A simulation device and test method for chloride ion transport under circumferential water and soil pressure of PHC pipe piles

Abstract

The present invention discloses a simulation device for chloride ion transmission under circumferential water and soil pressure of PHC pipe piles, which includes a loading device and an environmental simulation test chamber. It is characterized in that: the environmental simulation test chamber consists of an oil source system and an environmental test chamber. The oil source system sets the pressure of the soil pressure cell in the test chamber according to the actual engineering situation, realizes closed-loop control of the soil pressure, and real-time displays the soil pressure value, the oil pressure of the oil cylinder, and the test time; the loading device includes an oil cylinder and a pressing plate, and the loading device is used to load the chloride-containing saline soil mixture in the environmental test chamber, as well as the acting force of the mixed soil mass on the pipe pile under the action of the load and the box body constraint force, to simulate the circumferential water and soil pressure borne by the PHC pipe pile in the actual chloride-containing salt service environment in the coastal area, and solve the test method for the transmission performance of chloride ions in the PHC pipe pile in the actual service environment; the structure is simple, the manufacturing cost is low, the operation is convenient, and it conforms to the actual situation.

Description

Technical Field

[0001] The present invention belongs to the technical field related to civil engineering, and particularly relates to a simulation device and test method for chloride ion transport under the action of circumferential water and soil pressure of PHC pipe piles. Background Technique

[0002] The durability of pile foundation structures is an important factor affecting the safety of upper concrete structures. Compared with above-ground building structures, PHC pipe piles in coastal areas or near the sea work in environments such as airtight and humid, permanently immersed, or wet-dry alternation; in these underground geotechnical environments, the durability of concrete pile foundations is affected by multiple factors such as geotechnical media, circumferential water and soil pressure on the pile side, and corrosion by erosive ions in groundwater, and their service environment is far more complex than that of above-ground structures. The investigation by the Ministry of Transport on the status of concrete structures in China's port projects shows that more than 80% of the pile foundation structures of wharves have suffered serious or relatively serious steel bar corrosion damage, and some have shown steel bar corrosion damage only after serving for 5 - 10 years;

[0003] Existing chloride ion transport test methods are basically steady-state and non-steady-state diffusion test methods carried out in laboratories, and their research conditions are far from the actual service environment conditions of pile foundations, and they cannot accurately clarify the chloride ion transport behavior and the durability deterioration mechanism of pipe piles during actual service.

[0004] Existing research has shown that the action of load has an inestimable influence on the transport behavior of chloride ions in concrete.

[0005] Therefore, how to simulate the service environment of PHC pipe piles actually bearing circumferential water and soil pressure and carry out research on the transport performance of chloride ions based on this is a key technical problem in the field of concrete durability research. Summary of the Invention

[0006] The purpose of the present invention is to provide a simulation device for chloride ion transport under the action of circumferential water and soil pressure of PHC pipe piles to solve the problem of evaluation and characterization of chloride ion transport performance under the actual service environment of PHC pipe piles proposed in the above background technique.

[0007] Another purpose of the present invention is to provide a test method using the above simulation device for chloride ion transport under the action of circumferential water and soil pressure of PHC pipe piles to simulate the circumferential water and soil pressure borne by PHC pipe piles in the actual chloride salt-containing service environment in coastal areas and solve the test method for the transport performance of chloride ions in PHC pipe piles in the actual service environment.

[0008] To achieve the above purposes, the present invention provides the following technical solutions:

[0009] A simulation device for chloride ion transport under circumferential water and soil pressure of PHC pipe piles, comprising a loading device and an environmental simulation test chamber. The environmental simulation test chamber consists of an oil source system and an environmental test chamber. The oil source system sets the pressure of the soil pressure cell in the test chamber according to the actual engineering situation, realizes closed-loop control of the soil pressure, and displays the soil pressure value, the oil pressure of the oil cylinder, and the test time in real time;

[0010] The loading device includes an oil cylinder and a pressure plate. Through the oil cylinder and the pressure plate, a circumferential load is applied to the pipe pile specimen placed in the chloride salt mixed soil environmental test chamber to simulate the circumferential water and soil pressure borne by the PHC pipe pile in the actual chloride salt service environment in coastal areas.

[0011] Preferably, the oil source system is divided into four branch systems, and the four branches work independently of each other, realizing multiple paths and multiple workstations. Each test is independent of each other, which is convenient for operation and maintenance.

[0012] Preferably, a main circuit accumulator, a safety valve, a manual valve, a branch circuit accumulator, a pressure transmitter, a pressure compensation solenoid valve, and a pressure relief solenoid valve are provided on the branch circuit of the oil source system, and the main circuit accumulator, the safety valve, the branch circuit accumulator, the pressure transmitter, the pressure compensation solenoid valve, and the pressure relief solenoid valve are all electrically connected to the PLC controller.

[0013] Preferably, the environmental test chamber includes a test box body, a mixture of rock, soil and water, a cross beam, columns and a bottom plate. A test box body is provided in the middle of the upper surface of the bottom plate. Longitudinal columns are provided on both sides of the upper surface of the bottom plate close to the test box body. A cross beam is sleeved on the upper sides of the two columns, and the cross beam is fixed on the two columns by two nuts.

[0014] Preferably, a pipe pile sample is provided at the center of the interior of the test box body. The pipe pile sample and the test box body are filled with a soil and water mixture soil, and a plurality of soil pressure cells are arranged at equal intervals inside the soil and water mixture soil.

[0015] Preferably, the oil cylinder is installed in the middle of the upper surface of the cross beam, and the telescopic rod of the oil cylinder penetrates through the cross beam and extends into the test box body. A pressure plate is installed at the bottom of the telescopic rod of the oil cylinder. Through the telescopic movement of the telescopic rod of the oil cylinder, the pressure plate presses against the soil and water mixture soil to generate circumferential water and soil pressure, which is transmitted to the pipe pile sample buried in the soil.

[0016] In addition, the present invention also provides a test method using the above-mentioned simulation device for chloride ion transport under circumferential water and soil pressure of PHC pipe piles, including the following steps:

[0017] The first step: Cut a pipe pile with cracks of 50 cm in length, and level the two ends of the pipe pile specimen with cement mortar;

[0018] Step 2: Prepare a sodium chloride solution with the same concentration as the chloride ion concentration in the actual engineering environment; mix the sodium chloride solution and the actual engineering sand evenly in proportion.

[0019] Step 3: Place the pipe pile specimen in the environmental test chamber, fill the mixed soil and water mixture into the environmental test chamber, and compact it to ensure that the soil and water mixture fills the entire chamber.

[0020] Step 4: Start the oil source system of the test device, and control the pressure plate through the oil cylinder to load the soil in the environmental test chamber.

[0021] Step 5: Take out the PHC pipe pile specimen, collect the concrete sample by the core drilling method, and conduct the chloride ion concentration distribution test.

[0022] Compared with the prior art, the PHC pipe pile chloride ion transmission simulation device and method under circumferential soil and water pressure of the present invention have the following beneficial effects:

[0023] 1. The present invention simulates the circumferential soil and water pressure borne by the PHC pipe pile in the actual chloride salt service environment in the coastal area by loading the chloride salt soil and water mixture in the environmental test chamber through the loading device, and the acting force of the mixed soil on the pipe pile under the action of the load and the box constraint force, and solves the test method for the transmission performance of chloride ions in the PHC pipe pile in the actual service environment; 2. The structure of the present invention is simple, the manufacturing cost is low, the operation is convenient, and it fits the actual situation. Description of the Drawings

[0024] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0025] Figure 1 It is a schematic diagram of the PHC pipe pile chloride ion transmission simulation device under circumferential soil and water pressure proposed by the present invention;

[0026] Figure 2 is Figure 1 The semi-sectional perspective structure schematic diagram of;

[0027] Figure 3 is Figure 2 The front view structure schematic diagram of;

[0028] Figure 4 is Figure 1 The principle structure schematic diagram of;

[0029] Figure 5 is Figure 1 The test method control flow chart of;

[0030] Figure 6 is Figure 1Method step flowchart;

[0031] Figure 7 It is a graph showing the change in chloride ion content in concrete.

[0032] In the figure: 1. Cross beam; 2. Column; 3. Bottom plate; 4. Test box body; 5. Pressure plate; 6. Nut; 7. Oil cylinder; 8. Earth pressure cell; 9. Pipe pile sample; 10. Soil and water mixed soil; 11. Main circuit accumulator; 12. Manual valve; 13. Pressure sensor; 14. Pressure relief solenoid valve; 15. Branch circuit accumulator; 16. Pressure supplement solenoid valve; 17. Safety valve; 18. Touch screen; 19. PLC controller. Specific implementation manner

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] Please refer to Figures 1-6 As shown, a simulation device for chloride ion transmission under circumferential soil and water pressure of PHC pipe piles disclosed by the present invention includes a loading device and an environmental simulation test box. The environmental simulation test box is composed of an oil source system and an environmental test box. The oil source system sets the pressure of the earth pressure cell 8 in the test box according to the actual engineering situation, realizes closed-loop control of the soil pressure, and displays the soil pressure value, the oil pressure of the oil cylinder 7, and the test time in real time.

[0036] The loading device includes an oil cylinder 7 and a pressure plate 5. Through the oil cylinder 7 and the pressure plate 5, a circumferential load is applied to the pipe pile specimen placed in the environmental test box with chloride salt mixed soil to simulate the circumferential soil and water pressure borne by the PHC pipe pile in the actual chloride salt service environment in coastal areas.

[0037] The oil source system is divided into four branch systems, and the four branches work independently of each other, realizing multiple paths and multiple workstations. The tests of each path are independent of each other, which is convenient for operation and maintenance. Tests can be carried out simultaneously without affecting each other. When a specimen on a certain path is damaged, the solenoid valve of that path can be automatically closed, and the other paths can continue the experiment without being affected; on the branch of the oil source system, there are a main circuit accumulator 11, a safety valve 17, a manual valve 12, a branch circuit accumulator 15, a pressure transmitter, a pressure supplement solenoid valve 16, and a pressure relief solenoid valve 14. The main circuit accumulator 11, the safety valve 17, the branch circuit accumulator 15, the pressure transmitter, the pressure supplement solenoid valve 16, and the pressure relief solenoid valve 14 are all electrically connected to the PLC controller 19, and the PLC controller 19 is electrically connected to a touch screen 18;

[0038] The system pressure is 16MPa, the area of ​​the oil cylinder 7 is 125cm, and the diameter of the oil cylinder 7 is 13cm. It can apply a continuous pressure to the soil in the box. The annular water and soil pressure generated in the soil is transmitted to the pipe pile specimen buried in the soil. The data is monitored by the soil pressure box pre-buried in the soil, so as to simulate the annular water and soil pressure that the pipe pile is subjected to in the actual service environment.

[0039] The environmental test box includes a test box body 4, a rock-soil-water mixture, a crossbeam 1, a column 2 and a bottom plate 3, wherein the test box body 4 is provided in the middle of the upper surface of the bottom plate 3. The upper surface of the bottom plate 3 is provided with longitudinal columns 2 near the two sides of the test box body 4, and the upper sides of the two columns 2 are provided with a crossbeam 1, and the crossbeam 1 is fixed to the two columns 2 by two nuts 6. A pipe pile sample 9 is provided at the inner center of the test box body 4, and the pipe pile sample 9 and the test box body 4 are filled with water-soil mixed soil 10, and a plurality of soil pressure boxes 8 with equal spacing are provided inside the water-soil mixed soil 10. The test box body 4 is made of corrosion-resistant carbon steel pipe, and the inner surface is lined with a 1mm thick 304 stainless steel plate.

[0040] The oil cylinder 7 is installed in the middle of the upper surface of the beam 1, and the telescopic rod of the oil cylinder 7 passes through the beam 1 and extends to the test box 4. A pressure plate 5 is installed at the bottom of the telescopic rod of the oil cylinder 7, and through the extension and retraction of the telescopic rod of the oil cylinder 7, the pressure plate 5 presses on the water-soil mixed soil 10 to generate annular water-soil pressure, and transmits it to the pipe pile sample 9 buried in the soil.

[0041] Example 2

[0042] The test method of the chloride ion transmission simulation device under the annular water and soil pressure of the PHC pile comprises the following steps:

[0043] Step 1: Cut a 50cm long pipe pile with cracks and smooth both ends of the pipe pile specimen with cement mortar;

[0044] Step 2: Prepare a sodium chloride solution (2.5%) of the same concentration according to the chloride ion concentration in the actual engineering environment; refer to the actual engineering environment, mix the sodium chloride solution and the actual engineering sand in proportion (mass ratio 1:60);

[0045] Step 3: Place the pipe pile specimen in the environmental test chamber, fill the mixed water-soil mixture into the environmental test chamber, and compact it to ensure that the water-soil mixture fills the entire chamber;

[0046] Step 4: Start the oil source system of the test device, and control the pressure plate 5 to load the soil in the environmental test box through the oil cylinder 7, and set the loads to 25KPa, 50KPa, and 100KPa respectively;

[0047] When the environmental test chamber reaches the set soil pressure, the pressure sensor 13 feeds back the pressure signal to the oil source system, and the oil source system issues an instruction to close the pressure compensation solenoid valve 16, and the environmental test chamber maintains a constant pressure;

[0048] The oil source system monitors the soil pressure in real time through the soil pressure cell. If the soil pressure drops, the oil source system will control the pressure compensation solenoid valve 16 to pressurize the oil cylinder 7;

[0049] When the soil pressure rises, the oil source system issues an instruction to open the pressure relief solenoid valve 14 to relieve the pressure. After the soil reaches the set pressure, the pressure relief solenoid valve 14 closes, forming a closed-loop control system to keep the specimen under a long-term constant pressure and keep the pressure in the specimen within the controlled accuracy range (1 KPa);

[0050] When the test reaches the predetermined age, remove the load through the oil source system and remove the pressure plate 5;

[0051] Step 5: Take out the PHC pipe pile specimen, collect the concrete specimen by the core drilling method, and conduct the chloride ion concentration distribution test.

[0052] Step 6: According to the test method for chloride ions in hardened concrete, crush, screen, and grind the concrete core sample, extract the chloride ions in the concrete by the acid dissolution method, and use the titration method to test the chloride ion content. The chloride ion content in the concrete is as Figure 7 shown. The chloride ion content in the figure is the mass percentage of chloride ions in the core sample concrete.

[0053] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A simulation device for chloride ion transport under the action of circumferential water and soil pressure of PHC pipe piles, comprising a loading device and an environmental simulation test chamber, characterized in that: The environmental simulation test chamber consists of an oil source system and an environmental test chamber. The oil source system sets the pressure of the soil pressure cells in the test chamber according to the actual engineering situation, realizes closed-loop control of the soil pressure, and real-time displays the soil pressure value, the oil pressure of the oil cylinder, and the test time. The loading device includes an oil cylinder and a pressure plate. Through the oil cylinder and the pressure plate, a circumferential load is applied to the pipe pile specimen placed in the environmental test chamber filled with chloride salt mixed soil to simulate the circumferential water and soil pressure borne by the PHC pipe pile in the actual chloride salt service environment in coastal areas. The environmental test chamber includes a test chamber body, a geotechnical water mixture, a cross beam, columns, and a bottom plate. The test chamber body is provided in the middle of the upper surface of the bottom plate. Longitudinal columns are provided on both sides of the upper surface of the bottom plate near the test chamber body. A cross beam is sleeved on the upper sides of the two columns, and the cross beam is fixed to the two columns by two nuts. The oil cylinder is installed in the middle of the upper surface of the cross beam, and the telescopic rod of the oil cylinder penetrates through the cross beam and extends into the test chamber body. A pressure plate is installed at the bottom of the telescopic rod of the oil cylinder. Through the expansion and contraction of the telescopic rod of the oil cylinder, the pressure plate presses against the water and soil mixed soil to generate circumferential water and soil pressure, which is transmitted to the pipe pile sample buried in the soil.

2. The chloride ion transport simulation device under circumferential water and soil pressure of PHC pipe piles according to claim 1, characterized in that: The oil source system is divided into four branch systems, and the four branches work independently of each other, realizing multiple channels and multiple workstations. Each test is independent of each other, which is convenient for operation and maintenance.

3. The chloride ion transport simulation device under the action of circumferential water and soil pressure of PHC pipe piles as described in claim 2, characterized in that: The branch roads of the oil source system are provided with a main circuit accumulator, a safety valve, a manual valve, a branch circuit accumulator, a pressure transmitter, a pressure compensation solenoid valve, and a pressure relief solenoid valve. The main circuit accumulator, the safety valve, the branch circuit accumulator, the pressure transmitter, the pressure compensation solenoid valve, and the pressure relief solenoid valve are all electrically connected to the PLC controller.

4. The chloride ion transport simulation device under circumferential water and soil pressure of PHC pipe piles as described in claim 3, characterized in that: A pipe pile sample is provided at the center inside the test chamber body. The pipe pile sample and the test chamber body are filled with water and soil mixed soil, and a plurality of soil pressure cells are provided at equal intervals inside the water and soil mixed soil.

5. The test method of the chloride ion transport environment simulation device under the action of circumferential water and soil pressure of PHC pipe piles described in any one of claims 1-4, characterized in that, It includes the following steps: The first step: Cut a pipe pile with cracks of 50 cm in length, and smooth the two ends of the pipe pile specimen with cement mortar. The second step: Prepare a sodium chloride solution with the same concentration according to the chloride ion concentration in the actual engineering environment; mix the sodium chloride solution and the actual engineering sand evenly in proportion. The third step: Place the pipe pile specimen in the environmental test chamber, fill the mixed water and soil mixture into the environmental test chamber, and compact it to ensure that the water and soil mixture fills the entire chamber. The fourth step: Start the oil source system of the test device, and control the pressure plate through the oil cylinder to load the soil body in the environmental test chamber. The fifth step: Take out the PHC pipe pile specimen, collect concrete samples by the core drilling method, and conduct chloride ion concentration distribution tests.

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