Concrete creep device capable of adjusting confining pressure

Abstract

The concrete creep device capable of adjusting the confining pressure comprises a pressure chamber, the pressure chamber comprises an isolation sleeve, an upper pressure head and a lower pressure head are arranged at the upper end and the lower end of the pressure chamber respectively in a sliding mode, the upper pressure head and the lower pressure head both extend into the isolation sleeve to be matched with a concrete test piece, and an oil cavity is formed between the isolation sleeve and the inner wall of the pressure chamber. An inlet hole and an outlet hole are formed in the pressure chamber, the inlet hole is connected with an energy storage pressure tank through an oil supply pipe, and the energy storage pressure tank is connected with a hydraulic system. Compared with the prior art, axial load is applied through the upper pressure head and the lower pressure head, then the concrete test piece is isolated from hydraulic oil in the oil cavity by matching with the isolation sleeve, confining pressure is applied to the concrete test piece through the hydraulic oil, and the confining pressure applying device is simple in overall structure, low in manufacturing cost and difficulty and convenient to popularize and apply. The pressure in the oil cavity can be kept stable for a long time through the hydraulic system and the energy storage pressure tank, and it is ensured that the measured long-term creep deformation of the concrete is more accurate.

Description

Technical Field

[0001] This utility model relates to the field of concrete creep measurement technology, and in particular to a concrete creep device with adjustable confining pressure. Background Technology

[0002] Concrete creep is the slow plastic deformation of concrete structures over time under sustained loads, significantly impacting the long-term deformation, stress distribution, and durability of engineering structures. Studying creep behavior under confining pressure (lateral restraint stress) can reveal changes in the mechanical properties and microscopic mechanisms of materials under triaxial stress states, providing a basis for the design and safety assessment of practical structures such as underground engineering and bridge piers. Existing testing devices suffer from problems such as potentially large pressure fluctuations during loading and difficulty in maintaining confining pressure over long periods. Furthermore, the complexity of existing testing devices in design and manufacturing leads to high costs and hinders their widespread application. Utility Model Content

[0003] This invention provides a concrete creep device with adjustable confining pressure to solve the problems of high cost, large pressure fluctuations during testing, and difficulty in maintaining confining pressure for a long time in existing testing devices.

[0004] This utility model provides an adjustable confining pressure concrete creep device, including a pressure chamber. The pressure chamber includes an isolation sleeve. An upper pressure head and a lower pressure head are slidably disposed at the upper and lower ends of the pressure chamber, respectively. Both the upper and lower pressure heads extend into the isolation sleeve and cooperate with the concrete specimen. An oil cavity is provided between the isolation sleeve and the inner wall of the pressure chamber. The pressure chamber is provided with an inlet and an outlet. The inlet is connected to an energy storage pressure tank through an oil supply pipe. The energy storage pressure tank is connected to a hydraulic system.

[0005] Preferably, the upper and lower ends of the isolation sleeve both extend outward with pressing edges, and the two pressing edges are respectively attached to the top and bottom of the oil cavity.

[0006] Preferably, the pressure chamber includes a cylinder, an upper end cover, and a lower end cover, wherein the upper end cover and the cylinder are threadedly connected, and the upper pressure head passes through the upper end cover and extends into the isolation sleeve inside the cylinder.

[0007] Preferably, the lower end cap is threadedly connected to the cylinder.

[0008] Preferably, it also includes a support frame, on which an upper pressure plate and a lower pressure plate that can move up and down are provided, the upper pressure head is located below the upper pressure plate, and the lower pressure head is located above the lower pressure plate.

[0009] Preferably, a top plate is fixed to the upper end of the bracket, and a jack is provided between the top plate and the upper pressure plate.

[0010] Preferably, a base plate is fixed to the upper end of the bracket, and a spring is provided between the lower pressure plate and the base plate.

[0011] Preferably, the bracket includes multiple positioning screws, the upper pressure plate and the lower pressure plate are slidably connected to the positioning screws respectively, the positioning screws are threaded with a locking nut above the upper pressure plate, and the spring is provided on the positioning screw between the lower pressure plate and the base plate.

[0012] Preferably, both the upper and lower pressure heads are connected to a mounting bracket, and a dial indicator is provided between the two mounting brackets.

[0013] Preferably, the hydraulic system includes: a hydraulic pump, an oil tank, and a directional valve. The oil inlet of the hydraulic pump is connected to the oil tank, and the oil outlet of the hydraulic pump is connected to an energy storage pressure tank through a first pipe. The directional valve is installed on the oil supply pipe and is connected to the oil tank through a return pipe.

[0014] Preferably, the hydraulic system further includes a relief valve, which is disposed on the first pipeline, and the return oil pipe is connected to the relief valve through a second pipeline.

[0015] Compared with existing technologies, this invention applies axial loads through upper and lower pressure heads, then, in conjunction with an isolation sleeve, separates the concrete specimen from the hydraulic oil in the oil chamber and seals the moving upper and lower pressure heads. This achieves confining pressure on the concrete specimen using hydraulic oil. The overall structure is simple, with low manufacturing cost and difficulty, facilitating widespread application. The hydraulic system and energy storage pressure tank ensure stable pressure within the oil chamber over extended periods, guaranteeing more accurate measurements of long-term creep deformation in the concrete. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a partial structural schematic diagram of the present invention;

[0018] Figure 2 for Figure 1 The main view;

[0019] Figure 3 for Figure 1 Partial structural diagram;

[0020] Figure 4 for Figure 3 A cross-sectional view;

[0021] Figure 5 This is a schematic diagram of the structure of this utility model;

[0022] Figure 6 This is a structural schematic diagram of the hydraulic system of this utility model.

[0023] Figure label:

[0024] 1. Isolation sleeve, 2. Upper pressure head, 3. Lower pressure head, 4. Concrete specimen, 5. Oil chamber, 6. Manhole, 7. Exit hole, 8. Oil supply pipe, 9. Energy storage pressure tank, 10. Hydraulic system, 11. Pressing edge, 12. Cylinder, 13. Upper end cover, 14. Lower end cover, 15. Upper bearing plate, 16. Lower bearing plate, 17. Top plate, 18. Jack, 19. Base plate, 20. Spring, 21. Positioning screw, 22. Locking nut, 23. Card holder, 24. Dial indicator, 25. Pressure sensor, 26. Hydraulic pump, 27. Oil tank, 100. Pressure chamber, 200. Support. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0026] See attached document Figure 2 and attached Figure 4 This embodiment provides an adjustable confining pressure concrete creep device, including a pressure chamber 100. The pressure chamber 100 includes an isolation sleeve 1. An upper pressure head 2 and a lower pressure head 3 are slidably disposed at the upper and lower ends of the pressure chamber 100, respectively. Both the upper pressure head 2 and the lower pressure head 3 extend into the isolation sleeve 1 to cooperate with a concrete specimen 4. The concrete specimen 4 is cylindrical, square, or other shaped. An oil cavity 5 is provided between the isolation sleeve 1 and the inner wall of the pressure chamber 100. The isolation sleeve 1, the upper pressure head 2, and the lower pressure head 3 form a sealed cavity to prevent the hydraulic oil in the oil cavity 5 from contacting the concrete specimen 4. The pressure chamber 100 is provided with an inlet 6 and an outlet 7. (Refer to the attached diagram.) Figure 5The manhole 6 is connected to the energy storage pressure tank 9 via the oil supply pipe 8, and the energy storage pressure tank 9 is connected to the hydraulic system 10. The hydraulic system 10 sends hydraulic oil into the energy storage pressure tank 9, and then the energy storage pressure tank 9 sends it into the oil chamber 5 via the oil supply pipe 8. The energy storage pressure tank 9 is used to buffer the hydraulic oil, thereby stabilizing the pressure in the oil chamber 5 and avoiding violent fluctuations. In this utility model, before applying confining pressure, the pressure chamber 100 pre-compresses the concrete specimen 4 axially through the upper pressure head 2 and the lower pressure head 3. Then, the hydraulic oil supplied by the hydraulic system 10 enters the oil chamber 5 through the energy storage pressure tank 9. When hydraulic oil comes out of the outlet 7, the valve at the outlet 7 is closed. The hydraulic system 10 applies confining pressure to the concrete specimen 4 through the hydraulic oil. When the confining pressure reaches the preset value, the hydraulic system is closed, and the oil pressure in the oil chamber 5 is maintained for a long time by the energy storage pressure tank 9. The overall structure of this utility model is simple. The upper pressure head 2 and the lower pressure head 3 apply axial pressure to the concrete specimen 4 on one hand, and on the other hand, they cooperate with the isolation sleeve 1 to isolate the concrete specimen 4 so that the hydraulic oil in the oil chamber 5 can easily apply confining pressure to the concrete specimen 4. Furthermore, the cooperation between the hydraulic system 10 and the energy storage pressure tank 9 helps to maintain the stability of the pressure in the oil chamber 5.

[0027] Specifically, the gas in the energy storage pressure tank 9 absorbs oil pressure changes through compression or expansion, thereby maintaining stable oil pressure in the oil chamber 5. The energy storage pressure tank 9 achieves pressure stabilization and buffering through compressed air, with a maximum pressure of 20 MPa and on-off control accuracy of ±0.05 MPa.

[0028] As another embodiment of this utility model: the upper and lower ends of the isolation sleeve 1 are both extended outward with pressing edges 11. The two pressing edges 11 are respectively attached to the top and bottom of the oil cavity 5. The length of the isolation sleeve 1 is greater than the depth of the oil cavity 5. The pressing edges 11 at both ends of the isolation sleeve 1 will be tightly attached to the top and bottom of the oil cavity 5. This structure is simple and can effectively prevent the hydraulic oil in the oil cavity 5 from entering the location of the concrete specimen 4. At the same time, it can also effectively prevent the hydraulic oil in the oil cavity 5 from leaking from the upper pressing head 2 or the lower pressing head 3.

[0029] Specifically, the pressure edge 11 is fitted to the inner wall of the cylinder 12. This arrangement further improves the sealing of the pressure chamber 100, preventing hydraulic oil from leaking from the upper pressure head 2 and the lower pressure head 3 and from contacting the concrete specimen 4.

[0030] One embodiment of pressure chamber 100: Refer to the appendix Figure 1 The pressure chamber 100 includes a cylinder 12, an upper end cover 13, and a lower end cover 14. The upper end cover 13 and the cylinder 12 are threaded together. The upper pressure head 2 passes through the upper end cover 13 and extends into the isolation sleeve 1 inside the cylinder 12. The length of the isolation sleeve 1 is greater than the length of the cylinder 12. This structural design facilitates the assembly and disassembly of the concrete specimen 4 and the isolation sleeve 1.

[0031] In another embodiment of this utility model, the lower end cap 14 is threadedly connected to the cylinder 12.

[0032] In another embodiment of this utility model, this embodiment also includes a support 200, on which an upper pressure plate 15 and a lower pressure plate 16 are provided. The upper pressure plate 15 and the lower pressure plate 16 move up and down along the support 200. An upper pressure head 2 is located below the upper pressure plate 15, and a lower pressure head 3 is located above the lower pressure plate 16. Axial pressure is applied to the concrete specimen 4 by moving the upper pressure plate 15 and the lower pressure plate 16.

[0033] As another embodiment of this utility model: a top plate 17 is fixed at the upper end of the support 200, and a jack 18 is provided between the top plate 17 and the upper bearing plate 15. The jack 18 applies pressure to the upper bearing plate 15, thereby applying a load to the concrete specimen 4.

[0034] As another embodiment of this utility model: the upper end of the bracket 200 is fixed with a base plate 19, and a spring 20 is provided between the lower pressure plate 16 and the base plate 19. The spring 20 can buffer the load transmitted by the jack 18, thereby ensuring the stable transmission of the load.

[0035] One embodiment of the bracket 200: The bracket 200 includes multiple positioning screws 21. An upper pressure plate 15 and a lower pressure plate 16 are slidably connected to the positioning screws 21. A locking nut 22 is threaded onto the upper pressure plate 15 of each positioning screw 21. A spring 20 is located on the positioning screw 21 between the lower pressure plate 16 and the base plate 19. A jack 18 applies a load to the upper pressure plate 15. When the axial pressure reaches a preset value, the locking nut 22 tightens the upper pressure plate 15, thereby stabilizing the axial load. After the load is applied, the jack 18 and the top plate 17 can be removed.

[0036] Specifically, the positioning screw 21 has a nut above the top plate 17 and a nut below the bottom plate 19. This structural design facilitates the assembly and disassembly of the top plate 17 and the jack 18.

[0037] As another embodiment of this utility model: the upper pressure head 2 is connected to the upper bearing plate 15 by a ball joint, and the lower pressure head 3 is connected to the lower bearing plate 16 by a ball joint. In this structural design, the balance is adjusted by the ball joint to ensure that the concrete specimen 4 is subjected to uniform force during the loading process.

[0038] As another embodiment of this utility model: both the upper pressure head 2 and the lower pressure head 3 are connected to a retainer 23, and the two retainers 23 are detachably connected to the upper pressure head 2 and the lower pressure head 3 respectively. A dial indicator 24 is installed between the two retainers 23. The dial indicator 24 is used to accurately record the creep data of the concrete specimen 4.

[0039] As another embodiment of this utility model: the card holder 23 is provided with a first through hole adapted to the upper pressure head 2, one card holder 23 is sleeved on the upper pressure head 2 through the first through hole, and the other card holder 23 is sleeved on the lower pressure head 3 through the first through hole; a first locking screw is threadedly connected to the first through hole, and the upper pressure head 2 or the lower pressure head 3 is pressed by the first locking screw; the card holder 23 is provided with a second through hole adapted to the dial indicator 24, and a second locking screw is threadedly connected to the second through hole, and the second locking screw locks the two ends of the dial indicator 24 in the second through hole.

[0040] Specifically, the isolation sleeve 1 is made of flexible material.

[0041] As another embodiment of this utility model: refer to the appendix Figure 6 The hydraulic system 10 includes a hydraulic pump 26, an oil tank 27, and a directional valve. The oil inlet of the hydraulic pump 26 is connected to the oil tank 27, and the oil outlet of the hydraulic pump 26 is connected to the energy storage pressure tank 9 through a first pipe. The directional valve is installed on the oil supply pipe 8 and is connected to the oil tank 27 through the oil return pipe.

[0042] As another embodiment of this utility model: the hydraulic system 10 also includes an overflow valve, which is installed on the first pipeline. The return oil pipe is connected to the overflow valve through the second pipeline. By installing the overflow valve, the oil pressure in the first pipeline is prevented from being too high.

[0043] As another embodiment of this utility model: refer to the appendix Figure 3 A pressure sensor 25 is provided between the lower bearing plate 16 and the lower pressure head 3. The pressure sensor 25 is used to detect the magnitude of the axial load.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A concrete creep device with adjustable confining pressure, characterized in that, The device includes a pressure chamber, which includes an isolation sleeve. An upper pressure head and a lower pressure head are slidably disposed at the upper and lower ends of the pressure chamber, respectively. Both the upper and lower pressure heads extend into the isolation sleeve and cooperate with the concrete specimen. An oil cavity is provided between the isolation sleeve and the inner wall of the pressure chamber. The pressure chamber is provided with an inlet and an outlet. The inlet is connected to an energy storage pressure tank through an oil supply pipe. The energy storage pressure tank is connected to a hydraulic system.

2. The adjustable confining pressure concrete creep device according to claim 1, characterized in that, The upper and lower ends of the isolation sleeve both extend outward with pressing edges, and the two pressing edges are respectively attached to the top and bottom of the oil cavity.

3. The adjustable confining pressure concrete creep device according to claim 2, characterized in that, The pressure chamber includes a cylinder, an upper end cover, and a lower end cover. The upper end cover and the cylinder are threaded together, and the upper pressure head passes through the upper end cover and extends into the isolation sleeve inside the cylinder.

4. The concrete creep device with adjustable confining pressure according to claim 3, characterized in that, The lower end cap is threadedly connected to the cylinder.

5. The adjustable confining pressure concrete creep device according to claim 4, characterized in that, It also includes a support frame, on which are provided an upper pressure plate and a lower pressure plate that can move up and down. The upper pressure head is located below the upper pressure plate, and the lower pressure head is located above the lower pressure plate.

6. The concrete creep device with adjustable confining pressure according to claim 5, characterized in that, The upper end of the bracket is fixed with a top plate, and a jack is provided between the top plate and the upper pressure plate.

7. The concrete creep device with adjustable confining pressure according to claim 6, characterized in that, The upper end of the bracket is fixed with a base plate, and a spring is provided between the lower pressure plate and the base plate.

8. The concrete creep device with adjustable confining pressure according to claim 7, characterized in that, The bracket includes multiple positioning screws. The upper and lower pressure plates are slidably connected to the positioning screws. A locking nut is threaded onto the upper pressure plate of the positioning screw. The spring is located on the positioning screw between the lower pressure plate and the base plate.

9. The concrete creep device with adjustable confining pressure according to claim 8, characterized in that, Both the upper and lower pressure heads are connected to a mounting bracket, and a dial indicator is provided between the two mounting brackets.

10. The concrete creep device with adjustable confining pressure according to claim 1, characterized in that, The hydraulic system includes a hydraulic pump, an oil tank, and a directional valve. The oil inlet of the hydraulic pump is connected to the oil tank, and the oil outlet of the hydraulic pump is connected to an energy storage pressure tank through a first pipe. The directional valve is installed on the oil supply pipe and is connected to the oil tank through a return pipe.

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