Electrode array system and detection method based on integrated resistivity tomography

Abstract

The application provides a resistivity tomography electrode array system and a detection method based on integrated measurement and protection, relates to the related technical field of high-density electrical method physical detection, and comprises an electrode measurement module, an extension rod, an independent multi-channel cable bundle and an air pressure control module; the electrode measurement module comprises an air-electric connection interface, a ring-shaped air bag and a flexible electrode group, the ring-shaped air bag adopts a multi-chamber independent air path structure, and each chamber is parallelly supplied with air; the extension rod and the electrode measurement module are connected through threaded splicing; the air pressure control module comprises an air compressor and a pressure regulator, and the pressure regulator is used for achieving and maintaining the required contact quality between the flexible electrode group and the hole wall. While ensuring reliable and close contact between the electrode and the hole wall, the application effectively protects the hole wall from hole collapse and realizes flexible adjustment of the electrode spacing, so that the operation efficiency, data quality and engineering applicability of cross-hole resistivity detection are significantly improved.

Description

Technical Field

[0001] This invention mainly relates to the technical field of high-density electrical physical detection, specifically to a resistivity tomography imaging electrode array system and detection method based on integrated measurement and protection. Background Technology

[0002] High-density electrical resistivity tomography (EDT) is a crucial tool in engineering geophysical exploration, widely used in areas such as cavity detection in karst development zones and identification of seepage channels in hydraulic structures. Among these applications, trans-well resistivity tomography significantly improves detection accuracy through three-dimensional data acquisition between wells. A key aspect of conducting trans-well detection is ensuring close contact between the electrode and the borehole wall.

[0003] Existing cross-hole electrode devices have the following shortcomings: traditional gas expansion electrodes or mechanical push-type electrodes are prone to poor contact due to borehole wall collapse in loose strata, and bare hole detection lacks borehole wall protection, making deep hole operations high-risk of borehole collapse; fixed-spacing electrode measurement systems are difficult to adapt to complex geological requirements; existing segmented electrode systems have complex wiring structures and low installation efficiency. Summary of the Invention

[0004] To address the shortcomings of current technologies, this invention, combining existing technologies and focusing on practical applications, provides a resistivity tomography electrode array system and detection method based on integrated measurement and protection. While ensuring reliable and close contact between the electrodes and the borehole wall, it effectively protects the borehole wall from collapse and enables flexible adjustment of the electrode spacing, thereby significantly improving the operational efficiency, data quality, and engineering applicability of cross-bore resistivity detection.

[0005] The technical solution of the present invention is as follows:

[0006] According to one aspect of the present invention, a resistivity tomography electrode array system based on integrated measurement and protection is provided, including an electrode measurement module, and further including: an extension rod, an independent multi-channel cable bundle, and a pneumatic control module;

[0007] The electrode measurement module includes a gas-electric connection interface, an annular airbag, and a flexible electrode assembly. The flexible electrode assembly includes multiple arc-shaped conductive sheets embedded in an annular array on the outer surface of the annular airbag. The annular airbag adopts a multi-chamber independent gas path structure, with each chamber supplied with gas in parallel.

[0008] The extension rod and the electrode measurement module are connected by a threaded splice. An independent multi-channel cable bundle and an air duct pass through the inside of the extension rod and connect to the pneumatic and electrical interface.

[0009] The air pressure control module includes an air compressor and a pressure regulator. The air compressor is connected to the annular airbag via an air pipe and is used to control the expansion and contraction of the annular airbag. The pressure regulator has a built-in air pressure-expansion calibration algorithm, which is used to adjust the output air pressure of the air compressor based on the set value to control the expansion state of the annular airbag and achieve and maintain the required contact quality between the flexible electrode assembly and the hole wall.

[0010] Furthermore, the outer diameter of the extension rod is equal to the outer diameter of the electrode measurement module, so that after the extension rod and the electrode measurement module are spliced ​​and assembled, a smooth and continuous outer wall surface is formed.

[0011] Furthermore, the extension rod has multiple small water-filtering holes around its tube wall, allowing groundwater to freely permeate. The extension rod also has cable channels and air passages inside, with clips installed within these channels.

[0012] Furthermore, the independent multi-channel cable bundle consists of multiple sets of wires, each set of wires corresponding to one electrode measurement module. The cable bundle is connected to the pneumatic and electrical connection interface through a waterproof quick-connect connector.

[0013] Furthermore, the implementation steps of the pressure-expansion calibration algorithm are as follows:

[0014] 1) Calculate the radial expansion vector δ under air pressure P based on the airbag material parameters;

[0015] 2) Calculate the contact pressure F between the electrode and the borehole wall by combining the outer diameter of the inflated airbag and the borehole diameter;

[0016] 3) Based on contact pressure F and electrode deformation coefficient k f Calculate the equivalent embedding depth d e Finally, the fit index η is obtained by normalization through the S-shaped function, and the contact quality between the electrode and the hole wall is quantitatively determined by the fit index η.

[0017] Furthermore, the radial expansion δ under the action of air pressure P is calculated as follows:

[0018] ;

[0019] In the formula, δ(P) is the pressure-expansion function, representing the radial expansion deformation of the airbag under pressure P; R i R is the initial inner radius of the airbag; o ν is the initial outer radius of the airbag; E is the elastic modulus of the silicone material corresponding to the airbag; t is the airbag wall thickness; ν is Poisson's ratio.

[0020] The contact pressure F is calculated as follows:

[0021] ;

[0022] In the formula, F(P) is the air pressure-contact pressure function, reflecting the conversion of air pressure P into mechanical clamping force between the electrode and the hole wall; A c K represents the electrode contact area. s A is the formation stiffness coefficient; c The calculation method is as follows:

[0023] ;

[0024] In the formula, A c (δ) represents the electrode contact area; D z Where is the diameter of the borehole; L is the axial length of the airbag; k a δ is the contact efficiency coefficient; δ0 is the contact threshold.

[0025] Equivalent embedding depth d e The calculation method is as follows:

[0026] ;

[0027] In the formula: d e (P) is the pressure-equivalent embedding depth function, characterizing the contact quality between the flexible electrode and the hole wall under pressure P; k f F0 is the deformation coefficient of the flexible electrode; F0 is the initial contact pressure threshold.

[0028] The fit index η is calculated as follows:

[0029] ;

[0030] In the formula: η is the fit index; γ is the gain coefficient, which controls the sensitivity of the quality threshold; β is the contact difficulty coefficient, which reflects the difficulty of contact with the formation.

[0031] Furthermore, during the inflation of the annular airbag by the air compressor, the contact quality is obtained by calculating the η value in real time through the air pressure P. When η≤60%, it indicates insufficient fit and the need for pressurization; when 60%<η≤85%, it indicates that the measurement requirements are met; when η>85%, it indicates excellent fit.

[0032] Furthermore, the gain coefficient γ and the contact difficulty coefficient β are dynamically adjusted based on the formation type as follows:

[0033] When the formation curve is flat, the value of γ is 0.8-1.2;

[0034] When the stratigraphic curve is steep, γ should be 1.5-2.0.

[0035] When the stratigraphic curve exhibits a step-like shape, the value of γ is greater than 2.5;

[0036] When the strata are intact bedrock, β takes a value of 0.8-1.0;

[0037] When the stratum is sandy soil, β takes a value of 1.2-1.5;

[0038] When the strata are fractured zones, β takes values ​​of 1.8-2.2;

[0039] When the stratum is clay, β takes the value of 2.5-3.0.

[0040] According to another aspect of the present invention, a detection method based on the above-described system is provided, comprising the following steps:

[0041] S1. Hole preparation: Determine drilling parameters and inspect equipment;

[0042] S2. Electrode Array System Assembly: Based on the detection depth and resolution requirements, determine the number of electrode measurement modules and the length of the extension rod. Then, based on the borehole diameter, select the matching electrode measurement module and the diameter of the extension rod. Pass the independent multi-channel cable bundle and the air duct through the inside of the extension rod. Assemble the electrode array system using the "orifice segment assembly and segmented lowering" method. Finally, connect the end of the independent multi-channel cable bundle and the end of the air duct to the resistivity imaging host and air pressure control module on the ground.

[0043] S3. Airbag inflation and electrode contact with the wall: Activate the air pressure control unit and switch the air compressor to inflation mode. The pressure regulator controls the air compressor to output compressed air according to the measured air pressure value and the built-in air pressure-expansion calibration algorithm, so that the flexible electrode group and the hole wall can achieve and maintain the required contact quality.

[0044] S4. Array recovery and equipment disassembly: The air pressure control unit switches to the air extraction mode, extracts the gas in the annular airbag group, causing the airbag to contract. The flexible electrode group is released from the hole wall and reset under the elastic action. Then, the electrode array system is slowly lifted to avoid scratching the hole wall. The electrode is disassembled in sections at the hole in the reverse order of assembly. The electrode measurement module, extension rod, independent multi-channel cable bundle and air guide tube are sorted and organized.

[0045] Furthermore, in step S2, the diameters of the electrode measurement module and the extension rod are matched according to the following formula:

[0046] ;

[0047] In the formula: D c D is the diameter of the electrode measurement module. y D is the diameter of the extension rod; z The diameter of the borehole.

[0048] The beneficial effects of this invention are:

[0049] This invention provides a resistivity tomography electrode array system and detection method based on integrated measurement and protection, achieving integration of "pore wall support - electrode contact", which has the following advantages:

[0050] Electrode adaptive contact: The precise pressure control of the multi-chamber independent air path airbag and the introduction of a conformation measurement model to achieve precise control of contact quality enable the electrode array to adapt to different curvature hole walls and maintain constant contact pressure, completely solving the problem of poor coupling of traditional rigid electrodes in fractured formations or irregular hole walls, and ensuring the quality of measurement data.

[0051] Fault tolerance and continuity: The parallel air path design and check valve mechanism of the annular airbag group ensure that the remaining chambers can still maintain effective contact pressure when a single airbag leaks unexpectedly, which greatly reduces the risk of overall measurement interruption due to local failure and improves the applicability of operation in complex environments.

[0052] Modular and efficient deployment: The electrode measurement module and extension rod adopt quick-release pneumatic and electrical interfaces and standardized threaded connections. With the ability to adapt to multiple diameter specifications, it can realize rapid modular assembly of drilling holes of different diameters. At the same time, the smooth and continuous outer wall design avoids scratching the hole wall, and the water filter hole structure eliminates the piston effect, significantly improving on-site construction efficiency and safety. Attached Figure Description

[0053] Figure 1 This is a schematic diagram showing the electrode measurement module and extension rod of the present invention in a disassembled state.

[0054] Figure 2 This is a schematic diagram of the electrode measurement module structure of the present invention.

[0055] Figure 3 This is a schematic diagram of the extension rod structure of the present invention.

[0056] Figure 4 This is a flowchart quantifying the adhesion between the electrode and the hole wall in this invention. Detailed Implementation

[0057] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0058] This embodiment provides a resistivity tomography electrode array system based on integrated measurement and protection, referencing... Figure 1 , Figure 2 as well as Figure 3As shown, the resistivity tomography electrode array system mainly consists of electrode measurement module 1, extension rod 2, independent multi-channel cable bundle and air pressure control unit.

[0059] The electrode measurement module 1 is the core detection unit of the system. It adopts a modular, quick-release design and consists of an air-electric connection interface 3, an annular airbag 4, and a flexible electrode assembly 5. Controlled expansion of the annular airbag 4 pushes the flexible electrode assembly 5 to tightly conform to the borehole wall. The air-electric connection interface 3 integrates a quick-connect male air connector and a waterproof male electrical connector for rapid docking with the air duct and independent multi-channel cable bundle of the extension rod 2. The flexible electrode assembly 5 consists of multiple arc-shaped conductive sheets embedded in a ring array on the outer surface of the annular airbag 4. It can withstand tensile deformation of over 300% and adaptively conforms to borehole walls with different curvatures when the annular airbag 4 expands in a controlled manner, ensuring stable contact quality under various complex borehole wall conditions. The annular airbag 4 adopts a multi-chamber independent air path design. Each chamber is supplied with air in parallel through a check valve. In other words, the annular airbag 4 is designed as multiple independent chambers, each supplied with air through a separate air tube. All air tubes are then integrated into a quick-connect male air path connector. This ensures that if the airbag in a single chamber leaks unexpectedly, the airbags in the remaining chambers can still maintain sufficient contact pressure, guaranteeing measurement continuity. The check valve can be a pressure-controlled check valve. Its operating characteristic is that during forward air supply, if the air pressure does not reach a set threshold, the valve closes, effectively preventing gas backflow in the airbag. During the evacuation process, when the pressure difference exceeds the valve opening pressure, the check valve opens, allowing gas to be discharged smoothly. The electrode measurement module 1 has internal thread interfaces at both ends, connecting to the extension rod 2 via a threaded connection. The electrode measurement module 1 is available in various diameter sizes, allowing selection of a suitable diameter based on the borehole diameter.

[0060] Extension rod 2 is the load-bearing and pipeline channel component of the electrode array system, made of high-strength, lightweight materials. Both ends of extension rod 2 have external threaded interfaces, forming a smooth, continuous outer wall surface after connecting to electrode measurement module 1, effectively preventing scratching of the borehole wall during movement within the borehole. The internal ends of extension rod 2 have dedicated cable and air passage fixing clips, facilitating the installation of independent multi-channel cable bundles and air guide tubes. The clips are located inside extension rod 2, approximately 4-5 cm from both ends for easy operation. Multiple small water-filtering holes 6 are provided around the perimeter of extension rod 2, allowing groundwater to freely permeate, balancing the internal and external pressures of the rod, and preventing a piston effect during extraction. Extension rod 2 is also available in various diameter and length sizes, allowing selection of the appropriate size based on the borehole diameter.

[0061] The independent multi-channel cable bundle consists of multiple sets of wires, each set corresponding to one electrode measurement module 1. During measurement, multiple electrode measurement modules 1 and extension rods 2 are spliced ​​together to achieve multi-position measurement. Each electrode measurement module 1 has an independent electrode channel, which is connected to the wires. The wires from multiple electrode measurement modules 1 converge to form the independent multi-channel cable bundle. The cable bundle uses double-layer insulation to improve electrical safety and anti-interference capability. Both ends of the cable bundle are terminated with waterproof quick-connect female connectors for quick insertion with the waterproof male connectors on the electrode measurement modules 1, thereby achieving a reliable and waterproof electrical connection for each electrode channel.

[0062] The air pressure control unit consists of an air compressor and a pressure regulator. The air compressor provides the air source power and has the ability to switch between inflation and deflation functions to control the expansion and contraction of the annular airbag 4. The pressure regulator system has a built-in air pressure-expansion calibration algorithm, which can accurately adjust the output air pressure according to the set value, thereby achieving precise control of the expansion state of the annular airbag 4 and ensuring that the flexible electrode array and the hole wall achieve and maintain the required contact quality.

[0063] In the structure provided in this embodiment, the parallel air path design and check valve mechanism of the annular airbag 4 ensure that the remaining chambers can still maintain effective contact pressure when a single airbag leaks unexpectedly, greatly reducing the risk of overall measurement interruption due to local failure and improving the applicability of operation in complex environments; the electrode measurement module 1 and the extension rod 2 adopt quick-release pneumatic and electrical interfaces and standardized threaded connections, and with the ability to adapt to multiple diameter specifications, it can realize rapid modular assembly of drilling holes of different diameters. At the same time, the smooth and continuous outer wall design avoids scratching the hole wall, and the filter hole 6 structure eliminates the piston effect, significantly improving on-site construction efficiency and safety.

[0064] This invention also provides a detection method based on the above system, the specific operation process and implementation steps of which are as follows:

[0065] (1) Preparation of the hole

[0066] ① Drilling parameter measurement: Measure and record key information such as borehole depth, diameter, borehole diameter variation trend, borehole wall stability, groundwater conditions, geological conditions and strata, to provide a basis for subsequent equipment selection and organization;

[0067] ② Equipment inspection: Check the airtightness of the air pressure control unit and electrode measurement module to ensure there is no air leakage; check the continuity of the independent multi-channel cable bundle to ensure that all wires are properly conductive.

[0068] (2) Electrode array system assembly

[0069] Based on the required depth and resolution, determine the number of electrode measurement modules 1 and the length of the extension rod 2. Then, according to the diameter of the borehole, select the matching diameter of the electrode measurement module 1 and the extension rod 2 according to the diameter matching formula (1). Subsequently, pass the independent multi-channel cable bundle and the air guide tube through the inside of the extension rod 2 and fix them in an orderly manner through the fixing buckles inside the rod to prevent the pipeline from getting tangled or piling up inside the rod. Assemble the electrode array system by "assembling in sections at the borehole opening and lowering in sections". On the ground, connect the first electrode measurement module 1 to the lower end of the first extension rod 2 by thread, and slowly lower it into the borehole so that the upper end of the extension rod 2 is exposed at the borehole opening for installing the next electrode measurement module 1. Repeat this process until the bottom module of the electrode array reaches the bottom of the borehole or the predetermined position. Finally, connect the end of the independent multi-channel cable bundle and the end of the air guide tube to the resistivity imaging host and air pressure control system on the ground.

[0070] (1);

[0071] In the formula: D c D is the diameter of the electrode measurement module. y D is the diameter of the extension rod; z The diameter of the borehole.

[0072] (3) The airbag expands under pressure and the electrode adheres to the wall.

[0073] Activate the air pressure control unit to switch the air compressor to charging mode. The pressure regulator outputs compressed air according to the preset air pressure value and the built-in air pressure-expansion calibration algorithm. Based on this algorithm, the degree of adhesion between the electrode and the orifice wall can be quantified, thereby obtaining the contact quality between the electrode and the orifice wall. The specific process is as follows: Figure 4 As shown.

[0074] The pressure-expansion calibration algorithm mainly quantifies contact quality through four processes:

[0075] ① Pressure-Inflation Conversion: Calculate the radial expansion δ under pressure P based on the airbag material parameters:

[0076] (2);

[0077] In the formula: δ(P) is the pressure-expansion function, representing the radial expansion deformation of the airbag under the action of pressure P; R i R is the initial inner radius of the airbag; o ν is the initial outer radius of the airbag; E is the elastic modulus of the silicone material corresponding to the airbag; t is the airbag wall thickness; ν is Poisson's ratio.

[0078] ② Contact pressure calculation: Combining the outer diameter of the inflated airbag with the borehole diameter, derive the pressure (or contact pressure) F exerted by the electrode on the borehole wall:

[0079] (3);

[0080] In the formula: F(P) is the air pressure-contact pressure function, reflecting the conversion of air pressure P into mechanical clamping force between the electrode and the hole wall; A c K represents the electrode contact area. s This is the formation stiffness coefficient.

[0081] Among them, the electrode contact area A c The calculation method is as follows:

[0082] (4);

[0083] In the formula, A c (δ) represents the electrode contact area; D z Where is the diameter of the borehole; L is the axial length of the airbag; k a δ is the contact efficiency coefficient (dimensionless), calibrated experimentally, reflecting the rate at which the contact area increases with the expansion amount, with a value range of 0.8~1.5; δ0 is the contact threshold (mm). When the expansion amount of the airbag is greater than δ0, the electrode begins to contact the hole wall, usually taken as 1.0~2.0mm. When δ≤δ0, the expansion amount of the airbag is insufficient, the electrode has not yet contacted the hole wall, and the contact area is zero; when δ>δ0, the contact area increases with the increase of δ.

[0084] Specifically, k a The contact efficiency coefficient is a dimensionless parameter used to correct the deviation between the actual contact area between the electrode and the orifice wall after the airbag inflates and the theoretical maximum contact area. Its physical meaning is the ratio of the actual effective contact area to the theoretical maximum contact area. The theoretical maximum contact area is calculated from the axial length L of the airbag and its circumference after inflating; the actual effective contact area is affected by factors such as the curvature of the electrode surface, the roughness of the orifice wall, and the compressibility of the formation, and needs to be calibrated experimentally.

[0085] The experimental calibration was a standardized indentation test calibration, specifically as follows: 1) In a borehole simulation device for typical formations (such as sandstone and clay), the axial length L of the airbag and the borehole diameter Dz were fixed; 2) The air pressure P was gradually increased, and the airbag expansion δ and the actual contact area between the electrode and the borehole wall were measured (using a pressure sensing membrane or optical morphology scanning); 3) K was fitted. a The relationship with the expansion amount δ.

[0086] The specific basis for the value range (0.8~1.5) is as follows: Lower limit 0.8: corresponds to fractured strata or low expansion (<3mm), where uneven borehole walls lead to incomplete contact. Upper limit 1.5: in soft clay strata, the contact surface is expanded by lateral compression after electrode embedding (area exceeding the theoretical value). Reference table for values:

[0087] Serial Number Stratigraphic type <![CDATA[Suggestion k a > reason 1 intact bedrock 0.9~1.0 The hole walls are smooth and the contact is uniform. 2 Sand / fracture zone 1.0~1.2 Micro-embedding increases effective area 3 soft clay 1.3~1.5 Electrode compression of the formation leads to lateral extension

[0088] ③ Adhesion Measurement: Based on Contact Pressure F and Electrode Deformation Coefficient k f Calculate the equivalent embedding depth d e Formula (5) is used to obtain the fit index η formula (6) through S-shaped function normalization, which is used to quantitatively determine the contact quality between the electrode and the hole wall.

[0089] (5);

[0090] In the formula: d e (P) is the pressure-equivalent embedding depth function, characterizing the contact quality between the flexible electrode and the hole wall under pressure P; k f F0 is the deformation coefficient of the flexible electrode; F0 is the initial contact pressure threshold.

[0091] Where, k f F0 and F0 are intrinsic parameters of the electrode material, calibrated through standardized mechanical and electrical tests, specifically:

[0092] Flexible electrode deformation coefficient k f :

[0093] k f The (flexible electrode deformation coefficient) describes the embedment depth of a flexible electrode under unit pressure, reflecting the flexibility of the electrode material. The electrode sheet is placed on a standard formation module, and an increasing pressure F is applied; the embedment depth d is then measured. e ; Fit d e The slope of the -F curve is k. f .

[0094] Generally, the value range for silicone-based conductive composite materials is 0.05~0.08 mm / kPa; the value range for polyurethane conductive elastomers is 0.10~0.15 mm / kPa.

[0095] Initial contact pressure threshold F0:

[0096] F0 (initial contact pressure threshold) is the minimum pressure required for the electrode to make effective electrical contact with the borehole wall. It is calibrated by an electrical contact resistance test, where the electrode-formation interface resistance R is measured under pressure F, and the F corresponding to the point where R drops to a stable value is F0.

[0097] Generally speaking: for bedrock strata, the value range is 5~10N due to their low surface impedance; for clay strata, the value range is 15~20N due to the need to penetrate the mud skin; and for dry sand strata, the value range is 10~15N due to the need to destroy the oxide layer between particles.

[0098] (6);

[0099] In the formula: η is the fit index; γ is the gain coefficient, which controls the sensitivity of the quality threshold; β is the contact difficulty coefficient, which reflects the difficulty of contact with the formation.

[0100] In practice, the fit index η can be calculated by measuring the real-time air pressure P. During inflation, when η ≤ 60%, the fit is insufficient and pressurization is required; when 60% < η ≤ 85%, the measurement requirements are met; and when η > 85%, the fit is excellent. Therefore, the output pressure of the air compressor can be controlled according to the required contact quality and the fit index η to ensure that the flexible electrode assembly and the hole wall achieve and maintain the required contact quality.

[0101] In this embodiment, in order to further ensure the accuracy of the calculation results, the gain coefficient γ and the contact difficulty coefficient β can be dynamically adjusted according to the formation type. Table 1 below shows the suggested values ​​of γ under different formations, and Table 2 shows the suggested values ​​of β under different formations.

[0102] Table 1. Suggested values ​​of γ in different formations

[0103] γ value Curve shape Applicable Scenarios 0.8–1.2 gentle Hard rock strata 1.5–2.0 steep Fracturing zone >2.5 Step High precision for scientific research exploration

[0104] Table 2. Suggested values ​​of β for different formations

[0105] Stratigraphic type Recommended β value Geological interpretation Engineering significance intact bedrock 0.8–1.0 mm The hole walls are smooth and hard, making them easy to access. A small embedding is sufficient to meet the requirements. Sandy soil layer 1.2–1.5 mm Microcracks need to be filled Requires moderate pressure Fracturing zone 1.8–2.2 mm The debris buildup is severe and needs to be compacted. Requires significant pressure increase clay layer 2.5–3.0 mm The mud layer is thick and needs to be penetrated. Extremely difficult to access

[0106] (4) Array recovery and equipment disassembly

[0107] After data acquisition is complete, the air pressure control unit switches to the suction mode, and the pressure regulator controls the extraction of gas from the annular airbag 4, causing the annular airbag 4 to contract. Under the elastic action, the flexible electrode assembly 5 detaches from the orifice wall and resets. Subsequently, the electrode array system is slowly lifted to avoid scratching the orifice wall. At the orifice opening, the components are disassembled in the reverse order of assembly. The electrode measurement module 1, extension rod 2, independent multi-channel cable bundle, and air guide tube are sorted and organized, and the integrity of each component is checked to prepare for subsequent maintenance or reuse.

Claims

1. A resistivity tomography electrode array system based on integrated measurement and control, comprising an electrode measurement module, characterized in that, Also includes: Extension rod, independent multi-channel cable bundle, and pneumatic control module; The electrode measurement module includes a gas-electric connection interface, an annular airbag, and a flexible electrode group. The flexible electrode group includes multiple arc-shaped conductive sheets embedded in an annular array on the outer surface of the annular airbag. The annular airbag adopts a multi-chamber independent air passage structure, with each chamber supplied with air in parallel. The extension rod and the electrode measurement module are connected by a threaded splice. An independent multi-channel cable bundle and an air guide tube pass through the inside of the extension rod and connect to the pneumatic and electrical connection interface. The air pressure control module includes an air compressor and a pressure regulator. The air compressor is connected to the annular airbag through an air pipe and is used to control the expansion and contraction of the annular airbag. The pressure regulator has a built-in air pressure-expansion calibration algorithm, which is used to adjust the output air pressure of the air compressor based on the set value to control the expansion state of the annular airbag and make the flexible electrode group and the hole wall achieve and maintain the required contact quality. The implementation steps of the pressure-expansion calibration algorithm are as follows: 1) Calculate the radial expansion vector δ under air pressure P based on the airbag material parameters; 2) Calculate the contact pressure F between the electrode and the borehole wall by combining the outer diameter of the inflated airbag and the borehole diameter; 3) Based on contact pressure F and electrode deformation coefficient k f Calculate the equivalent embedding depth d e Finally, the fit index η is obtained by normalization through the S-shaped function, and the contact quality between the electrode and the hole wall is quantitatively determined by the fit index η. The radial expansion δ under air pressure P is calculated as follows: ； In the formula, δ(P) is the pressure-expansion function, representing the radial expansion deformation of the airbag under pressure P; R i R is the initial inner radius of the airbag; o ν is the initial outer radius of the airbag; E is the elastic modulus of the silicone material corresponding to the airbag; t is the airbag wall thickness; ν is Poisson's ratio. The contact pressure F is calculated as follows: ； In the formula, F(P) is the air pressure-contact pressure function, reflecting the conversion of air pressure P into mechanical clamping force between the electrode and the hole wall; A c K represents the electrode contact area. s Let A be the formation stiffness coefficient. c The calculation method is as follows: ； In the formula, A c (δ) represents the electrode contact area; D z Where is the diameter of the borehole; L is the axial length of the airbag; k a δ is the contact efficiency coefficient; δ0 is the contact threshold. Equivalent embedding depth d e The calculation method is as follows: ； In the formula: d e (P) is the pressure-equivalent embedding depth function, characterizing the contact quality between the flexible electrode and the hole wall under pressure P; k f F0 is the deformation coefficient of the flexible electrode; F0 is the initial contact pressure threshold. The fit index η is calculated as follows: ； In the formula: η is the fit index; γ is the gain coefficient, which controls the sensitivity of the quality threshold; β is the contact difficulty coefficient, which reflects the difficulty of contact with the formation.

2. The resistivity tomography electrode array system based on integrated measurement and protection as described in claim 1, characterized in that, The outer diameter of the extension rod is equal to the outer diameter of the electrode measurement module, so that after the extension rod and the electrode measurement module are spliced ​​and assembled, a smooth and continuous outer wall surface is formed.

3. The resistivity tomography electrode array system based on integrated measurement and protection according to claim 1, characterized in that, The extension rod has multiple small water-filtering holes around its tube wall, which allow groundwater to permeate freely. The extension rod also has cable channels and gas channels inside, with clips installed in the channels.

4. The resistivity tomography electrode array system based on integrated measurement and protection according to claim 1, characterized in that, The independent multi-channel cable bundle consists of multiple sets of wires, each set of wires corresponding to one electrode measurement module. The cable bundle is connected to the pneumatic-electric connection interface through a waterproof quick-connect connector.

5. The resistivity tomography electrode array system based on integrated measurement and protection according to claim 1, characterized in that, During the inflation of the annular airbag by the air compressor, the contact quality is obtained by calculating the η value in real time through the air pressure P. When η≤60%, it indicates that the fit is insufficient and pressure needs to be increased; when 60%<η≤85%, it indicates that the measurement requirements are met; when η>85%, it indicates that the fit is excellent.

6. The resistivity tomography electrode array system based on integrated measurement and protection according to claim 1, characterized in that, The gain coefficient γ and the contact difficulty coefficient β are dynamically adjusted based on the formation type as follows: When the formation curve is flat, the value of γ is 0.8-1.2; When the stratigraphic curve is steep, γ should be 1.5-2.

0. When the stratigraphic curve exhibits a step-like shape, the value of γ is greater than 2.5; When the strata are intact bedrock, β takes a value of 0.8-1.0; When the stratum is sandy soil, β takes a value of 1.2-1.5; When the strata are fractured zones, β takes values ​​of 1.8-2.2; When the stratum is clay, β takes the value of 2.5-3.

0.

7. A detection method based on the system according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Hole preparation: Determine drilling parameters and inspect equipment; S2. Electrode Array System Assembly: Based on the detection depth and resolution requirements, determine the number of electrode measurement modules and the length of the extension rod. Then, based on the borehole diameter, select the matching electrode measurement module and the diameter of the extension rod. Pass the independent multi-channel cable bundle and the air duct through the inside of the extension rod. Assemble the electrode array system using the "orifice segment assembly and segmented lowering" method. Finally, connect the end of the independent multi-channel cable bundle and the end of the air duct to the resistivity imaging host and air pressure control module on the ground. S3, Airbag inflation and electrode contact with the wall: Activate the air pressure control module, switch the air compressor to inflation mode, and the pressure regulator controls the air compressor to output compressed air according to the measured air pressure value and the built-in air pressure-expansion calibration algorithm, so that the flexible electrode group and the hole wall can achieve and maintain the required contact quality. S4. Array recovery and equipment disassembly: The air pressure control module switches to the air extraction mode, extracts the gas in the annular airbag group, causing the airbag to contract. The flexible electrode group is released from the hole wall and reset under the elastic action. Then, the electrode array system is slowly lifted to avoid scratching the hole wall. The electrode is disassembled in sections at the hole in the reverse order of assembly. The electrode measurement module, extension rod, independent multi-channel cable bundle and air guide tube are sorted and organized.

8. The detection method according to claim 7, characterized in that, In step S2, the diameters of the electrode measurement module and the extension rod are matched according to the following formula: ； In the formula: D c D is the diameter of the electrode measurement module. y D is the diameter of the extension rod; z The diameter of the borehole.

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