] A PCCP prestress loss testing device, comprising:

[0026] The base plate, anchoring section baffle and tensioning section baffle are all independently arranged;

[0027] Multiple test section curved baffles, each of which is welded to a base plate with different preset curvatures, are used to simulate the entire prototype pipe to be tested in proportion through a detachable modular structure, so as to truly simulate the actual working state of the PCCP;

[0028] The transverse reinforcement ribs are evenly distributed on the top of the bending baffle of the test section along the bending path of the bending baffle of the test section to ensure the integrity of the device and prevent the test reinforcement from being broken.

[0029] Preferably, triangular braces are provided on the nut side surface of the anchoring section baffle and the curved inner surface of the testing section curved baffle.

[0030] Preferably, a detachable hollow jack is provided on one side of the tensioning section baffle, and the hollow jack is used to apply a preset initial tensioning stress to the test reinforcement.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention can obtain multiple groups of experimental data by systematically changing the reinforcement diameter, bending curvature, and concrete strength. Through the established variable independent control capability and the provided accurate and stable loss rate data, the host can separate the specific influence of each single factor on the prestress loss rate, realize true decoupling analysis, and replace the prototype pipe test through modular combination. While truly simulating the working state of PCCP prestressed steel wire, it effectively shortens the test cycle, reduces the test cost, and can be recycled. At the same time, the reinforcement diameter, reinforcement bending diameter, concrete strength, and mortar strength are independently adjusted through replaceable modules, and various influencing parameters in the PCCP prestress loss test are accurately and effectively controlled. A detachable modular structure is used to simulate the overall prototype pipe, and independent adjustment modules of the reinforcement diameter, reinforcement bending diameter, concrete strength, and mortar strength are integrated to realize multi-parameter physically decoupled prestress loss test, thereby improving the test accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0034] Figure 1 Schematic diagram of the overall structure of the testing device of the present invention;

[0035] Figure 2 For the present invention Figure 1 A magnified view of the structure at point A;

[0036] Figure 3 It is a right side view of the testing device of the present invention;

[0037] Figure 4 It is a front view of the second embodiment of the present invention;

[0038] Figure 5 It is a rear view of the second embodiment of the present invention.

[0039] Explanations in the figure: 1. Base plate; 2. Tensioning section baffle; 3. Movable steel plate; 4. Hollow jack; 5. Horse stool; 6. Triangular brace; 7. Anchoring section steel pipe; 8. Main unit; 9. Fiber Bragg Grating (FBG) demodulator; 10. Test reinforcement; 11. Concrete contact formwork; 12. Test section bending baffle; 13. Transverse reinforcement; 14. Anchoring section baffle; 15. Tensioning section steel pipe; 16. Fiber optic lead; 17. Grating strain sensor. DETAILED DESCRIPTION

[0040] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0041] like Figure 1-5 As shown, a PCCP prestress loss testing device and method includes the following steps:

[0042] S1: Determine the equivalent bending curvature radius according to the target pipe diameter, select a test section bending baffle 12 that matches the equivalent bending curvature radius, pour concrete of the same strength as the target pipe core concrete at the test section bending baffle 12 based on the equivalent bending curvature radius, and cure until the test reaches a preset strength, thereby obtaining a concrete contact template 11 with curvature;

[0043] Specifically, the test section bending baffle 12 is precisely controlled according to the target pipe diameter and the bending geometry of the test section bending baffle 12 is proportionally restored to ensure that the curvature radius of the measuring section of the test reinforcement 10 is consistent with the target working condition, which is the key basic variable for studying the influence of "bending curvature".

[0044] Furthermore, by independently controlling the concrete strength and selecting a matching concrete strength grade based on the target pipe diameter, concrete of the test strength is poured in the concrete mold and tested to reach the test strength after 28 days of curing. This variable can be set independently of the curvature radius, which is a key basic variable for studying the influence of “concrete strength”.

[0045] Furthermore, the cured concrete contact template 11 provides a hard, stable contact surface with actual engineering material properties for the test reinforcement 10, simulating the bonding constraint state between the reinforcement and concrete in the actual structure, and providing a rigid and real contact interface for the test experiment.

[0046] Furthermore, by independently controlling the curvature and concrete strength grade, one of the variables can be changed while the other is fixed in subsequent test experiments, thereby separating their respective effects on prestress loss and thus achieving a basis for decoupling the “curvature” and “strength” variables.

[0047] S2: Pass the anchoring section of the test reinforcement 10 through the anchoring section baffle 14 and tighten the nut. Place a stress sensor between the nut and the anchoring section baffle 14 to monitor the stress changes of the test reinforcement 10 in real time.

[0048] Specifically, the test reinforcement 10 is made, and the two ends of the test reinforcement 10 are respectively passed through the anchoring section steel pipe 7 and the tensioning section steel pipe 15, and the anchoring section steel pipe 7 and the tensioning section steel pipe 15 are poured into the bonding anchor of epoxy resin and cement for anchoring. The anchoring section steel pipe 7 and the tensioning section steel pipe 15 are polished with sandpaper and cleaned with alcohol to remove rust. The epoxy resin is left to stand at room temperature for 7 days to ensure sufficient curing. The anchoring section steel pipe 7 and the tensioning section steel pipe 15 are hollow threaded steel pipes.

[0049] Furthermore, the anchoring section steel pipe 7 at one end of the test reinforcement 10 is passed through the anchoring section baffle 14, and a stress sensor is placed between the nut and the anchoring section baffle 14. The nut is tightened to provide a stable reaction point for the tensioning process and ensure the effective conduct of the test. The stress sensor can directly and in real time measure the actual stress state of the anchoring end, which is one of the most critical input data for calculating the prestress loss rate. It directly reflects the various loss factors after the tensioning is completed, and enables the test reinforcement 10 to maintain effective stress at the anchoring end.

[0050] S3: bending the measuring section of the test reinforcement 10 along the curvature of the concrete contact formwork 11 and attaching it to the contact interface of the concrete contact formwork 11;

[0051] Specifically, the contact interface of the concrete contact template 11 allows the measuring section of the test reinforcement 10 to accurately present the target curvature, thereby simulating the actual bending reinforcement working condition and ensuring that the geometric shape of the test reinforcement 10 in the bending section is consistent with the experimental design.

[0052] S4: Pass the tensioning section of the test reinforcement 10 through the tensioning section baffle 2 and apply a preset initial tensioning stress. After reaching the preset value, tighten the nut, remove the temporary loading device and let it stand for a preset time to eliminate residual stress;

[0053] Specifically, the tensioning section steel pipe 15 at one end of the test reinforcement 10 is passed through the tensioning section baffle 2, nut, horse stool 5, hollow jack 4, movable steel plate 3 and nut in sequence, and the nut at the movable steel plate 3 is tightened.

[0054] Furthermore, the hollow jack 4 is used to start applying the load, thereby applying a preset initial tensile stress to the test reinforcement 10, applying a controllable and known initial stress level in the test reinforcement 10, and establishing an initial prestressed state.

[0055] Furthermore, when the preset tensioning stress is reached, the nut at the tensioning section baffle 2 is tightened to lock the stress state, the nut at the movable steel plate 3 is loosened, the hollow jack 4 is removed, and the system is left to stand for a preset time. The main purpose of the standing process is to allow some instantaneous losses that are not related to time (such as anchor deformation, pad gap compaction, etc.) and the internal residual stress generated by the tensioning process to fully occur and stabilize, and to provide a starting point value for loss calculation for calculating the prestress loss rate through the locked initial tensioning stress.

[0056] S5: Attach grating strain sensors 17 to the maximum bending moment point and the inflection point of the measuring section of the test reinforcement 10. After the load is stabilized for a specified time, synchronously collect data from the stress sensor of the anchoring section and the data from the grating strain sensor 17 of the measuring section, and calculate the prestress loss rate through the host computer 8;

[0057] The independent control of the bending radius and concrete strength of S1 and the stress stabilization process of S4 are used to calculate and analyze the collected data, achieving decoupling analysis of the following parameters:

[0058] The influence of reinforcement diameter on prestress loss rate;

[0059] The influence of reinforcement bending curvature on prestress loss rate;

[0060] Effect of concrete strength on prestress loss rate.

[0061] Specifically, the grating strain sensor 17 is connected to the fiber optic Bragg grating demodulator 9 through an optical fiber lead 16. The fiber optic Bragg grating demodulator 9 obtains the data collected by the grating strain sensor 17 and transmits the data to the host 8. By systematically changing the diameter of the reinforcement (replacing the test reinforcement of different diameters), the bending curvature (replacing the bending baffle 12 of the test section of S1), the concrete strength (S1 uses concrete of different strengths), and repeating steps S2-S5, multiple sets of experimental data can be obtained. By utilizing the independent control capability of variables established by S1 and the precise and stable loss rate data provided by S4 / S5, the host can separate the specific influence of each single factor (diameter, curvature, strength) on the prestress loss rate, realize true decoupling analysis, and replace the prototype tube test through modular combination. While truly simulating the working state of PCCP prestressed steel wire, it effectively shortens the test cycle and reduces the test cost.

[0062] In S5 , one end of the measuring section of the test reinforcement 10 close to the tensioning section is taken as the starting point, the maximum bending moment point is the midpoint of the measuring section of the test reinforcement 10 , and the inflection point is the position at one quarter of the measuring section of the test reinforcement 10 .

[0063] Specifically, when the test reinforcement 10 is bent along an arc of a curvature radius, if the measuring section is a symmetrical arc section (such as a semicircle or a quarter circle), the curvature at the midpoint is the largest, and the peak tensile stress generated by the bending of the reinforcement occurs here. The grating strain sensor 17 at the midpoint directly monitors the most unfavorable stress point of the test reinforcement 10 in the bending state, reflecting the tensile deformation and local stress concentration caused by the maximum bending moment. The data at this point can be used to analyze the sensitivity of the reinforcement diameter and bending curvature to the prestress loss, and quantify the influence of the bending effect.

[0064] Furthermore, in the symmetrical bending section, the theoretical value of the bending moment at the inflection point (such as the 1 / 4 arc position) is zero. Here, the reinforcement is only subjected to axial tension and there is no additional bending stress. The strain data at the inflection point only reflects the axial tension. The difference with the midpoint data can separate the additional stress caused by pure bending, thereby separating the bending effect and the friction effect. If the strain value at the inflection point is lower than the converted value of the anchor end stress, it indicates that there is friction slip loss at the reinforcement-concrete interface, and this loss is related to the concrete strength and the surface properties of the reinforcement, thereby identifying the interface friction loss. By comparing the inflection point data of different concrete specimens, the influence of concrete strength on the interface bond slip (friction loss) can be independently analyzed, thereby decoupling the influence of concrete strength.

[0065] Furthermore, the selection of the midpoint and 1 / 4 point utilizes the symmetry of the bending section to ensure that the theoretical mechanical state of the measuring point position is clear (the bending moment at the midpoint is the largest, and the bending moment at the 1 / 4 point is zero), avoiding errors caused by random point selection. The 1 / 4 point is located in the transition zone between the beginning and end of the bending section, where the curvature changes significantly, and can sensitively capture the local detachment or slippage behavior of the reinforcement and concrete, thereby optimizing the sensor layout.

[0066] Grating strain sensors 17 are pasted on the top and outer sides of the maximum bending moment point and the inflection point.

[0067] Specifically, when the reinforcement is bent, there is a tensile and compressive stress gradient in the cross section, with the top (convex side) dominated by tensile stress and the outer side (concave side) dominated by compressive stress. The bidirectional adhesive sensor can simultaneously monitor the maximum tensile strain (top) and the maximum compressive strain (outer side) in the same cross section.

[0068] Furthermore, the contact pressure between the reinforcement and the concrete formwork is unevenly distributed. The contact pressure on the concave side (outer side) is greater, and the friction effect is stronger. The friction on the convex side (top) may be reduced due to micro-detachment. By comparing the two-directional data, the spatial heterogeneity of the interface constraint can be quantified.

[0069] Prestress loss rate in S5 The calculation formula is:

[0070] ;

[0071] in, is the slip at the reinforcement-concrete interface, =80-120GPa / mm is the slip influence coefficient, To preset the initial tensile stress, is the elastic modulus of the reinforcement, is the cross-sectional area of ​​the reinforcement, are the coordinates of the point with maximum bending moment.

[0072] The curvature radius of the curved baffle in the test section S1 satisfy: ;

[0073] in, The target diameter is 2200mm≤ ≤4000mm, is the pipe wall thickness compensation coefficient, and the range of the pipe wall thickness compensation coefficient is 50mm≤ ≤100mm.

[0074] The diameter of the tested reinforcement 10 in S1 ranges from 5 to 9 mm, and the concrete strength ranges from C30 to C60.

[0075] S4 rest time satisfy: ;

[0076] in, is the stress relaxation factor, and its value range is .

[0077] A PCCP prestress loss testing device, comprising:

[0078] The base plate 1, the anchoring section baffle 14 and the tensioning section baffle 2 are all independently provided;

[0079] Multiple test section curved baffles 12 are welded on the base plate 1 with different preset curvatures. The detachable modular structure simulates the entire prototype pipe to be tested in proportion to simulate the actual working state of the PCCP.

[0080] The transverse reinforcing ribs 13 are evenly distributed on the top of the testing section curved baffle 12 along the curved path of the testing section curved baffle 12 to ensure the integrity of the device and prevent the test ribs from being broken.

[0081] Triangular braces 6 are provided on the nut side surface of the anchoring section baffle 14 and the curved inner surface of the testing section curved baffle 12 .

[0082] Specifically, the stability of the anchoring section baffle 14 and the testing section curved baffle 12 is enhanced by providing the triangular braces 6 .

[0083] A detachable hollow jack 4 is provided on one side of the tensioning section baffle 2, and the hollow jack 4 is used to apply a preset initial tensioning stress to the test reinforcement.

[0084] Example 1: Bending test

[0085] Target parameter combination

[0086] Target pipe diameter: ;

[0087] Equivalent radius of curvature: ;

[0088] Rebar diameter: ;

[0089] Concrete strength: ;

[0090] Initial tensile stress: ;

[0091] Standing time: 72 hours.

[0092] S1: Determine the equivalent bending curvature radius based on the target pipe diameter , select the test section bending baffle 12 that matches the equivalent bending curvature radius, and pour concrete with the same strength as the target core concrete at the test section bending baffle 12 based on the equivalent bending curvature radius , curing for 28 days until the test reaches the preset strength, and obtaining a concrete contact formwork 11 with curvature;

[0093] S2: Pass the anchoring section of the test reinforcement 10 through the anchoring section baffle 14 and tighten the nut. Place a stress sensor between the nut and the anchoring section baffle 14 to monitor the stress changes of the test reinforcement 10 in real time.

[0094] S3: bending the measuring section of the test reinforcement 10 along the curvature of the concrete contact formwork 11 and attaching it to the contact interface of the concrete contact formwork 11;

[0095] S4: The tensioning section of the test reinforcement 10 passes through the tensioning section baffle 2 and applies a preset initial tensioning stress. , after reaching the preset value, tighten the nut, remove the temporary loading device and let it stand for 72 hours to eliminate residual stress;

[0096] S5: Attach grating strain sensors 17 to the maximum bending moment point and the inflection point of the measuring section of the test reinforcement 10. After the load is stabilized for a specified time, synchronously collect data from the stress sensor of the anchoring section and the data from the grating strain sensor 17 of the measuring section, and calculate the prestress loss rate through the host computer 8:

[0097] midpoint:

[0098] 1 / 4 point:

[0099]

[0100] Traditional loss rate:

[0101] Formula correction:

[0102] According to the data, the influence of reinforcement diameter on prestress loss rate, the influence of reinforcement bending curvature on prestress loss rate, and the influence of concrete strength on prestress loss rate are decoupled and an analysis report is obtained.

[0103] Example 2: Straight Line Test (Control Group)

[0104] Parameter configuration (only the curvature is different from that of embodiment 1), other parameters are the same as those of embodiment 1;

[0105] S1: Remove the test section bending baffle 12;

[0106] S2: Pass the anchoring section of the test reinforcement 10 through the anchoring section baffle 14 and tighten the nut. Place a stress sensor between the nut and the anchoring section baffle 14 to monitor the stress changes of the test reinforcement 10 in real time.

[0107] S3: Pass the tensioning section of the test reinforcement 10 through the tensioning section baffle 2, so that the test reinforcement 10 is in a straight state, and apply the preset initial tensioning stress , after reaching the preset value, tighten the nut, remove the temporary loading device and let it stand for 72 hours to eliminate residual stress;

[0108] S4: After the load is stabilized for a specified time, the data of the stress sensor in the anchoring section and the data of the grating strain sensor 17 in the measuring section are synchronously collected, and the prestress loss rate is calculated by the host 8:

[0109]

[0110] Midpoint strain:

[0111] Traditional loss rate:

[0112] Formula Correction: Strain Difference (approaching 0), slip , no curvature correction is required.

[0113] Based on the calculated data and comparing the bending data with the straight line data, the influence of the reinforcement diameter on the prestress loss rate, the influence of the reinforcement bending curvature on the prestress loss rate, and the influence of the concrete strength on the prestress loss rate are decoupled, and an analysis report is obtained.

[0114] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A PCCP prestress loss test method, characterized in that: The following steps are involved: S1: Determine the equivalent bending curvature radius based on the target pipe diameter, select a test section bending baffle that matches the equivalent bending curvature radius, pour concrete with the same strength as the target pipe core concrete at the test section bending baffle based on the equivalent bending curvature radius, and cure until the test reaches the preset strength to obtain a concrete contact formwork with curvature; S2: Pass the anchorage section of the test reinforcement through the anchorage section baffle and tighten the nut. Place a stress sensor between the nut and the anchorage section baffle to monitor the stress changes of the test reinforcement in real time. S3: bend the measuring section of the test reinforcement along the curvature of the concrete contact formwork and attach it to the contact interface of the concrete contact formwork; S4: The tensioning section of the test reinforcement passes through the tensioning section baffle and applies a preset initial tensioning stress. After reaching the preset value, tighten the nut, remove the temporary loading device and let it stand for a preset time to eliminate residual stress. S5: Attach grating strain sensors to the maximum bending moment point and inflection point of the measuring section of the test reinforcement. After the load is stabilized for a specified time, synchronously collect data from the stress sensor in the anchoring section and the grating strain sensor in the measuring section, and calculate the prestress loss rate through the host computer. The independent control of the bending radius and concrete strength of S1 and the stress stabilization process of S4 are used to calculate and analyze the collected data, achieving decoupling analysis of the following parameters: The influence of reinforcement diameter on prestress loss rate; The influence of reinforcement bending curvature on prestress loss rate; Effect of concrete strength on prestress loss rate.

2. A PCCP prestress loss testing method according to claim 1, characterized in that: In said S5, one end of the measuring section of the test reinforcement material close to the tensioning section is taken as the starting point, the maximum bending moment point is the midpoint of the measuring section of the test reinforcement material, and the inflection point is the position at one quarter of the measuring section of the test reinforcement material.

3. A PCCP prestress loss testing method according to claim 2, characterized in that: Grating strain sensors are pasted on the top and outer sides of the maximum bending moment point and the inflection point.

4. A PCCP prestress loss testing method according to claim 3, characterized in that: The prestress loss rate in S5 The calculation formula is: ； in, is the slip at the reinforcement-concrete interface, =80-120GPa / mm is the slip influence coefficient, To preset the initial tensile stress, is the elastic modulus of the reinforcement, is the cross-sectional area of ​​the reinforcement, are the coordinates of the point with maximum bending moment.

5. A PCCP prestress loss testing method according to claim 1, characterized in that: The curvature radius of the curved baffle in the test section S1 satisfy: ; in, The target diameter is 2200mm≤ ≤4000mm, is the pipe wall thickness compensation coefficient, and the range of the pipe wall thickness compensation coefficient is 50mm≤ ≤100mm.

6. A PCCP prestress loss testing method according to claim 5, characterized in that: The diameter of the tested reinforcement in S1 ranges from 5 to 9 mm, and the concrete strength ranges from C30 to C60.

7. A PCCP prestress loss testing method according to claim 4, characterized in that: The standing time in S4 satisfy: ; in, is the stress relaxation factor, and its value range is .

8. A PCCP prestress loss testing device, according to a PCCP prestress loss testing method according to any one of claims 1-7, characterized in that: include: The base plate, anchoring section baffle and tensioning section baffle are all independently arranged; Multiple test section curved baffles, each of which is welded to a base plate with different preset curvatures, are used to simulate the entire prototype pipe to be tested in proportion through a detachable modular structure, so as to truly simulate the actual working state of the PCCP; The transverse reinforcement ribs are evenly distributed on the top of the bending baffle of the test section along the bending path of the bending baffle of the test section to ensure the integrity of the device and prevent the test reinforcement from being broken.

9. The PCCP prestress loss testing device according to claim 8, characterized in that: Triangular diagonal braces are provided on the nut side surface of the anchoring section baffle and the curved inner surface of the testing section curved baffle.

10. The PCCP prestress loss testing device according to claim 9, characterized in that: A detachable hollow jack is provided on one side of the tensioning section baffle, and the hollow jack is used to apply a preset initial tensioning stress to the test reinforcement.

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