Freeze-thaw damage simulation test system for airport pavement in complex service environment

Abstract

The invention provides an airport pavement freeze-thaw damage simulation test system in a complex service environment, which comprises a test cabin, a temperature control system, a loading system, a spraying system, a scanning system and a control system, and is characterized in that the temperature control system is arranged on the inner top wall and the inner side wall of the test cabin and is used for simulating sunlight and a temperature gradient which is gradually reduced from top to bottom; the loading system is arranged in the test cabin and used for loading loads to the test piece and the reduced-scale road surface, the spraying system is arranged at the top of the test cabin and used for simulating damage of moisture and deicing fluid to the test piece and the reduced-scale road surface, the scanning system is arranged at the top of the test cabin and used for scanning morphology characteristics of the test piece and the reduced-scale road surface, and the control system is arranged outside the test cabin and used for controlling the test piece and the reduced-scale road surface. And the controller is in communication connection with the temperature control system, the loading system, the spraying system and the scanning system. According to the invention, the temperature, humidity, deicing fluid and mechanical load of an actual environment can be comprehensively simulated, comprehensive data support in a test process is provided, and the accuracy of material performance evaluation is improved.

Description

Technical Field

[0001] This invention relates to the field of technology, and in particular to a simulation test system for freeze-thaw damage of airport pavement under complex service environments. Background Technology

[0002] As a critical infrastructure for aircraft takeoff and landing, the material properties of airport runways directly affect flight safety and service life. In cold regions, airport runway surfaces undergo frequent freeze-thaw cycles. These cycles cause stress changes within the runway material, leading to damage such as cracks, spalling, and potholes. This damage not only increases runway maintenance costs but can also pose safety hazards for aircraft takeoff and landing.

[0003] Currently, freeze-thaw cycle testing of airport runway materials mainly relies on simulation devices in a laboratory environment. However, existing freeze-thaw cycle testing devices have several limitations. Traditional freeze-thaw cycle devices often use a single refrigeration or heating method, making it difficult to accurately simulate temperature gradient changes in real-world environments. For example, there is a significant difference between the surface temperature and the deep temperature of the runway, and existing devices cannot effectively simulate this temperature stratification phenomenon. In real-world environments, runway surfaces are not only affected by rain and snow but also by de-icing fluid spraying. Existing devices typically can only simulate a single moisture environment and cannot simultaneously simulate the alternating effects of water and de-icing fluid. Aircraft takeoffs and landings impose enormous mechanical loads on the runway surface, and these loads, combined with freeze-thaw cycles, accelerate the damage to runway materials. Existing devices mostly lack simulation of mechanical loads or apply loads in overly simplistic ways, failing to accurately reflect the dynamic stress during aircraft takeoffs and landings. Existing devices have limited ability to monitor key parameters such as specimen deformation and stress during testing, making it difficult to provide comprehensive data support and thus affecting the accurate evaluation of material properties.

[0004] The invention disclosed in CN118275486A is a hybrid test platform for simulating the full temperature range and large temperature difference environment of airport runways. It includes a control system, a refrigeration system, a heating device, a circulating air system, and a chassis. The chassis is divided into left and right compartments. The left compartment is further divided into an upper experimental compartment and a lower equipment compartment, with the experimental compartment further divided into front and rear compartments by a permeable panel. Some components of the circulating air system, heating device, and refrigeration system are installed in the rear compartment, while the remaining components of the refrigeration system are located in the equipment compartment. The front compartment is used to hold the runway material specimens to be tested. Some components of the control system are installed in the right compartment, while the remaining components are located in the experimental compartment. The control system is electrically connected to the refrigeration system, heating device, and circulating air system. Although this invention can simulate the full temperature range environment of airports through indoor testing and numerical simulation, its ability to monitor the deformation and stress parameters of the specimens during testing is limited, making it difficult to provide a comprehensive and accurate evaluation. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a simulation test system for freeze-thaw damage of airport pavement under complex service environments. This system comprehensively simulates the temperature, humidity, de-icing fluid, and mechanical loads in the actual environment, provides comprehensive data support during the testing process, and improves the accuracy of material performance evaluation.

[0006] To achieve the above objectives, the present invention provides a simulation test system for freeze-thaw damage of airport pavement under complex service environments, comprising a test chamber, a temperature control system, a loading system, a spray system, a scanning system, and a control system. The test chamber is a closed space. The temperature control system is located on the inner top wall and inner side wall of the test chamber to simulate sunlight and a gradually decreasing temperature gradient from top to bottom. The loading system is located inside the test chamber to apply loads to the test specimen and the scaled pavement. The spray system is located on the top wall of the test chamber to simulate the damage to the test specimen and the scaled pavement caused by moisture and de-icing fluid. The scanning system is located at the top of the test chamber to scan the morphological features of the test specimen and the scaled pavement. The control system is located outside the test chamber and is communicatively connected to the temperature control system, the loading system, the spray system, and the scanning system.

[0007] In this invention, a temperature control system simulates the effect of temperature on airport pavement in the actual environment, a spray system simulates the effect of humidity on airport pavement in the actual environment, a loading system simulates the effect of mechanical load on airport pavement in the actual environment, a combination of the temperature control system and the spray system simulates the icing environment in the actual environment, and a spray system simulates the effect of de-icing fluid on airport pavement. The control system is used to control the operation of the temperature control system, the loading system, and the spray system. The scanning system can analyze and scan the morphological features of the specimens and scaled pavement before and after the test, thereby improving the accuracy of airport pavement performance evaluation.

[0008] Optionally, the temperature control system includes a refrigeration device and a heating device. The refrigeration device includes a liquid nitrogen storage tank and a liquid nitrogen pipeline. The liquid nitrogen storage tank is located outside the test chamber, and the liquid nitrogen pipeline is located at the top inside the test chamber and communicates with the liquid nitrogen storage tank. The heating device includes a full-spectrum lamp bar and an electric heating wire. The full-spectrum lamp bar is located at the top inside the test chamber, and the electric heating wire is located on the side wall of the test chamber, with its resistance gradually decreasing from top to bottom.

[0009] In this invention, liquid nitrogen pipelines surround the inner top of the test chamber. By adjusting the flow rate of liquid nitrogen from the liquid nitrogen storage tank through the pipelines, the liquid nitrogen evaporates and cools the chamber, achieving a low-temperature environment. Full-spectrum light bars are used to simulate the effect of solar heat on the unit specimen and the scaled-down track surface. By setting the resistance of the electric heating wire to gradually decrease from top to bottom, a temperature gradient from top to bottom can be achieved, more accurately simulating the temperature difference between the ground and the air in a natural environment.

[0010] Optionally, the loading system includes a support, a load-pressurizing device, a motor, and rollers. The support is positioned above the specimen and the tapered track surface. The load-pressurizing device is mounted on the support. The rollers are rolled on the bottom of the load-pressurizing device and are connected to the motor drive. The bottom of the rollers can abut against the specimen and the tapered track surface. The rollers move on the support through rolling friction with the specimen and the tapered track surface.

[0011] In this invention, the roller contacts the test piece and the scaled runway surface. Due to the rolling friction, when the motor drives the roller to rotate, the roller can roll forward on the test piece and the scaled runway surface. The load pressing device is used to change the loading force of the roller on the test piece and the scaled runway surface to simulate the load situation when an aircraft is taxiing or landing on the runway.

[0012] Optionally, the load pressurizing device includes a hydraulic cylinder assembly, a loading plate, a first support plate, a second support plate, and multiple springs. The first support plate is slidably mounted on the bracket. The hydraulic cylinder assembly is located at the bottom of the first support plate. The loading plate is located at the movable end of the hydraulic cylinder assembly. The second support plate is located below the loading plate. Multiple springs are connected between the loading plate and the second support plate. The bottom of the second support plate is used to mount the rollers.

[0013] In this invention, the first support plate provides a mounting base for the hydraulic cylinder assembly, the second support plate provides a mounting base for the roller and the motor, the hydraulic cylinder assembly drives the roller to move downward to apply load pressure to the specimen and the tapered track surface, and multiple springs can transmit and buffer the load of the hydraulic cylinder assembly on the roller to avoid the roller pressing down directly on the specimen and the tapered track surface, thus preventing damage to the specimen and the tapered track surface.

[0014] Optionally, the system further includes a pavement groove and multiple specimen grooves, the pavement groove and multiple specimen grooves being spaced apart on the base of the support, the pavement groove being used to accommodate the scaled-down pavement, and the multiple specimen grooves being arranged in a rectangular array and used to accommodate multiple specimens in a one-to-one correspondence.

[0015] In this invention, multiple specimen slots are used to fix multiple specimens in a one-to-one correspondence, and the track surface slots are used to fix the scaled track surface, so that when the roller simulates loading loads on multiple specimens and the scaled track surface, the multiple specimens and the scaled track surface can remain stable. After the simulation process is completed, the specimens are used for mechanical property, durability performance, and scanning analysis, and the scaled track surface is used to analyze its structural integrity, surface damage, and mechanical property tests.

[0016] Optionally, the system further includes a pressure sensor, a temperature and humidity sensor, a temperature sensor, and strain gauges. The pressure sensor is located at the bottom of the track groove and the multiple specimen grooves and is used to monitor the load on the scaled track and the specimen in real time. The temperature and humidity sensor is located at the bottom of the track groove and the specimen grooves and is used to obtain the temperature and humidity of the test environment. The temperature sensor is located on the side of the scaled track and the specimen and is used to monitor the internal temperature gradient of the scaled track and the specimen. The strain gauges are embedded in the specimen and the scaled track.

[0017] Optionally, the spraying system includes a water tank and multiple nozzles. The water tank is located outside the test chamber, and the multiple nozzles are spaced apart on the inner top of the test chamber. The multiple nozzles are connected to the water tank via pipes, and a water pump connected to the pipes is installed inside the water tank. In this invention, the opening and closing of the multiple nozzles is controllable. By controlling the opening and closing of different nozzles, uniform spraying or localized spraying effects can be achieved.

[0018] Optionally, the water tank includes a first chamber for storing conventional water, a second chamber for storing de-icing fluid, and a third chamber for collecting meltwater, spray water, or de-icing fluid discharged from the bottom of the pavement tank and the specimen tank. The first chamber and the second chamber are connected to multiple nozzles via pipes, and the third chamber is connected to the pavement tank and the specimen tank via a water collection pipe.

[0019] In this invention, the water tank is divided into three independent parts for separately storing water and de-icing fluid, and collecting liquid from the pavement tank and test specimen tank. This allows for the simulation of the effects of rain, snow, and de-icing fluid on the runway surface, depending on actual conditions. The spraying device can work in coordination with the temperature control system. When the cooling device of the temperature control system is activated, the temperature inside the test chamber drops sharply, causing ice to form on the surfaces of the test specimen and scaled pavement, which can then be sprayed with de-icing fluid. When the heating device of the temperature control system is activated, the temperature inside the test chamber rises, allowing water to be sprayed to simulate the effects of rain on the runway.

[0020] Optionally, the scanning system includes a 3D scanner, a camera, and a data processing unit. Both the 3D scanner and the camera are located on the inner ceiling of the test chamber. The 3D scanner scans the surface morphology of the scaled track and the specimen to obtain 3D geometric information. The camera captures the color and texture of the scaled track and the specimen. The data processing unit is communicatively connected to the 3D scanner and the camera, and processes the data from the 3D scanner to generate a 3D model. In this invention, by using a camera in conjunction with a 3D scanner, a more comprehensive surface analysis of the scaled track and the specimen can be performed.

[0021] Optionally, the system further includes multiple variable frequency fans installed on the top and side walls of the test chamber, wherein the multiple variable frequency fans are used to simulate natural wind and downwash airflow. In this invention, the variable frequency fans installed on the side walls of the test chamber have a wind direction parallel to the runway surface, which can simulate natural wind, while the variable frequency fans installed on the top wall of the test chamber have a vertical downward airflow, which can simulate the downwash airflow generated by aircraft taxiing.

[0022] Beneficial effects:

[0023] 1. This invention can simulate the effects of temperature, humidity, and mechanical load on airport pavement in real-world environments through a temperature control system, a spray system, and a loading system. The temperature control system simulates the alternating low and high temperature environment, the temperature control system and spray system simulate the effects of actual moisture and de-icing fluid on the airport pavement, and the loading system simulates the mechanical load applied to the runway surface during aircraft takeoff and landing. This improves the realism and accuracy of the test, and makes the test results more reliable.

[0024] 2. This invention uses a temperature gradient simulation test that gradually decreases from top to bottom. Compared with the single cooling or heating method used in the prior art, it can more accurately simulate the temperature gradient changes in the actual environment, and reasonably simulate the difference between the surface temperature and the deep temperature of the airport runway, thus improving the reliability of the test.

[0025] 3. This invention uses a scanning system to collect the morphological features of specimens and scaled-down pavement under simulated environmental conditions of temperature, humidity, and mechanical load, and generates a three-dimensional model to facilitate the analysis of the scanning data. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the test system disclosed in this invention;

[0028] Figure 2 This is a schematic diagram of the internal structure of the test chamber of the test system disclosed in this invention;

[0029] Figure 3 This is a schematic diagram of the loading system of the test system disclosed in this invention;

[0030] Figure 4 This is a schematic diagram of the pavement groove and specimen groove of the test system disclosed in this invention.

[0031] Figure label:

[0032] 1. Test chamber; 2. Temperature control system; 21. Refrigeration unit; 211. Liquid nitrogen storage tank; 212. Liquid nitrogen pipeline; 213. Flow control valve; 22. Heating unit; 221. Full-spectrum light bar; 222. Electric heating wire; 3. Loading system; 31. Bracket; 311. Base; 312. Mounting rod; 313. Vertical rod; 32. Loading pressurization device; 321. Hydraulic cylinder assembly; 322. Loading pressure plate; 323. 324. First support plate; 325. Second support plate; 326. Spring; 327. First guide rod; 328. Second guide rod; 33. Motor; 34. Roller; 4. Spraying system; 41. Water tank; 411. First chamber; 412. Second chamber; 413. Third chamber; 42. Nozzle; 5. Scanning system; 61. Pad groove; 62. Specimen groove; 63. Drainage hole; 64. Water collection pipe; 7. Variable frequency fan.

[0033] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0036] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] See Figure 1 and Figure 2 According to an embodiment of the present invention, an airport pavement freeze-thaw damage simulation test system under complex service environment includes a test chamber 1, a temperature control system 2, a loading system 3, a spray system 4, a scanning system 5, and a control system. The test chamber 1 is a closed space. The temperature control system 2 is located on the inner top wall and inner side wall of the test chamber 1 to simulate sunlight and a temperature gradient that gradually decreases from top to bottom. The loading system 3 is located inside the test chamber 1 to apply loads to the test specimen and the scaled pavement. The spray system 4 is located on the top wall of the test chamber 1 to simulate the damage to the test specimen and the scaled pavement caused by moisture and de-icing fluid. The scanning system 5 is located on the top of the test chamber 1 to scan the morphological features of the test specimen and the scaled pavement. The control system is located outside the test chamber 1 and is communicatively connected to the temperature control system 2, the loading system 3, the spray system 4, and the scanning system 5.

[0038] In this invention, a temperature control system 2 simulates the effect of temperature on the airport pavement in the actual environment, a spray system 4 simulates the effect of humidity on the airport pavement in the actual environment, a loading system 3 simulates the effect of mechanical load on the airport pavement in the actual environment, the combination of the temperature control system 2 and the spray system 4 simulates the icing environment in the actual environment, and the spray system 4 simulates the effect of de-icing fluid on the airport pavement. A control system controls the operation of the temperature control system 2, the loading system 3, and the spray system 4. A scanning system 5 analyzes and scans the morphological characteristics of the specimens and scaled-down pavement before and after the test, thereby improving the accuracy of the airport pavement performance evaluation. Specifically, the test chamber 1 is made of high-strength thermal insulation material to ensure that the temperature inside the test chamber 1 remains stable.

[0039] See Figure 1 and Figure 2In some embodiments of the present invention, the temperature control system 2 includes a refrigeration device 21 and a heating device 22. The refrigeration device 21 includes a liquid nitrogen storage tank 211 and a liquid nitrogen pipeline 212. The liquid nitrogen storage tank 211 is located outside the test chamber 1, and the liquid nitrogen pipeline 212 is located at the inner top of the test chamber 1 and communicates with the liquid nitrogen storage tank 211. The heating device 22 includes a full-spectrum lamp bar 221 and an electric heating wire 222. The full-spectrum lamp bar 221 is located at the inner top of the test chamber 1, and the electric heating wire 222 is located on the side wall of the test chamber 1, and its resistance value gradually decreases from top to bottom.

[0040] In this invention, a liquid nitrogen pipeline 212 surrounds the inner top of the test chamber 1. A flow control valve 213 is also installed between the liquid nitrogen storage tank 211 and the liquid nitrogen pipeline 212. By adjusting the flow control valve 213, the flow rate of liquid nitrogen flowing through the liquid nitrogen pipeline 212 is changed, causing the liquid nitrogen to evaporate and cool down, thereby achieving a low-temperature environment inside the test chamber 1. A full-spectrum light bar 221 is used to simulate the effect of solar heat on the scaled-down pavement. By setting the resistance of the electric heating wire 222 to gradually decrease from top to bottom, a temperature gradient change from top to bottom can be achieved, more accurately simulating the temperature difference between the ground and the air in a natural environment.

[0041] See Figure 3 In some embodiments of the present invention, the loading system 3 includes a bracket 31, a load pressing device 32, a motor 33, and a roller 34. The bracket 31 is disposed above the specimen and the tapered track surface. The load pressing device 32 is disposed on the bracket 31. The roller 34 is rolled on the bottom of the load pressing device 32 and is driven and connected to the motor 33. The bottom of the roller 34 can abut against the specimen and the tapered track surface. The roller 34 moves on the bracket 31 by the rolling friction with the specimen and the tapered track surface.

[0042] In this invention, the roller 34 contacts the specimen and the scaled runway surface. Due to the rolling friction, when the motor 33 drives the roller 34 to rotate, the roller 34 can roll forward on the specimen and the scaled runway surface. The load applying device 32 is used to change the loading force of the roller 34 on the specimen and the scaled runway surface to simulate the load conditions when an aircraft taxis or lands on a runway. Specifically, the roller 34 is made of soft, high-friction rubber, and the surface of the roller 34 is patterned to ensure that when the motor 33 drives the roller 34 to rotate, the roller 34 can move relative to the specimen and the scaled runway surface while rotating.

[0043] See Figure 1 and Figure 3In some embodiments of the present invention, the load pressurizing device 32 includes a hydraulic cylinder assembly 321, a loading plate 322, a first support plate 323, a second support plate 324, and a plurality of springs 325. The first support plate 323 is slidably disposed on the bracket 31. The hydraulic cylinder assembly 321 is disposed at the bottom of the first support plate 323. The loading plate 322 is disposed at the movable end of the hydraulic cylinder assembly 321. The second support plate 324 is disposed below the loading plate 322. The plurality of springs 325 are connected between the loading plate 322 and the second support plate 324. The bottom of the second support plate 324 is used to install the roller 34.

[0044] In this invention, the first support plate 323 provides a mounting base for the hydraulic cylinder assembly 321, and the second support plate 324 provides a mounting base for the roller 34 and the motor 33. The hydraulic cylinder assembly 321 drives the roller 34 to move downward to apply load pressure to the specimen and the tapered track surface. Multiple springs 325 can buffer the load of the hydraulic cylinder assembly 321 on the roller 34, preventing the roller 34 from directly acting on the specimen and the tapered track surface when it presses down, thus avoiding damage to the specimen and the tapered track surface.

[0045] Specifically, the hydraulic cylinder assembly 321 includes a hydraulic pump station, an oil supply line, a return line, and two hydraulic cylinders. The two hydraulic cylinders are spaced apart at the bottom of the first support plate 323. The hydraulic pump station pumps hydraulic oil into the hydraulic cylinders through the oil supply line and pumps the hydraulic oil from the hydraulic cylinders back to the hydraulic pump station through the return line. There are two rollers 34, with one hydraulic cylinder corresponding to one roller 34. The two rollers 34 correspond one-to-one with the specimen and the scaling surface, respectively. By setting two hydraulic cylinders and two rollers 34, the mechanical load acting on the specimen and the scaling surface is made more stable and reliable. Of course, the present invention is not limited to this; it is also possible to set the number of hydraulic cylinders and rollers 34 to one each.

[0046] Specifically, the load-applying device 32 also includes multiple first guide rods 326 and multiple second guide rods 327. The multiple first guide rods 326 are spaced apart on both sides of the hydraulic cylinder assembly 321 and vertically pass through the first support plate 323 and the loading pressure plate 322. The multiple second guide rods 327 are spaced apart on both sides of the hydraulic cylinder assembly 321 and vertically pass through the first support plate 323 and the second support plate 324. The multiple first guide rods 326 and multiple second guide rods 327 are used to guide the vertical movement of the loading pressure plate 322 and the second support plate 324, thereby ensuring that the roller 34 can uniformly and stably apply load to the specimen and the scaled surface.

[0047] Specifically, the support 31 includes a base 311, two mounting rods 312, and four vertical rods 313. The base 311 supports the specimen and the scaling surface. The four vertical rods 313 are arranged in a rectangular array and their lower ends are fixedly connected to the base 311. The two mounting rods 312 are arranged in parallel at intervals and are fixedly connected to the upper ends of the corresponding two vertical rods 313. The first support plate 323 has sleeve structures formed at both ends, allowing it to slide along the length of the two mounting rods 312 via the sleeve structures. The height of the four vertical rods 313 is adjustable. By adjusting the vertical height of the four vertical rods 313, the vertical height of the rollers 34 can be changed, thereby adjusting the height difference between the rollers 34 and the specimen and scaling surface, so that the hydraulic cylinder can better provide load to the specimen and scaling surface through the rollers 34.

[0048] See Figure 4 In some embodiments of the present invention, the system further includes a pavement groove 61 and a plurality of specimen grooves 62, the pavement groove 61 and the plurality of specimen grooves 62 being spaced apart on the base 311 of the support 31, the pavement groove 61 being used to accommodate the scaled pavement, and the plurality of specimen grooves 62 being arranged in a rectangular array and used to accommodate a plurality of specimens in a one-to-one correspondence.

[0049] In this invention, the pavement groove 61 and multiple specimen grooves 62 are all placed on the base 311. The multiple specimen grooves 62 are used to fix multiple specimens one-to-one, and the pavement groove 61 is used to fix the scaled pavement, so that when the roller 34 simulates loading loads on the multiple specimens and the scaled pavement, the multiple specimens and the scaled pavement can remain stable. After the simulation process is completed, the specimens are used for mechanical performance, durability performance, and scanning analysis, and the scaled pavement is used to analyze its structural integrity, surface damage, and mechanical performance tests.

[0050] Specifically, the specimen slot 62 is a square slot measuring 100mm × 100mm, and multiple specimen slots 62 are arranged in a 2×5 rectangular array. The total length of the multiple specimen slots 62 is the same as the length of the pavement slot 61, ensuring that the specimens installed in the multiple specimen slots 62 are in the same simulated environment. Setting up multiple specimen slots 62 to hold multiple specimens reduces experimental error and improves the accuracy of test results. The bottoms of both the specimen slots 62 and the pavement slot 61 are concave to ensure that the specimens and the scaled-down pavement remain stable and do not shift during loading.

[0051] Specifically, drainage holes 63 are provided at the bottom of the pavement trough 61 and multiple specimen troughs 62. Water collection pipes 64 are connected to the outside of the drainage holes 63. The end of the water collection pipes 64 extends out of the test chamber 1 to prevent water sprayed by the spray system 4 from accumulating in the pavement trough 61 and specimen troughs 62.

[0052] Specifically, at least two position sensors are provided on the specimen groove 62. The at least two position sensors are located at both ends of the rolling path of the roller 34 on the specimen and are connected to the control system. They are used to detect that the roller 34 has reached the designated position on the specimen. Then, the control system controls the roller 34 to roll in the opposite direction to avoid the situation where the roller 34 cannot continue to move back and forth on the specimen due to the friction between the roller 34 and the specimen after it leaves the specimen.

[0053] In some embodiments of the present invention, the system further includes a pressure sensor, a temperature and humidity sensor, a temperature sensor, and strain gauges. The pressure sensor is disposed at the bottom of the track groove 61 and the plurality of specimen grooves 62 and is used to monitor the load on the scaled track and the specimen in real time. The temperature and humidity sensor is disposed at the bottom of the track groove 61 and the specimen groove 62 and is used to obtain the temperature and humidity of the test environment. The temperature sensor is disposed on the side of the scaled track and the specimen and is used to monitor the internal temperature gradient of the scaled track and the specimen. The strain gauges are embedded in the specimen and the scaled track.

[0054] See Figure 1 and Figure 2 In some embodiments of the present invention, the spray system 4 includes a water tank 41 and a plurality of spray nozzles 42. The water tank 41 is located outside the test chamber 1, and the plurality of spray nozzles 42 are spaced apart at the top of the test chamber 1. The plurality of spray nozzles 42 are connected to the water tank 41 via pipes, and a water pump connected to the pipes is installed inside the water tank 41. The opening and closing of the plurality of spray nozzles 42 can be controlled by a control system. By controlling the opening and closing of different spray nozzles 42, uniform spraying or localized spraying can be achieved. A water collection pipe 64 extends from the end of the test chamber 1 and is connected to a water pump in the third chamber 413 of the water tank 41 to realize the recycling of water flow, reduce water waste, and optimize drainage treatment.

[0055] See Figure 1 and Figure 2 In some embodiments of the present invention, the water tank 41 includes a first chamber 411 for storing conventional water, a second chamber 412 for storing de-icing fluid, and a third chamber 413 for collecting liquid in the test chamber 1. The first chamber 411 and the second chamber 412 are both connected to a plurality of nozzles 42 through pipes. The liquid in the runner 61 and the test specimen 62 is discharged into the third chamber 413 through the water collection pipe 64.

[0056] In this invention, the water tank 41 is divided into three independent parts for separately storing water and de-icing fluid, and collecting liquid from the pavement tank 61 and the test specimen tank 62. This allows for the simulation of the effects of rain, snow, and de-icing fluid on the runway surface, depending on actual conditions. The spraying device can work in coordination with the temperature control system 2. When the cooling device 21 of the temperature control system 2 is working, the temperature inside the test chamber 1 drops sharply, causing ice to form on the surfaces of the test specimen and the scaled pavement. De-icing fluid can then be sprayed through the nozzle 42. When the heating device 22 of the temperature control system 2 is working, the temperature inside the test chamber 1 rises, allowing water to be sprayed through the nozzle 42 to simulate the effects of rain on the runway.

[0057] See Figure 2 In some embodiments of the present invention, the scanning system 5 includes a 3D scanner, a camera, and a data processing unit. Both the 3D scanner and the camera are located on the inner ceiling of the test chamber 1. The 3D scanner is used to scan the surface morphology of the scaled track and the specimen to obtain 3D geometric information. The camera is used to capture the color and texture of the scaled track and the specimen. The data processing unit is communicatively connected to the 3D scanner and the camera, and is used to process the data from the 3D scanner and generate a 3D model. By using a camera in conjunction with the 3D scanner, a more comprehensive surface analysis of the scaled track can be performed.

[0058] See Figure 2 In some embodiments of the present invention, the system further includes a plurality of variable frequency fans 7 disposed on the top and side walls of the test chamber 1, the plurality of variable frequency fans 7 being used to simulate natural wind and downwash airflow. In the present invention, the airflow direction of the variable frequency fans 7 installed on the side walls of the test chamber 1 is parallel to the runway surface, which can simulate natural wind, while the airflow of the variable frequency fans 7 installed on the top wall of the test chamber 1 is vertically downward, which can simulate the downwash airflow generated by aircraft taxiing.

[0059] When the testing system of the present invention is working, multiple specimens are placed one-to-one into multiple specimen slots 62, and a scaled-down track surface is placed into a track surface slot 61. Before the test begins, the surfaces of the specimens and the scaled-down track surface are initially scanned using a 3D scanner and a camera to record the initial morphological features of the specimens and the scaled-down track surface. The cooling device 21 is started, and the flow rate of liquid nitrogen entering the liquid nitrogen pipeline 212 is increased by adjusting the flow control valve 213, so that the temperature in the test chamber 1 drops rapidly to the set temperature and is maintained at a low temperature for 2 hours to simulate a cold winter environment. During the low temperature stage, multiple nozzles 42 are connected to the first chamber 41 of the water tank 41. 1. Activate multiple nozzles 42 to spray conventional water, simulating the impact of rain and snow on the airport runway surface. Activate the heating device 22, adjust the resistance of the electric heating wire 222 and the power of the full-spectrum lamp strip 221 to gradually raise the temperature in the test chamber 1 to the set temperature, maintain this high temperature for 2 hours, simulating a daytime heating environment. During the heating phase, connect multiple nozzles 42 to the second chamber 412 of the water tank 41, and activate the multiple nozzles 42 to spray de-icing fluid, simulating the impact of de-icing operations on the airport runway surface. Set the spraying frequency and duration through the control system to ensure that the spraying operation is synchronized with the temperature cycle. Repeat the above steps to complete the set number of temperature cycles.

[0060] During temperature cycling, roller 34 maintains contact with the surfaces of the specimen and the scaling track. A load is applied via a hydraulic cylinder. Once the load stabilizes, motor 33 is activated to drive roller 34 to rotate. Due to friction between the specimen / scaling track surface and roller 34, the rotation of roller 34 generates a forward rolling force, thus propelling roller 34 forward on the specimen / scaling track. When roller 34 reaches the position sensor at the end, motor 33 is controlled to rotate in the opposite direction, and roller 34 rolls in the opposite direction to the position sensor at the other end. Then, motor 33 is controlled to rotate in the opposite direction again. 33 rotates in the forward direction to realize the cyclic rolling of roller 34 on the test specimen and the scaled-down pavement; when roller 34 rolls on the test specimen and the scaled-down pavement, the corresponding variable frequency fan 7 is started to simulate the airflow during aircraft take-off and landing; during the test, the 3D scanner and camera periodically scan the surface of the test specimen and the scaled-down pavement to record the changes in the surface morphology of the test specimen and the scaled-down pavement. After the test, the surface of the test specimen and the scaled-down pavement is scanned again to record the final surface morphology features and compare them with the initial scan data to evaluate the impact of freeze-thaw cycles on the pavement.

[0061] After completing the set number of freeze-thaw cycles, stop all systems and remove the test specimens and scaled-down pavement for visual inspection and performance testing. Perform compressive strength test, splitting tensile strength test, elastic modulus test, mass loss determination and scanning electron microscopy analysis on the test specimens. Perform surface crack width determination, pavement spalling test and slab bending fatigue test on the scaled-down pavement. Clean the test chamber 1 and nozzle 42, check the sealing of liquid nitrogen pipeline 212 and hydraulic system, and calibrate all sensors and hydraulic cylinder assembly 321 to ensure the accuracy of the next test.

[0062] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A simulation test system for freeze-thaw damage of airport pavement under complex service environments, characterized in that, The test chamber (1) includes a temperature control system (2), a loading system (3), a spray system (4), a scanning system (5), and a control system. The test chamber (1) is a closed space. The temperature control system (2) is located on the inner top wall and inner side wall of the test chamber (1) to simulate sunlight and a temperature gradient that gradually decreases from top to bottom. The loading system (3) is located inside the test chamber (1) to apply loads to the specimen and the scaled track surface. The spray system (4) is located on the top wall of the test chamber (1) to simulate the damage of moisture and de-icing fluid to the specimen and the scaled track surface. The scanning system (5) is located on the top of the test chamber (1) to scan the morphological features of the specimen and the scaled track surface. The control system is located outside the test chamber (1) and is communicatively connected to the temperature control system (2), the loading system (3), the spray system (4), and the scanning system (5).

2. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 1, characterized in that, The temperature control system (2) includes a refrigeration device (21) and a heating device (22). The refrigeration device (21) includes a liquid nitrogen storage tank (211) and a liquid nitrogen pipeline (212). The liquid nitrogen storage tank (211) is located outside the test chamber (1). The liquid nitrogen pipeline (212) is located at the top inside the test chamber (1) and is connected to the liquid nitrogen storage tank (211). The heating device (22) includes a full-spectrum lamp bar (221) and an electric heating wire (222). The full-spectrum lamp bar (221) is located at the top inside the test chamber (1). The electric heating wire (222) is located on the side wall of the test chamber (1) and its resistance value gradually decreases from top to bottom.

3. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 1, characterized in that, The loading system (3) includes a bracket (31), a load pressing device (32), a motor (33), and a roller (34). The bracket (31) is positioned above the specimen and the tapered track. The load pressing device (32) is positioned on the bracket (31). The roller (34) is rolled on the bottom of the load pressing device (32) and driven by the motor (33). The bottom of the roller (34) can abut against the specimen and the tapered track. The roller (34) moves on the bracket (31) by the rolling friction with the specimen and the tapered track.

4. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 3, characterized in that, The load pressurizing device (32) includes a hydraulic cylinder assembly (321), a loading plate (322), a first support plate (323), a second support plate (324), and a plurality of springs (325). The first support plate (323) is slidably disposed on the bracket (31). The hydraulic cylinder assembly (321) is disposed at the bottom of the first support plate (323). The loading plate (322) is disposed at the movable end of the hydraulic cylinder assembly (321). The second support plate (324) is disposed below the loading plate (322). The plurality of springs (325) are connected between the loading plate (322) and the second support plate (324). The bottom of the second support plate (324) is used to install the roller (34).

5. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 3, characterized in that, The system also includes a pavement groove (61) and a plurality of specimen grooves (62). The pavement groove (61) and the plurality of specimen grooves (62) are spaced apart on the base (311) of the support (31). The pavement groove (61) is used to accommodate the scaled pavement, and the plurality of specimen grooves (62) are arranged in a rectangular array and are used to accommodate a plurality of specimens in a one-to-one correspondence.

6. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 5, characterized in that, The system also includes a pressure sensor, a temperature and humidity sensor, a temperature sensor, and strain gauges. The pressure sensor is located at the bottom of the track groove (61) and the multiple specimen grooves (62) and is used to monitor the load on the scaled track and the specimen in real time. The temperature and humidity sensor is located at the bottom of the track groove (61) and the specimen groove (62) and is used to obtain the temperature and humidity of the test environment. The temperature sensor is located on the side of the scaled track and the specimen and is used to monitor the internal temperature gradient of the scaled track and the specimen. The strain gauges are embedded in the specimen and the scaled track.

7. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 5, characterized in that, The spray system (4) includes a water tank (41) and multiple nozzles (42). The water tank (41) is located outside the test chamber (1). The multiple nozzles (42) are spaced apart on the inner top of the test chamber (1). The multiple nozzles (42) are connected to the water tank (41) through pipes. A water pump connected to the pipes is installed inside the water tank (41).

8. The airport pavement freeze-thaw damage simulation test system under complex service environment according to claim 7, characterized in that, The water tank (41) includes a first chamber (411) for storing conventional water, a second chamber (412) for storing de-icing fluid, and a third chamber (413) for collecting meltwater, spray water, or de-icing fluid discharged from the bottom of the pavement trough (61) and the specimen trough (62). The first chamber (411) and the second chamber (412) are connected to a plurality of the nozzles (42) through pipes, and the third chamber (413) is connected to the pavement trough (61) and the specimen trough (62) through a water collection pipe (64).

9. A simulation test system for freeze-thaw damage of airport pavement under complex service environment according to any one of claims 1 to 8, characterized in that, The scanning system (5) includes a 3D scanner, a camera, and a data processing unit. The 3D scanner and the camera are both located on the inner top of the test chamber (1). The 3D scanner is used to scan the surface morphology of the scaled track and the specimen to obtain 3D geometric information. The camera is used to capture the color and texture of the scaled track and the specimen. The data processing unit is communicatively connected to the 3D scanner and the camera to process the data from the 3D scanner and generate a 3D model.

10. A simulation test system for freeze-thaw damage of airport pavement under complex service environment according to any one of claims 1 to 8, characterized in that, The system also includes multiple variable frequency fans (7) installed on the top and side walls of the test chamber (1), which are used to simulate natural wind and downwash airflow.

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