Concrete force, deformation, temperature and pore pressure synchronous testing device and method

Abstract

The present invention relates to a synchronous testing device and method for force, deformation, temperature and pore pressure of bearing concrete under high temperature. The device comprises a high temperature furnace and at least one pair of screws. The screws pass through four spaced-apart transverse plates, which are positioned and fixed by nuts. From top to bottom, hydraulic jacks, pressure sensors and concrete specimens to be tested are arranged in sequence between two adjacent transverse plates, and one side of the concrete specimen faces the furnace mouth of the high temperature furnace. A sealing insulation layer is pasted around the concrete specimen, and a thermocouple and a pore pressure testing device are embedded inside the concrete specimen. An extensometer is arranged on the side of the concrete specimen, and the extensometers are connected to a data acquisition instrument through signal lines. The synchronous testing device provides an important means for exploring the multi-field coupling response of heat, moisture, force, etc. inside concrete structural components under high temperature in fire, thereby providing technical support for ensuring the fire safety of concrete buildings / structures throughout their life cycle.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and in particular relates to a device and method for synchronously testing the force, deformation, temperature and pore pressure of bearing concrete at high temperature. Background Art

[0002] Under high temperatures in fire, concrete may explode and spall. This is mainly because concrete not only has to bear the load, but also the additional stress and pore vapor pressure caused by high temperature. Therefore, testing the synchronous response of concrete to multiple fields such as moisture, heat, and force at high temperatures has attracted a lot of attention. Jiang Chao et al. (2021) developed a related device (patent CN113237505A) to achieve synchronous testing of the internal temperature and pore pressure of concrete at high temperatures. However, the device did not achieve the load-bearing conditions, nor did it measure the force and deformation synchronously. In addition, scholars such as Sullivan et al. (1983) and Alogla & Kodur (2020) developed related devices to achieve synchronous testing of the force and deformation of loaded concrete at high temperatures, but the device could not synchronously measure the internal temperature and pore pressure of concrete. It can be seen that a synchronous testing device for the force, deformation, temperature and pore pressure of concrete under load conditions is urgently needed to be developed. Summary of the invention

[0003] The purpose of the present invention is to solve the above problems and to provide a synchronous testing device for the force, deformation, temperature and pore pressure of load-bearing concrete at high temperature, so as to realize synchronous and accurate testing of the force, deformation, temperature and pore pressure of load-bearing concrete at high temperature.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A synchronous testing device for concrete force, deformation, temperature and pore pressure, comprising a high-temperature furnace with a furnace port and at least one pair of screws, wherein the screws pass through four spaced-apart transverse partitions, and the upper side and / or the lower side of the transverse partitions are positioned and fixed by nuts sleeved on the screws;

[0006] From top to bottom, a hydraulic jack, a pressure sensor and a concrete specimen to be tested are sequentially arranged between two adjacent transverse partitions, and one side of the concrete specimen faces the furnace opening of the high-temperature furnace;

[0007] The concrete specimen is pasted with a sealing insulation layer all around, a thermocouple and a pore pressure test device are embedded inside, and an extensometer is set on the side.

[0008] The pressure sensor, the thermocouple, the pore pressure measuring device and the signal lines of the extensometer are all connected to the data acquisition instrument.

[0009] Furthermore, the nut is made of high-strength steel and its size matches that of the screw rod. The screw rod is made of high-strength steel and is a long threaded rod.

[0010] Furthermore, a circular ring-shaped gasket is provided between the nut and the transverse partition;

[0011] The annular pad is made of high-strength steel, has an inner diameter larger than the outer diameter of the screw, has no threads inside, and is used to evenly distribute the forces on components such as the nut, pressure sensor, and diaphragm, and to adjust the positions of the components.

[0012] Furthermore, the diaphragm is made of high-strength steel and is a rectangular steel plate with circular holes at both ends. The circular hole is consistent with the inner diameter of the annular pad, larger than the outer diameter of the screw, and has no threads inside, and is used to transmit pressure.

[0013] Furthermore, the pressure sensor is sleeved on the screw;

[0014] The pressure sensor has a circular hole passing through it, a measuring range of not less than 500kN, and an accuracy of not less than 1kN, and is used to monitor the actual pressure value borne on the surface of the concrete specimen in real time.

[0015] Furthermore, a specimen pad is arranged between the concrete specimen and the transverse partition. The specimen pad is made of high-strength steel and has a size larger than the stress-bearing surface of the concrete specimen to be tested, and is used to evenly apply stress on the specimen surface.

[0016] Furthermore, the sealing and heat-insulating layer is formed by combining a sealing material and a heat-insulating material.

[0017] Furthermore, the hydraulic jack is a pressure source, the maximum pressure value that can be applied is not less than 500kN, and the maximum stroke of the piston is not less than 10mm.

[0018] Furthermore, the pore pressure testing device is assembled from a metal tube and a pressure sensor; the thermocouple adopts a large-range armored K-type thermocouple; and the extensometer adopts a high-precision extensometer.

[0019] A method for synchronously testing concrete force, deformation, temperature and pore pressure, using the above-mentioned testing device for testing, comprises the following steps:

[0020] Before the test, connect the device first. After the device is connected, start the data acquisition instrument, start the hydraulic jack, apply pressure, and transmit the pressure to the concrete specimen. When the preset pressure value is applied,

[0021] The diaphragm at the lower end of the hydraulic jack is fixed by tightening the nut, so that the concrete specimen remains under the preset pressure after the hydraulic jack is removed;

[0022] Start the high-temperature furnace, implement the preset heating / cooling path, and synchronously measure the force, deformation, temperature and pore pressure values ​​measured by the pressure sensor, extensometer, thermocouple and pore pressure testing device during the heating / cooling process to achieve synchronous testing of the force, deformation, temperature and pore pressure of the load-bearing concrete under high temperature.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The concrete force, deformation, temperature and pore pressure synchronous testing device provided by the present invention can realize the synchronous testing of force, deformation, temperature and pore pressure of load-bearing concrete under high temperature, providing an important means for exploring the multi-field coupled response of heat, moisture, force, etc. inside the concrete structure under high temperature of fire, thereby providing technical support for ensuring the fire safety of concrete buildings / structures throughout their life cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic front view of the structure of an embodiment of the device of the present invention;

[0026] Figure 2 for Figure 1 Side section along the 1-1 axis;

[0027] In the figure: 1—nut (A~E), 2—screw, 3—annular pad (A~E), 4—cross partition (A~D), 5—specimen pad, 6—concrete specimen, 7—sealing insulation layer, 8—pressure sensor, 9—hydraulic jack, 10—high temperature furnace, 11—data acquisition instrument, 12—pore pressure testing device, 13—thermocouple, 14—extensometer. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 , 2 A synchronous testing device for force, deformation, temperature and pore pressure of bearing concrete under high temperature, comprising: a nut 1 (A-E), a screw 2, an annular pad 3 (A-E), a diaphragm 4 (A-D), a specimen pad 5, a concrete specimen 6, a sealing and heat insulation layer 7, a pressure sensor 8, a hydraulic jack 9, a high temperature furnace 10, a data acquisition instrument 11, a pore pressure testing device 12, a thermocouple 13 and an extensometer 14. The signal lines of the pressure sensor 8, the thermocouple 13, the pore pressure measuring device 12 and the extensometer 14 are connected to the data acquisition instrument 11.

[0030] There are two screw rods 2, which penetrate the nut 1, the annular pad 3, four transverse partitions 4 and the pressure sensor 8. A hydraulic jack 9, a pressure sensor 8 and a concrete specimen 6 are placed from top to bottom between the four transverse partitions 4. A sealing insulation layer 7 is pasted around the concrete specimen 6, and a thermocouple 13 and a pore pressure test device 12 are embedded inside the concrete specimen 6, and an extensometer 14 is arranged on the side thereof.

[0031] One side of the concrete specimen 6 is located at the mouth of the high-temperature furnace 10. Before the test, the device is connected first, but a certain gap is reserved between the nuts 1C and 1D and the diaphragms 4C and 4D respectively to prevent the nuts 1C and 1D from being stressed during pressurization, and to prevent the diaphragm 4C from falling when the concrete specimen 6 is destroyed. After the device is connected, start the data acquisition instrument 11 and tighten the nuts 1A and 1E. Then, start the hydraulic jack 9 to apply pressure, and the pressure is transmitted to the concrete specimen 6 in turn through the diaphragm 4B, the pressure sensor 8, the specimen pad 5, etc. When the preset pressure value is applied, tighten the nut 1B on the screw 2 to ensure that the deformation of the screw 2 within the range of the diaphragm 4B and the diaphragm 4D remains unchanged after the hydraulic jack 9 is removed, so that the concrete specimen 6 can withstand the preset pressure. After pressurization, the high-temperature furnace 10 is started to implement the preset heating / cooling path, and the force, deformation, temperature and pore pressure values ​​measured by the pressure sensor 8, extensometer 14, thermocouple 13 and pore pressure testing device 12 during the heating / cooling process are synchronously measured, thereby realizing the synchronous testing of the force, deformation, temperature and pore pressure of the bearing concrete under high temperature.

[0032] As a specific implementation manner, the nut 1 is made of high-strength steel and its size matches that of the screw rod 2 . The screw rod 2 is made of high-strength steel and is a long threaded rod, and its size matches that of the nut 1 .

[0033] As a specific implementation method, the annular pad 3 is made of high-strength steel, its inner diameter is slightly larger than the outer diameter of the screw 2, and there is no thread inside. It is used to evenly distribute the force on components such as the nut 1, pressure sensor 8, and diaphragm 4, and to adjust the position of each component.

[0034] As a specific implementation method, the diaphragm 4 is made of high-strength steel and is a rectangular steel plate with circular holes at both ends. The circular hole is consistent with the inner diameter of the annular pad 3, slightly larger than the outer diameter of the screw 2, and has no threads inside, and is used to transmit pressure.

[0035] As a specific implementation, the specimen pad 5 is made of high-strength steel and has a size slightly larger than the stress-bearing surface of the concrete specimen 6 to be tested, so as to evenly apply stress to the surface of the specimen.

[0036] As a specific implementation, a sealing insulation layer 7 is pasted around the concrete specimen 6, a thermocouple 13 and a pore pressure testing device 12 are embedded inside, an extensometer 14 is arranged on the external side, and the sealing insulation layer 7 is composed of a sealing material and a thermal insulation material.

[0037] As a specific implementation, the pressure sensor 8 has a penetrating circular hole, the size of the hole is consistent with the inner diameter of the annular pad 3, slightly larger than the outer diameter of the screw 2, the measuring range is not less than 500kN, and the accuracy is not less than 1kN, and is used to monitor the actual pressure value on the surface of the concrete specimen 6 in real time.

[0038] As a specific implementation, the hydraulic jack 9 is a pressure source, the maximum pressure value that can be applied is not less than 500 kN, and the maximum stroke of the piston is not less than 10 mm.

[0039] As a specific implementation method, the high temperature furnace 10 can realize multiple stages of continuous temperature rise / fall and long-term constant temperature. The data acquisition instrument 11 can realize synchronous real-time monitoring and storage of signals of the pressure sensor 8, the extensometer 14, the thermocouple 13, and the pore pressure testing device 12. The pore pressure testing device 12 is assembled from a metal tube and a pressure sensor. The thermocouple 13 adopts a large-range armored K-type thermocouple, and the extensometer 14 adopts a high-precision extensometer.

[0040] The specific test process is as follows: install all parts at the mouth of the high-temperature furnace according to the principle of bottom-up, keep all nuts 1 in a relaxed state, and connect the signal lines of the pressure sensor 8, extensometer 14, pore pressure test device 12 and thermocouple 13 to the data acquisition instrument 11. At the same time, start the data acquisition instrument 11 to monitor the data of each signal. Then, tighten the four nuts 1A and 1E to form a reaction device, and pay attention to keep a certain gap between the nuts 1C and 1D and the diaphragms 4C and 4D respectively. Thereafter, start the hydraulic jack 9 for loading. When the hydraulic jack 9 is loaded to the preset load value, tighten the two nuts 1B, and then remove the hydraulic jack 9 and its upper parts 1A, 3A, and 4A. Finally, start the high-temperature furnace 10, perform the temperature rise / fall test, and use the data acquisition instrument 11 to synchronously monitor and store the pressure value of the pressure sensor 8, the deformation value of the extensometer 14, the pressure value of the pore pressure test device 12, and the temperature value of the thermocouple 13. In this way, the force, deformation, temperature and pore pressure of the bearing concrete specimen 6 at high temperature are simultaneously tested.

[0041] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A synchronous testing device for concrete force, deformation, temperature and pore pressure, characterized in that: It comprises a high-temperature furnace (10) provided with a furnace opening and at least one pair of screw rods (2), wherein the screw rods (2) pass through four transverse partitions (4) arranged at intervals, and the upper and lower sides of the transverse partitions (4) are positioned and fixed by nuts (1) sleeved on the screw rods (2); From top to bottom, a hydraulic jack (9), a pressure sensor (8) and a concrete specimen (6) to be tested are sequentially arranged between two adjacent transverse partitions (4), with one side of the concrete specimen (6) facing the furnace opening of the high-temperature furnace (10); The concrete test piece (6) is bonded with a sealing insulation layer (7) around its periphery, has a thermocouple (13) and a pore pressure testing device (12) embedded in it, and has an extensometer (14) disposed on its side. The signal lines of the pressure sensor (8), the thermocouple (13), the pore pressure testing device (12) and the extensometer (14) are all connected to the data acquisition device (11); A circular gasket (3) is provided between the nut (1) and the transverse partition (4); The annular pad (3) is made of high-strength steel, has an inner diameter greater than the outer diameter of the screw (2), and has no internal threads; The diaphragm (4) is made of high-strength steel and is a rectangular steel plate with circular holes passing through at both ends, and the inner diameter of the circular hole is consistent with that of the annular pad (3); The pressure sensor (8) is sleeved on the screw rod (2); The pressure sensor (8) has a circular hole extending therethrough, a measuring range of not less than 500 kN, and an accuracy of not less than 1 kN; A specimen pad (5) is arranged between the concrete specimen (6) and the transverse partition (4); the specimen pad (5) is made of high-strength steel and has a size larger than the stress-bearing surface of the concrete specimen (6) to be tested; The pore pressure testing device (12) is assembled from a metal tube and a pressure sensor; The thermocouple (13) is an armored K-type thermocouple with a large range; The extensometer (14) is a high-precision extensometer.

2. A synchronous testing device for concrete force, deformation, temperature and pore pressure according to claim 1, characterized in that: The nut (1) is made of high-strength steel and has a size matching that of the screw rod (2). The screw rod (2) is made of high-strength steel and is a long rod with threads.

3. A synchronous testing device for concrete force, deformation, temperature and pore pressure according to claim 1, characterized in that: The sealing and heat-insulating layer (7) is formed by combining a sealing material and a heat-insulating material.

4. A synchronous testing device for concrete force, deformation, temperature and pore pressure according to claim 1, characterized in that: The hydraulic jack (9) is a pressure source, the maximum pressure value that can be applied is not less than 500 kN, and the maximum piston stroke is not less than 10 mm.

5. A method for synchronously testing concrete force, deformation, temperature and pore pressure, characterized in that: The test is performed using the test device as described in any one of claims 1 to 4, comprising the following steps: Before the test, the device is connected first. After the device is connected, the data acquisition instrument (11) is started, the hydraulic jack (9) is started, and pressure is applied. The pressure is transmitted to the concrete specimen (6). When the pressure reaches the preset value, The diaphragm located at the lower end of the hydraulic jack (9) is fixed by tightening the nut, so that the concrete test piece (6) remains under a preset pressure after the hydraulic jack (9) is removed; The high temperature furnace (10) is started, a preset temperature rise / fall path is implemented, and the force, deformation, temperature and pore pressure values ​​measured by the pressure sensor (8), the extensometer (14), the thermocouple (13) and the pore pressure testing device (12) during the temperature rise / fall process are synchronously measured, so as to achieve synchronous testing of the force, deformation, temperature and pore pressure of the bearing concrete at high temperature.

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