A kind of probe type sheet electrode-based microbial solidified soil resistivity test calibration device and dynamic monitoring method

Abstract

The present application relates to the technical field of microbial foundation detection, and discloses a kind of based on probe type sheet electrode's microbial solidified soil resistivity test calibration device and dynamic monitoring method, wherein a kind of based on probe type sheet electrode's microbial solidified soil resistivity test calibration device, including pressure chamber, the inside of the pressure chamber is installed with sample tube, the sample tube includes side hole, geotextile sleeve, upper and lower sealing cover, voltage pole connecting wire and current pole connecting wire;Side hole is evenly opened in the inner wall of the sample tube, four probe type sheet electrodes are fixedly installed on one side of the inner wall of the sample tube.The method in the present application discards the traditional single numerical calculation method, by indoor solution reference line stripping, and accurately captures the dynamic evolution inflection point of resistivity after first rapid drop in the field, directly and accurately quantifies the real generation amount of calcium carbonate playing a key solidification role, with very high engineering application value and scientific nature.

Description

Technical Field

[0001] This invention relates to the field of microbial foundation testing technology, specifically to a calibration device and dynamic monitoring method for resistivity testing of microbial solidified soil based on probe-type sheet electrodes. Background Technology

[0002] Microbial-induced calcium carbonate precipitation (MICP) is a novel, environmentally friendly technology for foundation reinforcement and geotechnical engineering treatment. This technology involves injecting specific microbial inoculum and a high-concentration calcium salt solution into the foundation soil. The biochemical reactions of the microorganisms generate solid calcium carbonate precipitates within the soil pores, thereby cementing the sand particles, increasing foundation strength, and reducing permeability. However, a major technical bottleneck in the practical application of MIP lies in the lack of a device and method capable of in-situ, continuously, non-destructively, and precisely quantitatively monitoring the calcium carbonate formation process and solidification effect within the foundation.

[0003] Soil resistivity is extremely sensitive to pore moisture and dissolved components, and is an important indicator reflecting changes in the internal structure of the foundation. However, during the MIP reinforcement process, the continuously injected bacterial solution and high-concentration calcium salt solution are both strong conductors, which will significantly reduce the soil resistivity; while the generated solid calcium carbonate is an insulator, which will block the conductive path and thus increase the resistivity. Existing testing methods often focus only on the absolute resistivity value at a single moment, failing to effectively separate the "conductive interference caused by high-concentration reaction liquid" from the "insulation effect brought about by solid calcium carbonate formation," resulting in distorted monitoring results and difficulty in dynamically and accurately reflecting the true degree of solidification. Therefore, they do not meet the existing requirements. To address this, we propose a resistivity testing and calibration device and dynamic monitoring method for microbial solidified soil based on probe-type sheet electrodes. Summary of the Invention

[0004] This invention provides a calibration device and dynamic monitoring method for resistivity testing of microbial solidified soil based on probe-type sheet electrodes. It has the beneficial effect of perfectly simulating the stress environment of deep foundations without compromising the watertightness and pressure bearing capacity of the pressure chamber. It solves the problem mentioned in the background art that when increasing the internal pressure of the pressure chamber to simulate deep strata, leakage and short circuits are very likely to occur from the wire extension hole. This not only makes it impossible to stably transmit multiple weak electrical signals under pressure, but also damages the normal function of the triaxial instrument itself.

[0005] The present invention provides the following technical solution: a calibration device and dynamic monitoring method for resistivity testing of microbial solidified soil based on probe-type sheet electrodes, wherein the calibration device for resistivity testing of microbial solidified soil based on probe-type sheet electrodes includes a pressure chamber, and a sample holding tube is installed inside the pressure chamber. The sample collection tube includes side holes, a geotextile nonwoven sleeve, upper and lower sealing caps, voltage electrode connection wires and current electrode connection wires; the side holes are evenly opened on the inner wall of the sample collection tube, four probe-type sheet electrodes are fixedly installed on one side of the inner wall of the sample collection tube, and the outer surface of the sample collection tube is covered with a geotextile nonwoven sleeve. Each of the four probe-type sheet electrodes has a probe-type sheet electrode at one end, wherein two of the probe-type sheet electrodes are current electrodes and the other two probe-type sheet electrodes are voltage electrodes; The other end of the probe-type sheet electrode penetrates the interior of the sample collection tube and extends along the inner wall of the sample collection tube to the outer surface of the sample collection tube. There are two voltage electrode connections and two current electrode connections. The four probe-type sheet electrodes are respectively connected to the voltage electrode connections and the current electrode connections. A circuit sealing node is installed on the outer surface of the sample tube. The circuit sealing node is used to seal the probe-type sheet electrodes located on the outer surface of the sample tube. Both ends of the sample tube are equipped with upper and lower sealing caps. The circuit sealing nodes are formed by curing insulating and waterproof resin. The voltage electrode connection line and the current electrode connection line converge upward along the inside of the sample tube and pass through the inside of the upper and lower sealing caps.

[0006] As an optional solution of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrode described in this invention, wherein: the sample tube is filled with sand to be tested, and one end of the probe-type sheet electrode is inserted into the sample tube as a flat probe and in contact with the sand to ensure a uniform electric field and sufficient electrical contact area. The installation method of the probe-type sheet electrode avoids physical disturbance to the in-situ pore structure of the soil inside the sample tube caused by the wiring inside the tube. The probe-type sheet electrode is made of a corrosion-resistant metal material.

[0007] As an optional solution for the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: the sample tube is an open cylinder with an outer diameter of 50 to 100 mm, a thickness of 2 to 5 mm, and a height of 150 to 250 mm. The diameter of the side holes uniformly opened on the outer surface of the sample tube is four to eight millimeters, and the distance between two adjacent side holes is ten to fifteen millimeters. The inner diameter of the geotextile nonwoven sleeve is 0.5 to 1 mm larger than the outer diameter of the sample-holding tube, the height is 10 to 20 mm higher than the sample-holding tube, and the thickness is 0.8 to 1.2 mm.

[0008] As an optional solution of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: a sealing chamber cover is installed on the upper surface of the pressure chamber, a fixing device is installed inside the pressure chamber, the sample holding tube is used to install the sample holding tube inside the pressure chamber, a pressure pump is installed on one side of the pressure chamber, and a pressure inlet pipe is fixedly installed on one side of the pressure pump. A four-wire resistance tester is installed on the other side of the pressure chamber, and a wire water-proof pipe is fixedly installed at the bottom of the pressure chamber. The wire water-proof pipe is used to connect to the four-wire resistance tester. A waterproof electrical connector is installed at one end of each of the two voltage pole connections and the current pole connection. A conductive spring is installed at one end of the water-proof tube of the conductor. The conductive spring is used to electrically connect the voltage pole connection and the current pole connection to the four-wire resistance tester.

[0009] As an optional solution of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: the waterproof electrical connector is embedded and fixed through the inner wall of the pressure chamber, one end of the waterproof electrical connector is connected to the wire waterproof pipe, and the other end of the waterproof electrical connector is connected to the voltage electrode connection line and the current electrode connection line. The waterproof electrical connector has four sets of mutually insulated conductive springs fixed inside. The conductive springs are used to insert into the waterproof electrical connector to form two independent and complete current and two voltage paths without damaging the watertightness and pressure bearing capacity of the pressure chamber, and are connected to an external four-wire resistance tester.

[0010] As an optional solution for the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: the pressure chamber is made of transparent insulating material, and the pressure range of the pressurizing pump is from zero to five hundred kPa, used to simulate in-situ stress at different depths.

[0011] As an optional embodiment of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: the probe-type sheet electrode extends horizontally into the tube to eliminate the boundary effect caused by the insulating tube wall.

[0012] As an optional embodiment of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: on one side wall of the sample tube, four probe-type sheet electrodes are arranged in a straight line to construct a conductive sand column in the central region of the tube, and current electrodes and voltage electrodes are alternately distributed to form a four-wire circuit.

[0013] As an optional solution of the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes described in this invention, wherein: the effective conductive area of ​​the theoretically conductive sand column is smaller than the actual cross-sectional area of ​​the sample, and its resistivity ρ satisfies the formula: ρ=0.75R·a with respect to the measured resistance R and the electrode spacing a.

[0014] This invention also provides a calibration device and dynamic monitoring method for testing the resistivity of microbially solidified soil based on probe-type sheet electrodes. Indoor pressure benchmark calibration: Before the MICP reaction on site, take sand and put it into the on-site testing device and place it inside the sample collection tube. Apply confining pressure corresponding to the on-site in-situ depth, and inject a pure reaction solution containing bacterial solution and high-concentration calcium salt. Use a four-wire resistance tester to record the background resistance characteristics of the solution and extract the high-concentration solution conductivity interference benchmark. In-situ multi-layer installation: The field testing device filled with sand is placed into the deep hole of the foundation to the specified depth, backfilled and manually compacted, and the four wires are connected to the four-wire resistance tester on the ground surface. Dynamic trend capture calculation: During MICP reinforcement by injecting calcium-containing solution into the foundation, the resistance data R between the two inner voltage electrodes is continuously recorded; By using a probe to pierce the soil in mid-air, this structure has the advantage of creating an undisturbed conductive sand column in the central region of the tube, and converting it into the resistivity ρ of the sample in real time according to the formula ρ=0.75R*a, where a is the distance between the two inner probe-type sheet electrodes. Curing effect projection: During the monitoring process, the dynamic inflection point is captured where resistivity p drops sharply due to the injection of highly conductive salt solution, and then reverses and rises again as solid insulating calcium carbonate precipitates continuously fill the pores; after the resistivity stabilizes, the absolute increase in resistivity is extracted, and combined with the baseline of solution interference stripped in the steps, the concentration of calcium carbonate generated inside the foundation and the actual curing effect are quantitatively projected and calculated. The present invention has the following beneficial effects: 1. This microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes features a unique double-layer probe-type sheet structure combined with a dedicated theoretical sand column model to achieve non-destructive and accurate measurements. The probe-type sheet electrodes in this invention penetrate the soil in a straight metal sheet shape, greatly reducing physical compression and disturbance to the undisturbed soil pore structure. Simultaneously, the wiring terminals extend through the wall, with all wiring located outside the sample collection tube, completely eliminating the risk of short circuits. More importantly, this invention utilizes the suspended insertion characteristic of the probe to construct a theoretically conductive sand column in the central region of the tube, unaffected by the outer insulating boundary. Based on this, a dedicated conversion formula ρ=0.75R*a is derived, eliminating boundary effects and fundamentally solving the systematic geometric errors caused by boundary effects in conventional soil box testing models, achieving high-precision in-situ resistivity conversion.

[0015] 2. This microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes overcomes the challenges of multi-path wiring and waterproof sealing under indoor high-pressure calibration. Existing triaxial apparatus modifications often involve direct drilling, wire threading, and adhesive application, which are prone to leakage under pressure. This invention innovatively introduces a threaded waterproof connector with four sets of conductive springs into the pressure chamber wall. Simply tightening it externally instantly connects four independent current and voltage circuits, perfectly simulating the stress environment of deep foundations without compromising the watertightness and pressure-bearing capacity of the pressure chamber.

[0016] 3. This probe-type sheet electrode-based microbial solidified soil resistivity testing and calibration device proposes a "dynamic reversal" monitoring logic to effectively remove interference from the reaction solution. Addressing the pain point of resistivity distortion caused by the coexistence of highly conductive solution and insulating calcium carbonate in MIP reinforcement, this method abandons the traditional single numerical measurement algorithm. By stripping the indoor solution baseline, it accurately captures the dynamic evolution inflection point of the resistance first dropping sharply and then rising on site, directly and accurately quantifying the actual amount of calcium carbonate generated, which plays a key role in solidification. It has extremely high engineering application value and scientific validity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the sample-holding tube structure of the present invention.

[0018] Figure 2 This is a schematic diagram showing the installation position of the probe-type sheet electrode of the present invention.

[0019] Figure 3 This is a schematic diagram of the cross-section of the sample-holding tube of the present invention.

[0020] Figure 4 This is a schematic diagram of the internal structure of the sealing compartment cover of the present invention.

[0021] Figure 5 This is a schematic diagram of the device of the present invention installed in the ground stratum.

[0022] In the diagram: 1. Sample container; 2. Side hole; 3. Geotextile nonwoven sleeve; 4. Upper and lower sealing caps; 5. Probe-type sheet electrode; 6. Voltage electrode connection; 7. Current electrode connection; 8. Circuit sealing node; 9. Pressure chamber; 10. Sealing chamber cover; 11. Fixing device; 12. Pressurized water inlet pipe; 13. Pressurized pump; 14. Four-wire resistance tester; 15. Wire waterproof pipe; 16. Waterproof electrical connector; 17. Conductive spring. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0024] Please see Figures 1-5 The device includes a pressure chamber 9, inside which a sample tube 1 is installed; and discloses a microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes. The sample tube 1 includes side holes 2, geotextile nonwoven sleeve 3, upper and lower sealing caps 4, voltage electrode connection 6 and current electrode connection 7; the side holes 2 are evenly opened on the inner wall of the sample tube 1, and four probe-type sheet electrodes 5 are fixedly installed on one side of the inner wall of the sample tube 1. The outer surface of the sample tube 1 is covered with a geotextile nonwoven sleeve 3. Each of the four probe-type sheet electrodes 5 has a probe-type sheet electrode at one end, two of which are current electrodes and the other two are voltage electrodes. The other end of the probe-type sheet electrode 5 penetrates the interior of the sample tube 1 and extends along the inner wall of the sample tube 1 to the outer surface of the sample tube 1. There are two voltage electrode connection lines 6 and two current electrode connection lines 7. Four probe-type sheet electrodes 5 are connected to the voltage electrode connection lines 6 and the current electrode connection lines 7 respectively. A line sealing node 8 is installed on the outer surface of the sample tube 1. The line sealing node 8 is used to seal the probe-type sheet electrodes 5 located on the outer surface of the sample tube 1. In this embodiment, as Figure 1 , Figure 2 as well as Figure 3 As shown, the core structure is the probe-type sheet electrode 5, which is made of corrosion-resistant inert titanium metal and is a straight metal sheet that directly penetrates the wall of the sample tube 1. One end extends horizontally into the tube as a flat probe, piercing directly into the sand inside the sample tube 1 like a blade. This ensures a large contact area required for a uniform electric field while greatly reducing the squeezing and disturbance to the pore structure of the original soil. like Figure 2 and Figure 3 As shown, the other end of the probe-type sheet electrode 5 extends directly outward to the outside of the sample tube 1 as a connection terminal. The connection terminals of the four electrodes are respectively heat-fused to the voltage electrode connection line 6 and the current electrode connection line 7 on the outer surface of the sample tube 1. In this embodiment, the welding connection is provided with a waterproof sealing node 8 for electrode wiring, which is formed by curing insulating and waterproof epoxy resin into a semi-circular dome, completely covering the exposed metal contact and the end of the metal sheet protruding outward. All four insulated wires are arranged on the outside of the sample tube 1, converge upwards and lead out through the opening of the upper sealing cap 4. This double-layer separation wiring design completely eliminates the damage to the soil caused by the wiring inside the tube and the risk of short circuit in the high-concentration reaction solution. Example 2

[0025] This embodiment is an improvement upon embodiment 1. For details, please refer to [link / reference]. Figures 1-5 Both ends of the sample tube 1 are equipped with upper and lower sealing caps 4. The line sealing node 8 is formed by curing insulating and waterproof resin. The voltage pole connection 6 and the current pole connection 7 converge upward along the inside of the sample tube 1 and pass through the upper and lower sealing caps 4 to be placed outside the sample tube 1. The sample tube 1 is filled with the sand to be tested. The probe-type sheet electrode at one end of the probe-type sheet electrode 5 is used to penetrate into the sample tube 1 and contact the sand to ensure a uniform electric field and sufficient electrical contact area. The installation method of the probe-type sheet electrode 5 avoids physical disturbance to the in-situ pore structure of the soil inside the sample tube 1 caused by the internal wiring. The probe-type sheet electrode 5 is made of a corrosion-resistant metal material. The sample tube 1 is an open cylinder with an outer diameter of 50 to 100 mm, a thickness of 2 to 5 mm, and a height of 150 to 250 mm. The diameter of the side holes 2 evenly opened on the outer surface of the sample tube 1 is four to eight millimeters, and the distance between two adjacent side holes 2 is ten to fifteen millimeters. The inner diameter of the geotextile nonwoven sleeve 3 is 0.5 to 1 mm larger than the outer diameter of the sample container 1, its height is 10 to 20 mm higher than that of the sample container 1, and its thickness is 0.8 to 1.2 mm. A sealing chamber cover 10 is installed on the upper surface of the pressure chamber 9. A fixing device 11 is installed inside the pressure chamber 9. The fixing device 11 is used to install the sample tube 1 inside the pressure chamber 9. A pressure pump 13 is installed on one side of the pressure chamber 9. A pressure inlet pipe 12 is fixedly installed on one side of the pressure pump 13. A four-wire resistance tester 14 is installed on the other side of the pressure chamber 9. A wire water-proof tube 15 is fixedly installed at the bottom of the pressure chamber 9. The wire water-proof tube 15 is used to connect to the four-wire resistance tester 14. Waterproof electrical connectors 16 are installed at one end of the two voltage pole connections 6 and the current pole connection 7. A conductive spring 17 is installed at one end of the conductor waterproof tube 15. The conductive spring 17 is used to electrically connect the voltage pole connection 6 and the current pole connection 7 to the four-wire resistance tester 14. A waterproof electrical connector 16 is embedded in and fixed through the inner wall of the pressure chamber 9. One end of the waterproof electrical connector 16 is connected to the wire water-proof pipe 15, and the other end of the waterproof electrical connector 16 is connected to the voltage electrode connection 6 and the current electrode connection 7. The waterproof electrical connector 16 has four sets of mutually insulated conductive springs 17 fixed inside. The conductive springs 17 are used to insert into the waterproof electrical connector 16 to form two independent and complete current and two voltage paths without damaging the water tightness and pressure bearing capacity of the pressure chamber 9, and are connected to the external four-wire resistance tester 14. The pressure chamber 9 is made of transparent insulating material, and the pressure range of the pressurization pump 13 is from zero to 500 kPa, used to simulate in-situ stress at different depths. The probe-type sheet electrode 5 extends horizontally into the tube to eliminate the boundary effect caused by the insulating tube wall. On one side of the sample tube 1, four probe-type sheet electrodes 5 are arranged in a straight line to form a conductive sand column in the central region of the tube, and the current electrodes and voltage electrodes are alternately distributed to form a four-wire circuit. The effective conductive area of ​​the theoretically conductive sand column is smaller than the actual cross-sectional area of ​​the sample. Its resistivity ρ, measured resistance R, and electrode spacing a satisfy the formula: ρ = 0.75R * a.

[0026] In this embodiment, the pressure chamber 9 is integrally made of transparent and insulating styrene-acrylonitrile material. The pressurization range of the pressurization pump 13 is from zero to 500 kPa, used to simulate in-situ stress at different depths. In this embodiment, in order to safely lead out the four wires under pressure, an innovative four-wire threaded waterproof connector 16 is used. It is embedded and fixed to the wall of the pressure chamber 9. The threaded waterproof connector 16 has four sets of mutually insulated conductive springs 17 fixed inside. By tightening the connector, the four sets of conductive springs inside are in close contact. Without completely damaging the watertightness of the pressure chamber and the 500 kPa pressure bearing capacity, two independent current and two voltage paths are instantly connected and connected to the external four-wire resistance tester 14. This completely solves the industry pain point that traditional triaxial instruments are prone to water leakage and short circuits when drilling and threading wires.

[0027] This invention also provides a calibration device and dynamic monitoring method for resistivity testing of microbially solidified soil based on probe-type sheet electrodes, wherein: (1) Indoor pressure benchmark calibration: Before the MICP reaction on site, take sand and put it into the on-site testing device and place it inside the sample tube 1. Apply confining pressure corresponding to the on-site in-situ depth, and inject a pure reaction solution containing bacterial solution and high-concentration calcium salt. Use a four-wire resistance tester 14 to record the background resistance characteristics of the solution and extract the high-concentration solution conductivity interference benchmark. (2) On-site in-situ multi-layer installation: The on-site testing device filled with sand is placed into the deep hole of the foundation to the specified depth, backfilled and manually compacted, and the four wires led out are connected to the four-wire resistance tester 14 on the ground surface. (3) Dynamic trend capture calculation: During the injection of calcium-containing solution into the foundation for MICP reinforcement, the resistance data R between the two inner voltage electrodes is continuously recorded.

[0028] By using a probe to pierce the soil in mid-air, this structure has the advantage of creating an undisturbed conductive sand column in the central region of the tube, and converting it into the resistivity p of the sample in real time according to the formula ρ=0.75R·a, where a is the distance between the two inner probe-type sheet electrodes 5. (4) Deduction of curing effect: During the monitoring process in step (3), the dynamic inflection point of resistivity p is captured, which is a sudden drop due to the injection of highly conductive salt solution, and then reverses and rises due to the continuous generation of solid insulating calcium carbonate precipitate, which fills the pores; after the resistivity tends to stabilize, the absolute increment of resistivity is extracted, and combined with the solution interference baseline stripped in step 1, the concentration of calcium carbonate generated inside the foundation and the actual curing effect are quantitatively deduced and calculated.

[0029] 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.

[0030] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A calibration device for resistivity testing of microbial solidified soil based on probe-type sheet electrodes, comprising a pressure chamber (9), characterized in that: The pressure chamber (9) is equipped with a sample holding tube (1); The sample collection tube (1) includes side holes (2), geotextile nonwoven sleeve (3), upper and lower sealing caps (4), voltage electrode connection (6) and current electrode connection (7); the side holes (2) are evenly opened on the inner wall of the sample collection tube (1), four probe-type sheet electrodes (5) are fixedly installed on one side of the inner wall of the sample collection tube (1), and the outer surface of the sample collection tube (1) is covered with geotextile nonwoven sleeve (3). Each of the four probe-type sheet electrodes (5) has a probe-type sheet electrode at one end, two of which are current electrodes and the other two are voltage electrodes. The other end of the probe-type sheet electrode (5) penetrates the interior of the sample tube (1) and directly penetrates to the outer surface of the sample tube (1) as a terminal. There are two voltage electrode connection lines (6) and two current electrode connection lines (7). The terminals of the four probe-type sheet electrodes (5) are respectively connected to the voltage electrode connection lines (6) and the current electrode connection lines (7). A line sealing node (8) is installed on the outer surface of the sample tube (1). The line sealing node (8) is used to seal the probe-type sheet electrodes (5) located on the outer surface of the sample tube (1). Both ends of the sample tube (1) are equipped with upper and lower sealing caps (4). The line sealing node (8) is formed by curing insulating and waterproof resin. The voltage pole connection line (6) and the current pole connection line (7) converge upward along the inside of the sample tube (1) and are led out along the inside of the upper sealing cap (4).

2. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 1, characterized in that: The sample tube (1) is filled with the sand to be tested. One end of the probe-type sheet electrode (5) is used to penetrate the sample tube (1) and contact the sand to ensure a uniform electric field and sufficient electrical contact area. The external installation method of the probe-type sheet electrode (5) avoids the physical disturbance of the in-situ pore structure of the soil inside the sample tube (1) caused by the internal wiring. The probe-type sheet electrode (5) is made of corrosion-resistant inert metal.

3. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 2, characterized in that: The sample tube (1) is a cylindrical body with an outer diameter of 50 to 100 mm, a thickness of 2 to 5 mm, and a height of 150 to 250 mm, open at both ends. The side holes (2) evenly opened on the outer surface of the sample tube (1) have a diameter of four to eight millimeters, and the distance between two adjacent side holes (2) is ten to fifteen millimeters. The inner diameter of the geotextile nonwoven sleeve (3) is 0.5 to 1 mm larger than the outer diameter of the sample tube (1), the height is 10 to 20 mm higher than the sample tube (1), and the thickness is 0.8 to 1.2 mm.

4. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 3, characterized in that: A sealing chamber cover (10) is installed on the upper surface of the pressure chamber (9). A fixing device (11) is installed inside the pressure chamber (9). The fixing device (11) is used to install the sample tube (1) inside the pressure chamber (9). A pressurizing pump (13) is installed on one side of the pressure chamber (9). A pressurizing water inlet pipe (12) is fixedly installed on one side of the pressurizing pump (13). A four-wire resistance tester (14) is installed on the other side of the pressure chamber (9). A wire water-proof tube (15) is fixedly installed at the bottom of the pressure chamber (9). The wire water-proof tube (15) is used to connect to the four-wire resistance tester (14). Waterproof electrical connectors (16) are installed at one end of the two voltage pole connections (6) and the current pole connections (7). A conductive spring (17) is installed at one end of the conductor waterproof tube (15). The conductive spring (17) is used to electrically connect the voltage pole connections (6) and the current pole connections (7) to the four-wire resistance tester (14).

5. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 4, characterized in that: The waterproof electrical connector (16) is embedded and fixed to the inner wall of the pressure chamber (9). One end of the waterproof electrical connector (16) is connected to the wire water-proof pipe (15), and the other end of the waterproof electrical connector (16) is connected to the voltage electrode connection (6) and the current electrode connection (7). The waterproof electrical connector (16) has four sets of mutually insulated conductive springs (17) fixed inside. The conductive springs (17) are used to insert into the waterproof electrical connector (16) to form two independent and complete current and two voltage paths without damaging the water tightness and pressure bearing capacity of the pressure chamber (9), and are connected to the external four-wire resistance tester (14).

6. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 5, characterized in that: The pressure chamber (9) is made of transparent insulating material, and the pressure range of the pressurizing pump (13) is from zero to five hundred kPa, which is used to simulate in-situ stress at different depths.

7. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 6, characterized in that: One end of the probe-type sheet electrode (5) extends horizontally into the tube to eliminate the boundary effect caused by the insulating tube wall.

8. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 7, characterized in that: On one side of the sample tube (1), four probe-type sheet electrodes (5) are arranged in a straight line to form a theoretical conductive sand column in the central region of the tube, and the current electrode and voltage electrode are alternately distributed to form a four-wire circuit.

9. The microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 8, characterized in that: The effective conductive area of ​​the theoretically conductive sand column is smaller than the actual cross-sectional area of ​​the sample, and its resistivity ρ satisfies the formula: ρ = 0.75R·a, the measured resistance R, and the electrode spacing a.

10. The dynamic monitoring method for the microbial solidified soil resistivity testing and calibration device based on probe-type sheet electrodes according to claim 9, characterized in that: S1. Indoor pressure benchmark calibration: Before the MICP reaction on site, take sand and put it into the on-site testing device and place it inside the sample tube (1). Apply confining pressure corresponding to the on-site in-situ depth and inject a pure reaction solution containing bacteria and high-concentration calcium salt. Use a four-wire resistance tester (14) to record the background resistance characteristics of the solution and extract the high-concentration solution conductivity interference benchmark. S2. On-site multi-layer installation: The on-site testing device filled with sand is placed into the deep hole of the foundation to the specified depth, backfilled and manually compacted, and the four wires are connected to the four-wire resistance tester (14) on the ground surface. S3. Dynamic trend capture calculation: During the injection of calcium-containing solution into the foundation for MICP reinforcement, the resistance data R between the two inner voltage electrodes is continuously recorded. By using a probe to pierce the soil in mid-air, this structure has the advantage of creating an undisturbed conductive sand column in the central area of ​​the tube, and converting it into the resistivity ρ of the sample in real time according to the formula ρ=0.75R*a, where a is the distance between the two inner probe-type sheet electrodes (5). S4. Deduction of curing effect: During the monitoring process in step S3, the dynamic inflection point is captured where the resistivity p drops sharply due to the injection of highly conductive salt solution, and then reverses and rises due to the continuous generation of solid insulating calcium carbonate precipitate filling the pores. After the resistivity tends to stabilize, the absolute increment of resistivity is extracted, and combined with the solution interference baseline stripped in step S1, the concentration of calcium carbonate generated inside the foundation and the actual curing effect are quantitatively deduced and calculated.

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