A testing device and testing method for the grouting performance of highway subgrades in severe cold regions

Abstract

The present invention provides a device and a test method for detecting the grouting performance of highway subgrades in severe cold regions. The device includes a model box and a grouting module arranged above the model box, and both are installed on the same steel bracket. A cold bath pipe is provided in the sandwich space of the side wall of the model box, and antifreeze is filled outside the cold bath pipe. The cold bath pipe is spirally wound in the sandwich space of the side wall. Heat-insulating cotton is sleeved outside both the side wall and the bottom of the model box. The present invention is applicable to the grouting performance test of highway subgrades in severe cold regions, deeply studies the diffusion characteristics of grouting liquid under low ground temperature conditions, establishes an evaluation system for the treatment effect of highway grouting in severe cold regions, and forms an optimal grouting technical solution with fast highway construction speed, low cost and good treatment effect. It has important theoretical significance and engineering value for scientifically understanding the law of subgrade grouting in cold regions, guiding the prevention and control of highway diseases, and improving the construction theory and maintenance technology level of highway subgrades in China.

Description

Technical Field

[0001] The present invention belongs to the field of research and development of instrument and equipment, and particularly relates to a testing device and a testing method for the grouting performance of highway subgrades in cold regions. Background Technique

[0002] Highway construction and maintenance are the key foundations for promoting traffic development. Under the combined action of long-term freeze-thaw cycles, wet-dry alternation, and traffic loads, many highway lines in cold regions generally suffer from frost heaving, thaw settlement, pumping mud, and other diseases after 5-10 years of operation. As a result, the subgrade structure is damaged, and the smoothness of the road surface deteriorates, posing serious challenges to the safety and comfort of highway operation and greatly increasing the maintenance cost of the line. Therefore, it is urgent to carry out research on the treatment and prevention technologies for frost heaving, thaw settlement, pumping mud, and other diseases of highway subgrades in cold regions.

[0003] As the main treatment method for frost heaving, thaw settlement, pumping mud, and other diseases of highway subgrades, grouting technology and supporting construction processes have been widely used at home and abroad. Traditional grouting has the advantages of convenient operation, high economic efficiency, and the construction process is not easily affected by traffic conditions and weather. However, in cold regions such as northern China and the Qinghai-Tibet Plateau, the surface temperature is low in winter, and permafrost and seasonal frozen soil are widely distributed, making the highway foundation very sensitive to the external environment and climate change. Engineering practice shows that when grouting is used to treat diseases in highway subgrades in cold regions, the repair effect can play a better role in the initial stage of grouting, but the medium- and long-term effects are not very satisfactory. The fundamental reason is that the understanding of the grouting performance and evolution law of highway subgrades in cold regions is unclear, resulting in great blindness in formulating grouting designs and constructions. For example, the selection of grouting control parameters mainly depends on practical experience. With the large-scale development of transportation infrastructure construction in northern China and the Qinghai-Tibet Plateau, the complex geological conditions, climate, and construction environment have put forward higher requirements for highway grouting technology. There is an urgent need to carry out basic science and applied research on the grouting performance and treatment effect tracking evaluation of highway subgrades in cold regions.

[0004] At present, there has been no report on the systematic and in-depth research on the grouting design theory and detection and evaluation methods in the low ground temperature conditions or frozen soil highway subgrades in cold regions. The Chinese utility model patent CN212336116U discloses a grouting experiment device, which includes a foundation environment device, a grouting device and a data acquisition system, and is used to record the diffusion law of grouting liquid in the simulated foundation and the distribution characteristics of grout veins. However, the disadvantages are that the position of the grouting port of this device is fixed and the grouting depth cannot be adjusted flexibly; secondly, the slurry storage tank is assembled by multiple components such as wooden boards, angle steels and steel pipes, which is not easy to carry out repeated tests, and the square model box causes a very significant boundary constraint effect on the soil; finally, the types and layout forms of the sensors are also relatively simple. For example, only the top seat displacement is measured for the soil deformation, and the deformation characteristics of the near-grouting area cannot be accurately characterized. In addition, the Chinese invention patents CN112697652A and CN111006951A respectively disclose the experimental devices and test methods for indoor grouting, and they cannot achieve real-time and accurate control of parameters such as grouting flow rate and grouting pressure; at the same time, the model box uses a cylindrical plexiglass barrel, although it can avoid the stress concentration phenomenon in the soil, but these devices do not consider the influence of the temperature field in the soil, that is, they cannot simulate the coupling effect of complex temperature and groundwater environment on the grouting performance, so they cannot provide a scientific and effective detection platform for the grouting theory and design methods of highway subgrades in cold regions.

[0005] Based on this, there is an urgent need to develop test equipment to carry out research on the grouting performance (such as fluidity, permeability, setting time, strength) of highway subgrades in cold regions with low ground temperature or frozen soil, the mechanical mechanism of the interaction between subgrade structure - filler - grout under grouting pressure, and the influence of the whole grouting process on the deformation of the surrounding soil and the bearing capacity and settlement of adjacent subgrade structures. The relevant results provide theoretical support and decision-making basis for promoting the progress of grouting design methods for diseases such as frost heaving, thaw settlement, and pumping mud in highway subgrades in cold regions such as the northern part of China and the Qinghai-Tibet Plateau, accelerating the formation of an evaluation system for grouting repair effects, and formulating the optimal prevention and control plan with short construction period, low cost and good repair effect. Summary of the Invention

[0006] To make up for the deficiencies in the research on the grouting theory and technology of highway subgrades in cold regions, the present invention aims to provide a test device and test method for detecting the grouting performance of highway subgrades in cold regions. The test device has many advantages such as high temperature controllability, wide application range, and strong time correlation of test data.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A test device for detecting the grouting performance of highway subgrades in cold regions, the device includes a model box and a grouting module arranged above the model box, and the grouting module is communicated with the inner cavity of the model box through a grouting pipe;

[0009] A water level gauge is provided on the model box. The water level gauge is communicated with the inner cavity of the model box. The bottom of the inner cavity of the model box is a water replenishing chamber. Above the water replenishing chamber is a soil specimen chamber. The end of the grouting pipe extends into the soil specimen chamber. The soil specimen chamber and the water replenishing chamber are separated by a porous plate.

[0010] A cold bath pipe is provided in the sandwich space of the side wall of the model box, and antifreeze is filled outside the cold bath pipe. The cold bath pipe is spirally wound in the sandwich space of the side wall. The upper end of the cold bath pipe is provided with a liquid inlet pipe, and the lower end of the cold bath pipe is provided with a liquid outlet pipe. The liquid inlet pipe and the liquid outlet pipe are both communicated with a cold bath instrument. Heat insulation cotton is sleeved outside the side wall and the bottom of the model box.

[0011] A plurality of sensor groups are provided in the soil specimen chamber. A surface displacement sensor is provided at the top of the soil specimen chamber. The sensor groups and the surface displacement sensor are both electrically connected to a processor. An endoscope is provided at the lower end of the surface displacement sensor.

[0012] Therefore, in the present invention, a cold bath pipe is provided in the sandwich space of the side wall of the model box to cool the soil specimen chamber for simulating the frozen soil environment in cold regions. The upper end of the cold bath pipe is a liquid inlet pipe, and the lower end of the cold bath pipe is a liquid outlet pipe to prevent the backflow of the cold bath liquid under the action of gravity. In order to prevent the box body from freezing and ensure that the internal temperature of the box body is not affected by external temperature conditions, antifreeze is filled outside the cold bath pipe. The antifreeze is transformer oil with an extremely low freezing point, and a layer of heat insulation cotton is wrapped outside the box body. Grouting is carried out on the frozen soil in the soil specimen chamber through the grouting module, and then the data and images collected by the endoscope, the sensor groups and the surface displacement sensor are sent to the processor, and the processor analyzes the collected stress state, displacement data and images.

[0013] The test device of the present invention can simulate the process of layered grouting of subgrade in cold regions, monitor the stress and strain and surface displacement of the grout veins and the surrounding soil under various water temperature conditions and different grouting pressures, analyze the internal stress field, surface displacement distribution characteristics of the subgrade soil during different grouting stages and different curing times, verify the mechanical mechanism of the interaction among the subgrade structure - filler - grout system, and thus feed back to engineering practice to realize the refined control of the grouting repair effect and the evaluation and comparison of the optimal scheme.

[0014] Furthermore, a driving unit for controlling its axial movement is provided on the grouting pipe. The endoscope and the driving unit are both electrically connected to a comprehensive console. The telescopic grouting pipe is arranged as a double-layer hollow screw structure, and the grouting port is lifted in a screw-in manner through a control head at the end connected to the comprehensive console.

[0015] Further, it further includes a bracket, the bracket includes a bracket bottom plate and a bracket partition located above the bracket bottom plate, the bracket bottom plate and the bracket partition are supported by bracket columns, the model box is arranged on the bracket bottom plate, the grouting module is arranged on the bracket partition, and the grouting pipe extends into the model box through the bracket partition.

[0016] Furthermore, the processor includes a data collector and an image analysis processor. The sensor group and the surface displacement sensor are both electrically connected to the data collector, and the data collector is electrically connected to the image analysis processor.

[0017] Furthermore, a water inlet pipe is arranged on one side of the water replenishing chamber, a drain pipe is arranged on the other side of the water replenishing chamber, the water inlet pipe is connected to the water tank, and the water tank is arranged on the lifting platform.

[0018] Even further, an antifreeze inlet valve and an air outlet valve are arranged at the top end of the side wall of the model box.

[0019] Even further, the sensor group includes multiple sets of earth pressure cells, thermometers, hygrometers, and pore pressure sensors arranged on the same depth plane.

[0020] Based on the same inventive concept, the present invention also provides a method for conducting tests using the above-mentioned grouting performance detection test device for highway subgrades in cold regions. The method includes the following steps:

[0021] Step 1: Keep the slurry outlet pipeline of the grouting module closed before the grouting operation.

[0022] Step 2: Load test soil samples into the soil sample chamber and compact them layer by layer. For each layer of test soil sample loaded, a sensor group must be buried at a preset position, and the top layer of test soil sample must be leveled to complete the loading of the test soil samples.

[0023] Step 3: Inject water into the water replenishing chamber through the water inlet pipe and observe the water level gauge. When the water level in the water replenishing chamber is stable at the expected value, stop injecting water and close the water inlet valve.

[0024] Step 4: Turn on the cold bath instrument, set the cold bath temperature, and cool and freeze the test soil samples in the model box.

[0025] Step 5: Vertically insert the grouting pipe into the center position of the soil sample chamber, and arrange the surface displacement sensor and the endoscope at the top of the model box.

[0026] Step 6: Turn on the grouting module. After the grouting pressure is stable, grout each layer of test soil samples in the model box layer by layer. Record the data after each layer of grouting is completed. After the last layer of grouting is completed, turn off the grouting module. After the data in the processor is stable, operate the endoscope to record the settlement and deformation images of the soil surface along multiple radial paths after grouting.

[0027] Step 7: Close the test device, remove the test soil sample, and complete the cleaning work of the test device.

[0028] Furthermore, before performing Step 2, it also includes: thickly applying a layer of vaseline on the side wall of the soil sample chamber.

[0029] Still further, after Step 5, it also includes: turn on the processor, and when the received value is stable and reaches the preset value, reset the data of the surface displacement sensor to zero.

[0030] A grouting performance detection test device and test method for highway subgrade in cold regions of the present invention have the following advantages:

[0031] 1). Using the device of the present invention, model test research on grouting repair of subgrade in cold regions under simulated water level and temperature combination conditions can be carried out, and it can simulate different soil properties, different freezing temperatures, different groundwater levels, various grouting pressures and stratified grouting methods, etc.

[0032] 2). A series of soil physical parameter measurement sensor groups are respectively arranged at different levels in the radial direction of the model box of the test device, including: surface displacement sensors, earth pressure cells, thermometers, hygrometers, pore pressure sensors, to realize real-time monitoring and recording of the development laws and characteristics of the stress field distribution, pore water pressure, and soil surface displacement in the simulated frozen soil subgrade soil layer during the grouting process.

[0033] 3). The grouting control module in the test device is arranged in the same vertical direction as the above-mentioned model box, restoring the actual grouting direction at the subgrade grouting site; the telescopic grouting pipe can instantaneously adjust the grouting depth through the console, and can maximize the simulation of different grouting schemes; the arranged sensor group realizes the organic unity of the grouting process and the development of the stress and strain states on the soil surface and inside, providing a more reliable data basis for subsequent research on the evolution law of the mechanical properties of the whole process of the subgrade engineering under different grouting schemes.

[0034] 4). The test device adopts a multi-layer temperature control system, uses small-diameter cold bath copper pipes to surround the box body, and immerses the copper pipes in transformer oil with an extremely low freezing point, realizing low-temperature freezing simulation while ensuring that other components outside the soil chamber of the model box do not freeze, so that other modules of the test device can work stably.

[0035] 5). By applying a set of frozen soil subgrade grouting and detection system, the present invention not only realizes convenient, instant, and accurate measurement of the mechanical and engineering characteristic indexes of different grouting construction schemes and different slurry curing times, but also realizes rapid cleaning and recycling of the soil sample detection chamber of the model box after detection, improves the detection efficiency, reduces a large amount of resource waste, and follows the design concept of green environmental protection. Description of the Drawings

[0036] Figure 1 is a structural schematic diagram of the present invention;

[0037] Figure 2 is Figure 1 a top view of the I-I cross-section of the model box in [[]] and the layout of internal sensors.

[0038] Explanation of markings in the figure: 1. Bracket bottom plate; 2. Bracket column; 3. Bracket; 4. Slide rail; 5. Model box; 6. Antifreeze inlet valve; 7. Antifreeze; 8. Thermal insulation cotton; 9. Air outlet valve; 10. Water level gauge; 11. Water level gauge valve; 12. Perforated plate; 13. Water tank inlet valve; 14. Water tank outlet valve; 15. Lift controller; 16. Lift; 17. Water level control console; 18. Lift control instrument; 19. Water inlet pipe; 20. Make-up water chamber; 21. Drain pipe; 22. Liquid outlet pipe; 23. Liquid inlet pipe; 24. Cold bath pipe; 25. Cold bath instrument; 26. Endoscope; 27. Comprehensive control console; 28. Drive unit; 29. Surface displacement sensor; 30. Earth pressure cell; 31. Thermometer; 32. Hygrometer; 33. Pore pressure sensor; 34. Anti-seepage joint; 35. Data collector; 36. Image analysis processor; 37. Motor; 38. Transmission gear; 39. Crankshaft; 40. Connecting rod; 41. Tie rod; 42. Piston; 43. Grout inlet pipe; 44. Pressure relief valve; 45. Oil pressure chamber; 46. Pressure gauge; 47. Grout discharge valve; 51. Grouting module; 54. Soil specimen chamber; 55. Processor; 56. Sensor group; 57. Grouting pipe; 59. Bracket partition; 60. Water tank. Specific embodiments

[0039] In order to better understand the purpose, structure and function of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] As Figure 1 and Figure 2 shown, a grouting performance detection test device for highway subgrade in cold regions of the present embodiment includes a bracket 3, a model box 5 and a grouting module 51 disposed above the model box 5. The model box 5 and the grouting module 51 are installed on the bracket 3. Both the model box 5 and the bracket 3 are made of steel material. On the one hand, it is to ensure sufficient strength, stiffness and stability. On the other hand, it is because the metal material has better heat conduction performance. The cross-section of the model box 5 is designed as a circle to ensure the consistency of the restraint conditions of the sample soil. In order to observe the surface displacement of the soil after grouting, no restraint is applied to the top of the box, and it is designed to be open. The bracket 3 includes a bracket bottom plate 1 and a bracket partition 59 located above the bracket bottom plate 1. The bracket bottom plate 1 and the bracket partition 59 are supported by bracket columns 2. The model box 5 is disposed on the bracket bottom plate 1, and the grouting module 51 is disposed on the bracket partition 59. The grouting module 51 is communicated with the inner cavity of the model box 5 through a grouting pipe 57.

[0041] Specifically, the grouting module 51 includes a motor 37, a crankshaft 39, a connecting rod 40, a pull rod 41, a piston 42, etc. The control of the grouting pressure is achieved through a pressure gauge 46 and a pressure relief valve 44, and the grouting flow rate is adjusted by controlling a slurry discharge valve 47. The grouting control module is fixed on a support partition 59 by bolts.

[0042] The grouting pipe 57 extends through the support partition 59 into the model box 5. A driving unit 28 for controlling its axial movement is provided on the grouting pipe 57. The driving unit 28 can adjust the grouting depth of the grouting pipe 57 according to test requirements. The driving units 28 are all electrically connected to the integrated console 27. The depth of the telescopic grouting pipe 28 inserted into the soil body in the model box is adjusted through the integrated console 27 to simulate the layered grouting method. The driving unit 28 is set as a double-layer hollow screw structure, and the rotational lifting of the grouting port is realized by connecting the integrated console 27 through a control head at the end. The integrated console 27 is suspended and fixed at the bottom of the support partition 59 through a steel truss. To reduce or eliminate the wear between the grouting pipe 57 and the hole drilled in the support partition 59, the hole diameter of the drilled hole should be 3 - 5 mm larger than the outer diameter of the grouting pipe 57, and a silica gel soft pad is clamped in the gap.

[0043] A water level gauge 10 is provided on the model box 5. The water level gauge 10 is communicated with the inner cavity of the model box 5. The bottom of the inner cavity of the model box 5 is a water replenishing chamber 20. Above the water replenishing chamber 20 is a soil sample chamber 54. The end of the grouting pipe 57 extends into the soil sample chamber 54. The soil sample chamber 54 and the water replenishing chamber 20 are separated by a porous plate 12 provided. The porous plate 12 should have a certain thickness to ensure strength and stiffness, and support blocks can be provided at the lower end of the water replenishing chamber 20 for reinforcement. The porous plate 12 is equipped with permeable stones and filter paper to prevent soil particles from entering the water replenishing chamber 20. A water inlet pipe 19 is provided on one side of the water replenishing chamber 20, and a drain pipe 21 is provided on the other side of the water replenishing chamber 20. The water inlet pipe 19 is connected to a water tank 60, and the water tank 60 is arranged on a lifting platform 16.

[0044] A cold bath tube 24 is provided in the side wall sandwich space of the model box 5, and antifreeze 7 is filled outside the cold bath tube 24. An antifreeze inlet valve 6 and an air outlet valve 9 are provided at the top of the side wall of the model box 5. The cold bath tube 24 is spirally wound in the side wall sandwich space. The upper end of the cold bath tube 24 is provided with a liquid inlet tube 23, and the lower end of the cold bath tube 24 is provided with a liquid outlet tube 22. The liquid inlet tube 23 and the liquid outlet tube 22 are both communicated with a cold bath instrument 25. Heat insulation cotton 8 is sleeved outside the side wall and the bottom of the model box 5. A plurality of sensor groups 56 are provided in the soil sample chamber 54. The sensor group 56 includes a plurality of soil pressure cells 30, thermometers 31, hygrometers 32, and pore pressure sensors 33 arranged on the same depth plane. A surface displacement sensor 29 is provided at the top of the soil sample chamber 54. The sensor group 56 and the surface displacement sensor 29 are both electrically connected to a processor 55. The processor 55 includes a data collector 35 and an image analysis processor 36. The sensor group 56 and the surface displacement sensor 29 are both electrically connected to the data collector 35, and the data collector 35 is electrically connected to the image analysis processor 36. An endoscope 26 is provided at the lower end of the surface displacement sensor 29. The endoscope 26 is electrically connected to an integrated console 27 with a movable probe, and can obtain surface displacement images from multiple angles. All the obtained image data and digital signals are transmitted to the data collector 35, and finally reflected on the image analysis processor 36 for further integrated analysis. More preferably, the surfaces of the sensors and the data lines are coated with a corrosion-resistant coating to prevent the sensors from being contaminated by the slurry; the wires of the two groups of sensor groups near the bottom of the box are led out through the anti-seepage joints on the box wall to reduce the disturbance to the soil structure.

[0045] A method for conducting an experiment using the highway subgrade grouting performance detection test device of this embodiment in a cold region includes the following steps:

[0046] Step 1: Pipeline inspection. Keep the grouting pipe 57 of the grouting module 51 closed before grouting work, and keep the pressure relief valve 44 open. Keep the antifreeze inlet valve 6 and the air outlet valve 9 of the model box open. After filling the antifreeze 7, close the antifreeze inlet valve.

[0047] Step 2: Soil sample filling and sensor group embedding. Lay permeable stones and filter paper at the bottom of the model box. Apply a thick layer of vaseline on the side wall of the soil sample chamber 54 of the model box 5 to facilitate demoulding after the test. Load the test soil samples in five layers from bottom to top and compact them layer by layer. Level the surface of the samples to complete the filling work of the samples. At the same time, each time a layer of soil sample is filled, a sensor group 56 must be buried at the preset position, and the cables of the sensor group 56 are led out from the anti-seepage joint 34 installed on the side wall of the model box 5. After the sensors in the soil are arranged, move the model box 5 along the slide rail 4 to the predetermined position of the bracket 3.

[0048] Step 3: Preparation of the water level control module. Connect the water outlet valve 14 of the water tank and the water inlet pipe 19 with a hose. Open the water level gauge valve 11, close the drain pipe 21, open the water inlet valve 13 of the water tank, the water outlet valve 14 and the water inlet pipe 19 to replenish water to the model box 5. When the water level stabilizes at the expected value, close the water inlet pipe 19. During the test process, adjust the water head height through the lifting platform 16 as needed.

[0049] Step 4: Open the valves of the liquid outlet pipe 22 and the liquid inlet pipe 23, and turn on the cold bath 25 to cool and freeze the soil in the model box. When the sensor indicates that the temperature reaches the expected value, maintain the cold bath temperature at this time.

[0050] Step 5: Preparation work for data collection. Vertically insert the grouting pipe 57 into the center position of the box body, and connect the driving unit 28 to the integrated console 27. Arrange the surface displacement sensors 29 and the endoscope 26 along the radial direction of the model box, and connect the data lines of the above-mentioned sensor group 56 to the data collector 35 together. Turn on the data collector and the image analysis processor 36 to complete the layout of the data collection and processing module. Turn on the data collection system, observe the sensor temperature and water level data. When the values reach the preset values and are stable, reset the data of the surface displacement sensor 29 to zero.

[0051] Step 6: Close the pressure relief valve 44 and open the slurry discharge valve 47; start the motor 37. After the grouting pressure is stable, start feeding and grouting. When the soil in the model box starts to be grouted, start the in-situ performance test of the subgrade grouting repair. The specific steps are as follows: Drive the position of the port of the grouting pipe 57 through the driving unit 28 to grout in layers. After each layer of grouting is completed, measure a set of stress, pore pressure and surface displacement data, and record the corresponding temperature and humidity conditions. After the last layer of grouting is completed, turn off the motor 37 and the slurry discharge valve 47 to stop grouting. After the sensor data is stable, operate the endoscope 26 through the integrated console 27 to record the surface settlement and deformation images of the soil after grouting along multiple radial paths.

[0052] Step 7: After completing the in-situ performance detection work of the above-mentioned soil grouting repair performance, turn off the test device of this embodiment, drain the residual slurry in the grouting pipe 57, take out the soil sample, and wash the model box 5 and the sensor measurement end with clear water; cut off the power supply, close the cold bath 25 and the valves of this test device to complete the instrument arrangement work.

[0053] It will be understood that the present invention is described by way of some embodiments, and those skilled in the art will know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A test device for detecting the grouting performance of highway subgrades in severe cold regions, characterized in that, It includes a model box (5) and a grouting module (51) arranged above the model box (5). The grouting module (51) is communicated with the inner cavity of the model box (5) through a grouting pipe (57). A water level gauge (10) is arranged on the model box (5). The water level gauge (10) is communicated with the inner cavity of the model box (5). The bottom of the inner cavity of the model box (5) is a water replenishing chamber (20). Above the water replenishing chamber (20) is a soil specimen chamber (54). The end of the grouting pipe (57) extends into the soil specimen chamber (54). The soil specimen chamber (54) and the water replenishing chamber (20) are separated by a porous plate (12) arranged therebetween. A cold bath pipe (24) is arranged in the side wall sandwich space of the model box (5), and antifreeze (7) is filled outside the cold bath pipe (24). The cold bath pipe (24) is arranged in the side wall sandwich space. The upper end of the cold bath pipe (24) is provided with a liquid inlet pipe (23), and the lower end of the cold bath pipe (24) is provided with a liquid outlet pipe (22). The liquid inlet pipe (23) and the liquid outlet pipe (22) are both communicated with a cold bath instrument (25). A plurality of sensor groups (56) are arranged in the soil specimen chamber (54). A surface displacement sensor (29) is arranged at the top of the soil specimen chamber (54). The sensor groups (56) and the surface displacement sensor (29) are both electrically connected to a processor (55). An endoscope (26) is arranged at the lower end of the surface displacement sensor (29). A driving unit (28) for controlling its axial movement is arranged on the grouting pipe (57). The endoscope (26) and the driving unit (28) are both electrically connected to an integrated console (27). The processor (55) includes a data collector (35) and an image analysis processor (36). The sensor groups (56) and the surface displacement sensor (29) are both electrically connected to the data collector (35). The data collector (35) is electrically connected to the image analysis processor (36).

2. The performance detection test device for the highway subgrade grouting in severe cold regions according to claim 1, wherein, It further includes a bracket (3). The bracket (3) includes a bracket bottom plate (1) and a bracket partition plate (59) located above the bracket bottom plate (1). The bracket bottom plate (1) and the bracket partition plate (59) are supported by bracket columns (2). The model box (5) is arranged on the bracket bottom plate (1), and the grouting module (51) is arranged on the bracket partition plate (59). The grouting pipe (57) passes through the bracket partition plate (59) and extends into the model box (5).

3. The performance detection test device for the highway subgrade grouting in severe cold regions according to claim 1, characterized in that, A water inlet pipe (19) is arranged on one side of the water replenishing chamber (20), and a drain pipe (21) is arranged on the other side of the water replenishing chamber (20). The water inlet pipe (19) is connected to a water tank (60), and the water tank (60) is arranged on a lifting platform (16).

4. The grouting performance detection test device for highway subgrade in severe cold regions according to claim 1, characterized in that An antifreeze inlet valve (6) and an air outlet valve (9) are arranged at the top end of the side wall of the model box (5).

5. The grouting performance detection test device for highway subgrade in severe cold regions according to claim 1, wherein The sensor group (56) includes a plurality of soil pressure cells (30), thermometers (31), hygrometers (32), and pore pressure sensors (33) arranged on the same depth plane.

6. A method of conducting tests using the test device for detecting the grouting performance of highway subgrades in severe cold regions as described in any one of claims 1 to 5, characterized in that, It includes the following steps: Step 1: Keep the slurry outlet pipeline of the grouting module (51) closed before grouting work; Step 2: Load the test soil sample into the soil sample chamber (54) and compact it layer by layer. For each layer of the test soil sample loaded, a sensor group (56) must be buried at a preset position, and the top layer of the test soil sample should be leveled to complete the loading of the test soil sample; Step 3: Inject water into the water replenishing chamber (20) through the water inlet pipe (19) and observe the water level gauge (10). When the water level in the water replenishing chamber (20) stabilizes at the expected value, stop injecting water and close the water inlet valve; Step 4: Turn on the cold bath instrument (25), set the cold bath temperature, and cool and freeze the test soil sample in the model box (5); Step 5: Vertically insert the grouting pipe (57) into the center position of the soil sample chamber (54), and arrange the surface displacement sensor (29) and the endoscope (26) on the top of the model box (5); Step 6: Turn on the grouting module (51). After the grouting pressure stabilizes, grout each layer of the test soil sample in the model box (5) layer by layer. Record the data after each layer of grouting is completed. After the last layer of grouting is completed, turn off the grouting module (51). After the data in the processor (55) stabilizes, operate the endoscope (26) to record the soil surface settlement and deformation images along multiple radial paths after grouting; Step 7: Turn off the test device, remove the test soil sample, and complete the cleaning of the test device.

7. The test method for detecting the grouting performance of highway subgrades in severe cold regions according to claim 6, characterized in that, Before Step 2, it also includes: thickly apply a layer of vaseline on the side wall of the soil sample chamber (54).

8. The test method for detecting the grouting performance of highway subgrades in severe cold regions according to claim 6, wherein After Step 5, it also includes: Turn on the processor (55). When the value received by the processor (55) stabilizes and reaches the preset value, reset the data of the surface displacement sensor (29) to zero.

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