Variable radiation gradient roadbed moisture migration phase change test device and method

Abstract

The invention provides a variable radiation gradient roadbed moisture migration phase change test device and method, and belongs to the technical field of frozen soil area roadbed engineering test.The variable radiation gradient roadbed moisture migration phase change test device comprises a test box, a roadbed is arranged in the test box, an asphalt layer is laid on the top of the roadbed, and a temperature adjusting mechanism is arranged in the roadbed; the temperature adjusting mechanism can adjust the roadbed to form a temperature gradient in the vertical direction; a variable radiation mechanism and a tracing mechanism are further arranged in the test box, the variable radiation mechanism is located above the asphalt layer, and the variable radiation mechanism can apply differential radiation to the asphalt layer in the width direction of the roadbed to form a radiation gradient; the tracing mechanism is located below the roadbed and can display the migration direction and the phase change process of moisture in the roadbed. The device has the beneficial effects that the solar radiation difference of the negative and positive slopes of the roadbed can be simulated, so that the experimental result is closer to the actual working condition of roadbed engineering.

Description

Technical Field

[0001] This application belongs to the field of roadbed engineering testing technology in permafrost areas, specifically relating to a test device and method for phase change of moisture migration in roadbed with variable radiation gradient. Background Technology

[0002] In road engineering projects in permafrost or seasonally permafrost regions, the migration and phase change of subgrade moisture are the core contributing factors to frost heave, thaw settlement, and other related problems. Moisture migrates to lower-temperature zones under the influence of temperature gradients and freezes, leading to subgrade structural deformation and pavement cracking, significantly reducing road service life and driving safety. Conversely, the thawing of moisture during temperature rise causes a decrease in soil strength, triggering thaw settlement. Therefore, accurately studying the laws governing subgrade moisture migration and phase change is a crucial prerequisite for optimizing subgrade design and preventing engineering problems in permafrost regions.

[0003] As shown in the patent published with CN119354821A, the existing frozen soil moisture migration detection device mainly consists of an experimental chamber, a temperature control unit, a water replenishment device, and a monitoring module: the experimental chamber is a detachable insulated frame, with the interior divided into storage spaces; the temperature control unit includes a heat-conducting ring, a shaft tube, and a liquid delivery system, which forms a temperature gradient along the roadbed axis by delivering coolant or heat-conducting oil in combination with the dynamic adjustment of the heat-conducting ring; the water replenishment device controls the soil moisture content through nozzles; and monitoring relies on nuclear magnetic resonance imaging (NMR) instruments to obtain moisture distribution data.

[0004] However, existing devices can only simulate the vertical temperature gradient change of the roadbed, without taking into account the difference in solar radiation between the sunny and shady slopes of the actual roadbed. The sunny slope receives strong radiation and has a high surface temperature, while the shady slope receives weak radiation and has a low temperature. This difference in radiation will directly change the temperature field distribution and moisture migration path of the roadbed, resulting in a significant deviation between the test environment and the actual roadbed working conditions. As a result, the moisture migration and phase change laws obtained are inaccurate, making it difficult to accurately guide the design and disease prevention of road engineering in permafrost areas. Summary of the Invention

[0005] This application addresses the problem that existing testing devices cannot simulate the difference in solar radiation between the sunny and shady slopes of a roadbed, which leads to deviations in test results. It provides a variable radiation gradient roadbed moisture migration phase change test device and method, which can simulate the difference in solar radiation between the sunny and shady slopes of a roadbed, making the test results closer to the actual working conditions of roadbed engineering.

[0006] Firstly, to address the above problems, the technical solution adopted in this application is a variable radiation gradient roadbed moisture migration phase change test device, comprising a test chamber, a roadbed inside the test chamber, an asphalt layer laid on top of the roadbed, a temperature regulating mechanism inside the roadbed, the temperature regulating mechanism being able to control the formation of a temperature gradient along the vertical direction of the roadbed; the test chamber also includes a variable radiation mechanism and a tracer mechanism, the variable radiation mechanism being located above the asphalt layer, the variable radiation mechanism being able to apply differentiated radiation to the asphalt layer along the width direction of the roadbed to form a radiation gradient; the tracer mechanism being located below the roadbed, the tracer mechanism being able to display the migration direction and phase change process of moisture within the roadbed.

[0007] The test chamber in this technical solution is filled with roadbed material, with an asphalt layer laid on top. A temperature control mechanism is installed within the roadbed to regulate the vertical temperature gradient. The test chamber also includes a variable radiation mechanism and a tracer mechanism. The variable radiation mechanism, located above the asphalt layer, applies differentiated radiation along the width of the roadbed, creating a radiation gradient. The tracer mechanism, located below the roadbed, displays the migration direction and phase change process of moisture within the roadbed. Therefore, this device, through the radiation gradient created by the variable radiation mechanism, can simulate the difference in solar radiation between sunny and shady slopes of the roadbed, making the experimental results closer to the actual working conditions of roadbed engineering.

[0008] Furthermore, a pressure sensor is installed between the asphalt layer and the top of the roadbed. The pressure sensor is electrically connected to a frost heave force measuring device, which can measure the frost heave force of the roadbed. Through the cooperation of the pressure sensor and the frost heave force measuring device, the forces generated during the frost heave process of the roadbed can be captured in real time and accurately, providing direct data support for analyzing the mechanical response of the roadbed to frost heave, and helping to conduct in-depth research on the impact of frost heave force on the stability of the roadbed structure.

[0009] Furthermore, several frost heave measurement devices are installed above the asphalt layer, and these devices are evenly distributed along the width of the roadbed. This uniform distribution of the frost heave measurement devices along the roadbed width allows for the simultaneous acquisition of frost heave deformation data at different width locations of the roadbed. This facilitates comparative analysis of frost heave differences along the width direction and provides a comprehensive data foundation for studying the influence of radiation gradients on the frost heave distribution of the roadbed.

[0010] Furthermore, the frost heave tester is a displacement sensor, fixed to the inner wall of the test chamber, with its detection end vertically facing the top surface of the asphalt layer. Fixing the displacement sensor to the inner wall of the test chamber and ensuring the detection end is vertically facing the top surface of the asphalt layer ensures that the sensor stably captures the vertical displacement of the asphalt layer caused by frost heave of the roadbed, avoiding measurement errors caused by deviations in the detection direction and significantly improving the accuracy of roadbed frost heave measurement.

[0011] Furthermore, the temperature control mechanism includes two negative temperature grids, located at the top and bottom of the roadbed respectively. Each grid is connected to a refrigeration compressor, and each compressor is equipped with a negative temperature controller and a condenser. By installing negative temperature grids at the top and bottom of the roadbed, and combining them with independent refrigeration compressors, controllers, and condensers, the temperature of the upper and lower parts of the roadbed can be flexibly controlled, stabilizing a vertical temperature gradient. This accurately simulates the temperature distribution of the roadbed in a real environment, providing realistic temperature conditions for studying moisture migration and phase change under temperature gradients.

[0012] Furthermore, the variable radiation mechanism includes several sleeves arranged vertically and evenly distributed along the width of the roadbed. Each sleeve contains a lifting assembly and a resistance disk. The lifting assembly controls the vertical movement of the corresponding resistance disk. All resistance disks are electrically connected to a temperature controller, which can independently regulate the temperature of each resistance disk. The vertically arranged and evenly distributed sleeves provide a stable mounting platform for the resistance disks. The lifting assembly can adjust the distance between the resistance disk and the asphalt layer, and the temperature controller can independently regulate the temperature of each resistance disk. The combination of these two elements can accurately construct differentiated radiation gradients along the width of the roadbed, meeting the simulation requirements of different combinations of radiation intensity and adapting to experimental research on various roadbed radiation scenarios with varying degrees of eccentricity.

[0013] Furthermore, the lifting assembly is an electric telescopic rod, which is vertically arranged. The cylinder of the electric telescopic rod is fixedly connected to the inner top of the test chamber, and the telescopic end of the electric telescopic rod is fixedly connected to the resistance disk. All electric telescopic rods are electrically connected to the displacement controller. The electric telescopic rod features stable lifting and high displacement accuracy. The way its cylinder is fixed to the inner top of the test chamber and its telescopic end is connected to the resistance disk ensures the stability of the resistance disk's position during lifting. Combined with the displacement controller, it enables synchronous or independent precise control of multiple resistance disks, ensuring the accuracy of radiation distance adjustment and thus maintaining the stability of the radiation gradient.

[0014] Furthermore, the tracer mechanism includes several sand-containing water tanks, which are evenly distributed along the width of the roadbed. Each sand-containing water tank corresponds vertically to a corresponding sleeve, and each sand-containing water tank is connected to an external water source through an independent inlet pipe. The even distribution of the sand-containing water tanks along the width and their vertical correspondence with the sleeves allows for precise matching of the radiation area and the water supply area, facilitating correlation analysis of water migration patterns under specific radiation conditions. The independent inlet pipe design ensures that the water supply to each tank does not interfere with each other, and allows for flexible control of water supply at different locations, providing a stable and independent water source for multi-source water tracer experiments.

[0015] Furthermore, the test chamber is made of transparent material, with each sand-containing water tank containing water of a different color. The transparent material allows researchers to directly observe the water migration path and phase change phenomena within the roadbed, obtaining direct observations without disassembling the equipment. This simplifies the observation process, avoids disruption of the test conditions caused by disassembly, and ensures the continuity of the test process and the authenticity of the observation results. The different colors of water serve as clear distinguishing markers, allowing for direct identification of the diffusion range and migration trajectory of water from different sand-containing water tanks within the roadbed during the test. This enables rapid location of phase change regions for each type of water, significantly improving the visualization of the water migration and phase change process, and facilitating accurate tracking and recording of dynamic water change patterns.

[0016] Secondly, this application also provides a method for testing the phase change of moisture migration in a variable radiation gradient roadbed, applied to a test apparatus for testing the phase change of moisture migration in a variable radiation gradient roadbed, comprising the following steps. A vertical temperature gradient is constructed by regulating the roadbed along the vertical direction using a temperature control mechanism; A radiation gradient is constructed by applying differentiated radiation to the asphalt layer along the width of the roadbed using a variable radiation mechanism. The phase change of moisture migration was observed in the test chamber, and data were collected using a frost heave force measuring instrument and a frost heave amount tester.

[0017] As can be seen from the above technical solutions, the beneficial effects of this application are as follows: 1. It can accurately simulate the actual working conditions of the roadbed. The variable radiation mechanism simulates the radiation difference between the sunny and shady slopes, and the temperature control mechanism constructs a vertical temperature gradient, making the experimental results more consistent with the actual engineering situation. 2. Accurate measurement of frost heave parameters: pressure sensors are equipped with frost heave force measuring devices and displacement sensors to measure frost heave amount, enabling real-time acquisition of roadbed frost heave force and deformation data, supporting mechanical response analysis; 3. The visualization effect of water migration and phase change is good. The transparent test chamber is equipped with tracer water of different colors, which can be used to directly observe the migration path and phase change area. It can also correlate radiation and water patterns through multi-source sand-containing water tanks. Attached Figure Description

[0018] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a cross-sectional schematic diagram of a specific embodiment of this application; Figure 2 This is a schematic diagram of the installation of the frost heave tester in a specific embodiment of this application.

[0020] In the diagram: 1. Test chamber; 2. Roadbed; 3. Asphalt layer; 4. Temperature control mechanism; 41. Negative temperature network; 42. Refrigeration compressor; 43. Negative temperature controller; 44. Condenser; 5. Variable radiation mechanism; 51. Sleeve; 52. Resistance disk; 53. Temperature controller; 54. Electric telescopic rod; 55. Displacement controller; 6. Tracer mechanism; 61. Sand-containing water tank; 62. Water inlet pipe; 7. Pressure sensor; 71. Frost heave force measuring device; 8. Frost heave amount tester. Detailed Implementation

[0021] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0022] Example 1: A test device for phase change of moisture migration in roadbed with variable radiation gradient, such as... Figure 1 As shown, the device includes a test chamber 1 with wheels at the bottom for easy movement. Inside the test chamber 1 is a roadbed 2, topped with an asphalt layer 3 to simulate the surface structure of an actual road. A temperature control mechanism 4 is installed inside the roadbed 2 to regulate the temperature gradient along the vertical direction. The test chamber 1 also includes a variable radiation mechanism 5 and a tracer mechanism 6. The variable radiation mechanism 5, located above the asphalt layer 3, applies differentiated radiation to the asphalt layer 3 along the width of the roadbed 2 to create a radiation gradient. The tracer mechanism 6, located below the roadbed 2, displays the migration direction and phase change process of moisture within the roadbed 2. A pressure sensor 7 is installed between the asphalt layer 3 and the top of the roadbed 2, and a frost heave force measuring device 71 is used to measure the frost heave force of the roadbed 2. Several frost heave measurement devices 8 are installed above the asphalt layer 3 to detect the frost heave of the roadbed 2.

[0023] The test chamber 1 is a hollow box-type structure, whose internal space is used to accommodate the roadbed 2 and various functional mechanisms. The wheels at the bottom of the test chamber 1 are fixed to the four corners or edges of the bottom of the test chamber 1 by bolts. The wheels are universal wheels with braking function to ensure stable fixation after the device is moved. The roadbed 2 is filled in the internal cavity of the test chamber 1. The roadbed 2 uses soil materials consistent with the actual project. During filling, it is compacted in layers to ensure that the density matches that of the actual roadbed 2. The asphalt layer 3 is laid on the top end face of the roadbed 2. The asphalt layer 3 is laid with hot-mix asphalt mixture. The thickness of the asphalt layer 3 is consistent with the thickness of the actual road asphalt surface layer, and the asphalt layer 3 is tightly attached to the top end face of the roadbed 2 without gaps.

[0024] The temperature control mechanism 4 includes two negative temperature nets 41, which are respectively located in the top and bottom areas of the roadbed 2. The negative temperature nets 41 are made of metal mesh and their dimensions are adapted to the cross-sectional dimensions of the roadbed 2. The negative temperature nets 41 are completely embedded inside the roadbed 2 and in close contact with the soil to ensure efficient temperature transfer. Each negative temperature net 41 is connected to a refrigeration compressor 42, which is placed on the outside of the test chamber 1 or on the surrounding ground. The output end of the refrigeration compressor 42 is electrically connected to the terminals of the negative temperature net 41 via low-temperature resistant wires. The wires pass through pre-set wiring holes on the side wall of the test chamber 1, and the wiring holes are sealed to prevent external interference. Environmental interference; Each refrigeration compressor 42 is equipped with a negative temperature controller 43 and a condenser 44. The negative temperature controller 43 is fixed to the top surface of the housing of the refrigeration compressor 42 by bolts. The signal input terminal of the negative temperature controller 43 is connected to the control module of the refrigeration compressor 42 through a wire to adjust the refrigeration power of the refrigeration compressor 42 and thus control the temperature of the negative temperature network 41. The condenser 44 is also fixed to the outside of the housing of the refrigeration compressor 42. The input terminal of the condenser 44 is connected to the heat dissipation port of the refrigeration compressor 42. The surface of the condenser 44 is equipped with heat dissipation fins to quickly dissipate the heat generated by the refrigeration compressor 42 during operation and ensure the stable operation of the refrigeration compressor 42.

[0025] The variable radiation mechanism 5 includes several sleeves 51, which are arranged vertically and evenly distributed along the width of the roadbed 2. In this embodiment, there are five sleeves 51, and the spacing between two adjacent sleeves 51 is adapted to the width of the roadbed 2. The sleeves 51 are cylindrical structures made of metal or high-strength plastic. The bottom of the sleeve 51 is fixed to the inner wall of the test chamber 1 by a bracket. One end of the bracket is welded or bolted to the inner side wall of the test chamber 1, and the other end is fixed to the middle of the outer wall of the sleeve 51, so that the sleeve 51 remains vertical and does not contact the asphalt layer 3. Each sleeve 51 is equipped with an electric telescopic rod 54, which is arranged vertically. The top of the cylinder of the electric telescopic rod 54 is fixed to the inner top of the test chamber 1 by bolts, and the mounting plate is welded to the inner top of the test chamber 1. The telescopic end of the electric telescopic rod 54 faces downward, and the end of the telescopic end is connected to the test chamber 1 by a flange or buckle structure. Resistance disk 52 is fixedly connected. Resistance disk 52 is a circular metal heating disk with a diameter slightly smaller than the inner diameter of sleeve 51, ensuring that resistance disk 52 can move freely up and down vertically within sleeve 51 without deviation. All resistance disks 52 are electrically connected to temperature controller 53, which is placed on the operating table outside the test chamber 1. Each resistance disk 52 is connected to the signal output terminal of temperature controller 53 through an independent wire. Temperature controller 53 can independently control the heating temperature of each resistance disk 52 by adjusting the output current. All electric telescopic rods 54 are electrically connected to displacement controller 55, which is also placed on the operating table. The control terminal of each electric telescopic rod 54 is connected to the output terminal of displacement controller 55 through a wire. Displacement controller 55 can adjust the extension and retraction of each electric telescopic rod 54, thereby controlling the distance between the corresponding resistance disk 52 and the asphalt layer 3.

[0026] The tracing mechanism 6 includes several sand-containing water tanks 61, which are evenly distributed along the width of the roadbed 2 and located below the roadbed 2. In this embodiment, there are five sand-containing water tanks 61. The spacing between two adjacent sand-containing water tanks 61 is consistent with the spacing between adjacent sleeves 51, ensuring that the position of each sand-containing water tank 61 corresponds vertically to the position of the corresponding sleeve 51. The sand-containing water tanks 61 adopt a transparent plastic box structure and are filled with sand particles with a particle size similar to that of the bottom layer of the roadbed 2. The sand-containing water tanks 61 pass through... The bottom support legs are bolted to the bottom inner wall of the test chamber 1; each sand-containing water tank 61 is connected to an external water source through a separate water inlet pipe 62. The water inlet pipe 62 is made of plastic flexible tubing or metal rigid pipe. One end of the water inlet pipe 62 is threaded to the interface at the bottom of the side wall of the sand-containing water tank 61. A sealing gasket is provided at the interface to prevent water leakage. The other end of the water inlet pipe 62 extends through the reserved hole in the side wall of the test chamber 1 to the outside of the test chamber 1 and is connected to the valve of the external water source. By controlling the valve, each sand-containing water tank 61 can be supplied with water independently.

[0027] A pressure sensor 7 is installed between the asphalt layer 3 and the top of the roadbed 2. The pressure sensor 7 is a thin piezoelectric sensor, and its number is set according to the width of the roadbed 2. The bottom surface of the pressure sensor 7 is in close contact with the top end face of the roadbed 2, and the top surface is in close contact with the bottom surface of the asphalt layer 3, to ensure that the pressure sensor 7 can fully sense the pressure generated by the roadbed 2 on the asphalt layer 3 when it freezes. The pressure sensor 7 is electrically connected to the frost heave force measuring device 71, which is placed on the operating table outside the test chamber 1. Each pressure sensor 7 is connected to the signal input terminal of the frost heave force measuring device 71 through a signal line. The signal line passes through the wire hole on the side wall of the test chamber 1, and a sealing sleeve is provided at the wire hole. The frost heave force measuring device 71 can convert the pressure signal transmitted by the pressure sensor 7 into a specific frost heave force value.

[0028] like Figure 2 As shown, several frost heave testers 8 are installed above the asphalt layer 3. These testers 8 are evenly distributed along the width of the roadbed 2. The spacing between two adjacent frost heave testers 8 is set according to the test accuracy requirements. The frost heave tester 8 is a displacement sensor. The fixed end of the displacement sensor is fixed to the mounting bracket on the inner wall of the test chamber 1 by bolts. The mounting bracket is welded to the inner wall of the test chamber 1. The detection end of the displacement sensor faces downward and is directly opposite the top surface of the asphalt layer 3 in the vertical direction. A small gap is maintained between the detection end and the top surface of the asphalt layer 3 to ensure that the detection end can accurately capture the displacement when the asphalt layer 3 is displaced upward due to the frost heave of the roadbed 2.

[0029] Example 2: Based on the variable radiation gradient roadbed moisture migration phase change test device provided in Example 1, this example further provides a variable radiation gradient roadbed moisture migration phase change test method, including the following steps: Before the test begins, the device is moved to the designated test area using the wheels at the bottom of the test chamber 1. Then, the connection status of each component is checked: the signal line of the pressure sensor 7 and the frost heave measuring device 71 is confirmed to be securely connected, the detection end of the frost heave tester 8 maintains a preset small gap with the top surface of the asphalt layer 3, and the wires and pipes of the temperature control mechanism 4, the radiation variable mechanism 5, and the tracer mechanism 6 are not loose or leaking.

[0030] A preset amount of water is added to the sand-containing water tank 61 of the tracer 6. The water in each sand-containing water tank 61 has a different color. The water supply is adjusted by the external water source valve connected by the water inlet pipe 62, so that the water in the sand-containing water tank 61 slowly seeps to the bottom layer of the roadbed 2 at its top, simulating the groundwater recharge in the actual environment of the roadbed 2. At this time, because the test chamber 1 is made of transparent material, the initial distribution of water at the bottom of the roadbed 2 can be observed.

[0031] Temperature control mechanism 4 is activated: The target temperatures of the top and bottom negative temperature nets 41 of the roadbed 2 are set by the negative temperature controller 43, so that the temperature of the top negative temperature net 41 is lower than that of the bottom to form a vertical temperature gradient. The negative temperature controller 43 transmits the signal to the control module of the refrigeration compressor 42 to drive the refrigeration compressor 42 to run. The generated cooling energy is transferred to the negative temperature net 41 through the low temperature resistant wire. The negative temperature net 41 is in close contact with the soil of the roadbed 2, which diffuses the cooling energy into the interior of the roadbed 2. The heat generated by the refrigeration compressor 42 when it is working is dissipated to the outside through the heat dissipation fins of the condenser 44 to ensure stable cooling efficiency. After running for a period of time, a stable temperature gradient is formed in the vertical direction inside the roadbed 2.

[0032] Activate the variable radiation mechanism 5: Based on the simulated radiation difference between sunny and shady slopes, adjust the extension and retraction of the electric telescopic rod 54 inside each sleeve 51 using the displacement controller 55, so that each resistance plate 52 maintains a different distance from the top surface of the asphalt layer 3. The closer the distance, the greater the radiation intensity. Then, set the heating temperature of each resistance plate 52 using the temperature controller 53. The temperature of each resistance plate 52 can be adjusted independently to further expand the radiation difference. The temperature controller 53 controls the heating of the resistance plate 52 by outputting different currents. The heat passes through the sleeve 51 and acts on the asphalt layer 3 below. Because the five sleeves 51 are evenly distributed along the width direction of the roadbed 2, and the distance and temperature of each resistance plate 52 are different, a stable radiation gradient is finally formed along the width direction of the asphalt layer 3 and the roadbed 2 below, simulating the difference in solar radiation at different locations.

[0033] During the continuous operation of the temperature control mechanism 4 and the radiation mechanism 5, the moisture in the roadbed 2 migrates under the combined action of the temperature gradient and the radiation gradient: the colored tracer water in the sand-containing water tank 61 diffuses upward or in the width direction from the bottom of the roadbed 2. The test personnel can directly observe the migration path of the water of different colors through the transparent test chamber 1, such as gathering in areas with lower temperatures; when the water migrates to areas with temperatures below freezing, a phase change will occur to form ice. The phase change range of water from different sources can be clearly distinguished by the color difference.

[0034] Meanwhile, the roadbed 2 generates frost heave force due to the expansion of water freezing. This force is transmitted from the top of the roadbed 2 to the bottom of the asphalt layer 3. The pressure sensor 7, which is attached to the bottom of the asphalt layer 3, senses the pressure change and transmits the pressure signal to the frost heave force measuring device 71 through the signal line. The frost heave force measuring device 71 converts the signal into a specific value and records the magnitude of the frost heave force at different locations in real time.

[0035] The frost heave of the roadbed 2 will also cause the top asphalt layer 3 to move vertically upward. The frost heave tester 8 above the asphalt layer 3 is a displacement sensor. Its detection end is facing the top surface of the asphalt layer 3. When the asphalt layer 3 moves, the detection end captures the change in displacement and records the frost heave deformation data at different width positions in real time. This data corresponds to the frost heave force data, making it easier to analyze the relationship between frost heave force and frost heave amount.

[0036] During the experiment, the vertical temperature gradient can be changed by adjusting the negative temperature controller 43 of the temperature control mechanism 4, or the radiation gradient parameters can be adjusted by adjusting the displacement controller 55 and temperature controller 53 of the variable radiation mechanism 5. The above steps are repeated to study the variation law of moisture migration, phase change and frost heave characteristics of the roadbed 2 under different gradient conditions.

[0037] As can be seen from the above embodiments, the beneficial effects of this application are as follows: 1. It can accurately simulate the actual working conditions of the roadbed. The variable radiation mechanism simulates the radiation difference between the sunny and shady slopes, and the temperature control mechanism constructs a vertical temperature gradient, making the experimental results more consistent with the actual engineering situation. 2. Accurate measurement of frost heave parameters: pressure sensors are equipped with frost heave force measuring devices and displacement sensors to measure frost heave amount, enabling real-time acquisition of roadbed frost heave force and deformation data, supporting mechanical response analysis; 3. The visualization effect of water migration and phase change is good. The transparent test chamber is equipped with tracer water of different colors, which can be used to directly observe the migration path and phase change area. It can also correlate radiation and water patterns through multi-source sand-containing water tanks.

[0038] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A variable radiation gradient roadbed moisture migration phase change test device, comprising a test chamber (1), a roadbed (2) provided inside the test chamber (1), and an asphalt layer (3) laid on top of the roadbed (2), characterized in that, The roadbed (2) is equipped with a temperature regulating mechanism (4), which can regulate the roadbed (2) to form a temperature gradient in the vertical direction; the test chamber (1) is also equipped with a variable radiation mechanism (5) and a tracer mechanism (6). The variable radiation mechanism (5) is located above the asphalt layer (3), and the variable radiation mechanism (5) can apply differential radiation to the asphalt layer (3) in the width direction of the roadbed (2) to form a radiation gradient; the tracer mechanism (6) is located below the roadbed (2), and the tracer mechanism (6) can display the migration direction and phase change process of moisture in the roadbed (2).

2. The experimental device for phase change of moisture migration in roadbed with variable radiation gradient according to claim 1, characterized in that, A pressure sensor (7) is installed between the top of the asphalt layer (3) and the roadbed (2). The pressure sensor (7) is electrically connected to the frost heave force measuring device (71), which can measure the frost heave force of the roadbed (2).

3. The experimental device for phase change of moisture migration in roadbed with variable radiation gradient according to claim 2, characterized in that, Several frost heave testers (8) are provided above the asphalt layer (3), and the several frost heave testers (8) are evenly distributed along the width direction of the roadbed (2).

4. The experimental device for phase change of moisture migration in roadbed with variable radiation gradient according to claim 3, characterized in that, The frost heave tester (8) is a displacement sensor. The frost heave tester (8) is fixed to the inner wall of the test chamber (1), and the detection end of the frost heave tester (8) is directly facing the top surface of the asphalt layer (3) in the vertical direction.

5. The experimental device for phase change of moisture migration in roadbed with variable radiation gradient according to claim 1, characterized in that, The temperature control mechanism (4) includes two negative temperature grids (41), which are respectively located at the top and bottom of the roadbed (2). The two negative temperature grids (41) are respectively connected to a refrigeration compressor (42), and each refrigeration compressor (42) is equipped with a negative temperature controller (43) and a condenser (44).

6. The experimental device for phase change of moisture migration in roadbed with variable radiation gradient according to claim 1, characterized in that, The variable radiation mechanism (5) includes several sleeves (51). The sleeves (51) are arranged vertically and evenly distributed along the width of the roadbed (2). Each sleeve (51) is equipped with a lifting component and a resistance disk (52). The lifting component can control the corresponding resistance disk (52) to rise and fall in the vertical direction. All resistance disks (52) are electrically connected to the temperature controller (53). The temperature controller (53) can independently regulate the temperature of each resistance disk (52).

7. The experimental apparatus for phase change of moisture migration in roadbed with variable radiation gradient according to claim 6, characterized in that, The lifting assembly is an electric telescopic rod (54). The electric telescopic rod (54) is arranged vertically. The cylinder of the electric telescopic rod (54) is fixedly connected to the inner top of the test chamber (1). The telescopic end of the electric telescopic rod (54) is fixedly connected to the resistance disk (52). All electric telescopic rods (54) are electrically connected to the displacement controller (55).

8. The experimental apparatus for phase change of moisture migration in roadbed with variable radiation gradient according to claim 6, characterized in that, The tracing mechanism (6) includes several sand-containing water tanks (61), which are evenly distributed along the width of the roadbed (2). Each sand-containing water tank (61) corresponds vertically to the corresponding sleeve (51), and each sand-containing water tank (61) is connected to an external water source through an independent water inlet pipe (62).

9. The experimental apparatus for phase change of moisture migration in roadbed with variable radiation gradient according to claim 8, characterized in that, The test chamber (1) is made of transparent material, and the water in each sand-containing water tank (61) has a different color.

10. A method for testing the phase transition of moisture migration in roadbeds with varying radiation gradients, characterized in that, The application of the variable radiation gradient roadbed moisture migration phase change test device as described in claim 3 includes the following steps: A vertical temperature gradient is constructed, and the temperature gradient of the roadbed (2) is controlled by the temperature control mechanism (4) to form a temperature gradient along the vertical direction; A radiation gradient is constructed by applying differential radiation to the asphalt layer (3) along the width direction of the roadbed (2) through a variable radiation mechanism (5) to form a radiation gradient; The phase change of water migration was observed in the test chamber (1), and data were collected using the frost heave force measuring device (71) and the frost heave amount tester (8).

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