Model test device based on water-force-freeze thawing coupling effect

Abstract

The utility model relates to the technical field of model tests, and discloses a model test device based on a water-force-freeze thawing coupling effect, which comprises a model test box, a soaking system, a freeze thawing circulation system and a loading system, the soaking system is arranged at the bottom of the inner side of the model test box, and a roadbed soil body is laid on the soaking system and used for conducting a soaking test on the roadbed soil body; the center position of the upper surface of the roadbed soil body is a loading area, and the two sides of the upper surface of the roadbed soil body are freeze-thaw circulation areas; the freeze-thaw circulation system is laid in the freeze-thaw circulation area and is used for performing freeze-thaw circulation test on the upper surface of the roadbed soil body; the stress end of the loading system is erected on the top of the model test box, and the force application end of the loading system is located in the loading area. By integrating the soaking system, the freezing and thawing circulating system and the loading system, the influence of various environmental factors on the roadbed soil body can be simulated at the same time, so that the performance of the roadbed soil body is evaluated more comprehensively.

Description

Technical Field

[0001] This utility model relates to the field of model testing technology, specifically a model testing device based on water-mechanical-freeze-thaw coupling. Background Technology

[0002] With the rapid development of basic highway construction and the continuous increase in highway network density, more and more highways need to traverse seasonally frozen areas. Because the roadbed is largely exposed to the elements, it is constantly affected by external factors such as freeze-thaw cycles, evaporation, precipitation, and loads, leading to continuous changes in the engineering properties of the roadbed soil. The most direct manifestation is the deterioration of soil strength caused by changes in water content and freeze-thaw conditions, resulting in engineering defects such as subsidence, wave-like structures, longitudinal cracks, and ditch instability, seriously affecting the normal operation of the road structure. Freeze-thaw cycles decompose coarse particles in the roadbed soil into fine particles, changing the skeletal connection between soil particles, increasing the void ratio, and gradually increasing the internal fissure rate of loess with the number of cycles, affecting its shear strength, permeability, and other properties. Furthermore, due to climatic and human factors, precipitation has increased in many areas in recent years, and groundwater levels have been rising. Roadbed immersion or rising groundwater levels lead to a significant increase in the water content of the soil inside the roadbed, reducing the matric suction at the soil particle shrinkage film and weakening the connection strength between soil particles. During this process, the soil's compression modulus decreases significantly, and its strength drops markedly, leading to a rapid increase in roadbed settlement and causing engineering disasters.

[0003] Currently, numerous devices exist for subgrade model testing, but most only study the impact of single factors on subgrade damage, and are not suitable for test conditions under complex circumstances. For example, to investigate the effects of freeze-thaw cycles on subgrade soil, high and low temperature test chambers are typically used to subject small samples to heating and cooling cycles, but these cannot perform freeze-thaw cycle analysis on large model soil samples, resulting in significant differences from actual working conditions. Similarly, to investigate the effects of water immersion on subgrade soil, spray rain systems are commonly used, but they cannot analyze settlement caused by rising groundwater levels. Therefore, developing novel model testing devices is of great significance for the special engineering research involving water-mechanical-freeze-thaw coupling. Utility Model Content

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a model test device based on water-mechanical-freeze-thaw coupling effect, so as to solve the technical problem that the existing device is difficult to analyze the bearing capacity of the roadbed under special coupling conditions.

[0005] This utility model is achieved through the following technical solution:

[0006] A model test device based on water-mechanical-freeze-thaw coupling includes a model test chamber, an immersion system, a freeze-thaw cycle system, and a loading system;

[0007] The immersion system is located at the bottom inner side of the model test chamber, and the subgrade soil is laid on the immersion system for immersion testing of the subgrade soil. The center of the upper surface of the subgrade soil is the loading area, and the two sides of the upper surface of the subgrade soil are the freeze-thaw cycle areas. The freeze-thaw cycle system is laid in the freeze-thaw cycle area for freeze-thaw cycle testing of the upper surface of the subgrade soil. The force-bearing end of the loading system is erected on the top of the model test chamber, and the force-applying end of the loading system is located in the loading area.

[0008] Preferably, the immersion system includes a water storage chamber; the water storage chamber is the same size as the bottom surface of the model test chamber; the bottom surface of the roadbed soil is fully covered on the upper surface of the water storage chamber, and the upper surface of the water storage chamber is provided with several small holes for immersing the roadbed soil and conducting drainage tests; the bottom of the water storage chamber is provided with a water inlet, and the inlet is connected to the water supply system through a pipe passing through the bottom of the model test chamber.

[0009] Furthermore, a permeable geotextile is laid between the upper surface of the water storage cell and the bottom surface of the roadbed soil to prevent the small holes from becoming clogged.

[0010] Furthermore, the water storage chamber is divided into four inner chambers, and the bottom surface of the roadbed soil is covered with the upper surface of the four inner chambers; several small holes are distributed on the upper surface of each inner chamber; the inner corners of the four inner chambers are the junction points; the water inlets are located at the junction points of the bottoms of the four inner chambers to form four water inlets, which are used to conduct settlement tests on the roadbed soil at different immersion positions; the four water inlets are connected to the water supply system through pipelines; each water inlet is equipped with a plug to control the connection and closure of the water inlet.

[0011] Preferably, the freeze-thaw cycle system includes condenser pipes; the condenser pipes are a plurality of U-shaped pipes connected in sequence, the condenser pipes end to end to form a circulation loop, and are laid on both sides of the freeze-thaw cycle area on the upper surface of the roadbed soil, the condenser pipes being filled with antifreeze.

[0012] Furthermore, the condenser tube is equipped with an interface, which extends to the outside of the model test chamber via an external pipe and connects to a low-temperature thermostatic bath for inputting antifreeze into the condenser tube.

[0013] Preferably, the force-bearing end of the loading system is a reaction frame, which is composed of several rectangular steel plates. The two sides of the reaction frame are fixed to the top of the model test box by bolts and are located directly above the subgrade soil. The reaction frame is provided with a steel plate at the loading area on the upper surface of the subgrade soil for contact with the force-applying end of the loading system.

[0014] Furthermore, laser displacement sensors are installed at opposite corners of the steel plate to measure the settlement and displacement of the subgrade soil at the force-applying end of the loading system during the loading process.

[0015] Furthermore, the force-applying end of the loading system is a jack; the jack is located in the loading area on the upper surface of the roadbed soil, the lifting end of the jack is in contact with the steel plate, and the lifting end of the jack is equipped with a digital stress sensor to measure the stress value during the loading process of the jack.

[0016] Preferably, the side walls of the model test chamber are made of transparent tempered glass, the bottom is made of steel plate, and support legs are welded to the four corners of the bottom.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] This invention provides a model testing device based on water-mechanical-freeze-thaw coupling. By integrating a water immersion system, a freeze-thaw cycle system, and a loading system, it can simultaneously simulate the influence of multiple environmental factors on subgrade soil, thereby providing a more comprehensive evaluation of the subgrade soil's performance. This integrated testing method better reflects actual conditions than single-factor testing, improving the accuracy and practicality of the test. The freeze-thaw cycle system enables model tests of subgrade deterioration under different freeze-thaw temperatures, freeze-thaw cycles, freeze-thaw times, and freeze-thaw paths. The water immersion system analyzes the influence of different immersion locations, flow rates, immersion speeds, and immersion times on subgrade soil settlement. The loading system allows for the observation of stress and settlement values ​​during the loading process, thus accurately studying the bearing capacity of the subgrade soil.

[0019] Furthermore, the bottom surface of the water storage chamber is the same size as that of the model test chamber, ensuring complete contact between the immersion area and the bottom surface of the roadbed soil. This allows for a more accurate simulation of the actual road condition under immersion conditions. The upper surface of the water storage chamber has several small holes, which are used not only for uniform immersion of the roadbed soil but also for drainage tests when needed, simulating the drainage process of an actual road after rainfall or water accumulation. A water inlet is located at the bottom of the water storage chamber, connected to the water supply system via a pipe running through the bottom of the model test chamber. This design ensures a stable and controllable water supply to the immersion system, facilitating the adjustment of parameters such as immersion flow rate, immersion speed, and immersion time to meet different testing needs. By adjusting parameters such as the flow rate and pressure at the water inlet, the immersion conditions of the immersion system can be precisely controlled, thereby enabling performance evaluation of the roadbed soil under different immersion conditions.

[0020] Furthermore, permeable geotextiles possess excellent permeability while effectively blocking fine particles, preventing them from entering and clogging the pores, thus ensuring the normal operation of the immersion system. Simultaneously, permeable geotextiles promote the even distribution and infiltration of water. Their excellent permeability allows water to more easily penetrate the subgrade soil through the geotextile, simulating a more realistic immersion environment.

[0021] Furthermore, by dividing the water storage chamber into four inner chambers and laying roadbed soil on the upper surface of each inner chamber, settlement tests of the roadbed soil at different water immersion locations can be conducted. This more accurately simulates the state of actual roads under different rainfall or water accumulation conditions, providing more comprehensive data support for road design and maintenance. Each inner chamber's bottom water inlet is equipped with a plug to control the connection and closure of the water inlet, and the water immersion status of each inner chamber can be independently controlled, enabling a more flexible testing scheme.

[0022] Furthermore, the U-shaped arrangement of the condenser tubes ensures a more uniform temperature distribution within the freeze-thaw cycle area, facilitating a more realistic simulation of freeze-thaw processes in natural environments and resulting in more consistent freeze-thaw effects on the roadbed soil at different locations. The condenser tubes are filled with antifreeze, which has superior thermal conductivity compared to air, allowing for rapid response to external temperature control equipment adjustments and enabling rapid temperature rises and falls. This accelerates the freeze-thaw cycle process and improves testing efficiency.

[0023] Furthermore, the condenser tube is equipped with an interface that extends through an external pipe to the outside of the model test chamber, connecting to a cryogenic bath for introducing antifreeze into the condenser tube. The cryogenic bath provides a stable low-temperature environment, ensuring that the temperature of the antifreeze inside the condenser tube is precisely controlled within the required range. This allows for more accurate temperature control during freeze-thaw cycles, contributing to improved test accuracy.

[0024] Furthermore, the reaction frame is composed of several rectangular steel plates, making its overall structure stable and capable of withstanding large loads. The rectangular steel plates possess good rigidity and strength, effectively resisting the stress and deformation generated during loading. The two sides of the reaction frame are bolted to the top of the model test chamber. This connection method is not only robust and reliable but also facilitates disassembly and reinstallation. Bolting also ensures the reaction frame maintains a stable position during loading, preventing displacement or tilting. Steel plates are installed on the reaction frame at the loading area corresponding to the upper surface of the subgrade soil for contact with the force-applying end of the loading system. This design clearly defines the loading area, ensuring that the loading force is accurately applied to the designated location in the subgrade soil.

[0025] Furthermore, by installing laser displacement sensors at opposite corners of the steel plate, the settlement and displacement of the roadbed soil can be monitored from two different angles. This helps eliminate errors caused by a single measurement point, improving the accuracy and reliability of the measurements.

[0026] Furthermore, the jack's lifting end is equipped with a digital stress sensor, capable of monitoring and recording stress values ​​in real time during the loading process. This sensor boasts high precision and stability, ensuring the accuracy of the measurement results. By monitoring the data from the stress sensor, the loading stress on the jack can be precisely controlled to reach the predetermined loading level. This helps ensure the stability and reliability of the loading process, improving the accuracy of the experiment.

[0027] Furthermore, the side walls of the model test chamber are made of transparent tempered glass, allowing researchers to directly observe the testing process inside. This visualization helps researchers understand the test status in a timely manner and capture key phenomena and changes during the test. Through the transparent tempered glass side walls, researchers can monitor key parameters such as deformation and settlement of the subgrade soil in real time without opening the test chamber or interrupting the test. This improves the continuity and accuracy of the test. The bottom of the model test chamber is made of steel plate, a material with good rigidity and strength, capable of withstanding large loads. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the model test device in an embodiment of the present invention;

[0029] Figure 2 This is a front view of the model testing device in an embodiment of this utility model;

[0030] Figure 3 This is a top view of the model testing device in an embodiment of this utility model;

[0031] Figure 4 This is a side view of the model testing device in an embodiment of this utility model;

[0032] Figure 5 This is a schematic diagram of the freeze-thaw cycle device in an embodiment of this utility model;

[0033] Figure 6 This is a schematic diagram of the immersion device in an embodiment of the present invention;

[0034] Figure 7 This is a top view of the water storage compartment in an embodiment of this utility model;

[0035] In the diagram: 1. Model test chamber; 2. Subgrade soil; 3. Reaction frame; 4. Jack; 5. Laser displacement sensor; 6. Digital display stress sensor; 7. Low temperature constant temperature bath; 8. Condenser pipe; 9. Water supply system; 10. Water storage compartment; 11. Steel plate; 101. Plug. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, products, or devices.

[0038] The purpose of this invention is to provide a model test device based on water-mechanical-freeze-thaw coupling to solve the technical problem that existing devices are difficult to analyze the bearing capacity of roadbeds under special coupling conditions.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] See Figure 1 , Figure 2 , Figure 3 as well as Figure 4This invention provides a model test device based on water-mechanical-freeze-thaw coupling, including a model test chamber 1, a water immersion system, a freeze-thaw cycle system, and a loading system. The water immersion system is located at the bottom inner side of the model test chamber 1, and a roadbed soil 2 is laid on the water immersion system for water immersion testing of the roadbed soil 2. The center of the upper surface of the roadbed soil 2 is the loading area, and the two sides of the upper surface of the roadbed soil 2 are the freeze-thaw cycle areas. The freeze-thaw cycle system is laid in the freeze-thaw cycle areas for freeze-thaw cycle testing of the upper surface of the roadbed soil 2. The force-bearing end of the loading system is mounted on the top of the model test chamber 1, and the force-applying end of the loading system is located in the loading area.

[0041] Specifically, according to Figure 6 As shown, the immersion system includes a water storage chamber 10; the water storage chamber 10 is the same size as the bottom surface of the model test chamber 1; the bottom surface of the roadbed soil 2 is fully covered on the upper surface of the water storage chamber 10, and the upper surface of the water storage chamber 10 is provided with several small holes for immersing the roadbed soil 2 and conducting drainage tests; the bottom of the water storage chamber 10 is provided with a water source inlet, and the inlet is connected to the water supply system 9 through a pipe passing through the bottom of the model test chamber 1.

[0042] The upper surface of the water storage cell 10 is laid with a permeable geotextile between the upper surface of the cell and the bottom surface of the subgrade soil 2 to prevent the small holes from being blocked.

[0043] Among them, according to Figure 7 As shown, the water storage compartment 10 is divided into four inner compartments, and the bottom surface of the roadbed soil 2 is covered with the upper surface of the four inner compartments; several small holes are distributed on the upper surface of each inner compartment; the inner corners of the four inner compartments are the junction points; the water source inlets are set at the junction points of the bottom of the four inner compartments to form four water source inlets, which are used to conduct settlement tests on the roadbed soil 2 at different immersion positions; the four water source inlets are connected to the water supply system 9 through pipelines; each water source inlet is provided with a plug 101 to control the connection and closure of the water source inlet.

[0044] Specifically, according to Figure 5 As shown, the freeze-thaw cycle system includes condenser pipes 8; the condenser pipes 8 are a series of U-shaped pipes connected in sequence, and the condenser pipes 8 end to end to form a circulation loop, which is laid on both sides of the freeze-thaw cycle area on the upper surface of the roadbed soil 2, and the condenser pipes 8 are filled with antifreeze.

[0045] The condenser tube 8 is equipped with an interface, which extends to the outside of the model test chamber 1 via an external pipe and connects to the low-temperature constant temperature bath 7 for inputting antifreeze into the condenser tube 8.

[0046] Specifically, the force-bearing end of the loading system is the reaction frame 3, which is composed of several rectangular steel plates. The two sides of the reaction frame 3 are fixed to the top of the model test box 1 by bolts and are located directly above the subgrade soil 2. The reaction frame 3 is provided with a steel plate 11 at the loading area on the upper surface of the subgrade soil 2 for contacting the force-applying end of the loading system.

[0047] Laser displacement sensors 5 are installed at opposite corners of the steel plate 11 to measure the settlement displacement of the subgrade soil 2 at the force application end of the loading system during the loading process.

[0048] The loading system has a jack 4 as the force-applying end. The jack 4 is located in the loading area on the upper surface of the roadbed soil 2. The lifting end of the jack 4 is in contact with the steel plate 11, and the lifting end of the jack 4 is equipped with a digital stress sensor 6 to measure the stress value during the loading process of the jack 4.

[0049] Specifically, the side walls of the model test chamber 1 are made of transparent tempered glass, the bottom is made of steel plate, and the four corners of the bottom are welded with support legs.

[0050] The low-temperature constant temperature bath 7 of this utility model can be programmed with a temperature cycle. By continuously freezing and thawing the antifreeze in the condenser tube, the freeze-thaw cycle of the roadbed model soil is achieved. By continuously freezing and thawing the antifreeze in the condenser tube 8, roadbed deterioration model tests can be conducted under different freeze-thaw temperatures, freeze-thaw cycles, freeze-thaw times, and freeze-thaw paths.

[0051] In this utility model, the water supply system 9 is a special water pump that can control the speed of water flow, water supply time, and water supply flow rate. It is connected to the water storage compartment 10 at the bottom of the model test chamber 1 through a PPR water pipe.

[0052] Example 1

[0053] The steps for conducting model tests using this device are as follows:

[0054] I. Constructing the Model Test Soil. Specifically, based on the various similarity constants from the model test, the roadbed section to be analyzed at the construction site is scaled down to the corresponding scale, thereby constructing the roadbed soil 2 in the model test chamber 1 using the calculated data. Before filling the soil, it is determined whether to lay permeable geotextile material at the bottom based on the test conditions and soil properties. In addition, the opening and closing status of the four plugs at the bottom of the water storage cell 10 should also be determined at this stage.

[0055] II. Installation of the reaction frame and monitoring device. Based on the specific test conditions, the reaction frame 3 is fixed directly above the subgrade soil 2 using bolts. The placement of the laser displacement sensor 5 and the digital stress sensor 6 is determined according to the loading position. The laser displacement sensor 5 is typically placed diagonally to accurately obtain the subgrade soil settlement values. The digital stress sensor 6 is located directly above the loading device and is used to control the stress magnitude during the loading process.

[0056] 3. Install the jacks. Adjust the extension length of the jacks 4 according to the filling height and position of the subgrade soil 2, ensuring that the bottom of the jacks 4 just contacts the subgrade soil 2 and the top just contacts the digital stress sensor 6. Extend and retract the jacks 4 using their compression rods to maintain a small reading on the digital stress sensor 6.

[0057] IV. Conduct Loading Tests. Different loading cycle paths should be adopted for different soil types. If the test soil is fine-grained, the subgrade soil 2 should be consolidated first, i.e., a constant load should be maintained by using jacks 4, and the four plugs at the bottom of the water storage chamber 10 should be opened to drain the consolidated soil. If the test soil is coarse-grained, the consolidation of the subgrade soil 2 can be disregarded, and loading can be carried out directly according to the test plan. During the loading process, the loading magnitude of jacks 4 should be controlled by the digital display stress sensor 6, and graded loading should be used until the subgrade soil 2 fails.

[0058] V. Data Processing. Based on the stress values ​​from the digital stress sensor 6 and the displacement values ​​from the laser displacement sensor 5 during the loading process, the load test curve of the subgrade soil 2 is plotted, and its bearing capacity is analyzed to provide reliable parameters for engineering construction.

[0059] Example 2:

[0060] The operational approach differs from Example 1 in that this analysis examines the damage to the subgrade soil 2 caused by rising groundwater levels. Before conducting the loading test, the parameters of the water supply system 9 should be determined based on the rising groundwater level, including: immersion volume, immersion time, and immersion rate. Then, the four plugs at the bottom of the water storage chamber 10 are opened, and the water supply system 9 is connected. Finally, following the loading scheme in Example 1, the subgrade soil is loaded in stages, and the stress values ​​of the digital stress sensor 6 and the displacement values ​​of the laser displacement sensor 5 are recorded to analyze the bearing capacity of the subgrade soil 2 under rising groundwater levels. Alternatively, one or more of the four plugs at the bottom of the water storage chamber 10 can be selectively opened through the test scheme to analyze the bearing capacity of the subgrade soil 2 under localized groundwater inrush or leakage conditions.

[0061] Example 3:

[0062] Unlike Example 1, this operation analyzes the damage to the subgrade soil 2 caused by the coupled effects of rising groundwater level and freeze-thaw cycles. First, before conducting the loading test, the parameters of the water supply system 9 should be determined based on the rising groundwater level, including: immersion volume, immersion time, and immersion rate. Then, the plug at the bottom of the water storage chamber 10 is opened and the water supply system 9 is connected. Second, condenser pipes 8 are laid on the surface of the subgrade soil 2, antifreeze is injected, and the parameters of the low-temperature constant-temperature bath 7 are determined, including: freeze-thaw temperature, number of freeze-thaw cycles, freeze-thaw time, and freeze-thaw path. Then, the low-temperature constant-temperature bath 7 is turned on, causing the condenser pipes 8 to continuously freeze and thaw, thereby achieving the coupling effect of freeze-thaw cycles and rising groundwater level. Finally, following the loading scheme in Example 1, the subgrade soil is loaded in stages, and the stress values ​​of the digital stress sensor 6 and the displacement values ​​of the laser displacement sensor 5 are recorded to analyze the bearing capacity of the subgrade soil 2 under the coupled conditions of freeze-thaw cycles and rising groundwater level.

[0063] In summary, this utility model provides a model test device based on water-mechanical-freeze-thaw coupling. A condenser pipe connected to a low-temperature constant-temperature bath is laid on top of the soil in the model test, thereby simulating test conditions such as different freeze-thaw temperatures, freeze-thaw cycles, freeze-thaw times, and freeze-thaw paths. The combination of the water storage compartment and the water supply system allows for simulation of test conditions such as different immersion locations, immersion flow rates, immersion speeds, and immersion times. Furthermore, by observing the stress and settlement values ​​of the loading system, the bearing capacity of the subgrade soil under multiple working conditions can be accurately studied, providing strong support for the analysis of actual working conditions.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A model test device based on water-mechanical-freeze-thaw coupling, characterized in that, Includes a model test chamber (1), an immersion system, a freeze-thaw cycle system, and a loading system; The immersion system is set at the bottom inside the model test box (1), and the subgrade soil (2) is laid on the immersion system for immersion testing of the subgrade soil (2); the center of the upper surface of the subgrade soil (2) is the loading area, and the two sides of the upper surface of the subgrade soil (2) are the freeze-thaw cycle areas; the freeze-thaw cycle system is laid in the freeze-thaw cycle area for freeze-thaw cycle testing of the upper surface of the subgrade soil (2); the force-bearing end of the loading system is set on the top of the model test box (1), and the force-applying end of the loading system is located in the loading area.

2. The model test device based on water-mechanical-freeze-thaw coupling according to claim 1, characterized in that, The immersion system includes a water storage chamber (10); the bottom surface of the water storage chamber (10) is the same size as that of the model test box (1); the bottom surface of the roadbed soil (2) is covered and placed on the upper surface of the water storage chamber (10), and the upper surface of the water storage chamber (10) is provided with several small holes for immersing the roadbed soil (2) and conducting drainage tests; the bottom of the water storage chamber (10) is provided with a water source inlet, and the inlet is connected to the water supply system (9) through a pipe passing through the bottom of the model test box (1).

3. The model test device based on water-mechanical-freeze-thaw coupling according to claim 2, characterized in that, A permeable geotextile is laid between the upper surface of the water storage cell (10) and the bottom surface of the roadbed soil (2) to prevent the small holes from being blocked.

4. The model test device based on water-mechanical-freeze-thaw coupling according to claim 3, characterized in that, The water storage chamber (10) is divided into four inner chambers. The bottom surface of the roadbed soil (2) is covered with the upper surface of the four inner chambers. Several small holes are distributed on the upper surface of each inner chamber. The inner corner of the four inner chambers is the junction point. The water source inlet is set at the junction point of the bottom of the four inner chambers to form four water source inlets, which are used to conduct settlement tests on the roadbed soil (2) at different immersion positions. The four water source inlets are connected to the water supply system (9) through pipelines. Each water source inlet is provided with a plug (101) to control the connection and closure of the water source inlet.

5. The model test device based on water-mechanical-freeze-thaw coupling according to claim 1, characterized in that, The freeze-thaw cycle system includes a condenser tube (8); the condenser tube (8) is a series of U-shaped tubes connected in sequence, and the condenser tubes (8) are adjacent to each other to form a cycle loop, and are laid on both sides of the freeze-thaw cycle area on the upper surface of the roadbed soil (2), and the condenser tube (8) is filled with antifreeze.

6. The model test device based on water-mechanical-freeze-thaw coupling according to claim 5, characterized in that, The condenser tube (8) is provided with an interface, which extends to the outside of the model test chamber (1) through an external pipe and is connected to a low-temperature constant temperature bath (7) for inputting antifreeze into the condenser tube (8).

7. The model test device based on water-mechanical-freeze-thaw coupling according to claim 1, characterized in that, The force-bearing end of the loading system is a reaction frame (3), which is composed of several rectangular steel plates. The two sides of the reaction frame (3) are fixed to the top of the model test box (1) by bolts and are located directly above the subgrade soil (2). The reaction frame (3) is provided with a steel plate (11) at the loading area on the upper surface of the subgrade soil (2) for contacting the force-applying end of the loading system.

8. The model test device based on water-mechanical-freeze-thaw coupling according to claim 7, characterized in that, Laser displacement sensors (5) are provided at opposite corners of the steel plate (11) to measure the settlement displacement of the subgrade soil (2) at the force application end of the loading system during the loading process.

9. A model test device based on water-mechanical-freeze-thaw coupling as described in claim 7, characterized in that, The force-applying end of the loading system is a jack (4); the jack (4) is located in the loading area on the upper surface of the roadbed soil (2), the lifting end of the jack (4) is in contact with the steel plate (11), and the lifting end of the jack (4) is equipped with a digital stress sensor (6) to measure the stress value during the loading process of the jack (4).

10. A model test device based on water-mechanical-freeze-thaw coupling as described in claim 1, characterized in that, The side walls of the model test chamber (1) are made of transparent tempered glass, the bottom is made of steel plate, and the four corners of the bottom are welded with support legs.

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