Asphalt mixture penetration shear test device capable of controlling confining pressure

Abstract

The utility model discloses an asphalt mixture penetration shear test device with controllable confining pressure, which comprises a to-be-tested mechanism, a pressure applying mechanism, a supporting mechanism and an upper limiting mechanism, the supporting mechanism is of a hollow structure, the to-be-tested mechanism and the pressure applying mechanism are both positioned in a hollow cavity of the supporting mechanism, and the to-be-tested mechanism is positioned at the top of the pressure applying mechanism; the pressure applying mechanism comprises an oil cylinder, a displacement plate and a sensor placing plate, the four corners of the displacement plate and the four corners of the sensor placing plate are connected with the inner side wall of the supporting mechanism, the bottom of the oil cylinder is embedded in the supporting mechanism, and a second displacement sensor and a temperature sensor are arranged in the middle of the sensor placing plate. The oil cylinder pushes the test piece upwards from the lower side of the test piece, thrust from bottom to top is applied to the test piece, so that the test piece is subjected to shear failure under the action of the pressure head, meanwhile, the pressure sensor at the bottom of the pressure head collects the pressure of the test piece, the shear strength of the test piece is determined, and the problem that the shear resistance of the test piece cannot be accurately simulated is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of road engineering tests, in particular to a penetration shear test device for asphalt mixture with controllable confining pressure. Background Technique

[0002] At present, the two main ways of asphalt mixture shear strength failure are the triaxial test method and the uniaxial penetration method. The uniaxial penetration method is to press a standard-sized circular indenter into an asphalt mixture with a diameter of 150 mm and a height of 100 mm. The test temperature is 60 °C, the loading rate is 1 mm / min, and the initial contact pressure is 0.05 kN. When the stress drops to 90% of the stress extreme point, the loading is stopped, the stress and displacement are recorded, and the shear strength of the asphalt mixture with a standard height is calculated according to the corresponding formula. The main disadvantage of this method is that during the uniaxial penetration process, the specimen is mainly under compression, and there is a shear area around the indenter. However, the measured penetration strength is the sum of the compressive and shear strengths of the mixture, and it cannot accurately reflect the shear performance of the asphalt mixture. Therefore, it is necessary to design a device that can better simulate the shear performance of asphalt mixture. Content of the Utility Model

[0003] The purpose of the utility model is to overcome the deficiencies in the above-mentioned prior art, and provide a penetration shear test device for asphalt mixture with controllable confining pressure. An oil cylinder is used to push the specimen upward from the lower side of the specimen, and a thrust from bottom to top is applied to the specimen to cause shear failure of the specimen under the action of the indenter. At the same time, a pressure sensor at the bottom of the indenter collects the pressure of the specimen to determine the shear strength of the specimen, solving the problem of inability to accurately simulate the shear performance of the specimen.

[0004] To achieve the above purpose, the technical solution adopted by the utility model is: a penetration shear test device for asphalt mixture with controllable confining pressure, including a to-be-tested mechanism, a pressure-applying mechanism, a support mechanism, and an upper limit mechanism. The upper limit mechanism is connected to the top of the support mechanism. The support mechanism is a hollow structure. The to-be-tested mechanism and the pressure-applying mechanism are both located in the hollow cavity of the support mechanism. The to-be-tested mechanism is located on top of the pressure-applying mechanism. The top of the to-be-tested mechanism is in contact with the bottom of the upper limit mechanism, so that when the pressure-applying mechanism pushes the to-be-tested mechanism upward, the upper limit mechanism restricts the movement of the to-be-tested mechanism. The pressure-applying mechanism includes an oil cylinder, a displacement plate, and a sensor placement plate. A through hole is provided in the middle of the displacement plate. The displacement plate is located above the sensor placement plate. The four corners of the displacement plate and the sensor placement plate are connected to the inner side wall of the support mechanism. The oil cylinder is vertically placed and its bottom is embedded in the inner bottom of the support mechanism. The top of the oil cylinder is located below the sensor placement plate to facilitate the oil cylinder to push the sensor placement plate to move up and down in the vertical direction. A second displacement sensor and a temperature sensor are provided in the middle of the side of the sensor placement plate away from the oil cylinder.

[0005] Preferably, the upper limit mechanism includes an upper pressure plate, a pressing head, a first displacement sensor, and a pressure sensor. The four corners of the upper pressure plate are all connected to the top of the support mechanism. The pressing head is installed in the middle of the lower side of the upper pressure plate. The pressure sensor is installed at the end of the pressing head away from the upper pressure plate. The number of the first displacement sensors is two, and the two first displacement sensors are both connected to the lower side of the upper pressure plate and are respectively located on both sides of the pressing head to facilitate detecting the displacement of the test piece.

[0006] Preferably, the support mechanism includes a lower pressure plate and outer limiting rods. The size of the lower pressure plate matches the size of the upper pressure plate. Outer limiting rods are provided at the four corners of the lower pressure plate. The top of each outer limiting rod is connected to the upper pressure plate, and the bottom of each outer limiting rod is connected to the lower pressure plate.

[0007] Preferably, the mechanism to be tested includes a heat preservation barrel, a test piece, an airbag, an inflation channel, an upper limiting plate, and a lower limiting plate. Pressing holes are provided in the middle of the upper limiting plate and the lower limiting plate. The size of the pressing holes matches the size of the pressing head to facilitate the pressing head passing through the pressing holes to contact the test piece. The upper limiting plate is threadedly connected to the top of the heat preservation barrel, and the lower limiting plate is threadedly connected to the bottom of the heat preservation barrel. The size of the test piece matches the size of the heat preservation barrel to facilitate the test piece being embedded in the accommodating chamber of the heat preservation barrel. The airbag is arranged around the outer side wall of the test piece and is located between the test piece and the heat preservation barrel. The airbag is respectively in contact with the outer side wall of the test piece and the inner side wall of the heat preservation barrel. The inflation channel passes through the side wall of the heat preservation barrel and is connected to the airbag to facilitate inflating the airbag.

[0008] Preferably, the diameter of the pressing head is 50 mm.

[0009] Preferably, the diameter of the test piece is 150 mm and the height is 100 mm.

[0010] Preferably, heating resistance wires are also arranged on the side wall of the heat preservation barrel.

[0011] The utility model has the following advantages compared with the prior art:

[0012] 1. The utility model uses an oil cylinder to push the test piece upward from the lower side of the test piece, applying an upward thrust to the test piece to cause shear failure of the test piece under the action of the pressing head. At the same time, the pressure sensor at the bottom of the pressing head collects the pressure of the test piece to determine the shear strength of the test piece, solving the problem of being unable to accurately simulate the shear performance of the test piece.

[0013] 2. The utility model uses a lower limiting plate and a displacement plate to pad up the lower part of the test piece, and at the same time, an airbag is arranged around the test piece to simulate the surrounding environment of the asphalt mixture in the actual situation. When shear failure occurs, the airbag can simultaneously generate corresponding pressure changes, so as to achieve the study of the actual situation of the asphalt mixture around the shear position.

[0014] 3. The utility model adds a heating resistance wire to the heat preservation barrel, and a temperature sensor is arranged at the bottom of the heat preservation barrel. The temperature data is collected in real time through the temperature sensor. When the temperature data collected by the temperature sensor is lower than the preset temperature, the heating resistance wire is turned on to heat the equipment, so that the test piece is sheared and damaged at the preset temperature, improving the accuracy of collecting shear data.

[0015] 4. By setting a displacement sensor, the utility model can monitor the displacement change of the whole process of the shear test of the test piece, so as to observe the displacement change around the test piece during shear failure and provide deformation support for subsequent tests.

[0016] The following further describes the present utility model in detail through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the front view of the present utility model;

[0018] Figure 2 is the side view of the present utility model;

[0019] Figure 3 is the main body sectional view of the present utility model.

[0020] Description of the reference numerals:

[0021] 1 - upper pressure plate; 2 - pressure head; 3 - outer limit rod;

[0022] 4 - heat preservation barrel; 5 - lower limit plate; 6 - displacement plate;

[0023] 7 - oil cylinder; 8 - lower pressure plate; 9 - first displacement sensor;

[0024] 10 - bolt; 11 - inflation channel; 12 - sensor placement plate;

[0025] 13 - second displacement sensor; 14 - temperature sensor;

[0026] 15 - upper limit plate; 16 - pressure sensor; 17 - test piece;

[0027] 18 - airbag; 19 - connecting plate; 20 - heating resistance wire;

[0028] 21 - pressing hole; 22 - through hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] As Figures 1 to 3As shown in the figure, the utility model includes a mechanism to be tested, a pressing mechanism, a supporting mechanism and an upper limit mechanism. The upper limit mechanism is connected to the top of the supporting mechanism. The supporting mechanism is of a hollow structure. Both the mechanism to be tested and the pressing mechanism are located in the hollow cavity of the supporting mechanism. The mechanism to be tested is located above the pressing mechanism. The top of the mechanism to be tested is in contact with the bottom of the upper limit mechanism, so that when the pressing mechanism pushes the mechanism to be tested upward, the upper limit mechanism restricts the movement of the mechanism to be tested. The pressing mechanism includes an oil cylinder 7, a displacement plate 6 and a sensor placement plate 12. A through hole 22 is provided in the middle of the displacement plate 6. The displacement plate 6 is located above the sensor placement plate 12. The four corners of the displacement plate 6 and the sensor placement plate 12 are connected to the inner side wall of the supporting mechanism. The oil cylinder 7 is vertically placed and its bottom is embedded in the inner bottom of the supporting mechanism. The top of the oil cylinder 7 is located below the sensor placement plate 12, so that the oil cylinder 7 can push the sensor placement plate 12 to move up and down in the vertical direction. In the middle of the side of the sensor placement plate 12 away from the oil cylinder 7, a second displacement sensor 13 and a temperature sensor 14 are provided.

[0030] In this embodiment, the pressing mechanism is embedded in the inner bottom of the supporting mechanism. The mechanism to be tested is installed above the pressing mechanism. The upper limit mechanism is connected to the supporting mechanism. The bottom of the upper limit mechanism is in contact with the top of the mechanism to be tested. The pressing mechanism is started. The pressing mechanism vertically pushes the mechanism to be tested upward. The position of the upper limit mechanism is fixed, and the failure position of the mechanism to be tested is ensured during the upward movement of the mechanism to be tested.

[0031] During operation, the oil cylinder 7 is started. The mechanism to be tested is located on the displacement plate 6. During the rising process of the oil cylinder 7, the sensor placement plate 12 is pushed upward. The sensor placement plate 12 and the displacement plate 6 rise synchronously. The displacement plate 6 pushes the mechanism to be tested thereon to rise. The part of the mechanism to be tested in contact with the upper limit mechanism undergoes shear failure. The second displacement sensor 13 continuously detects the displacement amount after the mechanism to be tested undergoes shear failure. The temperature sensor 14 continuously detects whether the shear device maintains a preset temperature. This preset temperature can be determined according to the actual test situation. It can be 60 degrees Celsius or 50 degrees Celsius. The temperature sensor 14 is a temperature sensor produced by Hangzhou Mekong Automation Technology Co., Ltd. with a model of pt100. The second displacement sensor 13 is a Panasonic small laser displacement sensor with a model of HL-G1. The oil cylinder 7 is an ordinary hydraulic oil cylinder.

[0032] The upper limit mechanism includes an upper pressure plate 1, a pressure head 2, a first displacement sensor 9 and a pressure sensor 16. The four corners of the upper pressure plate 1 are connected to the top of the supporting mechanism. The pressure head 2 is installed in the middle of the lower side of the upper pressure plate 1. The pressure sensor 16 is installed at the end of the pressure head 2 away from the upper pressure plate 1. The number of the first displacement sensors 9 is two. The two first displacement sensors 9 are both connected to the lower side of the upper pressure plate 1 and are respectively located on both sides of the pressure head 2 to facilitate detecting the displacement amount of the test piece 17.

[0033] In this embodiment, the upper pressure plate 1 is a square plate. The four corners of the upper pressure plate 1 are all connected to the top of the support mechanism, so that the support mechanism supports the upper pressure plate 1 at a fixed height. The pressure head 2 is perpendicular to the upper pressure plate 1. The top of the pressure head 2 along the length direction is connected to the bottom of the upper pressure plate 1, and the bottom of the pressure head 2 along the length direction is in contact with the mechanism to be tested. When the oil cylinder 7 pushes the mechanism to be tested upward, the pressure head 2 always maintains its current position. During the upward movement of the mechanism to be tested, the pressure head 2 continuously exerts extrusion on the mechanism to be tested. The pressure sensor 16 at the bottom of the pressure head 2 detects the pressure T received by the mechanism to be tested, and the first displacement sensor 9 detects the deformation of the mechanism to be tested after being extruded. The first displacement sensor 9 emits a laser signal and records the round-trip time t of the laser signal. According to the pressure T and the cross-sectional area of the mechanism to be tested under extrusion, the shear strength of the mechanism to be tested can be calculated. Shear provides a certain basis for the measurement of bearing capacity and fatigue. According to the round-trip time t of the signal detected by the first displacement sensor 9, the displacement X of the shear failure of the mechanism to be tested can be calculated, providing data support for other tests. The pressure sensor 16 is a micro pressure force sensor produced by Changzhou Ruierte Measurement and Control System Co., Ltd. with the model T107.

[0034] Further, the upper pressure plate 1 is of a circular structure. The four corner positions of the upper pressure plate 1 are the positions of the four endpoints of two mutually perpendicular diameters passing through the center of the upper pressure plate 1, and the pressure head 2 is located at the center of the upper pressure plate 1.

[0035] The support mechanism includes a lower pressure plate 8 and outer limit rods 3. The size of the lower pressure plate 8 matches the size of the upper pressure plate 1. Outer limit rods 3 are provided at the four corner positions of the lower pressure plate 8. The top of each outer limit rod 3 is connected to the upper pressure plate 1, and the bottom of each outer limit rod 3 is connected to the lower pressure plate 8.

[0036] In this embodiment, the lower pressure plate 8 is of a square structure. The four outer limit rods 3 are all perpendicular to the lower pressure plate 8. The bottom of each outer limit rod 3 is fixedly connected to the lower pressure plate 8, and the top of each outer limit rod 3 is threadedly connected to the upper pressure plate 1 through bolts 10. The oil cylinder 7 is embedded in the middle of the lower pressure plate 8. The displacement plate 6 is located above the sensor placement plate 12. The displacement plate 6 is welded to the sensor placement plate 12. The top of the oil cylinder 7 is welded to the bottom of the sensor placement plate 12 to facilitate the oil cylinder 7 to push the sensor placement plate 12 to move up and down in the vertical direction. When the sensor placement plate 12 moves, it drives the mechanism to be tested to move up and down in the vertical direction.

[0037] Furthermore, sliding grooves are provided on the inner side walls of each outer limiting rod 3, and vertical guide rods are arranged on the sliding grooves. The vertical guide rods are arranged along the height direction of the outer limiting rod 3 and can slide up and down along the height direction of the outer limiting rod 3. The top of the vertical guide rod is fixedly connected to the sensor placement plate 12 and the displacement plate 6. The displacement plate 6 is located above the sensor placement plate 12 and is welded to the sensor placement plate 12. After the oil cylinder 7 is started, under the cooperation of the sensor placement plate 12, the vertical guide rod and the outer limiting rod 3, the mechanism to be tested moves up and down along the height direction of the outer limiting rod 3. The arrangement of the vertical guide rod can improve the smoothness of the up and down movement of the sensor placement plate 12.

[0038] In another possible embodiment, sleeves are provided at the contact parts between the sensor placement plate 12 and the outer limiting rod 3. The sleeves are sleeved on the outer limiting rod 3, enabling the sensor placement plate 12 to move up and down along the height direction of the outer limiting rod 3. The oil cylinder 7 supports the sensor placement plate 12 upward, leaving a distance between the sensor placement plate 12 and the lower pressing plate 8. After the oil cylinder 7 is started, it pushes the sensor placement plate 12 to move upward along the height direction of the outer limiting rod 3. The sensor placement plate 12 drives the displacement plate 6 and the mechanism to be tested thereon to move upward synchronously, causing the pressing head 2 to squeeze the mechanism to be tested.

[0039] Furthermore, the lower pressing plate 8 is of a circular structure. The four corner positions of the lower pressing plate 8 are the positions of the four endpoints of two mutually perpendicular diameters passing through the center of the circle of the lower pressing plate 8. The bottom parts of the four outer limiting rods 3 are respectively fixedly connected to these four endpoints, and the oil cylinder 7 is embedded at the center of the circle of the lower pressing plate 8.

[0040] The mechanism to be tested includes a heat preservation barrel 4, a test piece 17, an airbag 18, an inflation channel 11, an upper limiting plate 15 and a lower limiting plate 5. Pressing holes 21 are provided in the middle of both the upper limiting plate 15 and the lower limiting plate 5. The size of the pressing holes 21 matches the size of the pressing head 2 to facilitate the pressing head 2 passing through the pressing holes 21 to contact the test piece 17. The upper limiting plate 15 is threadedly connected to the top of the heat preservation barrel 4, and the lower limiting plate 5 is threadedly connected to the bottom of the heat preservation barrel 4. The size of the test piece 17 matches the size of the heat preservation barrel 4 to facilitate the test piece 17 being embedded in the accommodation chamber of the heat preservation barrel 4. The airbag 18 is arranged around the outer side wall of the test piece 17 and is located between the test piece 17 and the heat preservation barrel 4. The airbag 18 is respectively in contact with the outer side wall of the test piece 17 and the inner side wall of the heat preservation barrel 4. The inflation channel 11 passes through the side wall of the heat preservation barrel 4 and is connected to the airbag 18 to facilitate inflating the airbag 18.

[0041] In this embodiment, a connecting plate 19 is arranged around the inner wall of the heat preservation barrel 4. The connecting plate 19 is in close contact with the inner wall of the heat preservation barrel 4. The side wall of the heat preservation barrel 4 is of a double-layer structure to facilitate improving the heat preservation effect. Both the top and bottom of the heat preservation barrel 4 are open. The bottom of the heat preservation barrel 4 is threadedly connected to the lower limit plate 5 through bolts 10. The test piece 17 heated to the target temperature is placed into the heat preservation barrel 4. The target temperature is determined according to the current test type of the test piece 17. The test piece 17 can be 60 degrees Celsius. According to different test types, the test piece 17 can also be 70 degrees Celsius. The test piece 17 is in contact with the airbag 18. One side of the airbag 18 away from the test piece 17 is in contact with the connecting plate 19. After the test piece 17 is placed, the upper limit plate 15 is threadedly connected to the top of the heat preservation barrel 4. Then the heat preservation barrel 4 is placed on the displacement plate 6 to align the through hole 22 of the displacement plate 6 with the pressing hole 21 of the lower limit plate 5. The position of the upper pressing plate 1 is adjusted to align the pressing head 2 with the pressing hole 21 of the upper limit plate 15. The oil cylinder 7 is started. The oil cylinder 7 pushes the sensor placement plate 12 and the displacement plate 6 to rise, and the heat preservation barrel 4 rises synchronously until the bottom of the pressing head 2 is in contact with the top of the test piece 17. The oil cylinder 7 stops working. The airbag 18 is inflated through the air inflation channel 11 to make the airbag 18 fully contact the test piece 17. The airbag 18 forms a horizontal force on the test piece 17. Thus, the preparation work is completed. The initial pressure between the pressing head 2 and the test piece 17 is recorded. The position of the test piece 17 in the initial state is recorded through the first displacement sensor 9 and the second displacement sensor 13. After the data recording is completed, the oil cylinder 7 is restarted. The oil cylinder 7 pushes the test piece 17 to move upward. The test piece 17 is an asphalt mixture test piece. The test piece 17 is subjected to the upward pressure from the oil cylinder 7. During the rising process of the oil cylinder 7, the pressing head 2 continuously presses the test piece 17. The test piece 17 causes the test piece 17 without intermediate limitation to undergo shear failure through the pressing hole 21 in the middle of the lower limit plate 5. At the same time, the pressure change of the test piece 17 when it fails is detected in real time through the pressure sensor 16 at the bottom of the pressing head 2. When the shear failure of the test piece 17 completely occupies the through hole 22 of the displacement plate 6, the oil cylinder 7 stops working, that is, a shear failure is completed. The first displacement sensor 9 uses a Panasonic small laser displacement sensor of model HL-G1.

[0042] The diameter of the pressing head 2 is 50 mm.

[0043] In this embodiment, according to the diameter of the pressing head 2, the aperture diameters of the pressing holes 21 of the upper limit plate 15 and the lower limit plate 5 and the aperture diameter of the through hole 22 of the displacement plate 6 are set so that the aperture diameters of the pressing holes 21 of the upper limit plate 15 and the lower limit plate 5 are the same as the diameter of the pressing head 2, or the aperture diameters of the pressing holes 21 of the upper limit plate 15 and the lower limit plate 5 are 2 mm larger than the diameter of the pressing head 2 to facilitate the pressing head 2 to pass through the pressing holes 21 up and down. The aperture diameter of the through hole 22 of the displacement plate 6 can be the same as the diameter of the pressing head 2 or larger than the diameter of the pressing head 2.

[0044] The diameter of the test piece 17 is 150 mm and the height is 100 mm.

[0045] In this embodiment, the size of the test piece 17 matches the size of the heat preservation barrel 4, which facilitates embedding the test piece 17 into the heat preservation barrel 4. According to the size of the test piece 17, the cross-sectional area of the test piece 17 can be obtained. During the shear failure experiment, the pressure sensor 16 continuously records the pressure T received by the test piece 17. Therefore, the shear strength of the test piece 17 can be obtained as follows:

[0046]

[0047] Where: τ is the shear strength of the test piece 17, MPa; T is the extreme value of the shear stress during the test, that is, the maximum value of the pressures received by multiple test pieces 17 collected by the pressure sensor 16, kN; r is the radius of the test piece 17.

[0048] Furthermore, after the shear failure experiment of the test piece 17, the first displacement sensor 9 and the second displacement sensor 13 collect displacement data of multiple test pieces 17. Since when the test piece 17 undergoes shear failure, the shear position will not only gather at the position where the indenter 2 acts, the first displacement sensor 9, as the upper sensor, can monitor the displacement deformation occurring around the upper side of the test piece 17, and the second displacement sensor 13, as the lower sensor, can monitor the deformation of the test piece 17 at the pressing hole 21. When the test piece 17 undergoes a shear failure test, the first displacement sensor 9 and the second displacement sensor 13 work in the form of laser. The laser signals emitted by the first displacement sensor 9 and the second displacement sensor 13 are reflected back to the first displacement sensor 9 and the second displacement sensor 13 through the surface of the test piece 17. By recording the round-trip time t of the laser by the first displacement sensor 9 and the second displacement sensor 13, the displacement X of the shear failure of the test piece 17 is calculated. The calculation formula is:

[0049]

[0050] Where: c is the speed of light in the atmosphere, mm / ms; t is the round-trip time of the laser signal, ms.

[0051] A heating resistance wire 20 is also provided on the side wall of the heat preservation barrel 4.

[0052] In this embodiment, the heating resistance wire is made of an iron-chromium-aluminum alloy material. The temperature sensor 14 continuously detects the temperature of the shearing device. When the temperature of the shearing device is lower than 60 degrees Celsius, the heating resistance wire 20 is turned on and heated through the heating resistance wire 20 to keep all components of the shearing device at 60 degrees Celsius all the time.

[0053] In use, first lower the oil cylinder 7 to the lowest height, unscrew the bolt 10 on the upper pressure plate 1 to disengage the upper pressure plate 1 from the support mechanism, then remove the inflation pipe 11 on the side wall of the heat preservation barrel 4, take out the heat preservation barrel 4 from the connecting plate 6, unscrew the bolt 10 at the top of the heat preservation barrel 4 to separate the upper limit plate 15 from the heat preservation barrel 4, and place the test piece 17 with a temperature of 60 °C, a diameter of 150 mm, and a height of 100 mm into the heat preservation barrel 4. After the position adjustment of the test piece 17 in the heat preservation barrel 4 is completed, reconnect the upper limit plate 15 to the heat preservation barrel 4 by threading, place the heat preservation barrel 4 on the displacement plate 6, thread-connect the upper pressure plate 1 to the outer limit rod 3 so that the pressure head 2 at the bottom of the upper pressure plate 1 coincides with the pressure hole 21 of the upper limit plate 15. Start the oil cylinder 7, and the oil cylinder 7 pushes the test piece 17 upward so that the bottom of the pressure head 2 contacts the test piece 17. Then the oil cylinder 7 stops working. Next, install the inflation pipe 11 on the side wall of the heat preservation barrel 4 and inflate the airbag 18 through the inflation pipe 11 to make the airbag 18 fully contact the test piece 17. The airbag 18 restricts the lateral displacement of the test piece 17 to simulate the pavement confining pressure under real conditions. Restart the oil cylinder 7, and the oil cylinder 7 pushes the sensor placement plate 12 upward. The displacement plate 6, the lower limit plate 5, and the test piece 17 on the sensor placement plate 12 move upward synchronously. The pressure head 2 exerts a downward pressure on the test piece 17, and the oil cylinder 7 exerts an upward pressure on the test piece 17 during the process of pushing the test piece 17. Through the pressure hole 21, the test piece 17 without intermediate limitation undergoes shear failure. The pressure sensor 16 at the top of the test piece 17 real-time detects the pressure change when the test piece 17 undergoes shear failure until the shear failure of the test piece 17 completely occupies the through hole 22 of the displacement plate 6, then the oil cylinder 7 stops working, and the shear failure test ends. According to the recorded data, calculate the shear strength and the displacement X at which the test piece 17 undergoes shear failure. By calculating the shear strength of the asphalt mixture, the quality and reliability of the asphalt mixture can be ensured.

[0054] The above is only a preferred embodiment of the present invention, and it does not impose any limitations on the present invention. Any simple modification, change, and equivalent structural transformation made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A penetration shear test device for asphalt mixture with controllable confining pressure, characterized in that: It includes the mechanism to be tested, a pressure-applying mechanism, a supporting mechanism and an upper limit mechanism. The upper limit mechanism is connected to the top of the supporting mechanism. The supporting mechanism is a hollow structure. Both the mechanism to be tested and the pressure-applying mechanism are located in the hollow cavity of the supporting mechanism. The mechanism to be tested is located on top of the pressure-applying mechanism. The top of the mechanism to be tested is in contact with the bottom of the upper limit mechanism so that when the pressure-applying mechanism pushes the mechanism to be tested upward, the upper limit mechanism restricts the movement of the mechanism to be tested. The pressure-applying mechanism includes an oil cylinder (7), a displacement plate (6) and a sensor placement plate (12). A through hole (22) is provided in the middle of the displacement plate (6). The displacement plate (6) is located above the sensor placement plate (12). The four corners of the displacement plate (6) and the sensor placement plate (12) are both connected to the inner side wall of the supporting mechanism. The oil cylinder (7) is placed vertically and its bottom is embedded in the inner bottom of the supporting mechanism. The top of the oil cylinder (7) is located below the sensor placement plate (12) so that the oil cylinder (7) can push the sensor placement plate (12) to move up and down in the vertical direction. A second displacement sensor (13) and a temperature sensor (14) are provided in the middle of the side of the sensor placement plate (12) away from the oil cylinder (7).

2. The penetration shear test device for asphalt mixture with controllable confining pressure according to claim 1, characterized in that: The upper limit mechanism includes an upper pressure plate (1), a pressure head (2), a first displacement sensor (9) and a pressure sensor (16). The four corners of the upper pressure plate (1) are all connected to the top of the supporting mechanism. The pressure head (2) is installed in the middle of the lower side of the upper pressure plate (1). The pressure sensor (16) is installed at the end of the pressure head (2) away from the upper pressure plate (1). The number of the first displacement sensors (9) is two. Both of the two first displacement sensors (9) are connected to the lower side of the upper pressure plate (1) and are respectively located on both sides of the pressure head (2) to facilitate the detection of the displacement of the test piece (17).

3. A penetration shear test device for asphalt mixture with controllable confining pressure according to claim 2, characterized in that: The supporting mechanism includes a lower pressure plate (8) and outer limit rods (3). The size of the lower pressure plate (8) matches that of the upper pressure plate (1). Outer limit rods (3) are provided at the four corners of the lower pressure plate (8). The top of each outer limit rod (3) is connected to the upper pressure plate (1), and the bottom of each outer limit rod (3) is connected to the lower pressure plate (8).

4. A penetration shear test device for asphalt mixture with controllable confining pressure according to claim 2, characterized in that: The mechanism to be tested includes a heat preservation barrel (4), a test piece (17), an airbag (18), an inflation channel (11), an upper limit plate (15) and a lower limit plate (5). Pressing holes (21) are provided in the middle of both the upper limit plate (15) and the lower limit plate (5). The size of the pressing holes (21) matches the size of the pressing head (2) to facilitate the pressing head (2) passing through the pressing holes (21) to contact the test piece (17). The upper limit plate (15) is threadedly connected to the top of the heat preservation barrel (4), and the lower limit plate (5) is threadedly connected to the bottom of the heat preservation barrel (4). The size of the test piece (17) matches the size of the heat preservation barrel (4) to facilitate the test piece (17) being embedded in the accommodation chamber of the heat preservation barrel (4). The airbag (18) is arranged around the outer sidewall of the test piece (17) and is located between the test piece (17) and the heat preservation barrel (4). The airbag (18) is in contact with the outer sidewall of the test piece (17) and the inner sidewall of the heat preservation barrel (4) respectively. The inflation channel (11) passes through the sidewall of the heat preservation barrel (4) and is connected to the airbag (18) to facilitate inflating the airbag (18).

5. A penetration shear test device for asphalt mixture with controllable confining pressure according to claim 2, characterized in that: The diameter of the pressing head (2) is 50 mm.

6. A penetration shear test device for asphalt mixture with controllable confining pressure according to claim 4, characterized in that: The diameter of the test piece (17) is 150 mm and the height is 100 mm.

7. A penetration shear test device for asphalt mixture with controllable confining pressure according to claim 4, characterized in that: A heating resistance wire (20) is further provided on the sidewall of the heat preservation barrel (4).

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