Device and method for testing moisture migration characteristics of low-temperature fractured rock mass

Abstract

The invention relates to a low-temperature fractured rock mass moisture migration characteristic testing device and testing method, and belongs to the technical field of cold region engineering. In order to solve the problem that the moisture migration condition in the fractured rock mass is difficult to comprehensively monitor in real time and the like at present, the device comprises a modular sample preparation system, a numerical control refrigeration module, a temperature detection module, a water replenishing module and a heat preservation module, the numerical control refrigeration modules are distributed above and below the concrete sample and used for regulating and controlling the temperature in the test process, the temperature detection module is located on one side of the numerical control refrigeration modules and connected with the concrete sample to feed back the temperature in the test process in real time, and the water supplementing module is located on the other side of the numerical control refrigeration modules and connected with the concrete sample. The heat preservation module is arranged on the side face of the concrete sample, the concrete sample is isolated from the external temperature, and the result credibility of the water migration characteristic test of the fractured rock mass is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of cold region engineering technology, and in particular to a device and method for testing water migration characteristics of low-temperature fractured rock mass. Background Art

[0002] In cold-region construction projects, such as highways, railways, and tunnels, water migration within fractured rock masses at low temperatures can significantly impact the stability of the rock mass and the durability of the engineering structures. This water migration can lead to phenomena such as frost heave and thaw settlement, which can in turn cause engineering failures.

[0003] However, the current research on the laws of water migration in low-temperature fractured rock masses is not in-depth enough. There is a lack of effective testing equipment and methods to accurately simulate and measure the water migration process in fractured rock masses under low-temperature conditions. Moreover, some existing testing methods cannot accurately control the low-temperature environment, and it is difficult to conduct comprehensive and real-time monitoring of water migration inside fractured rock masses. This seriously restricts the development of relevant theories of cold-region engineering and the safety of engineering practice.

[0004] Therefore, it is of great practical significance to develop a device and method that can accurately simulate and test the water migration characteristics of low-temperature fractured rock masses. Summary of the Invention

[0005] In response to the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a testing device and method for the moisture migration characteristics of low-temperature fractured rock mass. A moisture migration test platform is built for single-fracture low-temperature rock mass, a systematic test plan is formulated, and the test plan and steps are clarified, so as to effectively carry out experiments to reveal the moisture migration characteristics of single-fracture low-temperature rock mass.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention discloses a device for testing the water migration characteristics of low-temperature fractured rock mass, comprising:

[0008] Modular specimen preparation system for preparing concrete specimens;

[0009] Digitally controlled cooling modules, located above and below the concrete specimens, are used to control the temperature during the test.

[0010] The temperature detection module is located on one side of the CNC cooling module and is connected to the concrete sample to provide real-time feedback on the temperature during the test;

[0011] The water supply module is located on the other side of the CNC cooling module and is connected to the concrete sample, and is used to supply water to the concrete sample and obtain its water migration amount;

[0012] The insulation module is arranged on the side of the concrete sample and is used to isolate the concrete sample from the external temperature.

[0013] As a preferred implementation of the above technical solution, the process of making concrete samples by the modular sample preparation system includes five steps: mixing mortar, pouring into the mold, setting holes for initial setting, packaging dry samples, and saturating with water.

[0014] A further preferred solution is that the concrete sample is a half-disassembled rock sample with a diameter of 5 cm and a height of 10 cm.

[0015] A further preferred solution of the above scheme is: the CNC cooling module includes two CNC cooling platforms and two CNC coolers, the two CNC cooling platforms are respectively arranged in contact with the top and bottom of the concrete sample, and the two CNC coolers are arranged above and below the concrete sample, and the CNC coolers are connected to the CNC cooling platforms adjacent to them.

[0016] A further preferred solution of the above solution is: the temperature detection module includes a temperature sensor and a sensor digital display, the sensor digital display is located on one side of the concrete sample, and the sensor digital display is connected to the concrete sample through the temperature sensor.

[0017] A further preferred embodiment of the above scheme is as follows: the water supply module includes a Marg flask, a high-precision electronic scale, a lifting platform and a water supply bottom pipe. The lifting platform is located on the other side of the concrete sample. The Marg flask and the high-precision electronic scale are both arranged on the lifting platform, and the high-precision electronic scale is located at the bottom of the Marg flask. The water supply bottom pipe is arranged at the lower end of the concrete sample, and water is supplied from the Marg flask to the cracks of the concrete sample through the water supply bottom pipe.

[0018] Furthermore, the insulation module uses 2cm thick aluminum foil insulation cotton.

[0019] In a second aspect, the present invention further discloses a method for testing the water migration characteristics of low-temperature fractured rock mass, comprising the following steps:

[0020] S1: Prepare concrete specimens with vertical cracks, treat them according to design requirements and inspect them;

[0021] S2: Conduct non-water supplementation test and water supplementation test on concrete specimens respectively;

[0022] S3: Start the digital controlled cooler and adjust the temperature gradient of the digital controlled cooling platform according to the temperature reading of the sensor digital display in time to stabilize the temperature within the target range;

[0023] S4: When the temperature of the temperature sensor at each measuring point in the concrete sample reaches the target range and the fluctuation amplitude of the Martens flask weight within 1 hour is less than 0.1g, the data of the sensor digital display is exported and the digital controlled cooler is turned off;

[0024] S5: Extract the unfrozen water in the cracks of the concrete sample from the water supply bottom pipe and weigh it. Immediately remove the sample to observe and record the freezing position, determine the water migration mode and migration degree, and repeat steps S1-S5 until the test is completed.

[0025] Based on the above technical solution, further, in step S1, the processing and inspection process of the concrete sample is as follows:

[0026] The concrete specimens were soaked in saturated water at standard temperature for 24 h until the weight was stable;

[0027] Take out the cured concrete sample, drain it and seal the top surface with aluminum foil tape, fill the water supply bottom pipe with water and let it stand to observe whether there is any leakage to ensure the sealing of the concrete sample.

[0028] Based on the above technical solution, further, in step S2, the steps of the non-water replenishment test and the water replenishment test are as follows:

[0029] 1. No water replenishment test:

[0030] The water supply bottom pipe was sealed with sealing cement and aluminum foil tape, and the crack volume of each concrete sample was measured by injecting water one by one;

[0031] Then pour it out and use the syringe of the electronic scale to inject water into the crack again to the required position;

[0032] 2. Water replenishment test:

[0033] A temperature sensor was installed on the concrete sample, wrapped with aluminum foil and connected to a Malvern flask, and placed on a numerically controlled cooling platform.

[0034] Open the Martens flask, allow the water level in the crack to rise to the preset height, and observe the reading on the high-precision electronic scale until it stabilizes.

[0035] Compared with the prior art, the present invention can produce the following beneficial effects:

[0036] 1. The test device of the present invention can stably control the test temperature through a high-precision digitally controlled cooling module. By combining a temperature sensor with a sensor digital display, it can monitor the changes in physical parameters during water migration from multiple angles in real time and obtain comprehensive data. The water replenishment module replenishes water to the cracks in the concrete sample to provide a stable liquid level. The insulation module reduces the impact of external temperature on the sample isolation body, allowing it to maintain heat conduction along the one-dimensional direction of height as much as possible. This provides strong data support for research related to cold-region projects, thereby more safely and effectively solving the frozen rock problem encountered in cold-region projects.

[0037] 2. The test method of this invention develops modular, small-scale, rock-like concrete specimens that are easily disassembled and assembled. This provides a visual observation platform for the freezing conditions within fractured rock masses, increasing the credibility of the results. In subsequent studies, the water migration patterns under various factors can be qualitatively and quantitatively determined. This method establishes an integrated, dedicated platform adapted for specialized specimens. Using a numerically controlled cooling module and a temperature monitoring module, this method efficiently controls and observes changes in the temperature and moisture fields of fractured rock masses during unidirectional freezing tests, improving test accuracy. A new cross-validation technique for the freezing degree of the moisture field is proposed, further increasing the accuracy of the results. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0039] Figure 1 It is a structural schematic diagram of the present invention;

[0040] Figure 2 A detailed diagram of the modular sample preparation system of the present invention;

[0041] Figure 3 A concrete sample prepared according to the present invention;

[0042] Figure 4 This is a diagram showing the degree of water migration at different levels of the water replenishing solution of the present invention;

[0043] Figure 5 This is a graph showing the change in water migration degree of a sample with a -5 to 5°C gradient and a 5 cm liquid height under different crack openings.

[0044] Figure 6 This is a graph showing the change in water migration degree of a sample with a crack opening of 1 mm and a water replenishing liquid height of 5 cm under different temperature gradients;

[0045] In the figure: 1. CNC cooling module; 2. Temperature monitoring module; 3. Water supply module; 4. Modular sample preparation system; 5. Insulation module; 6. CNC cooling platform; 7. CNC cooler; 8. Temperature controller; 9. Temperature sensor; 10. Sensor digital display; 11. Martens flask; 12. High-precision electronic scale; 13. Lifting platform; 14. Water supply bottom pipe; 15. Concrete sample; 16. Aluminum foil insulation cotton; 17. Room temperature monitor. DETAILED DESCRIPTION

[0046] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0047] With reference to Figures 1-6 The present application provides a low-temperature fractured rock mass water migration characteristic testing device, comprising a modular sample preparation system 4, a numerical control cooling module 1, a temperature monitoring module 2, a water supplementing module 3 and a heat preservation module 5. The modular sample preparation system 4 is used for preparing a concrete sample 15. The numerical control cooling module 1 is distributed above and below the concrete sample 15 and is used for temperature regulation during the test process. The temperature monitoring module 2 is located on one side of the numerical control cooling module 1 and is connected with the concrete sample 15, and is used for real-time feedback of the temperature during the test process. The water supplementing module 3 is located on the other side of the numerical control cooling module 1 and is connected with the concrete sample 15, and is used for water supplementing of the concrete sample 15 and obtaining the water migration amount of the concrete sample 15. The heat preservation module 5 is arranged on the side of the concrete sample 15 and is used for isolating the concrete sample 15 from the external temperature.

[0048] As shown in Figure 2 The specific process of the modular sample preparation system 4 for preparing the concrete sample 15 includes:

[0049] (1) Mixing mortar: prefabricating a fractured cement mortar sample, and the material composition is ordinary Portland cement, quartz sand with a particle size less than 0.5 mm (to ensure smooth fracture surface) and distilled water. The cement mortar mixer is stirred for 15 min to fully mix them.

[0050] (2) Mould pouring: a hard plastic cylindrical mould with a diameter of 5 cm and a height of 10 cm is selected. In order to facilitate demoulding, oil-based release agent is applied on the mould and steel sheet, and after 20 min of air setting to form a film on the surface of the mould, pouring is started. Before pouring the cement mortar, a stainless steel sheet with a length of 12 cm, a width of 4.9 cm and a thickness of 1 cm is placed in the vertical direction in the mould and is firmly fixed without shaking. The cement mortar is poured in two layers at a uniform speed and is tamped to fill the mould. During the pouring process, the stainless steel sheet is always located in the center of the sample without deviation. Subsequently, the sample is placed on a vibration table and vibrated for 5 min to make the inside dense.

[0051] (3) Initial setting hole: After about 7h, open the mold, and when the mortar is not completely solidified, start from 0.5cm from the bottom of the mold, and every certain distance, use a needle to prick into the mortar 2cm vertically along the side of the crack surface to preset the temperature hole, according to the different temperature control accuracy, different number of temperature sensors are arranged, and after about 12h, the sample is completely solidified and demolded, the sample is pried along the steel sheet, and placed in a curing box for curing for 24h;

[0052] (4) Dry sample packaging: after the half sample is prepared, the sample is assembled in a dry state. First, a reserved hole for inserting a water supplement pipe is drilled at the bottom of the solidified crack surface using a punching device, and the length is 1cm, the crack opening is controlled by pasting double-sided transparent adhesive tape with different thicknesses around the sample, and the thickness of the adhesive tape is consistent with the designed opening of the crack, which is 0.5mm, 1mm, 1.5mm and 2mm respectively; then, the side and bottom surfaces of the sample are wrapped and sealed with 0.06mm thick aluminum foil tape; finally, the packaged sample is inserted into the water supplement bottom pipe and sealed with waterproof glue.

[0053] (5) Water saturation: the spliced and packaged sample is saturated in water for 24h, and a concrete sample 15 containing a vertical crack is obtained, as shown in Figure 3 The concrete sample 15 is a half disassembled rock sample, with a diameter of 5cm and a height of 10cm.

[0054] More specifically, the numerical control cooling module 1 includes two numerical control cooling platforms 6 and two numerical control coolers 7, the two numerical control cooling platforms 6 are contactingly arranged at the top and bottom of the concrete sample 15, the two numerical control cooling platforms 6 serve as the cold source and heat source in the one-way freezing process of the concrete sample 15, the two numerical control coolers 7 are arranged above and below the concrete sample 15, and the numerical control cooler 7 is connected with the numerical control cooling platform 6 close to it, and the numerical control cooler 7 is provided with a temperature controller 8 for switching between cold and hot; in the present application, the numerical control cooling platform 6 is a domestic self-developed refrigeration sheet, which can be cooled to -20℃, and the precision is ±0.1℃.

[0055] In some preferred embodiments, the temperature monitoring module 2 includes a temperature sensor 9 and a sensor digital display instrument 10, the sensor digital display instrument 10 is located on one side of the concrete sample 15, and the sensor digital display instrument 10 is connected with the concrete sample 15 through the temperature sensor 9, which can real-time reflect and record the data of the temperature gradient in the concrete sample 15 controlled by the numerical control cooling module 1 to the sensor digital display instrument 10, and transmit the data of the sensor digital display instrument 10 to the data collection system through the connecting line; in the present application, the temperature sensor 9 is a K-type ultra-fine welding point probe thermocouple temperature measurement component, which is placed in the reserved hole of the concrete sample 15, and the surface of the temperature sensor 9 and the wire part of the concrete sample 15 are sealed with transparent tape.

[0056] In the present invention, the water replenishment module 3 includes a Marg flask 11, a high-precision electronic scale 12, a lifting platform 13 and a water replenishment bottom pipe 14. The lifting platform 13 is located on the other side of the concrete sample 15. The Marg flask 11 and the high-precision electronic scale 12 are both set on the lifting platform 13 to accurately control the liquid level in the concrete sample 15. The high-precision electronic scale 12 is located at the bottom of the Marg flask 11, and the water replenishment bottom pipe 14 is set at the lower end of the concrete sample 15. Water is replenished from the Marg flask 11 to the cracks of the concrete sample 15 through the water replenishment bottom pipe 14. The total amount of water replenished by the Marg flask 11 to the concrete sample 15 can be obtained using the high-precision electronic scale 12, and the total amount of migrated water can also be read through the water level scale on the body of the Marg flask 11.

[0057] Furthermore, the insulation module 5 adopts 2 cm thick aluminum foil insulation cotton 16, and the aluminum foil insulation cotton 16 is pre-pierced with water supply holes, which plays an insulation role in the logarithmic control of the cold platform 6 and the concrete sample 15, reducing the impact of the external temperature on the isolation body of the concrete sample 15, so as to maintain heat conduction along the one-dimensional direction of height as much as possible, so as to ensure a unidirectional freezing environment during the test.

[0058] In the present invention, the digital controlled cooling module 1, the temperature monitoring module 2, the water supply module 3, the modular sample preparation system 4 and the insulation module 5 are in the same space environment as the room temperature monitor 17 to ensure that the test environment temperature is controllable and stable.

[0059] When using the low-temperature fractured rock mass moisture migration characteristic testing device of the present invention to test concrete samples, the following steps are included:

[0060] 1. According to the test requirements, prepare a concrete sample 15 with vertical cracks. Soak the concrete sample 15 at the standard temperature for 24 hours until the weight stabilizes. Take out the cured concrete sample 15, drain it and seal the top surface with aluminum foil tape. Fill the water supply bottom pipe 14 with water and observe whether there is any leakage to ensure that the concrete sample 15 is well sealed. Let it stand and observe for 10 minutes. If there is no leakage, the concrete sample 15 can be considered to meet the standard. Otherwise, repeat the above steps. If there is still leakage, the sample is discarded.

[0061] 2. Conduct a non-water supplementation test and a water supplementation test on concrete sample 15 respectively;

[0062] 1) No water replenishment test:

[0063] Seal the water supply bottom pipe 14 with sealing putty and aluminum foil tape, inject water into the crack volume of each concrete sample 15 one by one to measure, then pour out the water, and use the syringe of an electronic scale to re-inject water into the crack to the required position;

[0064] 2) Water replenishment test:

[0065] A temperature sensor 9 is installed on the concrete sample 15 and wrapped with aluminum foil insulation cotton 16, then connected to the Malchnitz flask 11 and placed on the numerically controlled cold platform 6. The Malchnitz flask 11 is opened to allow the water level in the crack to rise to a preset height. The reading of the high-precision electronic scale 12 is observed until it stabilizes.

[0066] 3. Start the digital controlled cooler 7 and adjust the temperature gradient of the digital controlled cooling platform 6 in time according to the temperature reading of the sensor digital display 10 to stabilize the temperature within the target range. When replenishing water with a constant head, manually record the weight of the Martens flask 11 every 15 minutes.

[0067] In the overall quick freezing test of step S3, an extended experiment was conducted on the material of the concrete sample 15. Materials with different thermal conductivity, such as glass sheets and iron sheets, were used to make cracked samples, enriching the test results, as shown in Table 1.

[0068] Table 1 Quick freezing of samples of different materials at -5℃ with 1mm crack opening and 8cm liquid height

[0069]

[0070] The overall quick freezing test test steps include: (1) quantitative water injection; (2) sample weighing; (3) sample freezing; after the overall quick freezing test is completed, the sample is disassembled to observe the freezing height of the ice body to determine whether water migration occurs.

[0071] In addition, the migration amount of the iron powder-doped sample was obtained when the crack opening was 1 mm, the sample was closed to the outside world, no water was added or water was added, and the initial liquid height was 5 cm, as shown in Tables 2 and 3.

[0072] Table 2 Total amount of freezing migration of iron powder-doped samples sealed without water replenishment

[0073]

[0074]

[0075] Table 3 Total amount of frozen migration of iron powder-doped samples after sealing and hydration

[0076]

[0077] 4. When the temperature of the temperature sensor 9 at each measuring point in the concrete sample 15 reaches the target range and the fluctuation of the weight of the Martens flask 11 within 1 hour is less than 0.1g, the data of the sensor digital display 10 is exported and the digital controlled cooler 7 is turned off;

[0078] 5. Extract the unfrozen water in the cracks of the concrete sample 15 from the water supply bottom pipe 14 and weigh it. Immediately remove the sample to observe and record the freezing position, and draw a relationship diagram between the water migration flux and the temperature gradient, freezing duration and other conditions, such as Figure 4-Figure 6As shown, determine the mode and extent of water migration and repeat the above steps until the test is completed.

[0079] In the one-way freezing test S5, a new cross-validation technique for the freezing degree of the moisture field was proposed, which includes the following process:

[0080] (1) Before the test, water is injected into the concrete specimen 15. The weight of water to be injected into the crack is determined based on the pore volume in the crack and the designed initial liquid level. The specimen is weighed before freezing, and the mass of the specimen before freezing is recorded.

[0081] (2) Install the insulation module 5 on the side of the concrete sample 15, place the concrete sample 15 on the numerically controlled cold platform 6, adjust the temperature gradient in advance through the temperature controller 8, and start unidirectional freezing;

[0082] (3) After freezing, the unfrozen water is extracted through the water supply bottom pipe 14 preset at the bottom of the concrete sample 15, weighed, and added to the frozen water (the volume is calculated after the water-ice phase transition) and compared with the initial water volume to obtain the mass of the gaseous migrated water. The volume of the frozen water can be calculated by opening the concrete sample 15 and observing the freezing condition of the sample side wall. The mass is calculated based on the crack opening and the freezing height.

[0083] After the freezing of concrete specimen 15 is completed, the freezing height is used as the final liquid level height and compared with the initial liquid level height. After excluding the factors affecting the sample water seepage loss and frost heave (i.e., whether the liquid level rises to 1 / 9 of the volume increase after the water-ice phase transition), it can be visually confirmed whether liquid water migration occurs in the fractured rock mass.

[0084] Some test data during the test are shown in Tables 4 to 6, where Tables 4, 5 and 6 correspond to Figure 4 、 Figure 5 、 Figure 6 :

[0085] Table 4 Water migration table of different crack openings

[0086]

[0087] Table 5 Rock mass water migration and water replenishment under water replenishment conditions

[0088]

[0089]

[0090] Table 6 Moisture migration of samples at different temperature gradients

[0091]

[0092] The present invention provides a device and method for testing the moisture migration characteristics of low-temperature fractured rock. Based on the characteristics of low-temperature fractured rock, a single-fracture low-temperature rock moisture migration test platform is built, a systematic experimental plan is formulated, concrete specimens that meet the test requirements are prepared, the test methods and steps are clarified, and a moisture migration test of a single-fracture low-temperature rock is carried out. Drawing on the frozen soil moisture migration device and considering the characteristics of fractured rock, a single-fracture low-temperature rock moisture migration test platform is built, and a systematic test plan is formulated by comprehensively considering the fracture characteristics, temperature conditions, water replenishment conditions, and rock thermal conductivity. At the same time, samples are prepared based on the parameter settings in the plan, and then the test methods and steps are clarified. Finally, experiments are carried out to reveal the moisture migration characteristics of single-fracture low-temperature rock.

[0093] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for testing the water migration characteristics of low-temperature fractured rock mass, characterized in that: include: A modular specimen preparation system (4) for preparing concrete specimens (15); Digitally controlled cooling modules (1), distributed above and below the concrete specimen (15), are used to control the temperature during the test; A temperature detection module (2), located on one side of the numerical control cooling module (1) and connected to the concrete sample (15), is used to provide real-time feedback on the temperature during the test; A water supply module (3), located on the other side of the numerical control cooling module (1) and connected to the concrete sample (15), is used to supply water to the concrete sample (15) and obtain its water migration amount; The heat-insulating module (5) is arranged on the side of the concrete sample (15) and is used to isolate the concrete sample (15) from the external temperature.

2. A low-temperature fractured rock mass water migration characteristic testing device according to claim 1, characterized in that: The process of making concrete samples (15) by the modular sample preparation system (4) includes five steps: mixing mortar, pouring into mold, setting holes for initial setting, packaging dry samples, and saturating with water.

3. A low-temperature fractured rock mass water migration characteristic testing device according to claim 2, characterized in that: The concrete sample (15) is a half-disassembled rock sample with a diameter of 5 cm and a height of 10 cm.

4. A low-temperature fractured rock mass water migration characteristic testing device according to claim 1, characterized in that: The numerical control cooling module (1) comprises two numerical control cooling platforms (6) and two numerical control coolers (7). The two numerical control cooling platforms (6) are respectively arranged in contact with the top and bottom of the concrete sample (15). The two numerical control coolers (7) are arranged above and below the concrete sample (15), and the numerical control coolers (7) are connected to the adjacent numerical control cooling platforms (6).

5. The device for testing water migration characteristics of low-temperature fractured rock mass according to claim 1, characterized in that: The temperature detection module (2) comprises a temperature sensor (8) and a sensor digital display (9). The sensor digital display (9) is located on one side of the concrete sample (15), and the sensor digital display (9) is connected to the concrete sample (15) via the temperature sensor (8).

6. The device for testing water migration characteristics of low-temperature fractured rock mass according to claim 1, characterized in that: The water supply module (3) comprises a Marg flask (11), a high-precision electronic scale (12), a lifting platform (13) and a water supply bottom pipe (14). The lifting platform (13) is located on the other side of the concrete sample (15). The Marg flask (11) and the high-precision electronic scale (12) are both arranged on the lifting platform (13), and the high-precision electronic scale (12) is located at the bottom of the Marg flask (11). The water supply bottom pipe (14) is arranged at the lower end of the concrete sample (15). Water is supplied from the Marg flask (11) to the cracks of the concrete sample (15) through the water supply bottom pipe (14).

7. The device for testing water migration characteristics of low-temperature fractured rock mass according to claim 1, characterized in that: The heat preservation module (5) adopts 2cm thick aluminum foil heat preservation cotton (16).

8. A method for testing the water migration characteristics of low-temperature fractured rock mass, characterized in that: The method is based on a low-temperature fractured rock mass water migration characteristic testing device according to any one of claims 1 to 7, and comprises the following steps: S1: Prepare a concrete specimen (15) with vertical cracks, treat it according to the design requirements and inspect it; S2: Conduct a non-water supplementation test and a water supplementation test on the concrete specimen (15); S3: Start the digital controlled cooler (7) and adjust the temperature gradient of the digital controlled cooling platform (6) in time according to the temperature reading of the sensor digital display (8) so that the temperature is stabilized within the target range; S4: When the temperature of the temperature sensor (9) at each measuring point in the concrete sample (15) reaches the target range and the fluctuation amplitude of the weight of the Martens flask (11) within 1 hour is less than 0.1g, the data of the sensor digital display (10) is exported and the digital control cooler (7) is turned off; S5: extract the unfrozen water in the cracks of the concrete sample (15) from the water supply bottom pipe (14) and weigh it, immediately remove the sample to observe and record the freezing position, determine the water migration mode and migration degree, and repeat steps S1-S5 until the test is completed.

9. A method for testing water migration characteristics of low-temperature fractured rock mass according to claim 8, characterized in that: In step S1, the processing and inspection process of the concrete sample (15) is as follows: The concrete specimen (15) was soaked in saturated water at standard temperature for 24 h until the weight stabilized; The cured concrete sample (15) is taken out, drained and sealed with aluminum foil tape on the top surface, and water is injected into the water supply bottom pipe (14) and left to stand to observe whether there is water leakage, thereby ensuring the sealing of the concrete sample (15).

10. A method for testing water migration characteristics of low-temperature fractured rock mass according to claim 8, characterized in that: In step S2, the steps of the non-water replenishment test and the water replenishment test are as follows:

1. No water replenishment test: The water supply bottom pipe is sealed with sealing cement and aluminum foil tape, and the crack volume of each concrete sample (15) is measured by injecting water one by one; Then pour it out and use the syringe of the electronic scale to re-inject water into the crack to the required position; 2. Water replenishment test: A temperature sensor (9) is installed on the concrete sample (15) and wrapped with aluminum foil insulation cotton (16) and connected to the Malvern flask (11), and placed on a numerically controlled cold platform (6); The Martens flask (11) is opened to allow the water level in the crack to rise to a preset height, and the reading of the high-precision electronic scale (12) is observed until it stabilizes.

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