Shallow-buried foundation pile electrical method detection method based on automatic parameter matching

Abstract

The invention discloses a shallow-buried foundation pile electrical method detection method based on automatic parameter matching, and the method comprises the steps: obtaining an estimated minimum diameter and a maximum top burial depth of a foundation pile in a to-be-detected region, and inputting the estimated minimum diameter and the maximum top burial depth into a layout scheme generator; and the layout scheme generator automatically calculates and generates an optimized measuring line length and an optimized electrode layout interval based on the estimated parameters, so that the electrodes are arranged along the measuring line at equal intervals. According to the method, measuring lines and electrodes are arranged in a to-be-measured area, electric field data are collected through an electrical prospecting receiver, an inversion calculation model is established in combination with coordinates of measuring points and geometric parameters of the electrodes, and underground medium grid resistivity distribution is solved through a nonlinear least square method. And identifying a resistivity abnormal area based on an inversion result, mapping the resistivity abnormal area to a plane coordinate system, generating a foundation pile plane distribution diagram, and realizing high-precision positioning of the foundation piles in the to-be-detected area. The method can standardize and quantify the electrical method layout process, improve the detection efficiency and the positioning precision, and reduce the field operation complexity and the number of repeated tests at the same time.

Description

Technical Field

[0001] This invention belongs to the field of urban underground pile detection technology, specifically relating to an electrical resistivity tomography method for shallow buried piles based on automatic parameter matching. Background Technology

[0002] With the acceleration of urbanization, the demolition of old buildings and the construction of new buildings in cities have become commonplace. While the above-ground structures are usually cleared relatively cleanly during demolition, the foundation piles below ground are often left behind. For some older buildings, although original foundation drawings may exist, the specific coordinates of the foundation piles are often unknown, and some engineering design data may even be lost, making it difficult for construction companies to accurately determine the number and distribution of foundation piles within the site. For example, during construction, the construction team discovers a large number of abandoned foundation piles during piling and excavation, forcing multiple adjustments to the design plan. This not only increases project costs but also extends the construction period.

[0003] Traditional geophysical methods have limitations in urban underground pile detection. While ground-penetrating radar (GPR) can be used for underground structure detection in certain scenarios, its detection results are not ideal in areas like Shanghai where the groundwater level is shallow. Borehole magnetic gradient methods can obtain relatively accurate results, but their cost is difficult to control effectively when the location of the piles is unknown, limiting their large-scale application.

[0004] In this field, those skilled in the art generally believe that the deployment parameters for electrical resistivity testing need to comprehensively consider on-site geological conditions, interference sources, and other complex factors, and are difficult to determine through simple mathematical relationships. In the prior art, CN110988999A discloses a detection method and system for pile foundations based on transpore resistivity CT inversion imaging analysis. The detection method includes determining the distribution range, size, shape, and dimensions of the pile foundation group, the distribution of the surrounding soil medium, and the interface conditions; establishing an initial pile foundation group model; presetting the mesh size using the finite element method and setting the initial resistivity value; performing forward modeling on each pile in the pile foundation group using a symmetrical electrode arrangement with the trans-hole resistivity CT method to obtain the corresponding apparent resistivity forward modeling parameters; then obtaining the inversion result using the least squares inversion method; comparing the inversion result with the actual strata and pile foundation conditions, adjusting the mesh size and electrode spacing until the inversion result matches the actual situation and the optimal electrode spacing parameter is obtained; based on the optimal electrode spacing parameter, conducting on-site detection using inter-well trans-hole resistivity CT to obtain experimental data, and then performing inversion mapping.

[0005] However, this method has the following limitations: 1. The trans-hole resistivity CT method requires precise placement of symmetrical electrodes, and the adjustment of the measuring lines and grids requires multiple iterations, which is highly dependent on the on-site construction conditions and is complex and time-consuming to operate. 2. In existing methods, the placement parameters such as electrode spacing and measuring line length rely on experience and repeated experiments, making it difficult to form a standardized scheme that can be quantified and calculated, thus hindering the large-scale application of electrical resistivity spectroscopy in the field of pile positioning.

[0006] Therefore, it is still necessary to propose a detection method that can automatically match electrical resistivity tomography (ERT) parameters based on the geometric parameters of the pile in the absence of complete design data, and quickly, cost-effectively, and with high precision locate shallow-buried piles, in order to overcome the aforementioned limitations of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the existing technology and provide a method for electrical resistivity tomography of shallow buried piles based on automatic parameter matching.

[0008] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for electrical resistivity tomography (EDT) of shallow-buried piles based on automatic parameter matching, comprising the following steps: Obtain the estimated minimum diameter and estimated maximum top burial depth of the piles within the area to be measured; Input the estimated minimum diameter and estimated maximum top burial depth into the layout scheme generator; The deployment scheme generator automatically generates optimized deployment parameters, including the test line length and electrode spacing, based on the input estimated parameters. Based on the generated layout parameters, survey lines and electrodes are laid out in the area to be measured, and electric field data is collected by electrical exploration receiver. The collected electric field data is combined with the coordinate position to perform inversion calculations to determine the planar distribution location of the foundation piles; Based on the inversion calculation results, a planar distribution map of the foundation piles is obtained, and the location of the foundation piles within the area to be measured is determined.

[0009] Furthermore, obtaining the estimated minimum diameter and estimated maximum top burial depth of the foundation piles within the test area specifically includes: Identify the area to be measured, and obtain the estimated minimum diameter and estimated maximum top burial depth of the piles in the area by referring to the design drawings or conducting on-site surveys. The estimated minimum diameter refers to the minimum diameter of the piles, and the estimated maximum top burial depth refers to the maximum value of the top burial depth of the piles. When complete information cannot be obtained from design drawings, the depth and diameter of the foundation piles are estimated by on-site drilling or detection methods to determine the estimated minimum diameter and maximum top depth of the foundation piles in the area to be tested.

[0010] Furthermore, the deployment scheme generator automatically generates optimized deployment parameters based on the input estimated parameters, specifically including: Based on the input estimated minimum diameter and estimated maximum top burial depth, the length of the measuring line and the spacing between electrodes are calculated using a preset parameter matching principle. The ratio between the measuring line length and the estimated maximum top burial depth is determined by a first matching coefficient, and the ratio between the electrode spacing and the estimated minimum diameter is determined by a second matching coefficient.

[0011] Furthermore, the parameter matching principle includes: Measurement line length Based on the first matching coefficient Compared with the estimated maximum top burial depth Confirmed, the formula is as follows: in, The first matching coefficient, To estimate the maximum top burial depth; This refers to the length of the survey line; Electrode spacing By the second matching coefficient Compared with the estimated minimum pile diameter Confirmed, the formula is as follows: in, This is the second matching coefficient; To estimate the minimum pile diameter; The spacing between the electrodes.

[0012] Furthermore, when the calculated survey line length and electrode spacing do not meet the requirement of equal spacing, the layout scheme generator adjusts the matching coefficient according to the preset adjustment priority, specifically as follows: Prioritize adjusting the electrode spacing within the allowable range of the second matching coefficient so that the electrode placement points can be evenly spaced along the survey line; If the requirement for equal spacing cannot be met after adjusting within the range of the second matching coefficient, the length of the survey line shall be adjusted within the allowable range of the first matching coefficient. The process continues until the determined survey line length and electrode spacing meet the requirement of equal spacing of electrodes along the survey line, and the adjusted layout parameters are output. The requirement for equidistant electrode placement includes: within the length of the measuring line, the number of electrode placement points is an integer, and the spacing between adjacent electrode placement points is consistent, with no remaining length or non-equidistant electrode placement points.

[0013] Furthermore, based on the generated deployment parameters, survey lines and electrodes are deployed in the area to be measured, and electric field data is collected by using an electrical resistivity tomography receiver. Specifically, this includes: A unified planar coordinate system is established within the area to be measured, and at least one survey line is laid out according to the length of the survey line. The actual length of the survey line is not less than the length of the survey line output by the layout scheme generator, and the direction and position of the survey line are designed according to the range of the area to be measured, covering all areas where foundation piles may exist. Multiple electrode placement points are arranged at equal intervals along the measurement line according to the electrode placement spacing, and several adjacent electrodes are selected to form a measurement unit in each measurement. The measurement unit includes four electrode placement points, wherein the electrodes located at both ends of the measurement unit serve as power supply electrodes, and the electrodes located between the power supply electrodes serve as measurement electrodes. An excitation current is applied to the power supply electrode by an electrical exploration transmitter, and the electric field response between the measuring electrodes is collected by an electrical exploration receiver to obtain the electric field data of the corresponding measuring unit. After completing the data acquisition of a measurement unit, the measurement unit is moved along the measurement line by one electrode layout interval, and the above power supply and data acquisition process is repeated until the measurement unit is located at the end of the measurement line and no longer meets the complete layout conditions. After completing the rolling measurement of the same measurement unit span, the number of electrodes participating in the measurement unit is increased to expand the measurement unit span, and the rolling measurement continues under the expanded measurement unit conditions to obtain electric field data at different scales within the measurement line range step by step.

[0014] Furthermore, the electric field data includes: When an excitation current is applied between the power supply electrodes by an electrical exploration transmitter, the potential difference information collected between the corresponding measurement electrodes is obtained. The measurement geometric parameters corresponding to the potential difference information include the magnitude of the power supply current, the distance between the power supply electrodes, and the distance between the measuring electrodes.

[0015] Furthermore, the process of inverting the collected electric field data with coordinate positions to determine the planar distribution location of the foundation piles specifically includes: The potential difference information, measurement geometric parameters, and spatial coordinates of the measurement unit in the planar coordinate system are integrated from the electric field data to form the input dataset required for the inversion calculation, specifically including: Potential difference information at measurement points Data was collected by an electrical resistivity survey receiver. Corresponding supply current ; Electrode geometric parameters This includes the electrode spacing for supplying electrodes and the electrode spacing for measuring electrodes; Spatial position of the measurement point in the plane coordinate system The location of the survey line and the spacing of the electrode layout are determined by the layout scheme generator. A subsurface medium grid model was established, and the area to be measured was divided into several uniform grid units; Based on the measurement principles of the four-electrode method or Wenner configuration, a forward electric field calculation model is established, mapping the resistivity of the grid cells to the theoretical potential difference, as shown in the following formula: in, Indicates the first k The theoretical potential difference at each measurement point; Indicates the first k The power supply current at each measurement point; Indicates the first k Electrode geometric parameters at each measurement point; Indicates the first k The measurement point corresponding to the th measurement point i The resistivity of each grid cell; This is the mapping function for the forward calculation model of the electric field; Based on the theoretical potential difference and the potential difference information at the measurement points, an optimization objective function is constructed. This objective function is then solved using the nonlinear least squares method to obtain the resistivity of each grid cell in the subsurface medium grid model. The optimization objective function is expressed as: in, Indicates the total number of measurement points; Indicates the first k The observed potential difference at each measurement point; Based on the resistivity distribution of each grid cell obtained through iterative solution The system identifies areas of abnormal resistivity, maps these areas onto a plane coordinate system, and uses the corresponding locations as potential pile locations to generate a planar distribution map of the piles, thus completing the spatial positioning of the piles.

[0016] Furthermore, the resistivity distribution of each grid cell obtained from the iterative solution... Identify regions of abnormal resistivity, specifically including: Calculate the resistivity difference of each grid cell relative to the resistivity of the surrounding background medium. ,in This represents the average background value of the resistivity in the region to be measured. Set resistivity anomaly threshold Based on a threshold, grid cells with resistivity significantly higher or lower than the background are selected, i.e., those that meet the criteria... The grid cells were identified as abnormal regions; Adjacent anomalous region grid cells are spatially clustered to form continuous anomalous regions.

[0017] Compared with the prior art, the present invention has the following advantages: (1) In the prior art, after the demolition of old buildings, the situation of piles remaining below the ground surface is quite common. However, the design drawings or engineering data are incomplete, making it difficult for construction units to accurately grasp the number and distribution of piles within the plot. This invention obtains the estimated minimum diameter and maximum top burial depth of the piles in the area to be measured, and inputs these parameters into the layout scheme generator to automatically generate optimized survey line lengths and electrode spacing, thus realizing the quantitative layout of the pile distribution in the area to be measured. Through this method, the planar distribution of piles can be quickly determined in the absence of complete design data, significantly reducing the uncertainty and construction risk of on-site surveys, and improving the accuracy and efficiency of pile positioning. In addition, although the borehole magnetic gradient method is accurate in the prior art, it is expensive when the pile location is unknown, which limits its large-scale application. This invention automatically matches the pile geometric parameters with the electrical method layout parameters through the layout scheme generator, optimizes the survey line length and electrode spacing, avoids blind trial and repeated drilling, and significantly reduces the detection cost. At the same time, the rolling measurement and multi-scale measurement unit design ensures comprehensive coverage of detection data, improving detection efficiency and economy.

[0018] (2) In the prior art, the traditional ground-penetrating radar method has unsatisfactory detection results in areas with shallow groundwater levels, making it difficult to effectively identify shallow-buried piles. This invention, by employing electrical detection combined with rolling measurement units and gradually increasing the span of the measurement units, collects electric field data across the entire survey line, effectively penetrating shallow soil layers and determining the planar distribution location of the piles through inversion calculations. This solves the problem of detecting shallow-buried piles and achieves high-precision positioning of piles under complex groundwater conditions. By gradually increasing the span of the measurement units and performing multi-scale rolling measurements, it ensures the collection of full-coverage electric field data at different spatial resolutions, improving detection accuracy and adaptability to complex areas, and achieving reliable positioning of diverse shallow-buried piles.

[0019] (3) In the prior art, it is difficult to standardize the parameters for electrical resistivity tomography (ERT) deployment, which requires reliance on experience and multiple field tests, resulting in complex and time-consuming operations. This invention establishes a stable correspondence between the length of the survey line and the depth of the pile, and between the electrode spacing and the diameter of the pile, through the principle of parameter matching. It also realizes automatic priority adjustment in the deployment scheme generator to ensure that the electrodes are deployed at equal intervals along the survey line. This solves the problem of deployment parameters relying on experience, realizes the standardization and quantifiable calculation of ERT deployment, reduces operational complexity, and improves the replicability and scalability of the detection scheme.

[0020] (4) In the existing technology, the trans-hole resistivity CT method requires precise placement of symmetrical electrodes, and the forward and inverse models require multiple iterations, making the on-site operation complex. This invention establishes a unified planar coordinate system, places electrodes at equal intervals according to optimized placement parameters, selects measurement units for rolling measurements, and combines the electric field forward model with nonlinear least squares inversion calculation to automatically generate grid resistivity distribution and pile plane distribution maps. This simplifies the on-site operation process, reduces the number of iterations, realizes automated and rapid data processing, and improves the convenience and accuracy of detection.

[0021] (5) In the prior art, the trans-hole resistivity CT method requires precise placement of symmetrical electrodes, and the forward and inverse models require multiple iterations, making on-site operation complex. This invention, by establishing a unified planar coordinate system, placing electrodes at equal intervals according to optimized parameters, selecting measurement units for rolling measurements, and combining the electric field forward model with nonlinear least squares inversion calculations, can automatically generate grid resistivity distribution and pile planar distribution maps. This simplifies the on-site operation process, reduces the number of iterations, achieves automated and rapid data processing, and improves the convenience and accuracy of the detection. Attached Figure Description

[0022] Figure 1 This is a flowchart of the electrical resistivity tomography method for shallow-buried piles according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first model according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the second model according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the first inversion graph according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the second inversion graph according to an embodiment of the present invention. 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] Example 1: Those skilled in the art generally believe that the deployment parameters of electrical resistivity tomography (OR) require comprehensive judgment based on complex factors such as on-site geological conditions and interference sources, and are difficult to standardize and determine through simple mathematical relationships. This technical bias has long hindered the standardization and large-scale application of OR in the field of pile positioning. This invention, through extensive simulations and experiments, unexpectedly discovered that for specific target bodies such as shallow-buried piles and pipelines, their geometric parameters ( ) and layout parameters ( There is a stable and optimal matching relationship between them, which overcomes the above-mentioned technical bias and realizes a technological leap from the unknown to the quantitatively calculable.

[0025] This embodiment specifically provides a method for electrical resistivity tomography (EDT) of shallow-buried piles based on automatic parameter matching, such as... Figure 1 As shown, it includes the following steps: Step S1: Obtain the estimated minimum diameter and estimated maximum top burial depth of the foundation piles within the area to be tested, specifically including: Identify the area to be measured, and obtain the estimated minimum diameter and estimated maximum top burial depth of the piles in the area by referring to the design drawings or conducting on-site surveys. The estimated minimum diameter refers to the minimum diameter of the piles, and the estimated maximum top burial depth refers to the maximum value of the top burial depth of the piles. When complete information cannot be obtained from design drawings, the depth and diameter of the foundation piles are estimated by on-site drilling or detection methods to determine the estimated minimum diameter and maximum top depth of the foundation piles in the area to be tested.

[0026] Step S2: Input the estimated minimum diameter and estimated maximum top burial depth into the layout scheme generator; Step S3: The deployment scheme generator automatically generates optimized deployment parameters based on the input estimated parameters; The layout parameters include the length of the survey line and the spacing between electrode installations; Step S3 specifically includes: Based on the input estimated minimum diameter and estimated maximum top burial depth, the length of the measuring line and the spacing between electrodes are calculated using a preset parameter matching principle. The ratio between the measuring line length and the estimated maximum top burial depth is determined by a first matching coefficient, and the ratio between the electrode spacing and the estimated minimum diameter is determined by a second matching coefficient.

[0027] When the calculated survey line length and electrode spacing do not meet the requirement of equal spacing, the layout scheme generator adjusts the matching coefficient according to the preset adjustment priority, specifically: Prioritize adjusting the electrode spacing within the allowable range of the second matching coefficient so that the electrode placement points can be evenly spaced along the survey line; If the requirement for equal spacing cannot be met after adjusting within the range of the second matching coefficient, the length of the survey line shall be adjusted within the allowable range of the first matching coefficient. The process continues until the determined survey line length and electrode spacing meet the requirement of equal spacing of electrodes along the survey line, and the adjusted layout parameters are output. The requirements for equidistant electrode placement include: within the length of the survey line, the number of electrode placement points is an integer, and the spacing between adjacent electrode placement points is consistent, with no remaining length or non-equidistant electrode placement points.

[0028] The principles of parameter matching include: Measurement line length Based on the first matching coefficient Compared with the estimated maximum top burial depth Confirmed, the formula is as follows: in, The first matching coefficient, To estimate the maximum top burial depth; This refers to the length of the survey line; Electrode spacing By the second matching coefficient Compared with the estimated minimum pile diameter Confirmed, the formula is as follows: in, This is the second matching coefficient; To estimate the minimum pile diameter; The spacing between the electrodes; The range of values ​​for the first and second matching coefficients was determined through extensive pile layout simulations, experimental data statistics, and field verification. Through over 100 forward simulations and 30 field experimental cases, this invention found that when the first matching coefficient is less than 8, the measuring line is too short to capture the complete electric field anomaly boundary, leading to missed detections or inaccurate positioning. When the first matching coefficient is greater than 12, the measuring line is too long, the data volume surges, and the computational efficiency decreases by more than 50%, without significantly improving positioning accuracy. Similarly, the preferred range for the second matching coefficient is 0.5 to 2, representing the optimal balance between resolution and detection depth / efficiency. Specifically, when the electrode spacing d is approximately equal to the minimum pile diameter D (i.e., K2=1), the positioning error can be stably controlled within 0.5m, an accuracy that traditional empirical methods (typically with errors exceeding 1-2m) cannot reliably achieve.

[0029] In step S3, the layout scheme generator automatically generates optimized survey line length L and electrode spacing d based on the input estimated minimum diameter D of the foundation pile and estimated maximum top burial depth H. This ensures that the survey line and electrode layout can fully cover the foundation piles in the area to be measured, while guaranteeing the effectiveness and accuracy of electric field data acquisition. Equally spaced electrode layout ensures consistent spatial resolution for data acquisition at each location during the rolling measurement process, avoiding uneven data density or missing local samples, thereby improving the stability and accuracy of the inversion calculation. By prioritizing the adjustment of the second matching coefficient K2 to achieve equal spacing of electrodes along the survey line, and adjusting the first matching coefficient K1 when necessary to correct the survey line length, not only can the number of electrodes be kept to an integer and the spacing uniform, but also the discontinuity in layout caused by remaining length can be avoided. By automatically calculating and adjusting the layout parameters using matching coefficients, the method achieves a quantitative conversion from pile geometry parameters to layout parameters, overcoming the uncertainty of traditional empirical layout. The equidistant layout improves the uniformity and comparability of electric field data, making subsequent inversion calculations more stable. The positioning error can be stably controlled within 0.5m, which is a significant improvement compared to the 1-2m error of traditional empirical methods. This method balances the coverage of the survey line and the efficiency of data acquisition, avoiding the problem of a surge in computation caused by excessively long survey lines, and achieving high-precision, fast, and low-cost positioning of shallow-buried piles.

[0030] Step S4: Based on the generated layout parameters, lay out the survey lines and electrodes in the area to be measured, and collect electric field data using an electrical exploration receiver. Specifically, this includes: Establish a unified planar coordinate system within the area to be measured, and lay at least one survey line according to the survey line length output by the layout scheme generator. The actual length of the survey line should not be less than the output survey line length. The direction and location of the survey line should be reasonably designed according to the scope of the area to be measured to ensure coverage of all possible locations of foundation piles, thereby ensuring that the electric field data can completely reflect the distribution of potential foundation piles. The electrodes are laid out at equal intervals along the survey line according to the electrode layout spacing output by the layout scheme generator, forming multiple electrode layout points. In each measurement, several adjacent electrodes are selected to form a measurement unit. The equal-interval layout ensures uniform spatial resolution of the measurement data, which is beneficial to the stability and accuracy of subsequent inversion calculations, while avoiding local uneven density or coverage omissions during data acquisition. The measurement unit includes four electrode placement points, with the electrodes at both ends serving as power supply electrodes and the middle electrode serving as measurement electrodes. An excitation current is applied to the power supply electrodes via an electrical exploration transmitter, and the electric field response between the measurement electrodes is collected via an electrical exploration receiver to obtain the electric field data of the corresponding measurement unit. This configuration can effectively acquire the response characteristics of the foundation pile to the electric field and achieve highly sensitive measurement. After data acquisition of one measurement unit is completed, the measurement unit is moved along the measurement line by one electrode spacing, and the power supply and data acquisition process is repeated until the measurement unit is located at the end of the measurement line and cannot be completely deployed. This rolling measurement method ensures continuous acquisition of electric field information along the measurement line, achieving spatial data continuity. After completing rolling measurements across the same measurement unit span, the span of the measurement unit is expanded by increasing the number of electrodes within the unit. Rolling measurements are then performed under the expanded unit conditions, thereby acquiring electric field data at different scales within the measurement line range step by step. This method of progressively expanding the measurement unit span balances measurement depth and resolution, enabling high-precision detection of foundation piles from shallow to slightly deeper layers, while simultaneously improving data acquisition efficiency and optimizing detection costs and time.

[0031] Step S5: Perform inversion calculations on the collected electric field data and coordinate positions to determine the planar distribution location of the foundation piles; The electric field data includes: When an excitation current is applied between the power supply electrodes by an electrical exploration transmitter, the potential difference information collected between the corresponding measurement electrodes is obtained. The measurement geometric parameters corresponding to the potential difference information include the magnitude of the supply current, the distance between the supply electrodes, and the distance between the measuring electrodes.

[0032] Step S5 specifically includes: The potential difference information, measurement geometric parameters, and spatial coordinates of the measurement unit in the planar coordinate system are integrated from the electric field data to form the input dataset required for the inversion calculation, specifically including: Potential difference information at measurement points Data was collected by an electrical resistivity survey receiver. Corresponding supply current ; Electrode geometric parameters This includes the electrode spacing for supplying electrodes and the electrode spacing for measuring electrodes; Spatial position of the measurement point in the plane coordinate system The location of the survey line and the spacing of the electrode layout are determined by the layout scheme generator. A subsurface medium grid model was established, and the area to be measured was divided into several uniform grid units; Based on the measurement principles of the four-electrode method or Wenner configuration, a forward electric field calculation model is established, mapping the resistivity of the grid cells to the theoretical potential difference, as shown in the following formula: in, Indicates the first k The theoretical potential difference at each measurement point; Indicates the first k The power supply current at each measurement point; Indicates the first k Electrode geometric parameters at each measurement point; Indicates the first k The measurement point corresponding to the th measurement point i The resistivity of each grid cell; This is the mapping function for the forward calculation model of the electric field; Based on the theoretical potential difference and the potential difference at the measurement points, an optimization objective function is constructed. This objective function is then solved using the nonlinear least squares method to obtain the resistivity of each grid cell in the subsurface medium grid model. The optimization objective function is expressed as: in, Indicates the total number of measurement points; Indicates the first k The observed potential difference at each measurement point; Based on the resistivity distribution of each grid cell obtained through iterative solution The system identifies areas of abnormal resistivity, maps these areas onto a plane coordinate system, and uses the corresponding locations as potential pile locations to generate a planar distribution map of the piles, thus completing the spatial positioning of the piles.

[0033] Based on the resistivity distribution of each grid cell obtained through iterative solution Identify regions of abnormal resistivity, specifically including: Calculate the resistivity difference of each grid cell relative to the resistivity of the surrounding background medium. ,in This represents the average background value of the resistivity in the region to be measured. Set resistivity anomaly threshold Based on a threshold, grid cells with resistivity significantly higher or lower than the background are selected, i.e., those that meet the criteria... The grid cells were identified as abnormal regions; Adjacent anomalous region grid cells are spatially clustered to form continuous anomalous regions.

[0034] Step S6: Based on the inversion calculation results, obtain the planar distribution map of the foundation piles and locate the positions of the foundation piles within the area to be measured.

[0035] Example 2: The specific detection process of this invention will be further illustrated with examples: like Figure 2 , Figure 3As shown, two preset models are used. Piles 1, 2, and 3 are all reinforced concrete structural columns. Pile 1 has a length, diameter, and top embedment depth of 8m, 0.8m, and 3m, respectively; pile 2 has a length, diameter, and top embedment depth of 8m, 0.8m, and 4m, respectively; and pile 3 has a length, diameter, and top embedment depth of 8m, 1m, and 3m, respectively. The background soil has a depth of 50m and a length of 100m. The soil is set as a homogeneous, isotropic clay layer with a resistivity of 20Ω·m, and the resistivity of all piles is set to 200Ω·m. Model 1 contains piles 1 and 2 within the soil; Model 2 contains piles 1 and 3 within the soil.

[0036] To verify the effectiveness and accuracy of the method of this invention, the following simplification can be made when verifying it through numerical simulation or physical model experiments: the centers of the two piles in each model are on a straight line; a measuring line is laid out, passing directly above the pre-set center of the pile in the model. This layout aims to eliminate other interferences and most directly verify the parameter matching relationship and the effectiveness of the detection method.

[0037] Input the parameters of the two models into the layout scheme generator of this invention. The layout parameter output results of the first model are as follows: The generator interface clearly displays the final layout scheme: "Recommended line length: 40.0m; Recommended electrode spacing: 0.8m"; The layout parameter output results of the second model are as follows: The generator interface clearly displays the final layout scheme: "Recommended line length: 30.0m; Recommended electrode spacing: 0.5m".

[0038] Following the aforementioned steps, survey data was collected and inverted to obtain an interpretation graph of the apparent resistivity and the coordinates of the observation points, as shown below. Figure 4 , Figure 5 As shown.

[0039] Analyze the apparent resistivity profile obtained from the inversion (e.g.) Figure 4 , Figure 5 As shown in the figure, it can be clearly observed that in the background medium (approximately 20 Ω·m, shown in green), two obvious high-resistivity anomaly regions (shown in white / blue, with a resistivity of approximately 30-40 Ω·m) appear at horizontal positions of approximately 21 m and 29 m, and the horizontal position of the center of the high-resistivity anomaly basically corresponds to the horizontal position in the model diagram.

[0040] Analysis concludes that the method of this invention successfully identified and located the planar distribution of shallow-buried piles, with a planar position error of less than 0.5m. This embodiment fully demonstrates that the present invention implements the parameter matching principle through a layout scheme generator, thereby achieving accurate and efficient detection of shallow-buried piles.

[0041] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0042] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for electrical resistivity tomography (EDT) of shallow-buried piles based on automatic parameter matching, characterized in that, Includes the following steps: Obtain the estimated minimum diameter and estimated maximum top burial depth of the piles within the area to be measured; Input the estimated minimum diameter and estimated maximum top burial depth into the layout scheme generator; The deployment scheme generator automatically generates optimized deployment parameters, including the test line length and electrode spacing, based on the input estimated parameters. Based on the generated layout parameters, survey lines and electrodes are laid out in the area to be measured, and electric field data is collected by electrical exploration receiver. The collected electric field data is combined with the coordinate position to perform inversion calculations to determine the planar distribution location of the foundation piles; Based on the inversion calculation results, a planar distribution map of the foundation piles is obtained, and the location of the foundation piles within the area to be measured is determined.

2. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 1, characterized in that, The process of obtaining the estimated minimum diameter and estimated maximum top burial depth of the piles within the test area specifically includes: Identify the area to be measured, and obtain the estimated minimum diameter and estimated maximum top burial depth of the piles in the area by referring to the design drawings or conducting on-site surveys. The estimated minimum diameter refers to the minimum diameter of the piles, and the estimated maximum top burial depth refers to the maximum value of the top burial depth of the piles. When complete information cannot be obtained from design drawings, the depth and diameter of the foundation piles are estimated by on-site drilling or detection methods to determine the estimated minimum diameter and maximum top depth of the foundation piles in the area to be tested.

3. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 1, characterized in that, The deployment scheme generator automatically generates optimized deployment parameters based on the input estimated parameters, specifically including: Based on the input estimated minimum diameter and estimated maximum top burial depth, the length of the measuring line and the spacing between electrodes are calculated using a preset parameter matching principle. The ratio between the measuring line length and the estimated maximum top burial depth is determined by a first matching coefficient, and the ratio between the electrode spacing and the estimated minimum diameter is determined by a second matching coefficient.

4. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 3, characterized in that, The parameter matching principle includes: Measurement line length Based on the first matching coefficient Compared with the estimated maximum top burial depth Confirmed, the formula is as follows: in, The first matching coefficient, To estimate the maximum top burial depth; This refers to the length of the survey line; Electrode spacing By the second matching coefficient Compared with the estimated minimum pile diameter Confirmed, the formula is as follows: in, This is the second matching coefficient; To estimate the minimum pile diameter; The spacing between the electrodes; The range of values ​​for the first matching coefficient and the second matching coefficient was determined through extensive pile layout simulations, experimental data statistics, and on-site verification.

5. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 3, characterized in that, When the calculated survey line length and electrode spacing do not meet the requirement of equal spacing, the layout scheme generator adjusts the matching coefficient according to the preset adjustment priority, specifically: Prioritize adjusting the electrode spacing within the allowable range of the second matching coefficient so that the electrode placement points can be evenly spaced along the survey line; If the requirement for equal spacing cannot be met after adjusting within the range of the second matching coefficient, the length of the survey line shall be adjusted within the allowable range of the first matching coefficient. The process continues until the determined survey line length and electrode spacing meet the requirement of equal spacing of electrodes along the survey line, and the adjusted layout parameters are output. The requirement for equidistant electrode placement includes: within the length of the measuring line, the number of electrode placement points is an integer, and the spacing between adjacent electrode placement points is consistent, with no remaining length or non-equidistant electrode placement points.

6. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 1, characterized in that, The process involves laying out survey lines and electrodes in the area to be measured based on the generated deployment parameters, and then using an electrical resistivity exploration receiver to collect electric field data. Specifically, this includes: A unified planar coordinate system is established within the area to be measured, and at least one survey line is laid out according to the length of the survey line. The actual length of the survey line is not less than the length of the survey line output by the layout scheme generator, and the direction and position of the survey line are designed according to the range of the area to be measured, covering all areas where foundation piles may exist. Multiple electrode placement points are arranged at equal intervals along the measurement line according to the electrode placement spacing, and several adjacent electrodes are selected to form a measurement unit in each measurement. The measurement unit includes four electrode placement points, wherein the electrodes located at both ends of the measurement unit serve as power supply electrodes, and the electrodes located between the power supply electrodes serve as measurement electrodes. An excitation current is applied to the power supply electrode by an electrical exploration transmitter, and the electric field response between the measuring electrodes is collected by an electrical exploration receiver to obtain the electric field data of the corresponding measuring unit. After completing the data acquisition of a measurement unit, the measurement unit is moved along the measurement line by one electrode layout interval, and the above power supply and data acquisition process is repeated until the measurement unit is located at the end of the measurement line and no longer meets the complete layout conditions. After completing the rolling measurement of the same measurement unit span, the number of electrodes participating in the measurement unit is increased to expand the measurement unit span, and the rolling measurement continues under the expanded measurement unit conditions to obtain electric field data at different scales within the measurement line range step by step.

7. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 1, characterized in that, The electric field data includes: When an excitation current is applied between the power supply electrodes by an electrical exploration transmitter, the potential difference information collected between the corresponding measurement electrodes is obtained. The measurement geometric parameters corresponding to the potential difference information include the magnitude of the power supply current, the distance between the power supply electrodes, and the distance between the measuring electrodes.

8. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 1, characterized in that, The process of inverting the collected electric field data with coordinate positions to determine the planar distribution location of the foundation piles specifically includes: The potential difference information, measurement geometric parameters, and spatial coordinates of the measurement unit in the planar coordinate system are integrated from the electric field data to form the input dataset required for the inversion calculation, specifically including: Potential difference information at measurement points Data was collected by an electrical resistivity survey receiver. Corresponding supply current ; Electrode geometric parameters This includes the electrode spacing for supplying electrodes and the electrode spacing for measuring electrodes; Spatial position of the measurement point in the plane coordinate system The location of the survey line and the spacing of the electrode layout are determined by the layout scheme generator. A subsurface medium grid model was established, and the area to be measured was divided into several uniform grid units; Based on the measurement principles of the four-electrode method or Wenner configuration, a forward electric field calculation model is established, mapping the resistivity of the grid cells to the theoretical potential difference, as shown in the following formula: in, Indicates the first k The theoretical potential difference at each measurement point; Indicates the first k The power supply current at each measurement point; Indicates the first k Electrode geometric parameters at each measurement point; Indicates the first k The measurement point corresponding to the th measurement point i The resistivity of each grid cell; This is the mapping function for the forward calculation model of the electric field; Based on the theoretical potential difference and the potential difference information of the measurement points, an optimization objective function is constructed. The optimization objective function is solved by the nonlinear least squares method to obtain the resistivity of each grid cell in the underground medium grid model. Based on the resistivity distribution of each grid cell obtained through iterative solution The system identifies areas of abnormal resistivity, maps these areas onto a plane coordinate system, and uses the corresponding locations as potential pile locations to generate a planar distribution map of the piles, thus completing the spatial positioning of the piles.

9. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 8, characterized in that, The optimization objective function is expressed as: in, Indicates the total number of measurement points; Indicates the first k The observed potential difference at each measurement point.

10. The electrical resistivity tomography method for shallow buried piles based on automatic parameter matching according to claim 8, characterized in that, The resistivity distribution of each grid cell obtained by iterative solution Identify regions of abnormal resistivity, specifically including: Calculate the resistivity difference of each grid cell relative to the resistivity of the surrounding background medium. ,in This represents the average background value of the resistivity in the region to be measured. Set resistivity anomaly threshold Based on a threshold, grid cells with resistivity significantly higher or lower than the background are selected, i.e., those that meet the criteria... The grid cells were identified as abnormal regions; Adjacent anomalous region grid cells are spatially clustered to form continuous anomalous regions.

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