Multifunctional freezing and thawing test device for simulating natural freezing and thawing environment

Abstract

The invention discloses a multifunctional freezing and thawing test device for simulating a natural freezing and thawing environment, which comprises a freezing and thawing box, a sample is arranged in the freezing and thawing box, the freezing and thawing box is attached to the sample, a freezing and thawing circulating system is arranged at the top of the freezing and thawing box, and an ultraviolet lamp and a humidity adjusting system are arranged at the top of the freezing and thawing box. The ultraviolet lamp and the humidity adjusting system are connected with an external power supply and environment, a temperature control water injector is arranged at the bottom of the freezing and thawing box and connected with an external switch and a bottom tray, and a water flow scouring simulation system is arranged in the freezing and thawing box on one side of the sample. A series of structures are arranged, an ultraviolet lamp, a simulated water flow scouring system and the like are used for simulating a slope freezing and thawing environment, a real environment is fully simulated, sensing structures such as an AE sensor and a strain gauge are additionally arranged, a fracture event and an acoustic emission event caused by ice growth in a rock mass are monitored, and rock mass crack propagation damage is evaluated. And the strain, ice wedge frost heaving force and crack tip extension width of different areas can be monitored.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering model tests, in particular to a multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment. Background Art

[0002] The freeze-thaw deterioration problem of rock slopes in cold regions is becoming increasingly prominent. Studying the deformation evolution process and instability mechanism of fractured rock slopes under freeze-thaw conditions, and then establishing a theoretical model of the stability of jointed rock slopes in cold regions, is of great significance for the prevention and control of major engineering disasters in cold regions. Among them, water and temperature are the primary factors of freeze-thaw weathering.

[0003] Existing technology directly places slope rock masses into freeze-thaw chambers for testing, essentially freezing the entire surface of the specimen. Under natural freeze-thaw conditions, unidirectional freezing only freezes the specimen from one direction. However, cold air cools the rock surface. Temperature gradients caused by temporal fluctuations or spatial differences determine the direction and magnitude of the heat flux and, to a certain extent, the movement of pore water. The temperature gradients are perpendicular to the heat flow isotherms until the warming effect of geothermal heat offsets the influence of the cold air on the surface. Under natural freeze-thaw conditions, only the top and surface of the slope are affected by freeze-thaw degradation. Summary of the Invention

[0004] The object of the present invention is to provide a multifunctional freeze-thaw test device that simulates a natural freeze-thaw environment, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a multifunctional freeze-thaw test device simulating a natural freeze-thaw environment, comprising a freeze-thaw box, a sample is provided inside the freeze-thaw box, the freeze-thaw box is arranged in contact with the sample, a freeze-thaw circulation system is provided on the top of the freeze-thaw box, an ultraviolet lamp and a humidity adjustment system are provided on the top of the freeze-thaw box, the ultraviolet lamp and the humidity adjustment system are connected to an external power supply and an environment, a temperature-controlled water injector is provided on the freeze-thaw box, the temperature-controlled water injector is connected to an external switch and a bottom tray, a simulated water flow flushing system is provided inside the freeze-thaw box on one side of the sample, the simulated water flow flushing system is connected to an external water source through a water pipe, an electromagnetic flowmeter is installed on the water pipe to accurately measure the water flow rate, thermal insulation cotton is provided between the gaps of the sample, a crack meter is provided on the top of the sample, acoustic emission probes are provided on both sides of the crack meter on the top of the sample, a strain gauge is provided on the locking section of the crack tip of the sample, a temperature sensor is provided in the crack of the sample, and a thin film pressure sensor is provided in the crack;

[0006] During the freeze-thaw process inside the freeze-thaw box, the surface temperature and the internal temperature of the crack of the model sample are monitored by a temperature sensor, the ice wedge heave force in different areas of the model is monitored by a flexible film pressure sensor, the strain of the model sample is monitored by a strain gauge data acquisition instrument, and the crack expansion width of the model sample is monitored by a crack meter.

[0007] Preferably, cracks are provided in the sample, and the cracks are established according to the geometric shape of the sample.

[0008] Preferably, the thickness of the thermal insulation cotton is 20 cm, and the freeze-thaw box is made of stainless steel.

[0009] Preferably, the sample mainly comprises rock blocks and slopes, and a testing unit is also provided on the sample.

[0010] Preferably, the specific steps of the multifunctional freeze-thaw test for simulating a freeze-thaw environment of samples in the freeze-thaw chamber are as follows:

[0011] S1. Dry the sample, seal the sides of the sample cracks with waterproof glue, and install various sensors of the test unit;

[0012] S2. Saturate the surface of the sample with water;

[0013] S3. Set up a data acquisition terminal on the test unit to collect data, inject test water into the sample cracks, and monitor for water leakage;

[0014] S4, setting the freezing temperature and melting temperature;

[0015] S5. Turn on the ultraviolet lamp, humidity control system, temperature-controlled water injector, and simulated water flushing system as needed for monitoring;

[0016] S6. Measure and record the crack expansion of the sample;

[0017] S7, freeze and thaw repeatedly until the sample cracks and breaks;

[0018] S8. Export all data during the experiment.

[0019] Preferably, the freezing temperature and melting temperature in S4 can be set according to demand, and the cooling and heating rates can be freely adjusted.

[0020] Preferably, during the water leakage monitoring in S3, when a water leakage occurs, waterproof glue is used to seal it again, and after the test water is injected, the sample is wrapped with plastic wrap to reduce water evaporation.

[0021] Preferably, the ultraviolet lamp, humidity adjustment system, temperature-controlled water injector and simulated water flow flushing system in S5 are adjusted according to the experimental requirements.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This multifunctional freeze-thaw test device simulates a natural freeze-thaw environment. In the present invention, ultraviolet lamps and a simulated water flow flushing system are used to simulate the freeze-thaw environment of the slope, fully simulating the real environment. At the same time, AE sensors, strain gauges and other sensing structures are additionally installed to monitor fracture events caused by ice growth in the rock mass, evaluate rock crack propagation damage through acoustic emission events, and monitor strain in different areas, ice wedge frost heave force, crack tip expansion width, and rock surface and internal temperature data, so as to study the frost heave force and rock crack propagation law and damage degradation mechanism during the freeze-thaw process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram of a one-way freeze-thaw test on a fractured rock sample of the present invention;

[0025] Figure 2 This is a double-sided freeze-thaw test diagram of the slope model of the present invention;

[0026] Figure 3 This is a generalized rock sample diagram of the trailing edge tension fracture in the present invention;

[0027] Figure 4 This is a diagram of a one-way freeze-thaw test of a fractured rock sample in the present invention;

[0028] Figure 5 This is a curve diagram of water temperature variation inside the crack in the present invention;

[0029] Figure 6 is the temperature field distribution diagram inside the crack in the present invention;

[0030] Figure 7 This is a diagram showing the change of frost heave force and deformation with temperature during the freezing and thawing process of the fractured rock sample in the present invention;

[0031] Figure 8 This is the acoustic emission response diagram of the fractured rock sample during the freeze-thaw process in the present invention;

[0032] Figure 9 This is a graph showing the ice wedge effect in stages II and III of the present invention;

[0033] Figure 10 The diagram is a diagram of the crack classification and proportions in the present invention;

[0034] Figure 11 This is a freeze-thaw failure morphology diagram of a 13mm wide crack rock sample in the present invention;

[0035] Figure 12 This is a freeze-thaw failure morphology diagram of a 4mm wide crack rock sample in the present invention;

[0036] Figure 13 This is a freeze-thaw failure morphology diagram of a 4mm wide crack rock sample in the present invention;

[0037] Figure 14 is the slope model diagram in the present invention;

[0038] Figure 15 This is a schematic diagram of the sensor installation in the present invention;

[0039] Figure 16 This is a diagram of the double-sided freeze-thaw test and monitoring equipment for the scaled slope model of the present invention;

[0040] Figure 17 This is a temperature variation curve inside the tension crack at the trailing edge of model N in the present invention;

[0041] Figure 18 The temperature field distribution diagram inside the N trailing edge tension crack of the model in the present invention;

[0042] Figure 19 This is a temperature change curve diagram of the side of model N in the present invention;

[0043] Figure 20 This is the temperature field distribution diagram of the N side of the model in the present invention;

[0044] Figure 21 This is the freeze-thaw damage evolution diagram of the locking section of model M-5 in the present invention;

[0045] Figure 22 is the maximum frost heave force diagram for different crack depth models in the present invention;

[0046] Figure 23 This is a diagram of the failure morphology of the slope with cracks of different depths in the present invention.

[0047] In the figure: 1. Sample; 2. Freeze-thaw chamber; 3. Freeze-thaw cycle system; 4. Ultraviolet lamp; 5. Humidity control system; 6. Temperature-controlled water injector; 7. Simulated water flow flushing system; 8. Insulation cotton; 9. Crack meter; 10. Acoustic emission probe; 11. Strain gauge; 12. Temperature sensor; 13. Thin film pressure sensor. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] like Figures 1 to 23 As shown, the multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment in this embodiment includes a freeze-thaw box 2, a sample 1 is provided inside the freeze-thaw box 2, a door is provided on one side of the freeze-thaw box 2 through a hinge, the freeze-thaw box 2 is arranged in contact with the sample 1, a freeze-thaw circulation system 3 is provided on the top of the freeze-thaw box 2, an ultraviolet lamp 4 and a humidity adjustment system 5 are provided on the top of the freeze-thaw box 2, the ultraviolet lamp 4 and the humidity adjustment system 5 are connected to an external power supply and an environment, and can adjust the ultraviolet intensity and the humidity inside the freeze-thaw box 2, a temperature-controlled water injector 6 is provided at the bottom of the freeze-thaw box 2, the temperature-controlled water injector 6 is connected to an external switch and a bottom tray, and can evenly inject water of a certain temperature around the sample 1, and the freeze-thaw box 2 on one side of the sample 1 is cooled. The sample 1 is provided with a simulated water flow flushing system 7, which is connected to an external water source through a water pipe. An electromagnetic flowmeter is installed on the water pipe to accurately measure the water flow rate. The electric regulating valve automatically adjusts the opening and flushing direction according to the set flow value and the flushing direction of the water flow, thereby achieving precise control of the water inlet flow rate. Insulation cotton 8 is provided between the gaps of the sample 1 to prevent cold air from seeping in and affecting the experimental results. A crack meter 9 is provided on the top of the sample 1, and acoustic emission probes 10 are provided on both sides of the crack meter 9 on the top of the sample 1. A strain gauge 11 is provided on the locking section of the crack tip of the sample 1, a temperature sensor 12 is provided in the crack of the sample 1, and a thin film pressure sensor 13 is provided inside the crack of the sample 1.

[0051] During the freezing and thawing process inside the freeze-thaw box 2, the surface temperature and the internal temperature of the crack of the model sample 1 are monitored by the temperature sensor 12, the ice wedge heave force in different areas of the model is monitored by the flexible film pressure sensor 13, the strain of the model sample 1 is monitored by the strain gauge data acquisition instrument 11, and the crack expansion width of the model sample 1 is monitored by the crack meter 9.

[0052] Specifically, cracks are provided in the sample 1 , and the cracks are established according to the geometric shape of the sample 1 .

[0053] Furthermore, the thickness of the heat-insulating cotton 8 is 20 cm, and the freeze-thaw box 2 is made of stainless steel.

[0054] Furthermore, sample 1 mainly includes rock blocks (one-way freeze-thaw) and slopes (two-sided freeze-thaw), and a test unit is also provided on sample 1.

[0055] Furthermore, the specific steps of the multifunctional freeze-thaw test for simulating a freeze-thaw environment of sample 1 in the freeze-thaw chamber 2 are as follows:

[0056] S1. Dry sample 1, seal the sides of the crack in sample 1 with waterproof glue, and install various sensors of the test unit;

[0057] S2, saturate the surface of sample 1 with water;

[0058] S3. Set up a data acquisition terminal on the test unit to collect data, inject test water into the cracks of sample 1, and monitor for water leakage;

[0059] S4, setting the freezing temperature and melting temperature;

[0060] S5, turn on the ultraviolet lamp 4, humidity control system 5, temperature-controlled water injector 6 and simulated water flow flushing system 7 as needed for monitoring;

[0061] S6. Measure and record the crack extension of sample 1;

[0062] S7, freeze and thaw repeatedly until sample 1 cracks and breaks;

[0063] S8. Export all data during the experiment.

[0064] Furthermore, the freezing temperature and melting temperature in S4 can be set according to demand, and the cooling and heating rates can be freely adjusted.

[0065] Furthermore, during water leakage monitoring in S3, waterproof glue is used to seal the sample again when a water leakage occurs, and after injecting the test water, plastic wrap is used to wrap the sample 1 to reduce water evaporation.

[0066] Furthermore, the ultraviolet lamp 4, humidity adjustment system 5, temperature-controlled water injector 6 and simulated water flow flushing system 7 in S5 are adjusted according to the experimental requirements.

[0067] The method of using this embodiment is as follows: when conducting experiments, sample 1 is treated and dried, the sides of the cracks in sample 1 are sealed with waterproof glue, and various sensors of the test unit are installed, among which the acoustic emission preamplifier and threshold value are selected to be 40dB. At the same time, the surface of sample 1 is saturated with water, and the test unit is provided with an acquisition terminal to collect data, inject test water into the cracks, and monitor for water leakage. The ultraviolet lamp 4, humidity adjustment system 5, temperature-controlled water injector 6 and simulated water flow flushing system 7 are adjusted according to their own experimental needs, the freezing temperature and melting temperature are set, and the crack expansion is measured and recorded in time. At the same time, freeze and thaw are repeated until sample 1 cracks and is damaged. After sample 1 is damaged, all data during the experiment are exported.

[0068] In the present invention, when leak monitoring occurs, waterproof glue is used to seal the leak again. After injecting test water, the sample 1 is wrapped with plastic wrap to reduce water evaporation. The ultraviolet lamp 4, humidity control system 5, temperature-controlled water injector 6, and simulated water flow flushing system 7 are adjusted according to the experimental requirements.

[0069] Since frost heave causes microcracks to expand and connect during the water-ice phase transition, high-frequency elastic vibrations are emitted. Therefore, acoustic emission (AE) is used to monitor fracture events caused by ice growth in rock masses. Rock crack expansion damage is evaluated through acoustic emission events. During the freeze-thaw process, the strain in different areas of the model, the frost heave force of the ice wedge, the expansion width of the crack tip, and the surface and internal temperature of the rock are monitored.

[0070] Unidirectional freeze-thaw test on fractured rock mass

[0071] Preparation of fractured rock samples: A partial tensile fracture of the rear edge of the "three-stage" rock slope in Sangri area (single fractured rock sample 100mm×100mm×200mm) was taken for unidirectional freeze-thaw research ( Figure 3 (a)). Observe the surface of the metamorphic sandstone sample, remove the rock samples with visible cracks, and then use an ultrasonic velocimeter to test the wave velocity. Select complete rock samples with similar longitudinal wave velocity to make cracks (Table 1). Simplify a single open crack with a 90° angle from the upper end surface downward along the center axis of the rock sample, and the crack of rock sample M is (100mm×13mm), the crack of rock sample N is (100mm×4mm), the crack of rock sample O is (66mm×4mm), and the crack of rock sample Q is (33mm×4mm) (as shown in Figure 1). Figure 3 ).

[0072] Table 1 Average physical parameters of metamorphic sandstone

[0073]

[0074] Test plan and steps, one-way freeze-thaw test:

[0075] (1) Seal the two sides of the crack of the specimen with waterproof glue, then fill the crack with water (rainwater), let it stand for 24 hours to ensure that there is no water leakage, install the temperature sensor, pressure film sensor, acoustic emission probe and strain gauge, and connect the acquisition system ( Figure 4 ).

[0076] (2) Wrap 10 cm of insulation cotton around the sides and bottom of the fractured rock sample, and then place it in a U-shaped foam box so that only the upper surface of the rock sample is exposed to the air.

[0077] (3) According to the temperature in Sangri area, the test temperature was set to -20℃~20℃. The cooling rate was 10℃ / h. After the temperature dropped to -20℃, the temperature was raised until all the ice wedges melted, which was one freeze-thaw cycle.

[0078] (4) The temperature, frost heave force, strain gauge deformation, and acoustic emission signal parameters are collected throughout the test process until the cracked rock sample freezes and thaws and cracks.

[0079] The freeze-thaw variation law of the fracture water temperature field: Taking the fracture rock mass with a width of 13mm (100mm length) as an example, the freeze-thaw evolution analysis under the condition of unidirectional freezing is carried out. Based on the freeze-thaw test results, the temperature variation curve of the water inside the fracture is drawn ( Figure 5 ).

[0080] Analysis of the influence of freeze-thaw cycles on rock damage with a single fracture

[0081] (1) Freeze-thaw response of single-fracture rock mass

[0082] While conducting unidirectional freeze-thaw tests on fractured rock samples M and N, the frost heave force, frost heave deformation and acoustic emission signals of the entire process were monitored. The temperature variation of frost heave force and deformation during the freeze-thaw process of fractured rock samples and the acoustic emission response were plotted based on the test data. Figure 7 、 Figure 8 The frost heave force evolution process can be divided into six stages by analogy with the six stages of the freezing and thawing process of fissure water, such as Figure 9 .

[0083] (2) Fracture crack analysis based on acoustic emission parameters

[0084] RA value = rise time / maximum amplitude (1)

[0085] AF value = count / duration (2)

[0086] Crack type identification is carried out based on the AE signal in the deep cooling stage after freezing, and the crack classification and comparison are as follows: Figure 10 .

[0087] from Figure 10 It can be seen that in the deep cooling stage after freezing of the 13mm wide crack rock sample, the tensile fracture accounts for the largest proportion, reaching 71.4%;

[0088] Mixed fractures account for 17.2%, while shear fractures account for only 11.4%, indicating that under the action of unidirectional freeze-thaw, the failure of fractured rock mass is mainly tensile fracture.

[0089] Tensile cracks propagate along the fissure path. The localization of cracking caused by frost heave damage is due to stress concentration. While crack propagation in intact rock is controlled by internal micropores and microcracks, in fractured rock, tensile crack propagation is controlled by large, extended cracks. These cracks centralize the trajectory of tensile cracks, leading to grain cracking and pore collapse, and increased acoustic emission activity. Most cracks at the crack tips bypass quartz grains, causing intergranular cracking, while a small number penetrate quartz grains, causing transgranular fracture.

[0090] Analysis of the influence of crack size on freeze-thaw damage

[0091] (1) Effect of crack width on freeze-thaw damage

[0092] A unidirectional freeze-thaw test was conducted on cracked rock samples with a width of 13 mm and 4 mm (length of 100 mm). The following main characteristics were summarized from the freeze-thaw failure morphology of the rock samples: Figure 11 and Figure 12 );

[0093] (2) Effect of crack length on freeze-thaw damage

[0094] The unidirectional freeze-thaw test was carried out on single-crack sandstone specimens with lengths of 100 mm, 66 mm, and 33 mm (4 mm width). Figure 13 )Summarize its main features:

[0095] The temperature difference between the top and bottom of a 100mm-long crack is large, reaching a maximum of 13°C. The temperature difference between the top and bottom of a 33mm-long crack is very small, with a maximum difference of only 2.7°C. The cooling and heating rates of water in the crack vary with crack length. As crack length increases, the cooling rate decreases and the freezing phase transition time increases. Shorter crack lengths result in faster melting and heating rates.

[0096] Double-sided freeze-thaw test on slope model

[0097] Water and temperature are important factors initiating freeze-thaw weathering. The tension cracks on the trailing edge are easily filled with rain and snow water. To simulate the natural freeze-thaw environment, a double-sided (top and slope) freeze-thaw device was developed and tested (see Figure 16 ).

[0098] (1) Seal the crack side with waterproof glue and saturate the top and slope surface (40mm) with water. Then fix the thin film pressure sensor (to measure the frost heave force), temperature sensor and acoustic emission probe ( Figure 15 ). The acoustic emission preamplifier and threshold value are selected as 40dB.

[0099] (2) Fill the rear edge tension crack with rainwater, wrap it with plastic wrap, and let it sit for 24 hours. If there is no leakage, connect it to the data acquisition system.

[0100] (3) According to the temperature changes in the Sangri area, the test temperature was set at 20℃~-20℃, and the freeze-thaw rate was 10℃ / h.

[0101] (4) After each freeze-thaw cycle, the crack extension was measured and recorded until the locked section was frozen and thawed and fractured, and all data were exported for statistical analysis.

[0102] Experimental analysis of freeze-thaw damage in locked sections of rock slopes

[0103] The three different depths of the rear edge tension crack slope models show similar trends in the internal crack water temperature changes during the freeze-thaw process. The longer the crack, the greater the temperature difference of the crack water during the freeze-thaw process. Taking model N as an example, the temperature change curve inside the rear edge tension crack is as follows: Figure 17 As shown, the temperature field distribution is Figure 18 As shown in Figure 2. The effects of multiple freeze-thaw cycles on the temperature field are basically the same. Figure 17 The freeze-thaw process of fissure water is divided into six stages.

[0104] Analysis of the influence of freeze-thaw cycles on the damage of the locking section

[0105] The locked section at the tip of the trailing edge tension crack is the weakest area of ​​freeze-thaw damage. Model M-5 with a moderate crack length is selected to show the freeze-thaw damage evolution curve of the locked section ( Figure 21 ).

[0106] Analysis of the influence of crack depth on frost heave damage

[0107] The freeze-thaw damage process of the "three-stage" slope with different depths of trailing-edge tension cracks is similar. The differences are as follows: the deeper the crack, the more water it stores, and the larger the ice wedge it forms. The greater the temperature difference between the top and bottom of the crack, the more significant the migration of water into the ice wedge. Figure 22 is the maximum frost heave force of the models with different crack depths. The frost heave force increases with the crack depth. When the crack depth increases from 40mm to 60mm, the frost heave force increases by 233N. When the crack depth increases from 60mm to 80mm, the frost heave force increases by 107N, and the increase rate is reduced by half. For 40, 60, and 80mm cracks, the locked segment breaks and fails after 14, 8, and 4 freeze-thaw cycles, respectively. The increase in crack length accelerates the failure of the locked segment. The failure morphology of the slope with different crack depths is shown in Figure 23 The fracture cracks all extend downward from the bottom of the cracks, connecting with the leading edge shear cracks. The fracture surface is relatively flat, with no shear marks, and the main cause of failure is frost heave tension. The longer and wider the trailing edge tension cracks, the stronger the water collection and conduction capacity, and the more severe the freeze-thaw impact.

[0108] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalent features for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment, comprising a freeze-thaw chamber (2), characterized in that: The freeze-thaw box (2) is provided with a sample (1) inside, and the freeze-thaw box (2) is arranged in contact with the sample (1). The top of the freeze-thaw box (2) is provided with a freeze-thaw circulation system (3). The top of the freeze-thaw box (2) is provided with an ultraviolet lamp (4) and a humidity adjustment system (5). The ultraviolet lamp (4) and the humidity adjustment system (5) are connected to an external power supply. The bottom of the freeze-thaw box (2) is provided with a temperature-controlled water injector (6), and the temperature-controlled water injector (6) is connected to an external switch and a bottom tray. The freeze-thaw box (2) on one side of the sample (1) is provided with a simulated water flow flushing system. The simulated water flow flushing system (7) is connected to an external water source through a water pipe, an electromagnetic flowmeter is installed on the water pipe to accurately measure the water flow rate, a thermal insulation cotton (8) is provided between the gaps of the sample (1), a crack meter (9) is provided on the top of the sample (1), an acoustic emission probe (10) is provided on the top of the sample (1), a strain gauge (11) is provided on the locking section of the crack tip of the sample (1), a temperature sensor (12) is provided in the crack of the sample (1), and a thin film pressure sensor (13) is provided inside the crack of the sample (1); During the freeze-thaw process inside the freeze-thaw box (2), the surface temperature of the model sample (1) and the internal temperature of the crack are monitored by a temperature sensor (12), the ice wedge heave force in different areas of the model is monitored by a flexible film pressure sensor (13), the strain of the model sample (1) is monitored by a strain gauge data acquisition device (11), and the crack expansion width of the model sample (1) is monitored by a crack meter (9).

2. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 1, characterized in that: The sample (1) is provided with cracks, which are established according to the geometric shape of the sample (1).

3. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 1, characterized in that: The thickness of the heat-insulating cotton (8) is 20 cm, and the freeze-thaw box (2) is made of stainless steel.

4. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 1, characterized in that: The sample (1) mainly comprises rock blocks and slopes, and a testing unit is also provided on the sample (1).

5. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 1, characterized in that: The specific steps of the multifunctional freeze-thaw test for simulating a freeze-thaw environment of the sample (1) in the freeze-thaw chamber (2) are as follows: S1. Dry the sample (1), seal the sides of the cracks in the sample (1) with waterproof glue, and install various sensors of the test unit; S2, saturating the surface of the sample (1) with water; S3, setting a collection terminal on the test unit to collect data, injecting water into the cracks of the sample (1), and performing water leakage monitoring; S4, setting the freezing temperature and melting temperature; S5, turning on the ultraviolet lamp (4), humidity control system (5), temperature-controlled water injector (6) and simulated water flow flushing system (7) as needed for monitoring; S6. measuring and recording the crack extension of sample (1); S7, freeze and thaw repeatedly until the sample (1) cracks and breaks; S8. Export all data during the experiment.

6. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 5, characterized in that: The freezing temperature and melting temperature in S4 can be set according to needs, and the cooling and heating rates can be freely adjusted.

7. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 5, characterized in that: During the water leakage monitoring in S3, when water leakage occurs, waterproof glue is used to seal the sample again, and after injecting test water, the sample (1) is wrapped with plastic wrap to reduce water evaporation.

8. The multifunctional freeze-thaw test device for simulating a natural freeze-thaw environment according to claim 5, characterized in that: The ultraviolet lamp (4), humidity adjustment system (5), temperature-controlled water injector (6) and simulated water flow flushing system (7) in S5 are adjusted according to the experimental requirements.

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