Asphalt pavement fatigue damage test device and test method under simulated humidity-temperature cycle

Abstract

The invention discloses a test device and a test method for simulating asphalt pavement fatigue damage under humidity-temperature circulation, and relates to the technical field of road engineering test equipment, the test device comprises an environmental box, a wheel rolling system, a rainfall system, a temperature control system, a containing assembly, a limiting assembly and a controller, the containing assembly comprises a bottom plate, an elastic cushion plate and a containing frame, the containing frame can simulate the horizontal constraint of the asphalt mixture test piece in the whole pavement structure so as to simulate the horizontal temperature stress, and the elastic base plate is arranged at the lower part of the asphalt mixture test piece, so that the vertical stress-strain characteristics of the asphalt pavement under the semi-rigid pavement structure can be simulated; further, the horizontal and vertical constraint states of the asphalt mixture test piece in the whole asphalt pavement structure can be really simulated, the humidity and temperature cyclic climate environment is simulated through the rainfall system and the temperature control system, and the wheel rolling system applies dynamic load to simulate the wheel rolling action of a travelling crane, so that the real pavement stress state is reproduced; and the accuracy of a test result is improved.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering test equipment, and in particular to a test device and a test method for fatigue damage of an asphalt pavement under simulated wet-temperature cycles. Background Art

[0002] The surface of the asphalt pavement is in direct contact with the natural environment and is subject to the influence of constantly changing external environmental factors. In addition, the repeated effects of vehicle loads will greatly damage its usability after a period of operation. Studies have found that the rainy season is the peak period for asphalt pavement damage, especially in hot and rainy areas in summer. Frequent rainfall causes the pavement material to be in a constant state of dry-wet conversion. Rainfall penetrates into the asphalt pavement to form high-speed dynamic water under the action of vehicle loads. The cumulative effect of the combined cycle of dynamic water pressure and temperature causes increased damage, greatly shortening the service life of the asphalt pavement and seriously affecting the road performance of the asphalt pavement. The asphalt mixture pavement is a complex structure. The existing test equipment cannot simulate the stress state of the asphalt mixture specimen in the real pavement structure, which leads to inaccurate test results. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a test device and a test method for fatigue damage of asphalt pavement under simulated wet-temperature cycle, which can simulate the stress state of asphalt mixture specimens in real pavement structure and improve the accuracy of test results.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides an asphalt pavement fatigue damage test device under simulated wet-temperature cycle, comprising an environmental box, a wheel rolling system, a rainfall system, a temperature control system, a containing component, a limit component and a controller, wherein the limit component is used to limit and fix the containing component at the bottom of the environmental box, the containing component comprises a bottom plate, an elastic pad and a containing frame, the bottom plate is arranged at the bottom of the environmental box, the elastic pad is arranged on the bottom plate, the containing frame is used to place asphalt mixture specimens, and the top surface of the elastic pad is used to connect with the bottom surface of one of the asphalt mixture specimens; the wheel rolling system is arranged at the upper part of the environmental box, and is used to roll the asphalt mixture specimen; the temperature control system comprises a heating component, a first temperature measuring component and a ventilation component, the heating component and the first temperature measuring component are both arranged in the environmental box, and the ventilation component is arranged on the environmental box; the rainfall system is used to spray water to the asphalt mixture specimen to simulate rainfall; the wheel rolling system, the rainfall system, the heating component, the first temperature measuring component and the ventilation component are all connected to the controller.

[0006] Preferably, a groove is provided on the upper portion of the bottom plate, and the elastic pad is arranged in the groove.

[0007] Preferably, the containing frame includes an inner frame, an outer frame and a connecting assembly, the interior of the inner frame is used to set the asphalt mixture specimen, the outer frame is sleeved on the outside of the inner frame, the connecting assembly is used to fix the outer frame to the inner frame, the lower part of the outer frame is provided with a plurality of tenons, and the upper part of the base plate is provided with a plurality of first tenons matching the tenon structure.

[0008] Preferably, the containing frames are provided in plurality, and the upper portion of the outer frame is provided with a plurality of second tenons matching the convex tenon structure.

[0009] Preferably, the ventilation components include an electric ventilation fan and electric shutters, the environmental chamber is provided with a mounting port, the electric ventilation fan is arranged in the mounting port, the electric shutters are arranged inside the environmental chamber and correspond to the position of the electric ventilation fan, and the electric ventilation fan and the electric shutters are both connected to the controller.

[0010] Preferably, the wheel rolling system includes a driving motor, a mounting rod, a mounting plate, a plurality of counterweights and a plurality of rolling assemblies. The driving motor is arranged at the bottom of the environmental chamber and connected to the controller. The lower end of the power output shaft of the driving motor is connected to the mounting rod. A first mounting hole is arranged on the mounting plate. A plurality of rolling assemblies are sequentially arranged at the lower part of the mounting plate along the circumferential direction. The mounting plate can be mounted on the mounting rod through the first mounting hole, and the mounting plate can rotate following the mounting rod. A second mounting hole is arranged on the counterweight. The counterweight can be mounted on the mounting rod through the second mounting hole and is located above the mounting plate, and the counterweight can rotate following the mounting rod.

[0011] Preferably, the wheel rolling system also includes two suspension support assemblies respectively located on both sides of the mounting plate, the suspension support assembly includes a screw rod, a support plate and a positioning bolt, the screw rod is installed on the top of the environmental box, and the screw rod extends into the environmental box, the support plate is provided on one side of the bottom of the screw rod, a first threaded hole is provided on the support plate, and a plurality of positioning holes are provided on the mounting plate along the circumference, and the positioning bolt is used to pass through one of the positioning holes and be installed in one of the first threaded holes.

[0012] Preferably, the rainfall system includes a temperature-controlled water tank, a temperature-control component, a second temperature-measuring component, a water level sensor, a first delivery pipe, a first water pump, a second delivery pipe, a second water pump and a spray component. The temperature-controlled water tank is arranged outside the environmental box, the temperature-control component, the second temperature-measuring component and the water level sensor are all arranged in the temperature-controlled water tank, one end of the first delivery pipe extends to the top of the temperature-controlled water tank, the first water pump is arranged on the first delivery pipe, one end of the second delivery pipe extends to the bottom of the temperature-controlled water tank, the second water pump is arranged on the second delivery pipe, the spray component is arranged at the upper part of the environmental box, the other end of the second delivery pipe is connected to the spray component, and the temperature-control component, the second temperature-measuring component, the water level sensor, the first water pump and the second water pump are all connected to the controller.

[0013] Preferably, the rainfall system further comprises a water discharge test bench, a water storage tank, a connecting pipe, a third delivery pipe and a third water pump, wherein the water storage tank is arranged at the lower part of the temperature-controlled water tank, one end of the third delivery pipe extends into the water storage tank, and the other end extends into the temperature-controlled water tank, the third water pump is arranged on the third delivery pipe and is located in the water storage tank, and the third water pump is connected to the controller; the water discharge test bench is arranged at the bottom of the environmental box, a water collection port is arranged in the middle of the water discharge test bench, and a plurality of water collection tanks are arranged on the water discharge test bench, each of which has a plurality of water collection tanks. The water collecting grooves are all connected with the water collecting port, one end of the connecting pipe is connected with the water collecting port, and the other end extends to the upper part of the water storage tank; the bottom plate is arranged on the water discharge test bench, and the limit assembly includes a U-shaped limit block, a fixed block, an adjusting bolt and a limit plate, the U-shaped limit block and the fixed block are respectively fixed on both sides of the upper part of the water discharge test bench, the opening of the U-shaped limit block faces the fixed block, the adjusting bolt is installed on the side of the fixed block close to the U-shaped limit block, and the limit plate is arranged on the side of the adjusting bolt away from the fixed block.

[0014] The present invention also provides a test method based on a test device for asphalt pavement fatigue damage under simulated wet-temperature cycles, comprising the following steps:

[0015] Step 1: Bond the annular side surface of the asphalt mixture specimen to the containing frame, bond the bottom surface of the asphalt mixture specimen to the top surface of the elastic pad through an adhesive layer of asphalt, and limit and fix the containing assembly to the bottom of the environmental box through a limiting assembly;

[0016] Step 2, the controller controls the wheel rolling system to apply a dynamic load to the asphalt mixture specimen, and the controller controls the rainfall system, the ventilation component and the heating component, and a certain rainfall time, a certain ventilation time and a certain heating time are used as a wet-temperature cycle and the cycle is repeated multiple times, thereby obtaining an asphalt mixture specimen that has been coupled with a wet-temperature cycle and a load;

[0017] Step 3: Take a core sample of an asphalt mixture specimen that has not been subjected to the coupling of moisture-temperature cycle and load, take out the first cylinder, and then slice the first cylinder from top to bottom to obtain a plurality of first pancake-shaped specimens. Perform uniaxial penetration tests on the plurality of first pancake-shaped specimens, measure the failure load of each of the first pancake-shaped specimens during uniaxial penetration, and calculate the shear strength of each of the first pancake-shaped specimens. The average value τ is obtained through the shear strength of each of the first pancake-shaped specimens. u , using τ u As the standard value of shear strength of asphalt mixture specimens;

[0018] Step 4: Drill core samples in the rolled area of ​​the asphalt mixture specimen that has been subjected to the coupling of moisture-temperature cycle and load, take out the second cylinder, and then slice the second cylinder from top to bottom to obtain a plurality of second pancake samples. Perform uniaxial penetration tests on the plurality of second pancake samples, measure the failure load of each second pancake sample during uniaxial penetration, and calculate the shear strength of each second pancake sample. The shear strength of the second pancake sample of the i-th layer is τ bi ;

[0019] Step 5: Calculate the shear strength attenuation rate of the second pancake-shaped specimen of the i-th layer according to the following formula:

[0020]

[0021] In the above formula, FDR bi is the shear strength decay rate of the second pancake specimen of the i-th layer, τ u It is the standard value of the shear strength of the asphalt mixture specimen; combined with the shear strength attenuation rate of the asphalt mixture specimen under the coupling of moisture-temperature cycle and load, the fatigue decay of the asphalt mixture under the coupling of moisture-temperature cycle and load is determined.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The asphalt pavement fatigue damage test device under simulated wet-temperature cycle of the present invention comprises an environmental chamber, a wheel rolling system, a rainfall system, a temperature control system, a containing component, a limiting component and a controller. The containing component comprises a bottom plate, an elastic pad and a containing frame. The bottom plate is arranged at the bottom of the environmental chamber, the elastic pad is arranged on the bottom plate, the annular side surface of the asphalt mixture specimen is bonded to the containing frame, the bottom surface of the asphalt mixture specimen is bonded to the top surface of the elastic pad by an adhesive layer of asphalt, and the containing component is limited and fixed to the bottom of the environmental chamber by the limiting component. The holding frame can simulate the horizontal constraints on the asphalt mixture specimen in the entire pavement structure, thereby simulating the horizontal temperature stress. By setting an elastic pad at the bottom of the asphalt mixture specimen, the vertical stress-strain characteristics of the asphalt pavement under the semi-rigid pavement structure can be simulated, and then the state of the asphalt mixture specimen being subject to horizontal and vertical constraints in the entire asphalt pavement structure can be truly simulated. At the same time, the rainfall system and temperature control system can be used to truly simulate the cyclic climate environment of sudden rainfall cooling and then high temperature in a high temperature environment, and dynamic loads can be applied through the wheel rolling system to simulate the rolling effect of the driving wheel, thereby reproducing the actual road stress state to improve the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the use of the asphalt pavement fatigue damage test device under simulated wet-temperature cycle provided by the present invention;

[0026] Figure 2 A schematic diagram of the structure of the suspension support assembly in the asphalt pavement fatigue damage test device under simulated wet-temperature cycle provided by the present invention when the mounting plate and the rolling assembly are suspended and supported;

[0027] Figure 3 This is an overall structural diagram of the components and asphalt mixture specimens contained in the asphalt pavement fatigue damage test device under simulated wet-temperature cycle provided by the present invention;

[0028] Figure 4 An exploded diagram of the components and asphalt mixture specimens contained in the asphalt pavement fatigue damage test device under simulated wet-temperature cycle provided by the present invention;

[0029] Figure 5 A schematic diagram of the structure of a water discharge test bench and a limiter assembly in a test device for fatigue damage of an asphalt pavement under simulated wet-temperature cycles provided by the present invention;

[0030] Figure 6 A schematic diagram of the structure of a mounting plate and multiple rolling components in a test device for fatigue damage of an asphalt pavement under simulated wet-temperature cycles provided by the present invention;

[0031] Figure 7 A schematic diagram of the structure of multiple rolling components in the asphalt pavement fatigue damage test device under simulated wet-temperature cycle provided by the present invention;

[0032] Figure 8 A schematic diagram of wheel tracks and sampling during a test of the asphalt pavement fatigue damage test device under simulated wet-temperature cycles provided by the present invention;

[0033] Fig. 9 It is a schematic diagram of performing a uniaxial penetration test on the first pancake-shaped sample or the second pancake-shaped sample in the present invention.

[0034] Description of reference numerals: 1. environmental chamber; 2. bottom plate; 3. groove; 4. first tenon; 5. elastic pad; 6. inner frame; 7. outer frame; 8. connecting bolt; 9. convex tenon; 10. second tenon; 11. asphalt mixture specimen; 12. driving motor; 13. mounting rod; 14. mounting plate; 15. counterweight; 16. first connecting rod; 17. connecting plate; 18. rubber wheel; 19. second connecting rod; 20. screw; 21. support plate; 22. positioning bolt; 23. heating component; 24. first temperature measuring component; 25. electric shutter; 26. electric ventilation fan; 27. temperature-controlled water tank; 28. Temperature control component; 29. ​​Second temperature measuring component; 30. Water level sensor; 31. First delivery pipe; 32. First water pump; 33. Second delivery pipe; 34. Second water pump; 35. Spray pipe; 36. Annular nozzle; 37. Water storage tank; 38. Third delivery pipe; 39. Third water pump; 40. Water discharge test bench; 41. U-shaped limit block; 42. Fixed block; 43. Adjustment bolt; 44. Limit plate; 45. T-shaped bolt; 46. First V-shaped groove; 47. Second V-shaped groove; 48. Water gathering port; 49. Connecting pipe; 50. Controller; 51. Crushed area; 52. Second cylinder. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a test device and a test method for fatigue damage of asphalt pavement under simulated wet-temperature cycle, which can simulate the stress state of asphalt mixture specimens in real pavement structure and improve the accuracy of test results.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1-Figure 9 As shown, this embodiment provides an asphalt pavement fatigue damage test device under simulated wet-temperature cycle, including an environmental box 1, a wheel rolling system, a rainfall system, a temperature control system, a containing component, a limiting component and a controller 50, the limiting component is used to limit and fix the containing component at the bottom of the environmental box 1, the containing component includes a bottom plate 2, an elastic pad 5 and a containing frame, the bottom plate 2 is arranged at the bottom of the environmental box 1, the elastic pad 5 is arranged on the bottom plate 2, the containing frame is used to place an asphalt mixture specimen 11, and the top surface of the elastic pad 5 is used to contact an asphalt mixture specimen 11. The bottom surface of the green mixture specimen 11 is connected; the wheel rolling system is arranged at the upper part of the environmental chamber 1, and is used to roll the asphalt mixture specimen 11; the temperature control system includes a heating component 23, a first temperature measuring component 24 and a ventilation component, the heating component 23 and the first temperature measuring component 24 are both arranged in the environmental chamber 1, and the ventilation component is arranged on the environmental chamber 1; the rainfall system is used to spray water to the asphalt mixture specimen 11 to simulate rainfall; the wheel rolling system, the rainfall system, the heating component 23, the first temperature measuring component 24 and the ventilation component are all connected to the controller 50.

[0039] The containing frame in this embodiment can simulate the horizontal constraints on the asphalt mixture specimen 11 in the entire pavement structure, thereby simulating horizontal temperature stress. By arranging an elastic pad 5 at the bottom of the asphalt mixture specimen 11, the vertical stress-strain characteristics of the asphalt pavement under the semi-rigid pavement structure can be simulated, and then the state of the asphalt mixture specimen 11 being subject to horizontal and vertical constraints in the entire asphalt pavement structure can be truly simulated. At the same time, the rainfall system and the temperature control system can truly simulate the cyclic climate environment of sudden rainfall cooling and then high temperature in a high temperature environment, while considering the comprehensive effects of large temperature differences, rainwater, and surface runoff water on the asphalt pavement, and applying dynamic loads through the wheel rolling system to simulate the wheel rolling effect of the road, thereby reproducing the actual road stress state to improve the accuracy of the test results.

[0040] In order to achieve stable placement of the elastic pad 5 , a groove 3 is provided on the upper portion of the bottom plate 2 , and the elastic pad 5 is arranged in the groove 3 , and the elastic pad 5 matches the groove 3 in structure.

[0041] The elastic pad 5 in this embodiment is a rubber pad with a rebound modulus of 50 MPa, which is used to simulate the rebound modulus of a semi-rigid roadbed. The bottom plate 2 is a steel bottom plate.

[0042] like Figure 4As shown, the containing frame includes an inner frame 6, an outer frame 7 and a connecting assembly. The interior of the inner frame 6 is used to set the asphalt mixture specimen 11, the outer frame 7 is sleeved on the outside of the inner frame 6, and the connecting assembly is used to fix the outer frame 7 on the inner frame 6. A plurality of tenons 9 are provided at the lower portion of the outer frame 7, and a plurality of first tenons 4 matching the structure of the tenons 9 are provided at the upper portion of the bottom plate 2, so that the outer frame 7 connected to the bottom plate 2 does not undergo horizontal displacement.

[0043] Specifically, the connecting assembly includes a plurality of connecting bolts 8, a plurality of through holes are provided on the outer frame 7, and a second threaded hole corresponding to the through holes is provided on the inner frame 6. Each connecting bolt 8 passes through a through hole and is installed in a second threaded hole to realize the connection between the outer frame 7 and the inner frame 6.

[0044] In this embodiment, the outer frame 7 is a steel outer frame, the inner frame 6 is a plastic inner frame, and the plastic inner frame 6 is a disposable consumable material.

[0045] like Figure 3 As shown, there are multiple containing frames, and the upper part of the outer frame 7 is provided with multiple second tenons 10 matching the structure of the convex tenons 9, so that two adjacent butt-jointed outer frames 7 do not undergo relative displacement in the horizontal direction.

[0046] When assembling the specimens, first use epoxy resin to bond the four walls of the prepared asphalt mixture specimen 11 to the inner frame 6, and then anchor the inner frame 6 to the outer frame 7 through the connecting bolts 8 to assemble into a single-layer module specimen group; when simulating one layer of asphalt mixture, place the elastic pad 5 on the bottom plate 2, and then bond the assembled single-layer module specimen group to the elastic pad 5 through the adhesive layer of asphalt. If it is necessary to simulate the asphalt mixture surface layer of the 2-layer and 3-layer structure, apply the adhesive layer of asphalt on the surface of the asphalt mixture specimen 11 of the single-layer module specimen group in the lower layer, and quickly place the single-layer module specimen group in the upper layer. Finally, place the entire module specimen group in the limit assembly. In this embodiment, a module specimen group of 1 to 3 layers can be assembled, so that different pavement structures can be simulated.

[0047] In this specific embodiment, the outer frame 7 and the inner frame 6 are both rectangular frames, the inner wall size of the outer frame 7 is 310mm×310mm×50mm, the thickness is 10mm, each side of the outer frame 7 is provided with 3 through holes, the top four corners are provided with 10mm×10mm×10mm second concave tenon 10, and the bottom four corners are provided with 10mm×10mm×10mm convex tenon 9, so that the adjacent outer frames 7 are not displaced in the horizontal direction after docking and installation. The inner wall size of the inner frame 6 is 300mm×300mm×50mm, the thickness is 5mm, and each side of the inner frame 6 is provided with 3 second threaded holes. The size of the elastic pad 5 is 310mm×310mm×20mm, the size of the groove 3 on the upper part of the bottom plate 2 is 310mm×310mm×10mm, which is used to place the elastic pad 5, and the top four corners of the bottom plate 2 are provided with a first concave tenon 4, which is used to nest the outer frame 7 at the bottom, so that the outer frame 7 at the bottom does not displace in the horizontal direction. The size of the asphalt mixture specimen 11 is 300 mm×300 m×50 mm.

[0048] The ventilation components in this embodiment include an electric ventilation fan 26 and an electric shutter 25. An installation port is provided on the environmental chamber 1. The electric ventilation fan 26 is arranged in the installation port. The electric shutter 25 is arranged inside the environmental chamber 1 and corresponds to the position of the electric ventilation fan 26. The electric ventilation fan 26 and the electric shutter 25 are both connected to the controller 50.

[0049] Specifically, two ventilation components are provided, and the two ventilation components are respectively provided on both sides of the environmental box 1 .

[0050] When moisture needs to be removed after simulated precipitation, the electric ventilation fan 26 and the electric shutters 25 are opened at the same time, and are closed at the same time after ventilation is completed to isolate the air inside and outside the environmental box 1. The heating component 23 and the first temperature measuring component 24 start working, and stop working when the temperature inside the environmental box 1 reaches a certain temperature.

[0051] The heating component 23 in this embodiment is a heating lamp, and the first temperature measuring component 24 is an in-box temperature sensor.

[0052] The wheel rolling system includes a driving motor 1, a mounting rod 13, a mounting plate 14, a plurality of counterweights 15 and a plurality of rolling components. The driving motor 1 is arranged at the bottom of the environmental chamber 1 and is connected to the controller 50. The lower end of the power output shaft of the driving motor 1 is connected to the mounting rod 13. The mounting plate 14 is provided with a first mounting hole. The plurality of rolling components are sequentially arranged at the lower part of the mounting plate 14 along the circumferential direction. The mounting plate 14 can be mounted on the mounting rod 13 through the first mounting hole, and the mounting plate 14 can rotate with the mounting rod 13. The counterweight 15 is provided with a second mounting hole. The counterweight 15 can be mounted on the mounting rod 13 through the second mounting hole and is located above the mounting plate 14, and the counterweight 15 can rotate with the mounting rod 13.

[0053] By adjusting the number of counterweights 15 arranged on the upper part of the mounting plate 14, the wheel load applied to the asphalt mixture specimen 11 can be adjusted, and by adjusting the rotational speed of the drive motor 1, different vehicle speeds can be simulated. It can be seen that the wheel rolling system in this embodiment can simulate the actual road surface stress conditions of the asphalt mixture specimen 11 under continuous, different vehicle speeds and different wheel loads.

[0054] In this specific embodiment, the mounting rod 13 is a rectangular rod, the first mounting hole is a first rectangular hole matching the rectangular rod structure, and the second mounting hole is a second rectangular hole matching the rectangular rod structure.

[0055] like Figure 6 and Figure 7 As shown, the rolling assembly includes a first connecting rod 16 , a connecting plate 17 and a rubber wheel 18 . The upper and lower ends of the first connecting rod 16 are respectively connected to the mounting plate 14 and the connecting plate 17 . The rubber wheel 18 is rotatably mounted on the lower part of the connecting plate 17 .

[0056] In order to make the structure more stable, any two adjacent connecting plates 17 are connected via a second connecting rod 19 .

[0057] The wheel rolling system also includes two suspension support assemblies respectively located on both sides of the mounting plate 14, the suspension support assembly includes a screw 20, a support plate 21 and a positioning bolt 22, the screw 20 is installed on the top of the environmental chamber 1, and the screw 20 extends into the environmental chamber 1, a support plate 21 is provided on one side of the bottom of the screw 20, a first threaded hole is provided on the support plate 21, a plurality of positioning holes are provided along the circumference of the mounting plate 14, and the positioning bolt 22 is used to pass through a positioning hole and be installed in a first threaded hole.

[0058] like Figure 1 As shown, when the asphalt mixture specimen 11 below needs to be replaced, the mounting plate 14 and the rolling assembly need to be lifted upward and kept at a certain height, and the support plate 21 is located on the side away from the mounting plate 14 by rotating the screw rod 20 so that it does not hinder the upward movement of the mounting plate 14, and the mounting plate 14 is lifted upward and located above the support plate 21. Figure 2 As shown, the screw rod 20 is rotated so that the support plate 21 is located below the mounting plate 14, and the positioning bolt 22 is extended through the positioning hole to a first threaded hole on the mounting plate 14. The suspension support components on both sides perform the above operations to achieve the suspension and support of the mounting plate 14. After the new asphalt mixture specimen 11 is installed, the positioning bolt 22 is removed, and the screw rod 20 is rotated to rotate the support plate 21 to the side away from the mounting plate 14 to achieve the lowering of the mounting plate 14.

[0059] The rainfall system includes a temperature-controlled water tank 27, a temperature-controlled component 28, a second temperature-measuring component 29, a water level sensor 30, a first delivery pipe 31, a first water pump 32, a second delivery pipe 33, a second water pump 34 and a spray component. The temperature-controlled water tank 27 is arranged outside the environmental box 1, and the temperature-controlled component 28, the second temperature-measuring component 29 and the water level sensor 30 are all arranged in the temperature-controlled water tank 27. The temperature-controlled component 28 is arranged at the lower part of the temperature-controlled water tank 27. The second temperature-measuring component 29 is used to monitor the temperature of the water in the temperature-controlled water tank 27. The water level sensor 30 is arranged Placed in the upper part of the temperature-controlled water tank 27, one end of the first delivery pipe 31 extends to the top of the temperature-controlled water tank 27, the first water pump 32 is arranged on the first delivery pipe 31, one end of the second delivery pipe 33 extends to the bottom of the temperature-controlled water tank 27, the second water pump 34 is arranged on the second delivery pipe 33, the spray component is arranged in the upper part of the environmental box 1, the other end of the second delivery pipe 33 is connected to the spray component, the temperature control component 28, the second temperature measuring component 29, the water level sensor 30, the first water pump 32 and the second water pump 34 are all connected to the controller 50.

[0060] The spray component in this embodiment includes an annular nozzle 36 and two spray pipes 25 respectively arranged on both sides of the upper part of the annular nozzle 36. The lower end of the spray pipe 25 is connected to the annular nozzle 36. The annular nozzle 36 is sleeved on the outside of the mounting rod 13. The upper end of the spray pipe 25 is installed on the top surface of the environmental box 1 and is connected to the second delivery pipe 33, so that water enters the spray pipe 25 through the second delivery pipe 33 and is then sprayed by the annular nozzle 36. The annular nozzle 36 is arranged directly above the asphalt mixture specimen 11 to evenly spray the surface of the asphalt mixture specimen 11. The rainfall is controlled by the controller 50 and the second water pump 34.

[0061] The environmental box 1 in this embodiment is provided with a box door, which is convenient for placing and removing the asphalt mixture test piece 11 by opening the box door. The side wall of the environmental box 1 is filled with insulation material to achieve the insulation of the internal environment of the box. The second delivery pipe 33 is arranged in the side wall of the environmental box 1, and the controller 50 controls the electronic components in the environmental box 1 through the circuit in the side wall of the environmental box 1.

[0062] like Figure 5As shown, the rainfall system also includes a water discharge test bench 40, a water storage tank 37, a connecting pipe 49, a third delivery pipe 38 and a third water pump 39. The water storage tank 37 is arranged at the lower part of the temperature-controlled water tank 27. One end of the third delivery pipe 38 extends into the water storage tank 37, and the other end extends into the temperature-controlled water tank 27. The third water pump 39 is arranged on the third delivery pipe 38 and is located in the water storage tank 37. The third water pump 39 is connected to the controller 50; the water discharge test bench 40 is arranged at the bottom of the environmental chamber 1, and a water collection port 48 is arranged in the middle of the water discharge test bench 40. A plurality of water collection tanks are arranged on the water discharge test bench 40, and each water collection tank is connected to the water collection port 48. One end of the connecting pipe 49 is connected to the water collection port 48, and the other end extends to the upper part of the water storage tank 37.

[0063] Specifically, the multiple water collecting grooves include a first V-shaped groove 46 and multiple second V-shaped grooves 47. The water collecting port 48 is arranged at the lowest point in the center of the first V-shaped groove 46. Each second V-shaped groove 47 is cross-arranged with the first V-shaped groove 46. The second V-shaped grooves 47 coincide with the intersection of the first V-shaped groove 46 and the lowest point in the center of the second V-shaped groove 47.

[0064] The bottom plate 2 is arranged on the water discharge test bench 40, and the limiting assembly includes a U-shaped limiting block 41, a fixed block 42, an adjusting bolt 43 and a limiting plate 44. The U-shaped limiting block 41 and the fixed block 42 are respectively fixed on both sides of the upper part of the water discharge test bench 40, and the opening of the U-shaped limiting block 41 faces the fixed block 42. The side of the fixed block 42 close to the U-shaped limiting block 41 is equipped with an adjusting bolt 43, and the side of the adjusting bolt 43 away from the fixed block 42 is equipped with a limiting plate 44. The fixed block 42 in this embodiment is fixed to the water discharge test bench 40 by a T-shaped bolt 45.

[0065] During installation, one side of the base plate 2 is located in the opening of the U-shaped limit block 41, and the U-shaped limit block 41 limits the front and rear displacement in the horizontal direction of the base plate 2. The adjusting bolt 43 is turned so that the limit plate 44 abuts against the other side of the base plate 2, thereby limiting the left and right displacement in the horizontal direction of the base plate 2 through the U-shaped limit block 41 and the limit plate 44.

[0066] The water discharge test bench 40 is arranged at the bottom of the environmental box 1, and collects the precipitation in the environmental box 1 and injects it into the water storage tank 37; the water storage tank 37 and the temperature control water tank 27 are arranged outside the environmental box 1, isolated from each other and connected by the third water pump 39. When all the water in the temperature control water tank 27 is delivered to the annular nozzle 36, the recovered water in the water storage tank 37 is delivered to the temperature control water tank 27 by the third water pump 39; the temperature control water tank 27 is provided with a temperature control component 28, a second temperature measuring component 29 and a water level sensor 30. When the water level sensor 30 detects that the water volume in the temperature control water tank 27 is lower than the working volume, the temperature control water tank 27 can replenish the lost water by connecting the external first delivery pipe 31 and the first water pump 32. When the second temperature measuring component 29 detects that the water temperature does not meet the preset value, the controller 50 controls the temperature control component 28 to cool or heat.

[0067] The temperature control component 28 in this embodiment is a temperature control copper tube, and the second temperature measuring component 29 is a water temperature sensor.

[0068] This embodiment also provides a test method based on a test device for simulating fatigue damage of asphalt pavement under a wet-temperature cycle, comprising the following steps:

[0069] Step 1: First prepare 2 to 4 asphalt mixture specimens 11 with the same raw materials and gradation, reserve at least one asphalt mixture specimen 11 that has not been subjected to the coupling of humidity and temperature cycle and load for subsequent sampling, and the remaining asphalt mixture specimens 11 are used for simulation tests. The annular side of the asphalt mixture specimen 11 is bonded to the containing frame, the bottom surface of the asphalt mixture specimen 11 is bonded to the top surface of the elastic pad 5 through the adhesive layer of asphalt, and the containing assembly is fixed to the bottom of the environmental chamber 1 through the limiting assembly.

[0070] Specifically, first use epoxy resin to bond the four walls of the prepared asphalt mixture specimen 11 into the inner frame 6, and then anchor the inner frame 6 to the outer frame 7 through the connecting bolts 8 to assemble into a single-layer module specimen group; place the elastic pad 5 on the bottom plate 2, apply a tack coat of asphalt on the upper surface of the elastic pad 5, and quickly place the assembled single-layer module specimen group on the elastic pad 5 to obtain a module specimen group; if it is necessary to simulate a multi-layer structure of an asphalt mixture surface layer, apply a tack coat of asphalt on the surface of the asphalt mixture specimen 11 of the single-layer module specimen group in the lower layer, and quickly place the single-layer module specimen group in the upper layer to assemble into the required asphalt mixture surface layer structure to obtain a module specimen group. Finally, place the module specimen group between the U-shaped limit block 41 and the limit plate 44 on the water discharge test bench 40, and turn the adjusting bolt 43 to fix it so that it does not move in the horizontal direction.

[0071] Step 2, the controller 50 controls the wheel rolling system to apply a dynamic load to the asphalt mixture specimen 11. The controller 50 controls the rainfall system, the ventilation component and the heating component 23, and repeats multiple times a wet-temperature cycle with a certain rainfall time, a certain ventilation time and a certain heating time, thereby obtaining an asphalt mixture specimen 11 that has been coupled with a wet-temperature cycle and a load.

[0072] Specifically, the test values ​​are set: the tire loading width of the rubber wheel 18 is 50mm, the wheel load is 0-3KN, the loading speed is 0-30km / h, the rainfall is 0-250mm / d, the air temperature in the environmental chamber 1 is 10-80℃, and the water temperature in the temperature-controlled water tank 27 is 0-70℃. The above test values ​​are set according to actual test requirements; a wet-temperature cycle is 5-10min of rainfall, 30s of ventilation, and 45-60min of heating, and the number of cycle cycles is 7-15 times. Start the test after the data is set.

[0073] The driving motor 1 drives the mounting plate 14 to rotate, thereby driving the rubber wheel 18 to roll the asphalt mixture specimen 11 at a preset dynamic speed. By adjusting the number of counterweights 15 , the rubber wheel 18 applies a preset dynamic load to the asphalt mixture specimen 11 .

[0074] The heating lamp and the temperature sensor in the box raise the temperature in the environmental box 1 to the preset temperature, and turn off after continuous heating for a preset time; rainfall occurs according to the preset time and water temperature, and at the same time, the water discharge test bench 40 collects the precipitation and transports it to the water storage tank 37; after the rainfall is over, the electric shutters 25 and the electric ventilation fan 26 are opened at the same time, and ventilation is carried out for 30 seconds, which is a wet-temperature cycle.

[0075] If there are special requirements for the surface temperature of the asphalt mixture specimen 11, a specimen surface temperature sensor can be set on the surface of the asphalt mixture specimen 11. The specimen surface temperature sensor is connected to the controller 50. The specimen surface temperature sensor in this embodiment is a patch temperature sensor. The target temperature of the surface of the asphalt mixture specimen 11 is preset in the controller 50 and detected by the specimen surface temperature sensor. The heating lamp is heated in the environmental chamber 1. When the surface temperature of the asphalt mixture specimen 11 reaches the preset temperature, it is turned off after heating for a predetermined period of time.

[0076] It should be noted that, according to the test requirements, the working process of the heating lamp is coordinated with the temperature sensor in the box or the temperature sensor on the surface of the test piece.

[0077] Step 3: Take a core sample of an asphalt mixture specimen 11 that has not been subjected to the coupling of moisture-temperature cycle and load, take out the first cylinder, and then slice the first cylinder from top to bottom to obtain a plurality of first pancake-shaped specimens. Perform uniaxial penetration tests on the plurality of first pancake-shaped specimens, measure the failure load of each first pancake-shaped specimen during uniaxial penetration, and calculate the shear strength of each first pancake-shaped specimen. The average value τ is obtained through the shear strength of each first pancake-shaped specimen. u , using τ u As the standard value of the shear strength of the asphalt mixture specimen 11.

[0078] Specifically, take out a first cylinder with a diameter of 50 mm and a height of 50 mm, and then slice the first cylinder into slices every 10 mm to obtain a first pancake-shaped sample with a diameter of 50 mm and a height of 10 mm. Mark them with serial numbers a1 to a5 from top to bottom, such as Fig. 9 As shown, each time a first pancake sample is placed on a steel pipe with an inner diameter of 35 mm, an outer diameter of 50 mm, and a height of 30 mm, and a uniaxial penetration test is performed on the MTS testing machine using a penetration head with a diameter of 10 mm to measure the failure load P of each layer when uniaxially penetrated from top to bottom. a1 ~P a5 , and calculate the shear strength τ of each slice a1 , τ a2 , τ a3 , τ a4 , τ a5 and τ a1 ~τ a5 Average value τ u The calculation formula is as follows:

[0079]

[0080] In the above formula, τ ai is the shear strength of the first pancake specimen of the i-th layer (MPa), P ai is the failure load of the first pancake specimen of the i-th layer (N), A is the cross-sectional area of ​​the penetration rod (mm 2 ).

[0081] In order to make the test results more accurate, for the same asphalt mixture specimen 11 that has not been subjected to the coupling of humidity and temperature cycles and loads, core sampling is performed to take n first cylinders for parallel testing, and then each first cylinder is sliced ​​from top to bottom in sequence, and the first pancake specimen of the i-th layer of each first cylinder is taken for uniaxial penetration test, and the average shear strength of the first pancake specimens of the i-th layer of all first cylinders is obtained. The shear strength of the jth first pancake-shaped specimen among the multiple first pancake-shaped specimens in the i-th layer is τ aij , for a data in a set of measured values ​​and the average value When the difference is greater than k times the standard deviation s, the measured value should be discarded and the average of the remaining measured values ​​should be used as the test result. When the number of tests n is 3, 4, 5, and 6, the k values ​​are 1.15, 1.46, 1.67, and 1.82 respectively. The calculation formula for the standard deviation s is as follows:

[0082]

[0083] Step 4: After simulating a large-scale wet-temperature cycle and load action, take out the module specimen group, unscrew the connecting bolts 8 and take out the asphalt mixture specimen 11 and the inner frame 6. Figure 8 As shown, a core sample is drilled in the rolled area 51 of the asphalt mixture specimen 11 that has been subjected to the coupling of moisture-temperature cycle and load, and the second cylinder 52 is taken out. The second cylinder 52 is then sliced ​​from top to bottom to obtain a plurality of second pancake-shaped samples. Uniaxial penetration tests are performed on the plurality of second pancake-shaped samples, and the failure load of each second pancake-shaped sample during uniaxial penetration is measured, and the shear strength of each second pancake-shaped sample is calculated. The shear strength of the second pancake-shaped sample of the i-th layer is τ bi .

[0084] Specifically, take out a second cylinder 52 with a diameter of 50 mm and a height of 50 mm, and then slice the second cylinder 52 into slices every 10 mm to obtain a second pancake-shaped sample with a diameter of 50 mm and a height of 10 mm. Mark them b1 to b5 in order from top to bottom, as shown in FIG. Fig. 9 As shown, a second pancake-shaped sample is then placed on a steel pipe with an inner diameter of 35 mm, an outer diameter of 50 mm, and a height of 30 mm. A uniaxial penetration test is performed on the MTS testing machine using a penetration head with a diameter of 10 mm to measure the failure load P of each layer when uniaxially penetrated from top to bottom. b1 ~P b5 , and calculate the shear strength τ of each slice b1 ~τ b5 The calculation formula is as follows:

[0085]

[0086] In the above formula, τ bi is the shear strength of the second pancake specimen of the i-th layer (MPa), P bi is the failure load of the second pancake specimen of the i-th layer (N), A is the cross-sectional area of ​​the penetration rod (mm 2 ).

[0087] Step 5: Calculate the shear strength attenuation rate of the second pancake specimen of the i-th layer according to the following formula:

[0088]

[0089] In the above formula, FDR biis the shear strength decay rate of the second pancake specimen of the i-th layer, τ u It is the standard value of the shear strength of asphalt mixture specimen 11.

[0090] The fatigue decay of the asphalt mixture under the coupling of moisture-temperature cycle and load is determined by combining the shear strength attenuation rate of the asphalt mixture specimen 11 under the coupling of moisture-temperature cycle and load. If the accuracy of the test results needs to be further improved, multiple second cylinders 52 can be drilled and sampled in parallel in the same asphalt mixture specimen 11 after the coupling of moisture-temperature cycle and load.

[0091] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A device for testing fatigue damage of asphalt pavement under simulated humidity and temperature cycle, characterized in that: It includes an environmental box, a wheel rolling system, a rainfall system, a temperature control system, a containing component, a limit component and a controller, the limit component is used to limit and fix the containing component at the bottom of the environmental box, the containing component includes a bottom plate, an elastic pad and a containing frame, the bottom plate is arranged at the bottom of the environmental box, the elastic pad is arranged on the bottom plate, the containing frame is used to place asphalt mixture specimens, and the top surface of the elastic pad is used to connect with the bottom surface of one of the asphalt mixture specimens; the wheel rolling system is arranged at the upper part of the environmental box, and is used to roll the asphalt mixture specimens; the temperature control system includes a heating component, a first temperature measuring component and a ventilation component, the heating component and the first temperature measuring component are both arranged in the environmental box, and the ventilation component is arranged on the environmental box; the rainfall system is used to spray water to the asphalt mixture specimens to simulate rainfall; the wheel rolling system, the rainfall system, the heating component, the first temperature measuring component and the ventilation component are all connected to the controller.

2. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 1 is characterized in that: A groove is arranged on the upper part of the bottom plate, and the elastic pad is arranged in the groove.

3. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 1 is characterized in that: The containing frame includes an inner frame, an outer frame and a connecting assembly. The interior of the inner frame is used to set the asphalt mixture specimen, and the outer frame is sleeved on the outside of the inner frame. The connecting assembly is used to fix the outer frame to the inner frame. The lower part of the outer frame is provided with a plurality of tenons, and the upper part of the bottom plate is provided with a plurality of first tenons matching the tenon structure.

4. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 3 is characterized in that: The containing frames are arranged in plurality, and the upper portion of the outer frame is provided with a plurality of second tenons matching the convex tenon structure.

5. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 1, characterized in that: The ventilation components include an electric ventilation fan and an electric shutter. The environmental chamber is provided with a mounting port, the electric ventilation fan is arranged in the mounting port, the electric shutter is arranged inside the environmental chamber and corresponds to the position of the electric ventilation fan, and the electric ventilation fan and the electric shutter are both connected to the controller.

6. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 1, characterized in that: The wheel rolling system includes a driving motor, a mounting rod, a mounting plate, a plurality of counterweights and a plurality of rolling assemblies. The driving motor is arranged at the bottom of the environmental chamber and connected to the controller. The lower end of the power output shaft of the driving motor is connected to the mounting rod. A first mounting hole is arranged on the mounting plate. A plurality of rolling assemblies are sequentially arranged at the lower part of the mounting plate along the circumferential direction. The mounting plate can be mounted on the mounting rod through the first mounting hole, and the mounting plate can rotate with the mounting rod. A second mounting hole is arranged on the counterweight. The counterweight can be mounted on the mounting rod through the second mounting hole and is located above the mounting plate, and the counterweight can rotate with the mounting rod.

7. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 6, characterized in that: The wheel rolling system also includes two suspension support assemblies respectively located on both sides of the mounting plate, the suspension support assembly includes a screw rod, a support plate and a positioning bolt, the screw rod is installed on the top of the environmental box, and the screw rod extends into the environmental box, the support plate is provided on one side of the bottom of the screw rod, the support plate is provided with a first threaded hole, and a plurality of positioning holes are provided on the mounting plate along the circumference, and the positioning bolt is used to pass through one of the positioning holes and be installed in one of the first threaded holes.

8. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 1, characterized in that: The rainfall system includes a temperature-controlled water tank, a temperature-control component, a second temperature-measuring component, a water level sensor, a first delivery pipe, a first water pump, a second delivery pipe, a second water pump and a spray component. The temperature-controlled water tank is arranged outside the environmental box, the temperature-control component, the second temperature-measuring component and the water level sensor are all arranged in the temperature-controlled water tank, one end of the first delivery pipe extends to the top of the temperature-controlled water tank, the first water pump is arranged on the first delivery pipe, one end of the second delivery pipe extends to the bottom of the temperature-controlled water tank, the second water pump is arranged on the second delivery pipe, the spray component is arranged at the upper part of the environmental box, the other end of the second delivery pipe is connected to the spray component, the temperature-control component, the second temperature-measuring component, the water level sensor, the first water pump and the second water pump are all connected to the controller.

9. The asphalt pavement fatigue damage test device under simulated wet-temperature cycle according to claim 8, characterized in that: The rainfall system also includes a water discharge test bench, a water storage tank, a connecting pipe, a third delivery pipe and a third water pump. The water storage tank is arranged at the lower part of the temperature-controlled water tank. One end of the third delivery pipe extends into the water storage tank, and the other end extends into the temperature-controlled water tank. The third water pump is arranged on the third delivery pipe and is located in the water storage tank. The third water pump is connected to the controller. The water discharge test bench is arranged at the bottom of the environmental box. A water collection port is arranged in the middle of the water discharge test bench. A plurality of water collection tanks are arranged on the water discharge test bench. Each of the water collection tanks has a plurality of water collection tanks. The grooves are all connected with the water gathering port, one end of the connecting pipe is connected with the water gathering port, and the other end extends to the upper part of the water storage tank; the bottom plate is arranged on the water discharge test bench, and the limit assembly includes a U-shaped limit block, a fixed block, an adjusting bolt and a limit plate, the U-shaped limit block and the fixed block are respectively fixed on both sides of the upper part of the water discharge test bench, the opening of the U-shaped limit block faces the fixed block, the adjusting bolt is installed on the side of the fixed block close to the U-shaped limit block, and the limit plate is arranged on the side of the adjusting bolt away from the fixed block.

10. A test method based on the asphalt pavement fatigue damage test device under simulated wet-temperature cycle as described in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Bond the annular side surface of the asphalt mixture specimen to the containing frame, bond the bottom surface of the asphalt mixture specimen to the top surface of the elastic pad through an adhesive layer of asphalt, and limit and fix the containing assembly to the bottom of the environmental box through a limiting assembly; Step 2, the controller controls the wheel rolling system to apply a dynamic load to the asphalt mixture specimen, and the controller controls the rainfall system, the ventilation component and the heating component, and a certain rainfall time, a certain ventilation time and a certain heating time are used as a wet-temperature cycle and the cycle is repeated multiple times, thereby obtaining an asphalt mixture specimen that has been coupled with a wet-temperature cycle and a load; Step 3: Take a core sample of an asphalt mixture specimen that has not been subjected to the coupling of moisture-temperature cycle and load, take out the first cylinder, and then slice the first cylinder from top to bottom to obtain a plurality of first pancake-shaped specimens. Perform uniaxial penetration tests on the plurality of first pancake-shaped specimens, measure the failure load of each of the first pancake-shaped specimens during uniaxial penetration, and calculate the shear strength of each of the first pancake-shaped specimens. The average value τ is obtained through the shear strength of each of the first pancake-shaped specimens. u , using τ u As the standard value of shear strength of asphalt mixture specimens; Step 4: Drill core samples in the rolled area of ​​the asphalt mixture specimen that has been subjected to the coupling of moisture-temperature cycle and load, take out the second cylinder, and then slice the second cylinder from top to bottom to obtain a plurality of second pancake samples. Perform uniaxial penetration tests on the plurality of second pancake samples, measure the failure load of each second pancake sample during uniaxial penetration, and calculate the shear strength of each second pancake sample. The shear strength of the second pancake sample of the i-th layer is τ bi ; Step 5: Calculate the shear strength attenuation rate of the second pancake-shaped specimen of the i-th layer according to the following formula: In the above formula, FDR bi is the shear strength decay rate of the second pancake specimen of the i-th layer, τ u It is the standard value of the shear strength of the asphalt mixture specimen; combined with the shear strength attenuation rate of the asphalt mixture specimen under the coupling of moisture-temperature cycle and load, the fatigue decay of the asphalt mixture under the coupling of moisture-temperature cycle and load is determined.

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