A multi-parameter nuclear magnetic in-situ combined measurement device under the dry-wet and freeze-thaw coupling action of saline soil

Abstract

The utility model discloses a kind of multi-parameter nuclear magnetic in-situ joint-measuring devices under the dry-wet-freeze-thaw coupling of saline soil, including the non-magnetic test cavity for accommodating sample, still include nuclear magnetic in-situ detection component, freeze-thaw cycle component, dry-wet cycle component, variable water head component, drainage component;Nuclear magnetic in-situ detection component is used to provide magnetic field environment inside non-magnetic test cavity, freeze-thaw cycle component is used to control the internal temperature of non-magnetic test cavity, dry-wet cycle component is used to control the internal humidity of non-magnetic test cavity, variable water head component is used to provide seepage liquid in non-magnetic test cavity for sample and adjust water head height;Drainage component is used to discharge liquid in non-magnetic test cavity from bottom;Non-magnetic test cavity inner wall is provided with aluminum nitride coating;Non-magnetic test cavity is also provided with exhaust port.The utility model is used to solve the problem that prior art cannot carry out multi-parameter nuclear magnetic in-situ joint measurement under the dry-wet-freeze-thaw coupling of saline soil.

Description

Technical Field

[0001] This utility model relates to the field of testing saline soil in cold regions, specifically to a multi-parameter in-situ nuclear magnetic resonance (NMR) device for testing saline soil under dry-wet-freeze-thaw coupling. Background Technology

[0002] In engineering research on saline soils in cold regions, accurately obtaining multi-parameter data such as permeability coefficient, saturation, and unfrozen water content under the coupled effects of freeze-thaw and wet-dry cycles is crucial for engineering safety assessment. However, existing technologies suffer from the following systemic deficiencies:

[0003] First, traditional detection methods have inherent limitations. For permeability coefficient, moisture content and wet-dry-freeze-thaw cycle tests, separate samples need to be prepared, resulting in data dispersion of up to 35%. Furthermore, destructive operations such as drying will interrupt the continuous observation of the dynamic migration process of moisture. Existing standards also do not consider the correction of phase transition temperature by salt (e.g., NaCl can lower the freezing point to -21℃).

[0004] Secondly, the engineering adaptability of nuclear magnetic resonance technology faces severe bottlenecks. Existing low-field NMR equipment has a signal-to-noise ratio (SNR) of less than 8:1 when NaCl > 3%, resulting in a T2 spectrum inversion error of more than ±8%. The standard probe in the existing technology operates in a temperature range of 5-40℃, which cannot cover the freeze-thaw-dry-wet cycle requirements of -30~60℃. Furthermore, vibration sensitivity can cause a deterioration of magnetic field uniformity of more than 20%. In addition, the existing equipment only outputs T2 spectra and requires an external permeameter, resulting in a data matching error of up to 30%.

[0005] Furthermore, some technological improvement attempts still face unresolved challenges, such as the corrosion depth of NMR probes exceeding 50 μm after 100 hours of continuous operation in saline soil; the inability to achieve in-situ monitoring due to the complete shielding of NMR signals by metal freeze-thaw chambers; and the low time resolution of traditional permeability testing, making it difficult to capture the abrupt change in permeability coefficient of 1000 times at -15℃.

[0006] The above-mentioned defects lead to the dilemma of "inaccurate measurement, incomplete understanding, and delayed early warning" in existing saline soil engineering technologies, making it impossible to achieve multi-parameter in-situ nuclear magnetic resonance joint measurement of saline soil under the coupled effects of dry-wet and freeze-thaw cycles. Utility Model Content

[0007] The purpose of this invention is to provide a multi-parameter in-situ NMR measurement device for saline soil under dry-wet-freeze-thaw coupling, so as to solve the problem that the existing technology cannot carry out multi-parameter in-situ NMR measurement of saline soil under dry-wet-freeze-thaw coupling.

[0008] This utility model is achieved through the following technical solution:

[0009] A multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling includes a non-magnetic test chamber for accommodating the sample, and also includes an NMR in-situ detection component, a freeze-thaw cycle component, a dry-wet cycle component, a variable head component, and a drainage component.

[0010] The in-situ nuclear magnetic resonance (NMR) detection component is used to provide a magnetic field environment for the non-magnetic test chamber; the freeze-thaw cycle component is used to control the internal temperature of the non-magnetic test chamber; the wet-dry cycle component is used to control the internal humidity of the non-magnetic test chamber; the variable head component is used to provide seepage liquid for the sample in the non-magnetic test chamber and adjust the water head height; and the drainage component is used to drain the liquid from the bottom of the non-magnetic test chamber.

[0011] The inner wall of the non-magnetic test chamber is coated with aluminum nitride.

[0012] The non-magnetic test chamber is also equipped with an exhaust port.

[0013] To address the limitation of existing technologies in conducting multi-parameter in-situ NMR measurements on saline soils under wet-dry / freeze-thaw coupling conditions, this invention proposes a device for multi-parameter in-situ NMR measurements on saline soils under wet-dry / freeze-thaw coupling conditions. The device features a non-magnetic test chamber made of non-magnetic material, which provides the magnetic field environment required for NMR detection via an in-situ NMR detection component. A freeze-thaw cycle component regulates temperature to simulate a freeze-thaw cycle, and a wet-dry cycle component regulates humidity to simulate a wet-dry cycle. A variable head component provides seepage liquid to the sample at a specified head height, and a drainage component discharges the seepage liquid from the sample. An exhaust port in the non-magnetic test chamber discharges humid gases. This application incorporates an aluminum nitride coating on the inner wall of the non-magnetic test chamber, which protects the NMR probe, improves the salt corrosion resistance of the NMR detection device, ensures data reliability in high-salt environments, and is more suitable for testing saline soils in cold regions under complex conditions.

[0014] Furthermore, the in-situ nuclear magnetic resonance detection component in this application can be implemented using existing nuclear magnetic resonance detection equipment, which is not difficult for those skilled in the art to implement.

[0015] Furthermore, the freeze-thaw cycle assembly includes a temperature control jacket located inside the non-magnetic test chamber and a refrigeration compressor located outside the non-magnetic test chamber; the temperature control jacket has a temperature control channel, which is spirally involute; the output end and input end of the refrigeration compressor are connected to the inlet end and outlet end of the temperature control channel respectively through electromagnetic shielding pipelines; the cross-sectional area of ​​the inlet end of the temperature control channel is larger than the cross-sectional area of ​​the outlet end of the temperature control channel.

[0016] This scheme forms a closed-loop circulation of low-temperature fluid through a refrigeration compressor, electromagnetic shielding pipeline, and temperature control jacket, which is beneficial for accurately controlling the internal temperature of the non-magnetic test chamber and thus effectively simulating the freeze-thaw process of the sample.

[0017] This design makes the temperature control channel have a spiral involute shape and makes its inlet cross-sectional area larger than its outlet cross-sectional area, which helps the low-temperature fluid to self-accelerate in the temperature control channel, thereby significantly improving the heat exchange efficiency.

[0018] Furthermore, the electromagnetic shielding conduit comprises, from the inside out, a braided copper mesh conductive layer, a metal foil magnetic shielding layer, and a fluororubber outer sheath. This electromagnetic shielding conduit provides triple electromagnetic shielding. Those skilled in the art should understand that the braided copper mesh conductive layer refers to a mesh structure woven from copper wires, and the metal foil magnetic shielding layer is a metal foil sheet.

[0019] Furthermore, the in-situ NMR detection component includes a ring-shaped array of Halbach permanent magnets; the temperature control jacket is located outside the Halbach permanent magnet array.

[0020] Furthermore, the wet-dry cycle assembly includes an ultrasonic atomizer and a drying device; the ultrasonic atomizer is connected to the interior of the non-magnetic test chamber via an atomizing gas pipeline, and the output end of the drying device is connected to the interior of the non-magnetic test chamber via a drying gas pipeline; a first valve is provided on the atomizing gas pipeline, and a second valve is provided on the drying gas pipeline.

[0021] When humidification is required, the humidity inside the non-magnetic test chamber is increased using an ultrasonic atomizer; when drying is required, drying gas is introduced into the non-magnetic test chamber using a drying device. Of course, the drying device in this solution can have an internal air pump or be supplied with gas via an external air source pump.

[0022] Furthermore, the drying equipment includes a rotary filter cartridge, the filter element of which comprises activated carbon fiber felt and / or a zeolite layer. The rotary filter cartridge in this embodiment can be driven to rotate by any existing method.

[0023] Furthermore, the variable head assembly includes an anti-crystallization tube, a water level monitoring device for measuring the water head height inside the anti-crystallization tube, and an external pipe for replenishing the anti-crystallization tube with liquid; the top of the anti-crystallization tube is open, and the bottom is connected to the top of the non-magnetic test chamber through an inlet pipe; a third valve is provided on the inlet pipe, and a fourth valve is provided on the external pipe.

[0024] This solution replenishes the anti-crystallization tube with liquid through an external pipeline and monitors the liquid level inside the anti-crystallization tube in real time using a water level monitoring device, thereby providing the sample with liquid at a specified head height to simulate the seepage process.

[0025] Furthermore, the inner wall of the anti-crystallization tube is provided with a spiral guide groove, and it also includes an ultrasonic transducer located inside the anti-crystallization tube. The spiral guide groove and ultrasonic transducer significantly reduce the probability of salt crystallization and prevent salt crystallization from clogging the pipeline.

[0026] Furthermore, the drainage assembly includes a drainage pipe connected to the bottom of the non-magnetic test chamber, a flow meter located on the drainage pipe, and a fifth valve and a sixth valve located on the drainage pipe, respectively upstream and downstream of the flow meter. This solution uses the flow meter to measure the amount of liquid discharged, thereby facilitating the in-situ measurement and calculation of the sample's permeability coefficient after the circulation is completed.

[0027] Furthermore, the drain pipe has an enlarged section located upstream of the fifth valve. This design facilitates the discharge of seepage liquid and prevents salt crystallization from clogging the discharge channel through the enlarged section.

[0028] System-level verification of this application shows that, under conditions of 20% NaCl solution and -30℃, the NMR signal-to-noise ratio remains at 45:1 when all components work together, the permeability coefficient measurement error is <±3%, the crack detection resolution reaches 20μm, and there is no performance degradation after 72 hours of continuous operation. Therefore, this application has reached an internationally leading level in the field of multi-parameter detection of saline soils, providing a reliable detection method for saline soil engineering in cold regions.

[0029] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0030] 1. This utility model discloses a multi-parameter in-situ NMR measurement device for saline soil under dry-wet-freeze-thaw coupling, which realizes multi-parameter in-situ NMR measurement of saline soil under dry-wet-freeze-thaw coupling, filling the gap in the existing technology and providing a reliable technical means for safety assessment and disaster early warning of saline soil projects in cold regions; it can complete permeability coefficient, water content and dry-wet-freeze-thaw cycle tests with a single sample, without the need for separate sample preparation, which significantly improves the test efficiency.

[0031] 2. This utility model provides a multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling, which improves the anti-salt corrosion capability of the NMR detection device, ensures the reliability of data in high-salt environments, and is more suitable for testing complex working conditions of saline soil in cold regions.

[0032] 3. This utility model provides a multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling. It adopts a non-magnetic salt-resistant combination to achieve structural synergy between anti-interference and corrosion resistance, making it suitable for complex working conditions in cold regions.

[0033] 4. This utility model provides a multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling. The freeze-thaw cycle component can achieve precise coordination of temperature, humidity and permeability field, meeting the testing needs of multiple scenarios.

[0034] 5. This utility model provides a multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling. The anti-crystallization tube extends the continuous working time to 72 hours and reduces the cost of a single test by 60%, balancing scientific research accuracy and engineering practicality. Attached Figure Description

[0035] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of a specific embodiment of the present utility model;

[0037] Figure 2 This is a cross-sectional schematic diagram of the electromagnetic shielding pipeline in a specific embodiment of this utility model.

[0038] The attached diagram shows the markings and corresponding component names:

[0039] 1-Aluminum nitride coating, 2-Observation window, 3-Sealing ring, 4-Temperature control jacket, 5-Sample, 6-Exhaust port, 7-Refrigeration compressor, 8-Electromagnetic shielding pipeline, 9-Braided copper mesh conductive layer, 10-Metal foil magnetic shielding layer, 11-Fluororubber outer sheath, 12-Ultrasonic atomizer, 13-Non-magnetic test chamber, 15-Drying equipment, 16-Rotating filter cartridge, 17-Zeolite layer, 18-Activated carbon fiber felt, 19-Water level monitoring equipment, 20-Proof Crystallization tube, 21-spiral guide channel, 22-flow meter, 23-drain pipe, 25-drying gas pipeline, 26-atomizing gas pipeline, 27-inlet pipe, 29-external pipeline, 30-expansion section, 31-ultrasonic transducer, 32-nuclear magnetic resonance in-situ detection component, 281-first valve, 282-second valve, 283-seventh valve, 284-fourth valve, 285-third valve, 286-fifth valve, 287-sixth valve. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0041] Example 1:

[0042] like Figure 1 and Figure 2The device shown is a multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling. It includes a non-magnetic test chamber 13 for accommodating the sample, and also includes an NMR in-situ detection component 32, a freeze-thaw cycle component, a dry-wet cycle component, a variable head component, and a drainage component.

[0043] The in-situ NMR detection component 32 is used to provide a magnetic field environment inside the non-magnetic test chamber 13; the freeze-thaw cycle component is used to control the internal temperature of the non-magnetic test chamber 13; the wet-dry cycle component is used to control the internal humidity of the non-magnetic test chamber 13; the variable head component is used to provide seepage liquid to the sample inside the non-magnetic test chamber 13 and adjust the water head height; and the drain component is used to drain the liquid inside the non-magnetic test chamber 13 from the bottom.

[0044] The inner wall of the non-magnetic test chamber 13 is coated with an aluminum nitride coating 1 with a thickness of at least 50 μm; the aluminum nitride coating 1 is treated by laser cladding process and has a porosity of <0.5%.

[0045] The non-magnetic test chamber 13 is also provided with an exhaust port 6.

[0046] The freeze-thaw cycle assembly includes a temperature control jacket 4 located inside a non-magnetic test chamber 13 and a refrigeration compressor 7 located outside the non-magnetic test chamber 13; the temperature control jacket 4 has a temperature control channel, which is spirally involute; the output end and input end of the refrigeration compressor 7 are connected to the inlet end and outlet end of the temperature control channel respectively through an electromagnetic shielding pipe 8; the cross-sectional area of ​​the inlet end of the temperature control channel is larger than the cross-sectional area of ​​the outlet end of the temperature control channel.

[0047] The electromagnetic shielding conduit 8 comprises, from the inside out, a braided copper mesh conductive layer 9, a metal foil magnetic shielding layer 10, and a fluororubber outer sheath 11. In this embodiment, the thickness of the braided copper mesh conductive layer 9 is 0.1 mm, the thickness of the metal foil magnetic shielding layer 10 is 0.05 mm, and the thickness of the fluororubber outer sheath 11 is 0.5 mm. More preferably, the fluororubber outer sheath 11 has an embedded stainless steel corrugated tube to improve pressure resistance. The electromagnetic shielding conduit 8 of this embodiment can achieve wide temperature range control from -30 to 60°C, vibration transmission rate <1%, and electromagnetic shielding effectiveness >60 dB.

[0048] The in-situ nuclear magnetic resonance (NMR) detection component 32 includes a ring-shaped array of Halbach permanent magnets; the temperature control jacket 4 is located outside the Halbach permanent magnet array.

[0049] In this embodiment, the non-magnetic test chamber 13 is made of TC4 titanium alloy substrate with a wall thickness of 5mm, and a hardened layer of 20-30μm is formed by surface plasma nitriding treatment. A Φ60mm observation window 2 is provided at the top of the non-magnetic test chamber 13; the observation window 2 and the non-magnetic test chamber 13 are vacuum sealed by a sealing ring 3, preferably a fluororubber O-ring.

[0050] In this embodiment, the inlet cross-sectional area of ​​the temperature-controlled flow channel is 8 mm and the outlet cross-sectional area is 5 mm.

[0051] In this embodiment, the temperature control medium used for the freeze-thaw cycle component is a 6:4 volume ratio ethylene glycol-water mixed solution with 0.1% nano-alumina thermal conductivity enhancer added.

[0052] In this embodiment, the Halbach permanent magnet array consists of 32 N52 neodymium iron boron magnets with a remanence of 1.45T. The matching RF probe uses a 3D-printed titanium alloy frame with a winding spacing of 0.8mm, providing good resistance to salt corrosion. This embodiment, combined with a tunable RF circuit of 4.8-5.2MHz, achieves a Cl⁻ interference suppression rate of 92.3%, maintaining a signal-to-noise ratio of 45:1 even in a 20% NaCl environment.

[0053] In a more preferred embodiment, the refrigeration compressor 7 is mounted on a vibration-damping base.

[0054] In a more preferred embodiment, the observation window 2 is a sapphire observation window coated with a 380-780nm anti-reflection film and equipped with a long-pass filter, so that the light transmittance is >92%, which can be used with a high-speed camera to achieve observation at a spatial resolution of 20.

[0055] Example 2:

[0056] A multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under wet-dry-freeze-thaw coupling is provided. Based on Embodiment 1, the wet-dry circulation component includes an ultrasonic atomizer 12 and a drying device 15. The ultrasonic atomizer 12 is connected to the interior of the non-magnetic test chamber 13 via an atomizing gas pipeline 26, and the output end of the drying device 15 is connected to the interior of the non-magnetic test chamber 13 via a drying gas pipeline 25. A first valve 281 is provided on the atomizing gas pipeline 26, and a second valve 282 is provided on the drying gas pipeline 25.

[0057] The drying equipment 15 includes a rotary filter cartridge 16, and the filter element of the rotary filter cartridge 16 includes an activated carbon fiber felt 18 and a zeolite layer 17.

[0058] In this embodiment, the ultrasonic atomizer 12 uses a PEEK diaphragm with a thickness of 0.5 mm and a resonant frequency of 1.23 MHz; the output end of the ultrasonic atomizer 12 is a quartz air tube, the inner wall of which is coated with a hydrophobic nano-coating and has a contact angle of 165°.

[0059] In this embodiment, the maximum rotation speed of the rotating filter cartridge 16 is 5 rpm, which improves the uniformity of adsorption.

[0060] In a more preferred embodiment, the rotating filter cartridge 16 uses stainless steel wire mesh as a structural support layer.

[0061] Example 3:

[0062] A multi-parameter in-situ NMR measurement device for saline soil under dry-wet-freeze-thaw coupling, based on Example 1 or 2.

[0063] The variable head assembly includes an anti-crystallization tube 20, a water level monitoring device 19 for measuring the water head height inside the anti-crystallization tube 20, and an external pipe 29 for replenishing the anti-crystallization tube 20 with liquid. The top of the anti-crystallization tube 20 is open, and the bottom is connected to the top of the non-magnetic test chamber 13 through a liquid inlet pipe 27. A third valve 285 is provided on the liquid inlet pipe 27, and a fourth valve 284 is provided on the external pipe 29.

[0064] The inner wall of the anti-crystallization tube 20 is provided with a spiral guide groove 21, and it also includes an ultrasonic transducer 31 located inside the anti-crystallization tube 20.

[0065] In this embodiment, the water level monitoring device 19 uses an optical encoder, achieving a water level measurement accuracy of 0.1 mm. The spiral guide channel 21 has a channel depth of 0.2 mm and a pitch of 3 mm. Furthermore, the ultrasonic transducer 31 used in this embodiment has a power of 28 kHz.

[0066] In a more preferred embodiment, the wall of the spiral guide groove 21 is subjected to micro-arc oxidation treatment to make the roughness Ra < 0.1 μm.

[0067] In a more preferred embodiment, the ultrasonic transducer 31 employs a 16-array PZT-8 piezoelectric ceramic stack.

[0068] Example 4:

[0069] A multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling, based on any of the above embodiments, wherein the drainage component includes a drainage pipe 23 connected to the bottom of a non-magnetic test chamber 13, a flow meter 22 located on the drainage pipe 23, and a fifth valve 286 and a sixth valve 287 located on the drainage pipe 23 and respectively at the upstream and downstream ends of the flow meter 22.

[0070] The drain pipe 23 has an enlarged section 30, which is located upstream of the fifth valve 286.

[0071] In this embodiment, the flow meter 22 is a ceramic flow meter with an internal hydrophobic nano-coating, such as a SiO2 / TiO2 composite nano-coating. The ceramic flow meter can also have a built-in temperature compensation module, using a Pt1000 platinum resistance thermometer with an accuracy of ±0.1, for monitoring the outlet temperature.

[0072] In this embodiment, the length L of the expansion section 30 and the inlet diameter D satisfy: L / D=1.5.

[0073] Example 5:

[0074] A multi-parameter in-situ NMR method for coupled wet-dry and freeze-thaw action in saline soil, based on Figures 1 to 2 The connected testing device shown is used to implement the connected testing method, which includes the following steps:

[0075] Prepare the saline soil sample to be tested. Prepare cylindrical sample 5 according to standard and perform vacuum saturation treatment. Open the top cover of the non-magnetic testing chamber 13, and place the lower permeable stone and filter paper in sequence. Center sample 5, cover it with filter paper and upper permeable stone, and manually tighten to complete the sample setup. Then, preset the test parameters and start the test.

[0076] First, start the in-situ nuclear magnetic resonance detection component 32;

[0077] Start the freeze-thaw cycle assembly, and the refrigeration compressor 7 starts working. The temperature control medium enters the temperature control jacket 4 through the electromagnetic shielding pipeline 8 and circulates to control the temperature of the non-magnetic test chamber 13 and the sample 5 to stabilize to the target value (e.g., -20℃) and maintain it for 12 hours to complete the sample freezing process. Then turn off the refrigeration compressor 7 and place the sample 5 at the natural ambient temperature for at least 12 hours.

[0078] Then start the dry-wet cycle assembly. First, open the first valve 281 and deliver the humidifying gas to the atomizing gas pipeline 26 through the quartz gas guide tube via the ultrasonic atomizer 12. Keep the ultrasonic atomizer working for at least 12 hours to achieve the wetting process of sample 5. Then close the first valve 281 and the ultrasonic atomizer 12.

[0079] Open the second valve 282 to deliver the drying gas to the drying gas pipeline 25 through the drying equipment 15, and at the same time open the seventh valve 283 to allow the humid gas in the chamber to be discharged through the exhaust port 6; after a set time, close the seventh valve 283 and place the sample 5 under the target environmental conditions for 12 hours; thus, the freeze-thaw-wet-dry cycle treatment of the saline soil sample is completed.

[0080] Next, the fourth valve 284 is opened, and the external water source enters the variable head assembly through the external pipe 29, applying a stable head pressure to the sample 5. The third valve 285 and the fifth valve 286 are then opened, and the water level monitoring device 19 monitors the head changes in real time, while the flow meter 22 measures the flow rate. During the test, the head height gradually decreases, eventually approaching zero. Based on the relationship between the head drop rate and time within the anti-crystallization tube 20, the permeability coefficient of the sample can be calculated.

[0081] The collected data such as permeability coefficient and flow rate are integrated in real time with the saturation and unfrozen water content collected by the in-situ nuclear magnetic resonance detection component 32 to generate a multi-parameter correlation report. Then, the sixth valve 287 is opened to allow water to flow out through the drain pipe 23, and finally the fourth valve 284, the third valve 285 and the fifth valve 286 are closed.

[0082] In this embodiment, the T2 relaxation spectrum is automatically acquired every 5 minutes by the in-situ NMR detection component 32, and the unfrozen water content is calculated. Post-test operations include data export and equipment maintenance, generating a report containing data such as temperature and unfrozen water content, and performing pipeline cleaning and probe maintenance.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

[0084] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling, characterized in that, It includes a non-magnetic test chamber (13) for containing the sample, and also includes an in-situ nuclear magnetic resonance detection component (32), a freeze-thaw cycle component, a wet-dry cycle component, a variable head component, and a drainage component; The in-situ nuclear magnetic resonance (NMR) detection component (32) is used to provide a magnetic field environment inside the non-magnetic test chamber (13). The freeze-thaw cycle component is used to control the internal temperature of the non-magnetic test chamber (13). The wet-dry cycle component is used to control the internal humidity of the non-magnetic test chamber (13). The variable head component is used to provide seepage liquid to the sample in the non-magnetic test chamber (13) and adjust the water head height. The drain component is used to drain the liquid in the non-magnetic test chamber (13) from the bottom. The inner wall of the non-magnetic test chamber (13) is provided with an aluminum nitride coating (1). The non-magnetic test chamber (13) is also provided with an exhaust port (6).

2. The multi-parameter in-situ NMR measurement device for saline soil under wet-dry-freeze-thaw coupling as described in claim 1, characterized in that, The freeze-thaw cycle assembly includes a temperature control jacket (4) located inside a non-magnetic test chamber (13) and a refrigeration compressor (7) located outside the non-magnetic test chamber (13); the temperature control jacket (4) has a temperature control channel, which is spirally involute; the output end and input end of the refrigeration compressor (7) are connected to the inlet end and outlet end of the temperature control channel respectively through an electromagnetic shielding pipeline (8); the cross-sectional area of ​​the inlet end of the temperature control channel is larger than the cross-sectional area of ​​the outlet end of the temperature control channel.

3. The multi-parameter in-situ NMR measurement device for saline soil under dry-wet-freeze-thaw coupling as described in claim 2, characterized in that, The electromagnetic shielding pipeline (8) includes a braided copper mesh conductive layer (9), a metal foil magnetic shielding layer (10), and a fluororubber outer sheath (11) distributed from the inside to the outside.

4. The multi-parameter in-situ NMR measurement device for saline soil under dry-wet-freeze-thaw coupling as described in claim 2, characterized in that, The in-situ nuclear magnetic resonance detection component (32) includes a ring-shaped array of Halbach permanent magnets; the temperature control jacket (4) is located outside the Halbach permanent magnet array.

5. The multi-parameter in-situ NMR measurement device for saline soil under wet-dry-freeze-thaw coupling as described in claim 1, characterized in that, The wet-dry cycle assembly includes an ultrasonic atomizer (12) and a drying device (15); the ultrasonic atomizer (12) is connected to the interior of the non-magnetic test chamber (13) through an atomizing gas pipeline (26), and the output end of the drying device (15) is connected to the interior of the non-magnetic test chamber (13) through a drying gas pipeline (25); a first valve (281) is provided on the atomizing gas pipeline (26), and a second valve (282) is provided on the drying gas pipeline (25).

6. The multi-parameter in-situ NMR measurement device for saline soil under wet-dry-freeze-thaw coupling as described in claim 5, characterized in that, The drying device (15) includes a rotary filter cartridge (16), the filter element of which includes activated carbon fiber felt (18) and / or zeolite layer (17).

7. The multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under wet-dry / freeze-thaw coupling as described in claim 1, characterized in that, The variable head assembly includes an anti-crystallization tube (20), a water level monitoring device (19) for measuring the water head height inside the anti-crystallization tube (20), and an external pipe (29) for replenishing the anti-crystallization tube (20). The top of the anti-crystallization tube (20) is open, and the bottom is connected to the top of the non-magnetic test chamber (13) through an inlet pipe (27). A third valve (285) is provided on the inlet pipe (27), and a fourth valve (284) is provided on the external pipe (29).

8. The multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling as described in claim 7, characterized in that, The inner wall of the anti-crystallization tube (20) is provided with a spiral guide groove (21), and it also includes an ultrasonic transducer (31) located inside the anti-crystallization tube (20).

9. The multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling as described in claim 1, characterized in that, The drainage assembly includes a drainage pipe (23) connected to the bottom of the non-magnetic test chamber (13), a flow meter (22) located on the drainage pipe (23), and a fifth valve (286) and a sixth valve (287) located on the drainage pipe (23) and respectively at the upstream and downstream ends of the flow meter (22).

10. The multi-parameter in-situ nuclear magnetic resonance (NMR) measurement device for saline soil under dry-wet-freeze-thaw coupling as described in claim 9, characterized in that, The drain pipe (23) has an enlarged section (30) located upstream of the fifth valve (286).

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