A multifunctional large-scale frost heave and thaw settlement model test device and test method

Abstract

This invention relates to the field of geotechnical engineering technology, and in particular to a multifunctional large-scale frost heave and thaw settlement model test device and test method. The device includes a main frame, and further includes: several glass plates, each detachably installed within the main frame, with test materials placed within the cavity formed by the glass plates and the main frame; a freezing assembly, including several freezing holes formed on the glass plates, with freezing pipes connected to the freezing holes and the freezing pipes connected to a high-low temperature cooling circulation system; and a movable glass plate, with a movable glass plate detachably installed on the glass plate, and the freezing holes located around the periphery of the movable glass plate. The multifunctional large-scale frost heave and thaw settlement model test device disclosed in this invention can conduct simulation tests of the entire process of frost heave-connecting tunnel excavation-thaw settlement, and by comparing the test results, a suitable freezing pipe layout scheme for on-site freezing construction can be found.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and in particular to a multifunctional large-scale frost heave and thaw settlement model test device and test method. Background Technology

[0002] The freezing of soil causes volume expansion, while thawing closes the pores, leading to subsidence and resulting in frost heave and thaw settlement. This characteristic is one of the most prominent features of permafrost, severely impacting the long-term stability of engineering structures. Particularly in seasonally frozen and artificially frozen areas, where hydrogeological conditions are complex, deformation and instability of engineering structures caused by soil frost heave and thaw settlement are frequent, resulting in significant economic losses.

[0003] Currently, many researchers study the frost heave and thaw settlement characteristics of soil in subway connecting passages through model tests. They conduct these tests and use the results to guide on-site construction. However, most current testing devices can only perform frost heave tests or simple thaw settlement tests. This results in relatively limited research data, simulates only a single construction phase, and creates small physical models. Furthermore, conducting multiple data acquisition tests requires different testing devices to be used simultaneously, which increases costs, hinders data collection, and limits data availability. Therefore, existing testing devices cannot simulate the entire process of frost heave, connecting passage excavation, and thaw settlement.

[0004] Therefore, there is an urgent need for a multifunctional large-scale frost heave and thaw settlement model test device and test method to solve the above technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a multifunctional large-scale frost heave and thaw settlement model test device and test method to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a multifunctional large-scale frost heave and thaw settlement model test device, including a main frame, and further comprising:

[0007] A glass plate, wherein a plurality of glass plates are provided, and the plurality of glass plates are detachably installed within the main frame, and test materials are placed in the cavity formed by the glass plates and the main frame;

[0008] The freezing assembly includes a plurality of freezing holes formed in the glass plate, a freezing tube disposed in the freezing hole, a freezing pipeline connected to the liquid outlet end of the freezing tube, and a high and low temperature cooling circulation integrated machine connected to the freezing pipeline.

[0009] A movable glass plate, wherein a movable glass plate is detachably mounted on the glass plate, and a plurality of the freezing holes are located on the periphery of the movable glass plate.

[0010] Preferably, there are at least three glass plates, including:

[0011] A bottom glass panel, which slides within the main frame;

[0012] An intermediate glass plate is slidably connected to the bottom glass plate. A movable glass plate is detachably connected to the intermediate glass plate, and a plurality of freezing holes are provided on it. The freezing holes are arranged circumferentially on the outside of the movable glass plate.

[0013] A top glass panel that slides onto the middle glass panel.

[0014] Preferably, it also includes a monitoring and analysis system, the monitoring and analysis system comprising:

[0015] A full-field strain monitoring system is placed on the side of the main frame where freezing holes are provided;

[0016] The full-field strain monitoring system is electrically connected to the computer, and the full-field strain monitoring system collects and transmits the monitored data to the computer for subsequent analysis.

[0017] Preferably, the test material also includes earth pressure cells, wherein a plurality of earth pressure cells are embedded within the test material, and the earth pressure cells are electrically connected to the computer.

[0018] Preferably, it further includes an axial pressure system disposed on the main frame, the axial pressure system comprising:

[0019] A force transmission plate is provided above the test material;

[0020] A force transmission base is mounted on the force transmission component;

[0021] A hydraulic jack is mounted on the main frame, and when the hydraulic jack applies downward pressure, the force-applying end of the hydraulic jack contacts the force transmission seat.

[0022] An axial hydraulic servo control system is electrically connected to the hydraulic jack.

[0023] Preferably, it further includes an axial pressure system disposed on the main frame, the axial pressure system comprising:

[0024] A force transmission plate is provided above the test material;

[0025] A force transmission base is mounted on the force transmission component;

[0026] A hydraulic jack is mounted on the main frame, and when the hydraulic jack applies downward pressure, the force-applying end of the hydraulic jack contacts the force transmission seat.

[0027] An axial hydraulic servo control system is electrically connected to the hydraulic jack.

[0028] Preferably, it also includes a seepage system, the seepage system comprising:

[0029] Water-permeable components are respectively embedded on the two inner side walls of the main frame;

[0030] A water circulation assembly includes a water storage tank, an inlet pipe connected to the outlet end of the water storage tank, the inlet pipe passing through a permeable component, and an outlet pipe passing through another permeable component, the outlet end of the outlet pipe being connected to the water storage tank.

[0031] Preferably, an outlet valve is fixedly installed on the inlet pipe; and an inlet valve is fixedly installed on the outlet pipe.

[0032] To achieve the above objectives, the present invention also provides the following solution: a multifunctional large-scale freeze-thaw settlement model test method, characterized in that: based on the above-mentioned multifunctional large-scale freeze-thaw settlement model test device, the test steps are as follows:

[0033] Assemble the test apparatus;

[0034] Frost heave test: The soil frost heave test is initiated by circulating cold liquid at a specified temperature through the freezing pipe.

[0035] Excavation test of the connecting passage: The movable glass panel was removed, and the soil inside the section was excavated. After the excavation was completed, the movable glass panel was reinstalled.

[0036] Thaw settlement test: The soil thaw settlement test is carried out by circulating hot liquid at a specified temperature in a freezing pipe;

[0037] Data acquisition: Data is collected and stored using a monitoring and analysis system;

[0038] The experiment is complete. The experimental setup is dismantled and the experimental materials are removed.

[0039] This invention discloses the following technical advantages: The multifunctional large-scale frost heave and thaw settlement model testing device disclosed in this invention can not only complete frost heave tests through freezing components, but also simulate the excavation of connecting channels by disassembling movable glass plates. Simultaneously, by controlling the temperature of the liquid through a high-low temperature cooling circulation integrated machine, the thaw settlement test can be simulated when the liquid entering the freezing pipeline is a hydrothermal liquid. This multifunctional large-scale frost heave and thaw settlement model testing device can conduct simulation tests of the entire process of frost heave-connecting channel excavation-thaw settlement. By comparing the test results, a suitable freezing pipe layout scheme for on-site freezing construction can be found. This invention has a simple structure, reasonable design, convenient operation, and multiple simulation variables, providing experimental data support for the optimized design of freezing pipes. It has good performance and is easy to promote and use. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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 these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of the multifunctional large-scale freeze-thaw settlement model test device disclosed in this invention;

[0042] Figure 2 for Figure 1 The main view of the central framework;

[0043] Figure 3 for Figure 2 The left view;

[0044] Figure 4 This is a schematic diagram of the glass plate installation structure;

[0045] Figure 5 This is a schematic diagram of the earth pressure monitoring system.

[0046] Figure 6 This is a schematic diagram of the grouting system.

[0047] Figure 7 This is a schematic diagram of a rectangular cross-section;

[0048] Figure 8 This is a schematic diagram of a circular cross-section structure;

[0049] Figure 9 A schematic diagram of a straight-walled, semi-circular arched cross-section;

[0050] Figure 10 This is a partial structural diagram of the slide.

[0051] Figure 11 This is a schematic diagram of the permeable panel structure.

[0052] The components include: 1. Main frame; 1-1. Slide rail; 1-2. Roller; 2. Pad; 3. Force transmission plate; 4. Glass plate; 4-1. Bottom glass plate; 4-2. Middle glass plate; 4-3. Top glass plate; 5. Freezing pipe; 6. Grouting pipe; 7. Displacement gauge; 8. Hydraulic jack; 9. Force transmission base; 10. Connecting hole; 11. Temperature measuring line; 12. Temperature monitoring system; 12-1. Temperature sensor; 12-2. Temperature acquisition instrument; 13. Moisture content measuring line; 14. Moisture content monitoring system; 15. Freezing pipeline; 16. High and low temperature cooling circulation integrated machine; 17. Axial hydraulic servo control system; 18. Axial... 19. Hydraulic press sensor line; 20. Displacement monitoring system; 21. Displacement measuring line; 22. Movable glass plate; 23. Full-field strain monitoring system; 24. Water storage tank; 25. Water outlet valve; 26. Water inlet pipe; 27. Water inlet valve; 28. Grouting pipeline; 28. Grouting system; 28-1. Grouting pipeline; 28-2. Solenoid valve; 28-3. Pressure gauge; 28-4. Flow meter; 28-5. Controller; 28-6. Booster; 28-7. Liquid storage tank; 29. ​​Computer; 30. Permeable plate; 30-1. Filter screen layer; 30-2. Filter layer; 30-3. Permeable layer; 31. Earth pressure box; 32. Water outlet pipe. Detailed Implementation

[0053] 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 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 are within the scope of protection of the present invention.

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Reference Figures 1-11 This invention provides a multifunctional large-scale frost heave and thaw settlement model test device, including a main frame 1, and further comprising:

[0056] Glass plate 4, several glass plates 4 are provided, and several glass plates 4 can be detachably installed in the main frame 1. The test material is placed in the cavity formed by the glass plate 4 and the main frame 1.

[0057] The freezing assembly includes several freezing holes formed on the glass plate 4, freezing tubes 5 are installed in the freezing holes, the liquid outlet end of the freezing tubes 5 is connected to a freezing pipeline 15, and the freezing pipeline 15 is connected to a high and low temperature cooling circulation integrated machine 16.

[0058] Movable glass plate 21 is detachably installed on glass plate 4, and several freezing holes are located around the movable glass plate 21.

[0059] Specifically, such as Figure 1 As shown, the multifunctional large-scale frost heave and thaw settlement model test device disclosed in this invention can not only complete frost heave tests through freezing components, but also simulate the excavation of connecting channels by disassembling the movable glass plate 21. Simultaneously, the temperature of the liquid is controlled by the high-low temperature cooling circulation integrated machine 16, so that when the liquid entering the freezing pipe 15 and freezing pipe 5 is a hydrothermal liquid, a thaw settlement test can be simulated. By comparing the test results, a suitable arrangement scheme for the freezing pipe 5 for on-site freezing construction can be found. This invention has a simple structure, reasonable design, convenient operation, and multiple simulation variables, providing experimental data support for the optimized design of the freezing pipe 5. It has good performance and is easy to promote and use. Furthermore, to simulate the effects of overall freezing and partial freezing by simulating freezing pipes 5 of different lengths, the length of the freezing pipe 5 inserted into the freezing hole can be adjusted as needed. In addition, as... Figures 7-9 As shown, in order to study the influence of different cross-sectional forms of connecting passage excavation on soil frost heave and thaw settlement, the shape of the movable glass plate 21 can be adjusted according to the needs of the site. Its shape is preferably, but not limited to, a rectangular cross-section, a circular cross-section, and a straight-wall semi-circular arched cross-section. At the same time, in order to facilitate the assembly and disassembly of the movable glass plate 21, it can be directly fastened to the glass plate 4 by means of a snap-fit ​​method. When it needs to be removed, it can also be lifted and removed along the gap between the two by an auxiliary tool. At the same time, it can also reduce the number of freezing pipes 5 inserted to adjust the shape of the frozen area and simulate the frost heave test of the area formed by different shapes.

[0060] Further optimization of the design involves at least three glass plates 4, including:

[0061] The bottom glass plate 4-1 is slidably attached to the main frame 1.

[0062] The middle glass plate 4-2 is slidably connected to the bottom glass plate 4-1. The middle glass plate 4-2 is detachably connected to the movable glass plate 21, and several freezing holes are also provided on it. The freezing holes are arranged circumferentially on the outside of the movable glass plate 21.

[0063] The top glass plate 4-3 is slidably attached to the middle glass plate 4-2.

[0064] Specifically, such as Figure 1 , Figure 3 and Figure 4As shown, glass plate 4 is assembled in three layers, which allows for easy placement of the test material and ensures its compactness. Before the test, the bottom glass plate 4-1 is slid into the slide 1-1 of the main frame 1. Then, the test material is poured into the cavity formed by the bottom glass plate 4-1 and the main frame 1 and compacted. After it meets the specified requirements, the middle glass plate 4-2 is slid onto the bottom glass plate 4-1. To facilitate the smooth sliding of the middle glass plate 4-2 and the bottom glass plate 4-1, a slide (not shown in the figure) can be provided on the upper part of the bottom glass plate 4-1 for easier installation. The test material is then poured in and compacted again, following the same steps and requirements as before. Finally, the top glass plate 4-3 is slid onto the middle glass plate 4-2, with a slide between them. To facilitate the sliding of the glass plates 4 into the main frame 1, through grooves (not marked in the figure) are provided on both sides of the main frame 1 for easy installation of the glass plates 4. In addition, as... Figure 10 As shown, in order to allow the bottom glass plate 4-1 to slide smoothly into the main frame 1, a slide rail 1-1 is provided on the main frame 1. At the same time, several rollers 1-2 are rotatably installed on the slide rail 1-1. In this way, when the bottom glass plate 4-1 needs to be installed, the bottom glass plate 4-1 can be pushed in directly along the slide rail 1-1. The rollers 1-2 make it easier for the bottom glass plate 4-1 to slide.

[0065] Further optimization of the plan also includes a monitoring and analysis system, which includes:

[0066] The full-field strain monitoring system 22 is placed on the side of the main frame 1 where the freezing holes are provided;

[0067] Computer 29 and full-field strain monitoring system 22 are electrically connected to computer 29, and the full-field strain monitoring system 22 collects and transmits the monitored data to computer 29 for subsequent analysis and feedback.

[0068] Specifically, such as Figure 1 As shown, in order to ensure the comprehensiveness of the monitoring data, the present invention uses a full-field strain monitoring system 22 and a computer 29 in combination. The full-field strain monitoring system 22 is placed in front of the multifunctional large-scale frost heave and thaw settlement model test device. The full-field strain monitoring system 22 can be used to monitor and collect changes in stress field, displacement field and other factors during the frost heave, excavation and thaw settlement process of the soil. Finally, the data is transmitted to the computer 29 for feedback control and output, and the freezing scheme is optimized based on the test measurement results.

[0069] In one embodiment, to ensure the monitoring of other values ​​of the test material, a moisture content monitoring sensor and a temperature sensor 12-1 are placed in the test material. The moisture content monitoring sensor is then connected to the moisture content monitoring system 14 via a moisture content measuring line 13, and the temperature sensor 12-1 is connected to the temperature monitoring system 12 via a temperature measuring line 11. The temperature monitoring system 12 includes a temperature acquisition instrument 12-2, which is electrically connected to the temperature sensor 12-1. The moisture content monitoring sensor and the temperature sensor 12-1 are used to monitor the moisture content and temperature value in the test material, respectively. The moisture content monitoring system 14 and the temperature acquisition instrument 12-2 are electrically connected to a computer 29, and the relevant data collected are stored in the computer 29 and analyzed.

[0070] Further optimization of the scheme also includes earth pressure cells 31. Several earth pressure cells 31 are embedded in the test material. The earth pressure cells 31 are electrically connected to the data acquisition system 33. The data acquisition system 33 is electrically connected to the computer 29 and stores the acquired data in the computer 29.

[0071] Specifically, such as Figure 5 As shown, the earth pressure cells 31 array is distributed around the connecting passage. During the placement of the soil, the earth pressure cells 31 pre-embedded in the soil can be used to measure the pressure changes in the soil caused by construction conditions.

[0072] Further optimization of the scheme also includes an axial pressure system installed on the main frame 1, the axial pressure system comprising:

[0073] Force transmission plate 3 is installed above the test material;

[0074] Force transmission seat 9, a force transmission seat 9 is installed on the force transmission component;

[0075] Hydraulic jack 8 is installed on the main frame 1, and when hydraulic jack 8 applies downward pressure, the force-applying end of hydraulic jack 8 contacts the force transmission seat 9.

[0076] Axial hydraulic servo control system 17 is electrically connected to hydraulic jack 8.

[0077] Specifically, such as Figure 1As shown, in order to further improve the accuracy of test data acquisition and better conduct the test, a pad 2 is placed above the force transmission plate 3. At the same time, in order to monitor the overall frost heave and thaw settlement of the test soil, a displacement gauge 7 is installed on the main frame 1. A displacement monitoring system 19 is connected through the displacement measuring line 20. The displacement monitoring system 19 collects the data on the displacement gauge 7, thereby monitoring the overall frost heave and thaw settlement of the test soil, and transmitting it to the computer 29 for storage and analysis. At the start of the experiment, when simulating the self-weight of the overlying strata of the tunnel, the axial hydraulic servo control system 17 connects to the axial hydraulic press sensor line 18 to control the hydraulic jacks 8 to apply a specified static load downwards. Similarly, when simulating the effect of dynamic loads on soil frost heave and thaw settlement, the axial hydraulic servo control system 17 connects to the axial hydraulic press sensor line 18 to control the hydraulic jacks 8 to apply dynamic loads downwards. The dynamic loads can realize square wave, triangular wave, sine wave, exponential wave, logarithmic wave, and other waveform loads with controllable frequencies. Furthermore, each hydraulic jack 8 can be controlled to apply a dynamic load separately to simulate the effect of local dynamic loads on soil frost heave and thaw settlement. In addition, the earth pressure cell 31 pre-embedded in the soil can be used to measure the pressure changes in the soil under static load, dynamic load, excavation, and other conditions.

[0078] Further optimization of the scheme also includes grouting system 28, which includes:

[0079] Grouting holes are opened on the glass plate 4, and several holes are opened. A grouting pipe 28-1 is installed in the grouting hole, and a solenoid valve 28-2 is fixedly installed on the grouting pipe 28-1.

[0080] The liquid storage tank 28-7 is connected to the grouting pipeline 28-1 at its outlet end.

[0081] The monitoring components include a pressure gauge 28-3 and a flow meter 28-4 respectively installed on the grouting pipeline 28-1;

[0082] Controller 28-5 is electrically connected to pressure gauge 28-3 and flow meter 28-4 respectively. Controller 28-5 controls the opening and closing of solenoid valve 28-2.

[0083] Furthermore, a booster 28-6 is fixedly installed on the outlet end of the liquid storage tank 28-7, and the booster 28-6 is electrically connected to the controller 28-5.

[0084] Specifically, such as Figure 1 and Figure 6 As shown, in order to conduct simulation experiments on melt-sinking deformation control, several grouting holes were opened on glass plate 4, and as... Figure 2 and Figure 4As shown, grouting holes and freezing holes are spaced apart, with two grouting holes located on either side of a freezing hole. When thaw settlement occurs and grouting is required on the thawed test material, computer 29 analyzes and judges the data, transmitting the analyzed data to controller 28-5. Controller 28-5 controls solenoid valve 28-2 to open, allowing grout in storage tank 28-7 to enter the test material through grouting pipe 28-1. During the test, computer 29 can analyze deformation and displacement monitoring data in real time, continuously adjusting the grouting pressure to achieve intelligent control of grouting in the thaw settlement area until the soil deformation stabilizes. This test device can perform intelligent grouting based on the actual thaw settlement effect of the soil, achieving automatic compensation grouting in the thaw settlement area and realizing the purpose of intelligent control of thaw settlement grouting. It simulates the entire process of soil frost heave, connecting channel excavation, thaw settlement, and grouting.

[0085] Further optimization of the plan also includes a seepage system, which includes:

[0086] Permeable components are embedded in the two inner side walls of the main frame 1;

[0087] The water circulation component includes a water storage tank 23. The outlet end of the water storage tank 23 is connected to an inlet pipe 25. The inlet pipe 25 passes through a permeable part, and an outlet pipe 32 passes through another permeable part. The outlet end of the outlet pipe 32 is connected to the water storage tank 23.

[0088] Furthermore, an outlet valve 24 is fixedly installed on the inlet pipe 25; and an inlet valve 26 is fixedly installed on the outlet pipe 32.

[0089] Specifically, such as Figure 11As shown, to further ensure the clarity of the water entering the test material and to ensure the stable operation of the permeable system, the permeable plate 30 is a porous permeable plate, including a filter layer 30-1, a filter layer 30-2, and a permeable layer 30-3. The filter layer 30-1 is located on the outermost layer, close to the inlet pipe 25, to prevent large particles of impurities from entering the interior of the permeable plate 30 and to keep it flat. The filter layer 30-2 is located behind the filter layer 30-1 and is made of fine-particle material, which can filter smaller particles of impurities and keep the interior of the permeable plate 30 clean. The permeable layer 30-3 is located behind the filter layer 30-2, close to the interior of the test material, and is made of porous material with large porosity, which can promote rapid water permeation and maintain an appropriate amount of moisture. At the same time, to ensure the sealing between the permeable plate 30 and the main frame 1, the connection points are sealed. During the experiment, the inlet valve 26 and the outlet valve 24 are opened. Under pressure, the water in the storage tank 23 flows along the inlet pipe 25 through the permeable plate 30 into the test material in the main frame 1, thus forming seepage. The water flows through the test material and finally through the permeable plate 30 into the storage tank 23 along the outlet pipe 32, thus forming a stable loop. By changing the pressure in the storage tank 23, the effect of different seepage conditions on the frost heave and thaw settlement of the soil can be studied.

[0090] This invention also provides a multifunctional large-scale freeze-thaw settlement model test method. Based on the above-mentioned multifunctional large-scale freeze-thaw settlement model test device, the test steps are as follows:

[0091] Assemble the test apparatus;

[0092] Frost heave test: The cold liquid at a specified temperature is circulated through the freezing pipe 15 to start the frost heave test of the soil.

[0093] Excavation test of the connecting passage: Remove the movable glass panel 21, excavate the soil inside the section, and reinstall the movable glass panel 21 after the excavation is completed.

[0094] Thaw settlement test: The soil thaw settlement test is carried out by circulating hot liquid at a specified temperature in the freezing pipe 5.

[0095] Data acquisition: Data is collected and stored using a monitoring and analysis system;

[0096] The experiment is complete. The experimental setup is dismantled and the experimental materials are removed.

[0097] Example 1

[0098] The freeze-thaw settlement test was conducted under simulated self-weight conditions, and the specific steps are as follows:

[0099] 1. At the start of the test, the test apparatus is installed first. Through slots are provided at the front and rear of the main frame 1, and slide rails 1-1 are installed at the bottom of the main frame 1. Pre-designed glass plates 4 are slid into the through slots at the front and rear of the main frame 1 from the sides. Then, the test soil is installed in layers to form the freezing test chamber. Since the glass plates 4 are detachable, when conducting tests with different freezing pipe 5 arrangements, only different glass plates 4 need to be replaced at the front and rear of the main frame 1. The freezing holes on the glass plates 4 are pre-designed and can have various forms, as shown in the attached diagram. Figure 2 As shown, adjustments can be made according to requirements.

[0100] 2. During the process of placing the prepared soil with a certain moisture content into the test chamber, sensors such as temperature, moisture content, and earth pressure cell 31 are buried in designated positions. After the test soil is placed, the freezing tube 5 is inserted into the freezing hole on the glass plate 4 according to the test requirements, and an appropriate insertion depth is set. By adjusting the length of the freezing tube 5, partial freezing and full-depth freezing effects can be achieved. After the test soil is placed, the force transmission plate 3 and the pad 2 are placed on top of the test soil in sequence. Finally, the force transmission seat 9 and the displacement gauge 7 are placed on the pad 2.

[0101] 3. Connect temperature, moisture content, and displacement sensors to their respective monitoring systems and computer 29. During the test, their changes can be monitored. Turn on the high-definition camera of the full-field strain monitoring system 22 to start shooting. Control the hydraulic jack 8 by connecting the axial hydraulic press sensor line 18 through the axial hydraulic servo control system 17 to apply a certain amount of static load to the soil and provide different stress environments, thereby simulating the real ground stress and surrounding disturbance stress in the test area.

[0102] 4. After setting the high and low temperature cooling circulation integrated machine 16 to the specified temperature (e.g., -30℃), turn on the circulation switch. The coolant will enter the freezing pipe 5 through the freezing pipe 15 and circulate, thus starting the soil frost heave test.

[0103] 5. After the frost heave test is completed, the movable glass plate 21 is disassembled, and then the soil inside the section is excavated. After the excavation is completed, the movable glass plate 21 is reinstalled.

[0104] 6. After excavation is completed, set the high and low temperature cooling circulation integrated machine 16 to the specified temperature (e.g., 70℃). At this time, the hot liquid circulates in the freezing pipe 5 to carry out the soil thaw settlement test.

[0105] 7. After the thaw settlement test is completed, the test is finished. Turn off the high and low temperature cooling cycle integrated machine 16, turn off the high-definition camera in the full-field strain monitoring system 22, unload the load, and save the test data. Then, in sequence, remove the freezing tube 5, remove all glass plates 4, and remove the test soil to prepare for the next test.

[0106] Example 2

[0107] The freeze-thaw settlement test and thaw settlement grouting were conducted under simulated self-weight conditions. The specific steps are as follows:

[0108] 1. At the start of the test, the test apparatus is installed first. Through slots are provided at the front and rear of the main frame 1, and slide rails 1-1 are installed at the bottom of the main frame 1. Pre-designed glass plates 4 are slid into the through slots at the front and rear of the main frame 1 from the sides. Then, the test soil is installed in layers to form the freezing test chamber. Since the glass plates 4 are detachable, when conducting tests with different arrangements of freezing pipes 5 and grouting pipes 6, only different glass plates 4 need to be replaced at the front and rear of the main frame 1. The freezing holes and grouting holes on the glass plates 4 are pre-designed and can take various forms, as shown in the attached diagram. Figure 2 As shown, adjustments can be made according to requirements.

[0109] 2. During the process of placing the prepared soil with a certain moisture content into the test chamber, sensors such as temperature, moisture content, and earth pressure cell 31 are buried in designated positions. After the test soil is placed, according to the test requirements, the freezing tube 5 is inserted into the freezing hole on the glass plate 4, and then the grouting tube 6 is inserted into the grouting hole on the glass plate 4, with an appropriate insertion depth set. By adjusting the length of the freezing tube 5, partial freezing and full-depth freezing effects can be achieved. After the test soil is placed, the force transmission plate 3 and the pad 2 are placed on top of the test soil in sequence. Finally, the force transmission seat 9 and the displacement gauge 7 are placed on the pad 2.

[0110] 3. Connect temperature, moisture content and displacement sensors to their respective monitoring systems and computer 29. During the test, their changes can be monitored. Turn on the high-definition camera of the full-field strain monitoring system 22 to start shooting. Control the hydraulic jack 8 by connecting the axial hydraulic press sensor line 18 through the axial hydraulic servo control system 17 to apply a certain amount of static load to the soil and provide different stress environments, thereby simulating the real ground stress in the test area.

[0111] 4. After setting the high and low temperature cooling circulation integrated machine 16 to the specified temperature (e.g., -30℃), turn on the circulation switch. The coolant will enter the freezing pipe 5 through the freezing pipe 15 and circulate, thus starting the soil frost heave test.

[0112] 5. After the frost heave test is completed, the movable glass plate 21 is disassembled, and then the soil inside the section is excavated. After the excavation is completed, the movable glass plate 21 is reinstalled.

[0113] 6. After excavation, the high and low temperature cooling circulation integrated machine 16 is set to the specified temperature (e.g., 70℃). At this time, the hot liquid circulates in the freezing pipe 5 to conduct the soil thaw settlement test. Simultaneously, the grouting system 28, based on data analysis and judgment from the computer 29, will automatically open the solenoid valve 28-2 on the grouting pipeline 28-1 and inject grout at a certain pressure into the grouting pipe 6. During the test, the computer 29 can analyze deformation and displacement monitoring data in real time, continuously adjust the grouting pressure, and realize intelligent control of grouting in the thaw settlement area until the soil deformation stabilizes.

[0114] 7. After the thaw settlement test is completed, the test is finished. Turn off the high and low temperature cooling cycle integrated machine 16, turn off the high-definition camera in the full-field strain monitoring system 22, unload the load, and save the test data. Then, in sequence, remove the freezing pipe 5 and the grouting pipe 6, remove all glass plates 4, and take out the test soil to prepare for the next test.

[0115] Example 3

[0116] The specific steps for conducting freeze-thaw settlement tests and thaw settlement grouting under simulated dynamic disturbance conditions are as follows:

[0117] Steps 1-3 in this working condition are the same as the preliminary operations in steps 1-3 of Example 1. Subsequently, when the soil freezing test begins, during the soil freezing process, the axial hydraulic servo control system 17 connects to the axial hydraulic press sensor line 18 to control the hydraulic jack 8, applying different forms of dynamic loads to the soil, such as square waves and sine waves, to simulate the impact of dynamic load disturbance on the soil freezing effect. At this time, the dynamic load can be continuously applied or turned off. The subsequent steps are the same as in Example 1. The addition of dynamic load allows for the study of the impact of dynamic load on the entire process of soil freezing, connecting passage excavation, and thawing grouting.

[0118] Example 4

[0119] The freeze-thaw settlement test and thaw settlement grouting were carried out under simulated self-weight and seepage field conditions. The specific steps are as follows:

[0120] Steps 1 to 3 in this working condition are the same as the preliminary operations of steps 1 to 3 in Example 1.

[0121] After steps 1-3 are completed, the inlet valve and outlet valve 24 are opened. Water in the storage tank 23, under pressure, flows along the inlet pipe 25 through the permeable plate 30 into the test chamber, thus forming seepage. The water flows through the soil and finally through the permeable plate 30 into the storage tank 23 along the outlet pipe 32, forming a stable loop. By changing the pressure in the storage tank 23, the effect of different seepage conditions on the frost heave and thaw settlement effect of the soil can be studied. Subsequent steps are the same as steps 4-7 in Example 1. At this time, the seepage process can be continuously applied or closed, allowing for the study of its impact on the entire process of soil freezing, connecting channel excavation, and thaw settlement grouting.

[0122] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0123] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A multifunctional large-scale freeze-thaw settlement model test device, comprising a main frame (1), characterized in that: Also includes: A glass plate (4) is provided in a plurality of them, and the plurality of glass plates (4) are detachably installed in the main frame (1). The test material is placed in the cavity formed by the glass plate (4) and the main frame (1). The freezing assembly includes several freezing holes opened on the glass plate (4), a freezing tube (5) is provided in the freezing hole, the liquid outlet end of the freezing tube (5) is connected to a freezing pipeline (15), and the freezing pipeline (15) is connected to a high and low temperature cooling circulation integrated machine (16). Movable glass plate (21), the movable glass plate (21) is detachably installed on the glass plate (4), and a plurality of the freezing holes are located around the movable glass plate (21); The glass plate (4) includes: Bottom glass plate (4-1), which is slidably fitted within the main frame (1); The middle glass plate (4-2) is slidably connected to the bottom glass plate (4-1). A movable glass plate (21) is detachably connected to the middle glass plate (4-2), and a number of freezing holes are also provided on it. The freezing holes are arranged circumferentially on the outside of the movable glass plate (21). A top glass panel (4-3) is slidably attached to the middle glass panel (4-2); It also includes a monitoring and analysis system, which includes a computer (29). It also includes earth pressure cells (31), a plurality of earth pressure cells (31) are embedded in the test material, and the earth pressure cells (31) are electrically connected to the computer (29); It also includes a grouting system (28), which comprises: Grouting holes are opened on the glass plate (4), and several holes are opened. A grouting pipeline (28-1) is provided in the grouting hole, and a solenoid valve (28-2) is fixedly installed on the grouting pipeline (28-1). The grouting holes and the freezing holes are spaced apart, with two grouting holes located on either side of one freezing hole; A liquid storage tank (28-7) is provided, with its outlet end connected to the grouting pipeline (28-1). The monitoring component includes a pressure gauge (28-3) and a flow meter (28-4) respectively installed on the grouting pipeline (28-1); A controller (28-5) is electrically connected to the pressure gauge (28-3) and the flow meter (28-4) respectively, and the controller (28-5) controls the opening and closing of the solenoid valve (28-2); It also includes a seepage system, which comprises: Water-permeable components are respectively embedded on the two inner side walls of the main frame (1); The water circulation component includes a water storage tank (23), the outlet end of which is connected to an inlet pipe (25), the inlet pipe (25) is inserted into a permeable part, and an outlet pipe (32) is inserted into another permeable part, the outlet end of which is connected to the water storage tank (23). A water outlet valve (24) is fixedly installed on the water inlet pipe (25); a water inlet valve is fixedly installed on the water outlet pipe (32); It also includes an axial pressure system disposed on the main frame (1), the axial pressure system comprising: Force transmission plate (3), a force transmission plate (3) is provided above the test material; Force transmission seat (9), the force transmission plate (3) is equipped with force transmission seat (9); A hydraulic jack (8) is mounted on the main frame (1), and when the hydraulic jack (8) applies downward pressure, the force-applying end of the hydraulic jack (8) contacts the force transmission seat (9); An axial hydraulic servo control system (17) is electrically connected to the hydraulic jack (8). A pad (2) is placed above the force transmission plate (3). In order to monitor the overall frost heave and thaw settlement of the test soil, a displacement gauge (7) is installed on the main frame (1). A displacement monitoring system (19) is connected through the displacement measuring line (20). The displacement monitoring system (19) collects the data on the displacement gauge (7) to monitor the overall frost heave and thaw settlement of the test soil and transmits it to the computer (29) for storage and analysis.

2. The multifunctional large-scale freeze-thaw settlement model test device according to claim 1, characterized in that: The monitoring and analysis system includes: A full-field strain monitoring system (22) is placed on one side of the main frame (1) where freezing holes are provided; The computer (29) is electrically connected to the full-field strain monitoring system (22), and the full-field strain monitoring system (22) collects and transmits the monitored data to the computer (29) for subsequent analysis.

3. The multifunctional large-scale freeze-thaw settlement model test device according to claim 1, characterized in that: A booster (28-6) is fixedly installed on the outlet end of the liquid storage tank (28-7), and the booster (28-6) is electrically connected to the controller (28-5).

4. A multifunctional large-scale frost heave and thaw settlement model test method, characterized in that: Based on the multifunctional large-scale freeze-heave-thaw settlement model test device according to claim 1, the test steps are as follows: Assemble the test device: The freezing holes and grouting holes on the glass plate (4) are designed in advance; after the test soil is placed, the freezing pipe (5) is inserted into the freezing hole on the glass plate (4) according to the test requirements, and the grouting pipe (6) is inserted into the grouting hole on the glass plate (4). The appropriate depth of insertion is set. By adjusting the length of the freezing pipe (5), the effects of local freezing and full-depth freezing can be achieved. Open the inlet valve and outlet valve (24), and the water in the storage tank (23) can flow into the test chamber through the permeable plate (30) along the inlet pipe (25) under pressure, thus forming seepage. The water flows through the soil and finally through the permeable plate (30) along the outlet pipe (32) into the storage tank (23), thus forming a stable loop. By changing the pressure in the storage tank (23), the effect of different seepage conditions on the frost heave and thaw settlement of the soil can be studied. Frost heave test: The cold liquid at a specified temperature is circulated through the freezing pipe (15) to start the frost heave test of the soil. Excavation test of connecting passage: The movable glass panel (21) was removed, and the soil inside the section was excavated. After the excavation was completed, the movable glass panel (21) was reinstalled. Melt-settlement test: The hot liquid at a specified temperature is circulated in the freezing pipe (5) to conduct the soil melt-settlement test; After excavation, the high and low temperature cooling circulation integrated machine (16) is set to the specified temperature. At this time, the hot liquid circulates in the freezing pipe (5) to carry out the soil thawing and settlement test. At the same time, the grouting system (28) will automatically open the solenoid valve (28-2) on the grouting pipeline (28-1) according to the data analysis of the computer (29) and inject grout of a certain pressure into the grouting pipe (6). During the test, the computer (29) can analyze the deformation and displacement monitoring data in real time, continuously adjust the grouting pressure, realize intelligent control of grouting in the thawing and settlement area until the soil deformation is stable. Data acquisition: Data is collected and stored using a monitoring and analysis system; The experiment is complete. The experimental setup is dismantled and the experimental materials are removed.

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