A method for using a test device for simulating ion erosion of the PCCP protective layer

Abstract

A method for using a test device for simulating ion erosion of a PCCP protective layer, comprising the following steps: S1 Divide regions: Select a test object. First, divide the test object into 4 partitions, namely partition I, partition II, partition III, and partition IV; then divide each partition into 3 test regions, namely test region A, test region B, and test region C; S2 Develop a test plan: In partition I, conduct a sulfate ion erosion comparison, in partition II, conduct a chloride ion erosion comparison, in partition III, conduct a protective measure comparison, and in partition IV, conduct a mixed comparison test; S3 Develop a comparison plan; S4 Develop a wet-dry cycling plan; S5 Configure test conditions; S6 Perform liquid filling; S7 Perform wet-dry cycling; S8 Determine whether to end the wet-dry cycling: If Seq = L, the wet-dry cycling should be ended, so continue with S9; otherwise, it means that not all wet-dry cycling treatments have been completed, so return to S6; S9 Extract samples; S10 Analyze the results.

Description

Technical Field

[0001] The present disclosure relates to the field of ion erosion experiments in construction engineering, and particularly to a method for using a test device for simulating ion erosion of a PCCP protective layer under the influence of multiple factors under load action. Background Art

[0002] In northwest China, there is a large area of saline soil. Structural cracking, pulverization, steel bar corrosion, and local erosion caused by the erosion of corrosive salts such as sulfates and chlorides are likely to pose potential safety hazards to engineering buildings. Prestressed Concrete Cylinder Pipe (PCCP) refers to a water conveyance pipe made by winding circumferential prestressed steel wires on a high-strength concrete pipe core with a steel cylinder and then spraying a dense cement mortar protective layer on it. In northwest China, there are problems of unbalanced water resource distribution, and the natural water resources in some areas are difficult to meet the industrial water demand. A large number of long-distance water conveyance pipeline projects are needed for water resource allocation. Along with saline soil erosion, groundwater accumulation, and developed irrigation agriculture, the soil salinity of the strata where buried pipelines are located is complex and variable. For example, different values of PH, Cl - and SO4 2- may all cause PCCP corrosion or even burst.

[0003] Currently, the research on ion erosion of PCCP mainly adopts a simplified method, that is, an ordinary immersion test without load action, and the influence of load has not been considered. The ion erosion of the PCCP protective layer is the result of the combined action of materials, load, and environment. In the process of pipe making, the roller spraying process of the PCCP mortar protective layer, the relaxation of steel wires during curing, the creep and shrinkage of concrete, and the load borne by the pipe body during operation will all cause physical and loaded state changes in the mortar protective layer, affecting the ion erosion process.

[0004] To meet the engineering needs, improving the durability test method of PCCP is an inevitable process to solve the durability problem. It is particularly necessary to design a method for simulating the ion erosion of the PCCP protective layer under the action of equivalent internal pressure. Summary of the Invention

[0005] In view of the above technical problems in the related art, the present disclosure provides a method for using a test device for simulating ion erosion of a PCCP protective layer, which overcomes the above-mentioned deficiencies of the prior art through a method for using a test device for simulating ion erosion of a PCCP protective layer.

[0006] To achieve the above technical purpose, the technical solution of the present disclosure is realized as follows:

[0007] A method for using a test device for simulating ion erosion of a PCCP protective layer includes the following steps:

[0008] S1 Division of regions: Select the test object for simulating the PCCP protective layer. First, divide the test object into 4 partitions, namely Partition I, Partition II, Partition III, and Partition IV. Then, divide each partition into 3 test areas, namely Test Area A, Test Area B, and Test Area C.

[0009] S2 Formulation of test plan: In Partition I, conduct a comparison of sulfate ion erosion at different concentrations; in Partition II, conduct a comparison of chloride ion erosion at different concentrations; in Partition III, conduct a comparison of different protection measures; in Partition IV, conduct a mixed comparison test.

[0010] S3 Formulation of comparison scheme:

[0011] For Test Area A, Test Area B, and Test Area C in Partition I, configure 1% concentration Na2SO4 solution, 3% concentration Na2SO4 solution, and 5% concentration Na2SO4 solution respectively.

[0012] For Test Area A, Test Area B, and Test Area C in Partition II, configure 1% concentration NaCl solution, 3% concentration NaCl solution, and 5% concentration NaCl solution respectively.

[0013] For Test Area A, Test Area B, and Test Area C in Partition III, first configure 5% concentration NaCl solution respectively, and then apply protective coatings one, two, and three respectively and plan to conduct wet-dry cycling treatment.

[0014] For Test Area A, Test Area B, and Test Area C in Partition IV, configure 5% concentration NaCl solution, 5% concentration Na2SO4 solution, and a mixed solution of 5% concentration NaCl and 5% concentration Na2SO4 respectively. Test Area A and Test Area B are respectively planned to conduct wet-dry cycling treatment.

[0015] S4 Formulation of wet-dry cycling scheme: Each test area planned to conduct wet-dry cycling treatment is regarded as a separate area to be wet-dry cycled. Define the upper limit value of the wet-dry cycling treatment as L times, and define the number of times of the current wet-dry cycling treatment as Seq, and initialize Seq to 0----that is, the 3 test areas A, B, and C in Partition III, and Test Area A and Test Area B in Partition IV are respectively regarded as a said area to be wet-dry cycled, and each needs to conduct L times of wet-dry cycling, and Seq represents the cumulative number of times of wet-dry cycling treatment that has been carried out.

[0016] S5 Provision of test conditions: Finally, equip each test area with a corresponding test device. The test device includes a solution erosion container, and the solution erosion container is closely attached to one side of the corresponding test area, and the other side of the test area is immersed in water.

[0017] S6 Perform liquid filling: Use the solution configured for each test area to fill the solution erosion container of its corresponding test device until it is full and remains full;

[0018] S7 Perform wet-dry cycling: For all areas to be wet-dry cycled, soak for N days and dry for M days respectively. Specifically, for the test device corresponding to each area to be wet-dry cycled, first make the solution erosion container be filled with the corresponding solution and remain for N days - that is, the soaking operation; then drain the solution in the solution erosion container, dry the area to be wet-dry cycled and the test device and maintain the dry state for M days - that is, the drying operation; finally, increment Seq by 1 and record the wet-dry operation of this cycle.

[0019] S8 Determine whether to end the wet-dry cycling: If Seq = L, it means that the cumulative number of wet-dry cycles has reached the upper limit of the cycle, and the wet-dry cycling should be ended, so continue with S9; otherwise, it means that not all wet-dry cycle treatments have been completed, so return to S6;

[0020] S9 Extract samples: After waiting for time T, select several of the said test areas, and then extract several core samples; S10 Result analysis: Process all core samples into slices respectively; grind the slices of each core sample, measure the chloride ion concentration by titration method, measure the sulfate ion concentration by weighing method, draw the curve of the concentration of ions invading the core sample varying with depth, and compare the test results of different partitions.

[0021] Optionally, the slice thickness depends on actual needs and is preferably 3 mm.

[0022] Optionally, in S7, N = 2 and M = 1, which means that for each wet-dry cycle treatment, it is necessary to soak for 2 days and dry for 1 day respectively.

[0023] Optionally, in S5 or S8, L = 10, which means that the number of wet-dry cycle treatments should be cycled 10 times.

[0024] Optionally, in S9, T is 10 days, which means that after the wet-dry cycle treatment, continue to wait for 10 days before sampling.

[0025] Optionally, the specific structure of the test device can be implemented by existing technologies, or preferably: the solution erosion container can be provided with a container inner cavity, the container inner cavity is connected downward to a solution placement barrel and upward to a liquid level display barrel, and a liquid extraction hose is connected between the inside of the liquid level display barrel and the inside of the solution placement barrel;

[0026] Optionally, several transparent windows are provided on the front side of the solution erosion container, and the back side of the solution erosion container is closely attached to the corresponding test area. Preferably, 3 transparent windows are provided on the front side of the solution erosion container.

[0027] Preferably, a water pump is connected to the lower end of the liquid extraction hose inside the solution placement barrel, and a blower is further connected to the inner cavity of the container to participate in the drying work of the wet and dry cycle.

[0028] Preferably, in S6, for the liquid filling operation of each test area, the following steps are performed on the corresponding test device:

[0029] S6.1: Turn on the water pump to extract the solution configured in the solution placement barrel. The configured solution flows from bottom to top through the liquid extraction hose into the liquid level display barrel and then into the solution erosion container.

[0030] S6.2: Observe through the liquid level display barrel whether the solution erosion container is full.

[0031] S6.3: If the solution erosion container is full, turn off the water pump; otherwise, return to S6.1.

[0032] Preferably, the test object depends on actual needs and can be the PCCP pipe body 13.

[0033] Preferably, Zone I, Zone II, Zone III, and Zone IV are all demarcated on the PCCP pipe body. The circumferential surface of the PCCP pipe body is demarcated from bottom to top as Zone I, Zone II, Zone III, and Zone IV respectively. Each zone is divided into three test areas, and each test area is provided with a corresponding test device.

[0034] Therefore, all test devices are arranged on the circumferential surface of the PCCP pipe body. One side of all test areas is located on the outer side wall of the PCCP pipe body and the other side is located on the inner side wall of the PCCP pipe body; and because the solution erosion container is closely attached to one side of the corresponding test area, the solution erosion container is realized to be closely attached to the outer side wall of the PCCP pipe body. During implementation, the solution erosion container is closely attached to one side of the corresponding test area, and water is injected into the PCCP pipe body, so the other side of the test area is wetted by the water body.

[0035] Preferably, the sampling method in S9 depends on needs and can be: select several test areas, remove the transparent windows of the corresponding test devices, and extract several core samples from the PCCP pipe body with a water drill. Subsequently, the drilled holes can be blocked and the transparent windows can be reinstalled, so as to be convenient for repeated use to execute other test schemes.

[0036] Preferably, the PCCP pipe body is sleeved outside the steel inner liner. A base is provided at the bottom of the steel inner liner. The bottom of the PCCP pipe body is closely attached to the top of the base. The space enclosed between the inner side wall of the PCCP pipe body and the outer side wall of the steel inner liner forms the inner cavity of the pipe body; by injecting water into the inner cavity of the pipe body, water is injected into the PCCP pipe body.

[0037] Preferably, a layered scaffold is erected around the PCCP pipe body, and the PCCP pipe body is subdivided into Zone I, Zone II, Zone III, and Zone IV by the scaffold.

[0038] Preferably, a PCCP pipe exhaust port is connected to the top of the PCCP pipe body, and an internal pressure loading machine is connected to the bottom of the PCCP pipe body through a water conduit, and water is injected into the inner cavity of the pipe through the internal pressure loading machine.

[0039] Preferably, the water conduit is provided with an internal water pressure gauge, and the internal water pressure gauge continuously monitors the water pressure inside the water conduit.

[0040] Preferably, in each test device, at least one air inlet is provided at the top of the inner cavity of the container, and the blower can be connected to the inner cavity of the container through a tee connection pipe or at least one conduit through the corresponding air inlet.

[0041] Preferably, the transparent window is made of a transparent PC board; the solution erosion container adopts an anti-rust outer shell; hoops for fixing it on the circumferential surface of the PCCP pipe body are respectively provided on the upper and lower sides of the solution erosion container.

[0042] Preferably, a rain-proof pressing plate is provided at the top of the liquid level display barrel, and an exhaust port is provided on the rain-proof pressing plate, and the exhaust port is communicated with the inside of the liquid level display barrel.

[0043] Preferably, at least one air inlet is provided at the top of the inner cavity of the container, and the blower can be connected to the inner cavity of the container through a tee connection pipe or at least one conduit through the corresponding air inlet.

[0044] Preferably, a liquid discharge port is provided at the bottom of the inner cavity of the container, and the liquid discharge port is communicated with the solution placement barrel; a liquid inlet is provided at the top of the inner cavity of the container, and the liquid inlet is communicated with the liquid level display barrel.

[0045] Preferably, the PCCP pipe body can be connected to the outside through a connecting flange. The specific method can be: a connecting flange is respectively provided at the top and bottom of the PCCP pipe body, a flange water injection port and a flange exhaust port are provided on the connecting flange, the flange water injection port and the flange exhaust port are respectively communicated with the inner cavity of the pipe, the flange exhaust port located at the top can be connected to the PCCP pipe exhaust port, and the flange water injection port located at the bottom is communicated with the water conduit, so as to realize the injection of water into the inner cavity of the pipe or the discharge of air through the connecting flange. The connecting flange belongs to the prior art. During implementation, the internal pressure loading machine drives water to flow through the water conduit, and then injects water into the inner cavity of the pipe through the flange water injection port, and discharges the air in the inner cavity of the pipe through the flange exhaust port.

[0046] Advantages of the present disclosure: Compared with the prior art, the present disclosure solves the process simulation of ion erosion of the PCCP protective layer under the actual loading state and explores the key factors affecting the erosion effect.

[0047] The present disclosure divides the PCCP pipe body into several partitions, each partition is further divided into several test areas, and each area is an independent test unit equipped with an independent test device. Therefore, there will be no cross - situation of any test solution between different test units, thus ensuring the accuracy of the test results and avoiding the test result error problem caused by the inter - mixing of test solutions due to the need to design multiple test pools in the prior art. Through the cooperation of components such as an internal pressure loader, the present disclosure can achieve artificial or automatic control of the simulated load value, thereby simulating different test conditions or environments in various regions, and further expanding the scope of application of the present disclosure.

[0048] With the in - depth development of water diversion and drainage projects in the high - salinity and complex environment of the northwest, in the face of the need for modern high - quality water conservancy infrastructure construction, the research on the law of ion erosion under real load levels can provide guarantee for the safe operation of long - distance water conveyance pipelines and strong support for the construction of the national water network. The device - level supporting tests have great theoretical and practical significance for the durability design and evaluation of PCCP in high - salinity areas, which can promote the technological improvement of the PCCP industry and help its popularization in complex erosion environments.

[0049] The present disclosure avoids the problem of low load levels caused by the brittleness and discreteness of concrete in ion erosion tests under general loads, reflects the high tensile strain characteristics of the PCCP protective layer, realizes the research on ion erosion characteristics under long - term real loads and multi - factor influences, and more accurately reveals the time - varying law of ion erosion of PCCP protection. Taking the unloaded immersion test as a control group, with the help of the PCCP internal pressure loading equipment, a multi - partition independent ion erosion device is designed on the surface of the protective layer, which can consider loads, single chloride / sulfate ion erosion, coupled ion erosion, ion concentration, wet - dry cycles, and surface protection measures, and carry out prototype test research on ion erosion under long - term high internal pressure. Brief Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0051] Figure 1 It is a schematic structural diagram of the test device for simulating ion erosion of the PCCP protective layer described in the present disclosure.

[0052] Figure 2 It is a schematic structural diagram of the preferred test device of the present disclosure.

[0053] Figure 3It is the front view of the solution erosion container used by the test device described in the present disclosure.

[0054] Figure 4 It is the perspective view of the solution erosion container used by the test device described in the present disclosure.

[0055] Figure 5 It is the bottom view cross-sectional view of the cooperation between the test device and the PCCP pipe body when the test object uses the PCCP pipe body.

[0056] Figure 6 It is the front view cross-sectional view of the cooperation between the test device and the PCCP pipe body when the test object uses the PCCP pipe body.

[0057] Figure 7 It is the three-dimensional structure schematic diagram of the PCCP pipe body, internal pressure loading machine, water guide pipe, internal pressure loading machine, and connecting flange (removing the test device, scaffolding, etc.) when the test object uses the PCCP pipe body.

[0058] In the figure: 1. Solution placement bucket; 2. Hoop; 3. Liquid outlet; 4. Vertical sealing strip; 5. Solution erosion container; 501. Transparent window; 6. Three-way connecting pipe; 7. Blower; 8. Exhaust port; 9. Rainproof pressing plate; 10. Liquid level display bucket; 11. Liquid extraction hose; 12. Liquid extraction pump; 13. PCCP pipe body; 14. PCCP pipe exhaust port; 15. Scaffolding; 16. Internal pressure loading machine; 1601. Top opening of the internal pressure loading machine; 17. Water pressure gauge; 18. Water guide pipe; 19. Connecting flange; 1901. Flange water injection port; 1902. Flange exhaust port; 20. Steel inner tank; 2001. Base. Specific embodiments

[0059] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0060] As Figures 1-7 shown, in order to facilitate the understanding of the above technical solutions of the present disclosure, the above technical solutions of the present disclosure will be described in detail below in terms of specific usage methods.

[0061] The method for using the simulated ion erosion of the PCCP protective layer includes the following steps:

[0062] S1 Division of regions: Select a test object for simulating the PCCP protective layer. First, divide the test object into 4 partitions, namely Partition I, Partition II, Partition III, and Partition IV. Then, divide each partition into 3 test areas, namely Test Area A, Test Area B, and Test Area C.

[0063] S2 Formulation of test plan: In Partition I, conduct a comparison of sulfate ion erosion at different concentrations; in Partition II, conduct a comparison of chloride ion erosion at different concentrations; in Partition III, conduct a comparison of different protection measures; in Partition IV, conduct a mixed comparison test.

[0064] S3 Formulation of comparison scheme:

[0065] For Test Area A, Test Area B, and Test Area C in Partition I, configure 1% concentration Na2SO4 solution, 3% concentration Na2SO4 solution, and 5% concentration Na2SO4 solution respectively.

[0066] For Test Area A, Test Area B, and Test Area C in Partition II, configure 1% concentration NaCl solution, 3% concentration NaCl solution, and 5% concentration NaCl solution respectively.

[0067] For Test Area A, Test Area B, and Test Area C in Partition III, first configure 5% concentration NaCl solution respectively, and then apply protective coatings I, II, and III respectively and plan to conduct wet-dry cycling treatment.

[0068] For Test Area A, Test Area B, and Test Area C in Partition IV, configure 5% concentration NaCl solution, 5% concentration Na2SO4 solution, and a mixed solution of 5% concentration NaCl and 5% concentration Na2SO4 respectively. Test Area A and Test Area B are planned to conduct wet-dry cycling treatment respectively.

[0069] S4 Formulation of wet-dry cycling scheme: Each test area planned to conduct wet-dry cycling treatment is regarded as a separate area to be wet-dry cycled. Define the upper limit value of the wet-dry cycling treatment as L times, and define the number of times of the current wet-dry cycling treatment as Seq, and initialize Seq to 0. That is, the 3 test areas A, B, and C in Partition III, and Test Area A and Test Area B in Partition IV are regarded as one such area to be wet-dry cycled respectively, and each needs to conduct L times of wet-dry cycling, and Seq represents the cumulative number of times of wet-dry cycling treatment that has been carried out.

[0070] S5 Provision of test conditions: Finally, equip each test area with a corresponding test device. The test device includes a solution erosion container 5, and the solution erosion container 5 is closely attached to one side of the corresponding test area, and the other side of the test area is immersed in water.

[0071] S6 Perform liquid filling: Use the solution configured for each test area to fill the solution erosion container 5 of its corresponding test device until it is full and remains full;

[0072] S7 Perform wet-dry cycling: For all areas to be wet-dry cycled, soak for N days and dry for M days respectively. Specifically, for the test device corresponding to each area to be wet-dry cycled, first make the solution erosion container 5 filled with the corresponding solution and keep it for N days - that is, the soaking operation; then drain the solution in the solution erosion container 5, dry the area to be wet-dry cycled and the test device and maintain the dry state for M days - that is, the drying operation; finally, increment Seq by 1 and record the wet-dry operation of this cycle.

[0073] S8 Determine whether to end the wet-dry cycling: If Seq = L, it means that the cumulative number of wet-dry cycles has reached the upper limit of the cycle, and the wet-dry cycling should be ended, so continue with S9; otherwise, it means that not all wet-dry cycle processes have been completed, so return to S6;

[0074] S9 Extract samples: After waiting for time T, select several of the said test areas, and then extract several core samples; S10 Result analysis: Process all core samples into slices respectively; Grind the slices of each core sample, measure the chloride ion concentration by titration method, measure the sulfate ion concentration by weighing method, draw the curve of the concentration of ions invading the core sample changing with depth, and compare the test results of different partitions.

[0075] In a certain embodiment, the slice thickness depends on actual needs and is preferably 3 mm.

[0076] In a certain embodiment, in S7, N = 2 and M = 1, which means that for each wet-dry cycle process, it is necessary to soak for 2 days and dry for 1 day respectively.

[0077] In a certain embodiment, in S5 or S8, L = 10, which means that the number of wet-dry cycle processes should be cycled 10 times.

[0078] In a certain embodiment, in S9, T is 10 days, which means that after the wet-dry cycle process, continue to wait for 10 days before sampling.

[0079] In a certain embodiment, the specific structure of the test device can be implemented by the prior art, or preferably: the solution erosion container 5 can be provided with a container inner cavity, the container inner cavity is connected to a solution placement barrel 1 downward and to a liquid level display barrel 10 upward, and a liquid extraction hose 11 is connected between the inside of the liquid level display barrel 10 and the inside of the solution placement barrel 1.

[0080] In a certain embodiment, several transparent windows 501 are provided on the front side of the solution erosion container 5, and the rear side of the solution erosion container 5 is closely attached to the corresponding test area. Preferably, 3 transparent windows 501 are provided on the front side of the solution erosion container 5.

[0081] In a certain embodiment, a water pump 12 is connected to the lower end of the liquid extraction hose 11 inside the solution placement barrel 1, and a blower 7 is further connected to the inner cavity of the container. The blower 7 participates in the drying work of the dry-wet cycle.

[0082] In a certain embodiment, in S6, for the liquid filling operation of each test area, the following steps are performed on the corresponding test device:

[0083] S6.1: Turn on the water pump 12 to extract the solution configured in the solution placement barrel 1. The configured solution flows from bottom to top through the liquid extraction hose 11 into the liquid level display barrel 10 and then into the solution erosion container 5.

[0084] S6.2: Observe through the liquid level display barrel 10 whether the solution erosion container 5 is full.

[0085] S6.3: If the solution erosion container 5 is full, turn off the water pump 12; otherwise, return to S6.1.

[0086] In a certain embodiment, the test object depends on actual needs and can be the PCCP pipe body 13.

[0087] In a certain embodiment, the partition I, partition II, partition III, and partition IV are all divided on the PCCP pipe body 13. The circumferential surface of the PCCP pipe body 13 is divided into partition I, partition II, partition III, and partition IV from bottom to top respectively. Each partition is divided into three test areas, and each test area is respectively provided with a corresponding test device.

[0088] Therefore, all the test devices are arranged on the circumferential surface of the PCCP pipe body 13. One side of all the test areas is located on the outer wall of the PCCP pipe body 13 and the other side is located on the inner wall of the PCCP pipe body 13. Since the solution erosion container 5 is close to one side of the corresponding test area, the solution erosion container 5 is close to the outer wall of the PCCP pipe body 13.

[0089] During implementation, the solution erosion container 5 is close to one side of the corresponding test area, and water is injected into the PCCP pipe body 13. Therefore, the other side of the test area is wetted by water. The rear side of the solution erosion container 5 actually serves as one side close to the test area or the subsequent outer wall of the PCCP pipe body 13.

[0090] In a certain embodiment, the sampling method in S9 depends on needs and can be: select several test areas, remove the transparent window 501 of the corresponding test device, and extract several core samples from the PCCP pipe body 13 with a water drill. Subsequently, the drilled holes can be blocked and the transparent window 501 can be installed again, so as to be conveniently reused for implementing other test schemes.

[0091] In a certain embodiment, the PCCP pipe body 13 is sleeved outside the steel inner liner 20. A base 2001 is provided at the bottom of the steel inner liner 20. The bottom of the PCCP pipe body 13 is closely attached to the top of the base 2001. The space enclosed between the inner side wall of the PCCP pipe body 13 and the outer side wall of the steel inner liner 20 forms the inner cavity of the pipe. By injecting water into the inner cavity of the pipe, the PCCP pipe body 13 is filled with water.

[0092] In a certain embodiment, a layered scaffold 15 is erected around the PCCP pipe body 13. The PCCP pipe body 13 is subdivided into Zone I, Zone II, Zone III, and Zone IV by the scaffold 15.

[0093] In a certain embodiment, a PCCP pipe exhaust port 14 is connected to the top of the PCCP pipe body 13. The bottom of the PCCP pipe body 13 is connected to an internal pressure loading machine 16 through a water conduit 18. Water is injected into the inner cavity of the pipe through the internal pressure loading machine 16.

[0094] In a certain embodiment, a water pressure gauge 17 is provided on the water conduit 18. The water pressure gauge 17 continuously monitors the water pressure inside the water conduit 18.

[0095] In a certain embodiment, in each test device, at least one or more air inlets are provided at the top of the inner cavity of the container. The blower 7 can be connected to the inner cavity of the container through a three-way connecting pipe 6 or at least one or more conduits through the corresponding air inlets.

[0096] In a certain embodiment, the transparent window 501 is made of a transparent PC board; the solution erosion container 5 adopts an anti-rust outer shell; hoops 2 for fixing it on the circumferential surface of the PCCP pipe body 13 are respectively provided on the upper and lower sides of the solution erosion container 5.

[0097] In a certain embodiment, a rain-proof pressing plate 9 is provided at the top of the liquid level display barrel 10. An exhaust port 8 is provided on the rain-proof pressing plate 9, and the exhaust port 8 is communicated with the inside of the liquid level display barrel 10.

[0098] In a certain embodiment, at least one or more air inlets are provided at the top of the inner cavity of the container. The blower 7 can be connected to the inner cavity of the container through a three-way connecting pipe 6 or at least one or more conduits through the corresponding air inlets.

[0099] In a certain embodiment, a liquid discharge port 3 is provided at the bottom of the inner cavity of the container. The liquid discharge port 3 is communicated with the solution placement barrel 1; an inlet port is provided at the top of the inner cavity of the container, and the inlet port is communicated with the liquid level display barrel 10.

[0100] In a certain embodiment, the PCCP pipe body 13 can be connected to the outside through a connecting flange 19. The specific method can be as follows: A connecting flange 19 is provided at the top and bottom of the PCCP pipe body 13 respectively. A flange water injection port 1901 and a flange exhaust port 1902 are provided on the connecting flange 19. The flange water injection port 1901 and the flange exhaust port 1902 are respectively communicated with the inner cavity of the pipe. The flange exhaust port 1902 located at the top can be communicated with the PCCP pipe exhaust port 14, and the flange water injection port 1901 located at the bottom is communicated with the water guide pipe 18, so as to realize the injection of water into the inner cavity of the pipe or the discharge of air through the connecting flange 19. The connecting flange 19 belongs to the prior art. During implementation, the internal pressure loading machine 16 drives water to flow through the water guide pipe 18, and then injects water into the inner cavity of the pipe through the flange water injection port 1901, and discharges the air in the inner cavity of the pipe through the flange exhaust port 1902.

[0101] For example: If the PCCP pipe body 13 is used as the test object, the test device for simulating the ion erosion of the prestressed concrete cylinder pipe (PCCP) protective layer under load acts through the internal pressure loading machine 16, the PCCP pipe body 13, several solution erosion containers 5 and other cooperative components. The PCCP pipe body 13 acts as the simulated PCCP protective layer, and the solution erosion container 5 acts as the container for containing the erosive solution for testing. The rear side of the solution erosion container 5 is closely attached to the circumferential surface of the PCCP pipe body 13 (simulating the PCCP protective layer). Several transparent windows 501 are provided on the solution erosion container 5; the inner cavity of the solution erosion container 5 can be connected downward to the solution placement bucket 1 and upward to the liquid level display bucket 10 or the blower 7; a water pump is installed in the solution placement bucket, and the pump body is connected to the liquid level display bucket 10 through a flexible hose; the solution erosion container 5 can realize the dry-wet cycle of the PCCP pipe body 13 (simulating the PCCP protective layer) with the help of the water pump 12 and the blower 7; the solution erosion container 5 can also realize remote page monitoring with the help of a camera. Compared with the prior art, this test device can simulate the process of ion erosion of the protective layer of PCCP in the real loaded state, reduces the infrastructure cost and the consumption of erosion solution, and solves the problem of mutual penetration of different erosion solutions, and can comprehensively consider the influence of various factors such as solution type and concentration, coating type and thickness, long-term immersion, dry-wet cycle and cathodic protection on the durability of PCCP. Among them, the PCCP pipe body 13 represents the prestressed concrete cylinder pipe, abbreviated as PCCP, and the full English name is - Prestressed Concrete Cylinder Pipe.

[0102] Working principle of the disclosed method: During the implementation of the usage method of the test device for simulating ion erosion of the PCCP protective layer, an internal water pressure can be applied to the inner wall of the PCCP pipe body 13 through a pressurizing device such as an internal pressure loader, so the actual load-bearing state of the PCCP protective layer can be simulated. The PCCP pipe body 13 is divided into N partitions by a scaffolding, and each partition is further divided into M test partitions by the M solution erosion containers 5 arranged thereon. Each test partition can be configured with an independent test solution or coated with a specific protective coating or subjected to wet-dry treatment, etc. Preferably, N = 4 and M = 3, that is, there are a total of 4 partitions, and each partition is provided with 3 solution erosion containers 5 and correspondingly divided into 3 test areas (A, B, C), that is, each solution erosion container 5 or the test device corresponds to an independent test partition, and the test partitions A, B, and C in each partition can be independently eroded or compared, etc. Of course, as tested by the above usage method, for different test partitions in the same partition, it is undoubtedly most suitable to conduct the same-column test, so that different ion test solutions with different concentrations can be tested, and the test can also be carried out for the case of whether there is a protective coating or whether wet-dry treatment has been done, so as to compare different test results and assist subsequent analysis work. The multi-region independent erosion device for the PCCP protective layer can utilize 1 PCCP pipe body to realize the analysis of the multi-factor influence of ion erosion.

[0103] In the usage method described in the present disclosure, the comparison scheme formulated in S3 is shown in Table 1 below:

[0104]

[0105] Table 1 - Comparison scheme for multi-factor erosion

[0106] Theoretical principle of the present disclosure: Based on the assumption of a rigid curve cantilever beam, establish the relationship between the distributed load of the PCCP pipe body 13 and the internal force of the pipe wall section, and obtain the bending moment and axial force coefficients under the test operation combined load. Based on the plane section assumption, calculate the internal force of the pipe wall section of the PCCP pipe body 13, construct the bending moment and axial force balance equations and the Newton iteration format, and obtain the maximum circumferential strain of the PCCP protective layer simulated under the action of the operation combined load. According to the thick-walled cylinder theory under plane strain problems, combined with the boundary conditions and displacement coordination conditions, obtain the equivalent relationship between the test internal pressure load and the circumferential strain of the protective layer, and form the equivalent conversion of the test internal pressure and the operation combined load.

[0107] Taking the unloaded immersion test as the control group, with the help of the PCCP pipe body 13 and the internal pressure loading machine 16, a multi-zone independent test device is designed on the surface of the protective layer simulated by the PCCP pipe body. As shown in Table 1, considering load, single chloride / sulfate ion erosion, coupled ion erosion, ion concentration, wet-dry cycle and surface protection measures, different zones are divided, and different test areas are divided by the test device within the zones to carry out prototype test research on ion erosion and the like under long-term high internal pressure. After the test is carried out, at a specific time, the depth and concentration of ion erosion of the protective layer are measured to explore the time-varying law of ion erosion of the protective layer.

[0108] Based on the unsteady-state diffusion theory, a time-varying model considering ion diffusion under long-term high working pressure is proposed. The undetermined coefficients of the partial differential equation are fitted and the surface ion concentration and ion diffusion coefficient are obtained. Exponential functions and power functions are constructed to reflect the time-varying laws of the surface ion concentration and ion diffusion coefficient, forming a time-varying model of ion diffusion. On the basis of the research on the single-ion erosion law in the saturated state, combined with the analysis of the data of the unloaded immersion test, the effects of load, ion type (single and coupled), ion concentration, wet-dry cycle and surface protection measures on the time-varying laws of the surface ion concentration and ion diffusion coefficient are explored. Finally, a unified time-varying law characterization function is formed according to the results obtained by the above-mentioned usage method.

[0109] In summary, through the unique design of the present disclosure, the present disclosure avoids the problem of low load level caused by the brittleness and discreteness of concrete in the ion erosion test under general load, reflects the high tensile strain characteristics of the PCCP protective layer, realizes the research on the ion erosion characteristics under long-term real load and multi-factor influence, and more accurately reveals the time-varying law of ion erosion of the PCCP protection. The present disclosure takes the unloaded immersion test as the control group, with the help of the PCCP internal pressure loading equipment, designs a multi-zone independent ion erosion device on the surface of the protective layer, and can consider load, single chloride / sulfate ion erosion, coupled ion erosion, ion concentration, wet-dry cycle and surface protection measures to carry out prototype test research on ion erosion under long-term high internal pressure.

[0110] The above are only the preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for using a test device for simulating ion erosion of a PCCP protective layer, characterized in that, The steps include: S1 Divide regions: Select a test object for simulating the PCCP protective layer. First, divide the test object into 4 partitions, namely Partition I, Partition II, Partition III, and Partition IV. Then, divide each partition into 3 test regions, namely Test Region A, Test Region B, and Test Region C. The test object is a PCCP pipe body (13). The PCCP pipe body (13) is sleeved outside a steel inner liner (20). A base (2001) is provided at the bottom of the steel inner liner (20). The bottom of the PCCP pipe body (13) is closely attached to the top of the base (2001). The space enclosed between the inner side wall of the PCCP pipe body (13) and the outer side wall of the steel inner liner (20) forms a pipe inner cavity. The bottom of the PCCP pipe body (13) is connected to an internal pressure loading machine (16) through a water conduit (18), and water is injected into the pipe inner cavity through the internal pressure loading machine (16). S2 Formulate a test plan: In Partition I, perform a comparison of sulfate ion erosion at different concentrations. In Partition II, perform a comparison of chloride ion erosion at different concentrations. In Partition III, perform a comparison of different protection measures. In Partition IV, perform a mixed comparison test. S3 Formulate a comparison scheme: For Test Region A, Test Region B, and Test Region C in Partition I, configure 1% concentration Na2SO4 solution, 3% concentration Na2SO4 solution, and 5% concentration Na2SO4 solution respectively. For Test Region A, Test Region B, and Test Region C in Partition II, configure 1% concentration NaCl solution, 3% concentration NaCl solution, and 5% concentration NaCl solution respectively. For Test Region A, Test Region B, and Test Region C in Partition III, first configure 5% concentration NaCl solution respectively, and then apply protective coatings I, II, and III respectively and plan to perform wet-dry cycling treatment. For Test Region A, Test Region B, and Test Region C in Partition IV, configure 5% concentration NaCl solution, 5% concentration Na2SO4 solution, and a mixed solution of 5% concentration NaCl and 5% concentration Na2SO4 respectively. Test Region A and Test Region B are respectively planned to perform wet-dry cycling treatment. S4 Formulate a wet-dry cycling scheme: Each test region planned to perform wet-dry cycling treatment is regarded as a separate region to be wet-dry cycled. Define the upper limit value of the wet-dry cycling treatment as L times, and define the number of times of the current wet-dry cycling treatment as Seq, and initialize Seq to 0----that is, the 3 test regions A, B, and C in Partition III, and Test Regions A and B in Partition IV are respectively regarded as a region to be wet-dry cycled, and each needs to perform L times of wet-dry cycling, and Seq represents the cumulative number of times of wet-dry cycling treatment that has been carried out. Test conditions for S5: Finally, for each of the test areas, a corresponding test device is equipped respectively; the test device includes a solution erosion container (5), the solution erosion container (5) is close to one side of the corresponding test area, and the other side of the test area is wetted by water body; S6 Perform liquid filling: Use the solution configured for each test area to fill the solution erosion container (5) of its corresponding test device until it is full and remains full; S7 Perform wet-dry cycle: For all the areas to be subjected to wet-dry cycle, wet for N days and dry for M days respectively. Specifically, for the test device corresponding to each area to be subjected to wet-dry cycle, first make the solution erosion container (5) be filled with the corresponding solution and keep it for N days - that is, the wetting operation; then drain the solution in the solution erosion container (5), dry the area to be subjected to wet-dry cycle and the test device and maintain the dry state for M days - that is, the drying operation; finally, Seq is incremented by 1, and the wet-dry operation of this cycle is recorded. S8 Determine whether to end the wet-dry cycle: If Seq = L, it means that the cumulative number of wet-dry cycles has reached the upper limit of the cycle, and the wet-dry cycle should be ended, so continue with S9; otherwise, it means that not all wet-dry cycle treatments have been completed, so return to S6; S9 Extract samples: After waiting for time T, select several of the test areas, and then extract several core samples; S10 Result analysis: Process all the core samples into slices respectively; grind the slices of each core sample, measure the chloride ion concentration by titration method, measure the sulfate ion concentration by weighing method, draw the curve of the concentration of ions invading the core sample changing with depth, and compare the test results of different partitions.

2. The usage method according to claim 1, characterized in that, The thickness of the slice is preferably 3 mm.

3. The usage method according to claim 1, characterized in that, In S7, N = 2 and M = 1, which means that for each wet-dry cycle treatment, it is necessary to wet for 2 days and dry for 1 day respectively.

4. The usage method according to claim 1, characterized in that, In S5 or S8, L = 10, which means that the wet-dry cycle treatment needs to be cycled 10 times.

5. The usage method according to claim 1, characterized in that, In S9, the T is 10 days, which means that after the wet-dry cycle treatment, wait for another 10 days before sampling.

6. The usage method according to claim 1, characterized in that The solution erosion container (5) is provided with a container inner cavity, the container inner cavity is connected to a solution placement bucket (1) downward and a liquid level display bucket (10) upward, and a liquid extraction hose (11) is connected between the inside of the liquid level display bucket (10) and the inside of the solution placement bucket (1); The front side of the solution erosion container (5) is provided with a plurality of transparent windows (501), and the rear side of the solution erosion container (5) is close to the corresponding test area; The lower end of the liquid extraction hose (11) located inside the solution placement bucket (1) is connected to a liquid extraction pump (12), and the container inner cavity is also connected to a blower (7), and the blower (7) participates in the drying work of the wet-dry cycle.

7. The usage method according to claim 6, characterized in that, In S6, for the liquid filling operation of each test area, the following steps are performed on its corresponding test device: S6.1: Turn on the water pump (12) to extract the solution configured in the solution storage barrel (1). The configured solution flows upward through the liquid extraction hose (11) into the liquid level display barrel (10) and then into the solution erosion container (5). S6.2: Observe through the liquid level display barrel (10) whether the solution erosion container (5) is full. S6.3: If the solution erosion container (5) is full, turn off the water pump (12); otherwise, return to S6.

1.

8. The usage method according to claim 6, wherein, The partition I, partition II, partition III, and partition IV are all demarcated on the PCCP pipe body (13). The circumferential surface of the PCCP pipe body (13) is demarcated into the partition I, partition II, partition III, and partition IV from bottom to top. Each partition is divided into three test areas, and each test area is respectively provided with a corresponding test device. Therefore, all the test devices are arranged on the circumferential surface of the PCCP pipe body (13). One side of all the test areas is located on the outer wall of the PCCP pipe body (13), and the other side is located on the inner wall of the PCCP pipe body (13). Since the solution erosion container (5) is closely attached to the corresponding test area, the solution erosion container (5) is actually closely attached to the outer wall of the PCCP pipe body (13). During implementation, the solution erosion container (5) is closely attached to one side of the corresponding test area, and water is injected into the PCCP pipe body (13), so that the other side of the test area is wetted by the water body.

9. The method of use according to claim 8, wherein A layered scaffold (15) is erected around the PCCP pipe body (13), and the PCCP pipe body (13) is subdivided into the partition I, partition II, partition III, and partition IV by the scaffold (15). By injecting water into the inner cavity of the pipe body, the PCCP pipe body (13) is filled with water.

10. The usage method according to claim 9, characterized in that, A PCCP pipe exhaust port (14) is connected to the top of the PCCP pipe body (13). The water guide pipe (18) is provided with an internal water pressure gauge (17), and the internal water pressure gauge (17) continuously monitors the water pressure inside the water guide pipe (18).

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