Magnetic control area magnetic anomaly evaluation method based on magnetic rock mass parameter inversion

Abstract

The invention relates to the technical field of rock mass magnetic data processing, in particular to a magnetic control area magnetic anomaly evaluation method based on magnetic rock mass parameter inversion. Sampling the target magnetic rock mass to obtain measurement data and magnetic parameters; performing inversion on the magnetic parameters of the target magnetic rock mass to obtain optimized magnetic parameters; establishing a hysteresis loop according to the optimized magnetic parameters; re-optimizing the optimized magnetic parameter by using a J-A hysteresis model to obtain an optimal magnetic parameter; establishing a coefficient matrix according to the measurement data of the target magnetic rock mass, and calculating the magnetic field of the target magnetic rock mass in combination with the optimal magnetic parameter; and performing forward modeling calculation on the magnetic field of the target magnetic rock mass to obtain a magnetic anomaly region of the target magnetic rock mass for evaluation. The magnetic anomaly evaluation method provided by the invention can accurately evaluate the magnetic characteristics of the vein, thereby providing more accurate underground condition data for engineers, obtaining the size of the magnetic anomaly under extreme conditions, and helping formulate a more reasonable construction scheme.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass magnetic data processing, and in particular to a magnetic anomaly assessment method for a magnetically controlled area based on magnetic rock mass parameter inversion. Background Art

[0002] Most ships are built with ferromagnetic materials such as steel. The magnetic field generated by these materials may not only interfere with the normal operation of certain shipboard equipment, but also pose a threat to the concealment and safety of the ship. In order to reduce the magnetic field generated by ferromagnetic hulls and other structures during the construction and navigation of the ship, the ship needs to be moored in a non-magnetic space area with a strong alternating attenuated pulse magnetic field for demagnetization. In engineering practice, the construction of such a space requires that there is no interference from other magnetic materials (except ships) in the space. Such a space area is called a magnetic control area. The geomagnetic environment in the magnetic control area is required to be uniform and without obvious distortion. The materials used to build the magnetic control area are also required to be made of non-magnetic or low-magnetic materials.

[0003] Since the magnetic control area has high requirements for the geographical magnetic environment, the magnetic control area is divided into uniform rectangular grids, and the difference between the maximum and minimum values ​​of the vertical component of the magnetic induction intensity of all grids is no more than 100nT, in order to meet the demagnetization requirements of the site during ship demagnetization; however, during the construction of the magnetic control area, due to the limitations of actual construction costs and geographical location conditions, the magnetic control area may be affected by the magnetic rock mass of the local rock strata, resulting in magnetic anomaly areas in the magnetic control area, which will have a certain degree of impact on the ship's magnetic measurement and magnetic processing related work.

[0004] Since magnetic rock may exist in the area where the magnetic control zone is located, the current method of completely removing the magnetic ore has huge civil construction costs and is likely to extend the construction time. Therefore, it is particularly important to conduct a magnetic field assessment of the magnetic rock in the magnetic control zone to make the next construction decision. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a magnetic anomaly assessment method for a magnetically controlled area based on the inversion of magnetic rock mass parameters. The scheme includes: sampling the target magnetic rock mass to obtain measurement data and magnetic parameters; inverting the magnetic parameters of the target magnetic rock mass to obtain optimized magnetic parameters; establishing a hysteresis loop according to the optimized magnetic parameters; re-optimizing the optimized magnetic parameters using the JA hysteresis model to obtain the optimal magnetic parameters; establishing a coefficient matrix according to the measurement data of the target magnetic rock mass, and calculating the magnetic field of the target magnetic rock mass in combination with the optimal magnetic parameters; forward modeling the magnetic field of the target magnetic rock mass to obtain the magnetic anomaly area of ​​the target magnetic rock mass for assessment. The magnetic anomaly assessment method proposed in the present invention can accurately assess the magnetic characteristics of the ore vein, thereby providing engineers with more accurate underground situation data, deriving the size of the magnetic anomaly under extreme conditions, and helping to formulate a more reasonable construction plan.

[0006] The present invention adopts the following technical scheme, a method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion, comprising:

[0007] Sampling the target magnetic rock mass to obtain measurement data and magnetic parameters of the target magnetic rock mass;

[0008] Inverting the magnetic parameters of the target magnetic rock mass using a differential evolution algorithm to obtain optimized magnetic parameters;

[0009] Establish a hysteresis loop of the target magnetic rock mass according to the optimized magnetic parameters; re-optimize the optimized magnetic parameters using the JA hysteresis model of the target magnetic rock mass to obtain the optimal magnetic parameters;

[0010] Establishing a coefficient matrix according to the measurement data of the target magnetic rock mass, and calculating the magnetic field of the target magnetic rock mass in combination with the optimal magnetic parameters;

[0011] The magnetic field of the target magnetic rock mass is forward calculated to obtain the magnetic anomaly area of ​​the target magnetic rock mass for evaluation.

[0012] Furthermore, the measurement data and magnetic parameters of the target magnetic rock mass include:

[0013] Sampling the target magnetic rock mass to obtain the collected ore, wherein the measurement data includes: ore size, ore shape parameters, ore position parameters in the vein, and position parameters of each measurement point on the measurement plane;

[0014] The magnetic parameters include: magnetization intensity, magnetic permeability and coercive force.

[0015] Furthermore, the magnetic parameters of the target magnetic rock mass are inverted using a differential evolution algorithm, including:

[0016] The inversion model of the target magnetic rock mass is established using the differential evolution algorithm, and the magnetic data of the magnetic ore is used as the input of the inversion model;

[0017] Gridding the target ore, and obtaining the magnetization intensity of the target magnetic rock mass corresponding to the fitted grid according to the magnetic data of the target magnetic rock mass and the inversion model;

[0018] The magnetization intensity of the fitted grid is iteratively optimized according to the magnetic data of the target magnetic rock mass to obtain the optimized magnetic parameters.

[0019] Furthermore, the JA hysteresis model expression of the target magnetic rock mass is:

[0020]

[0021] Where M is the magnetization intensity, M an is the hysteresis-free magnetization, H e is the effective magnetic field strength, δ M is the confinement coefficient, α is the coupling mean field parameter within the magnetic domain, c is the reversibility coefficient, k is the pinning coefficient, δ is the direction coefficient, represents the first-order differential equation about the hysteresis loop.

[0022] Furthermore, the optimized magnetic parameters are optimized again, including:

[0023] The target magnetic rock mass is subjected to multiple amplitude magnetic field attenuation impacts and corresponding magnetic field magnetization treatments of multiple magnitudes to obtain optimized magnetic parameters under different magnetization states;

[0024] Establishing a plurality of corresponding hysteresis loops according to the optimized magnetic parameters under different magnetization states, and re-optimizing the optimized magnetic parameters according to the established plurality of hysteresis loops to obtain the optimal magnetic parameters;

[0025] The optimal magnetic parameters are mapped to each fitting grid of the target magnetic rock mass using a mapping relationship.

[0026] Furthermore, the method for calculating the magnetic field of the target magnetic rock mass is:

[0027] The measurement plane is set for the target magnetic rock mass by using the integral equation method, and a coefficient matrix is ​​established according to the positional relationship between the fitted grid of the target magnetic rock mass and the set measurement plane.

[0028] A matrix operation is performed on the optimal magnetic parameters and the coefficient matrix to obtain the magnetic field of the target magnetic rock mass.

[0029] Furthermore, forward calculation of the magnetic field of the target magnetic rock mass includes:

[0030] When the target magnetic rock mass uses the maximum magnetic permeability, an expansion coefficient of the magnetic rock mass is set when the magnetic permeability is a variable; the expansion coefficient represents the proportion of the magnetic rock in the total magnetic rock mass and the setting range of the magnetic parameters of the magnetic rock;

[0031] According to the expansion coefficient and the forward calculation model, the magnetic anomaly area of ​​the target magnetic rock mass is obtained.

[0032] Furthermore, the magnetic anomaly area of ​​the target magnetic rock mass is obtained for evaluation, specifically:

[0033] The magnetic anomaly area, the measurement plane and the fitting grid of the target magnetic rock mass are respectively mapped, and the magnetic field distribution map of the target magnetic rock mass is established according to the positional relationship between the magnetic anomaly area and the fitting grid;

[0034] According to each measuring point in the measuring plane of the target magnetic rock mass and the magnetic field distribution map, a three-dimensional magnetic field distribution map of the target magnetic rock mass is established by using a contour drawing method;

[0035] The magnetic anomaly area is observed and evaluated based on the three-dimensional magnetic field distribution map.

[0036] The beneficial effects of the present invention are as follows: the magnetic anomaly evaluation method proposed in the present invention can accurately simulate and analyze the magnetic field generated by the magnetic rock mass, and by analyzing the collected ore samples, the magnetic characteristics of these samples can be obtained, and then the magnetic field distribution of the entire magnetic rock mass can be highly accurately estimated; in the process of estimation, the present invention evaluates the magnetic anomaly by paying attention to the magnetic anomaly phenomenon, and can deeply understand the geological characteristics of the magnetic rock mass, and provide a solid scientific basis for the decision-making plan of the magnetic control area; establishing the JA hysteresis model can better obtain all-round data of rock samples and magnetic rock masses, and by adjusting and optimizing relevant parameters, it can also analyze the magnetic anomaly that may occur under extreme conditions, and provide all-round data support for solving the magnetic anomaly problem.

[0037] The application of this technology is not limited to the field of geological exploration, but also has important significance for magnetic assessment of civil engineering, ship hulls and satellites. In civil engineering construction, it is crucial to avoid magnetic anomaly areas in magnetic control areas, because magnetic anomalies may have serious impacts on the stability, safety and efficiency of construction projects. Traditional treatment methods often require the excavation of magnetic rock masses, which not only requires huge manpower and material resources, but may also cause damage to the ecological environment. This technology can identify and avoid potential magnetic anomaly areas in advance through accurate magnetic field calculation and magnetic anomaly inversion, thereby greatly reducing the cost of civil construction and improving the overall benefits of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a schematic flow chart of a method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a magnetic rock mass subdivision unit and calculation field points for digging 1.6 m downwards according to an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of a magnetic rock mass subdivision unit and calculation field points for digging 2.4 m downwards according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of a magnetic rock mass subdivision unit and calculation field points for digging 3.2 m downwards according to an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of a magnetic rock mass subdivision unit and calculation field points for digging 4.0 m downwards according to an embodiment of the present invention;

[0044] Figure 6 A schematic diagram of a magnetic rock mass subdivision unit and calculation field points for digging 4.8 m downwards according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of the change of the magnetization curve of a rock material under an external attenuated magnetic field according to an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of a hysteresis loop under different magnetization states according to an embodiment of the present invention;

[0047] Fig. 9 A schematic diagram of a simulation result of the influence of a 1mT magnetizing magnetic field according to an embodiment of the present invention;

[0048] Fig.10 A schematic diagram of a simulation result of the influence of a 2mT magnetizing magnetic field according to an embodiment of the present invention;

[0049] Fig.11 A schematic diagram of a simulation result of the influence of a 3mT magnetizing magnetic field according to an embodiment of the present invention;

[0050] Fig.12 This is a schematic diagram of the spatial additional magnetic field distribution characteristics of the magnetic rock mass in the middle of the coil when digging down to a depth of 1.6m according to an embodiment of the present invention;

[0051] Fig.13 This is a schematic diagram of the spatial additional magnetic field distribution characteristics of the magnetic rock mass in the middle of the coil when digging down to a depth of 2.4m according to an embodiment of the present invention;

[0052] Fig.14 This is a schematic diagram of the spatial additional magnetic field distribution characteristics of the magnetic rock mass in the middle of the coil when digging down to a depth of 3.2 m according to an embodiment of the present invention;

[0053] Fig.15 This is a schematic diagram of the spatial additional magnetic field distribution characteristics of the magnetic rock mass in the middle of the coil when digging down to a depth of 4.0m according to an embodiment of the present invention;

[0054] Fig.16 This is a schematic diagram of the spatial additional magnetic field distribution characteristics of the magnetic rock mass in the middle of the coil when digging down to a depth of 4.8m according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] A flow chart of a method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to an embodiment of the present invention is shown in FIG. Figure 1 As shown, including:

[0057] The first step is to sample the magnetic rock mass to be studied.

[0058] The ore collected in the embodiment of the present invention can represent the magnetic state of a certain area of ​​the magnetic rock mass. The size of the ore can be measured in the laboratory. The amount of measured data can obtain an accurate inversion model of the magnetic rock mass. In addition to recording the magnetic field measurement data, the position parameters of each measurement point on the measurement plane, the shape parameters of the ore sample, and the experimental data under different magnetization conditions should all be recorded.

[0059] Step 2: Inverse and optimize the remanent magnetism and magnetic susceptibility of magnetic ore.

[0060] In the embodiment of the present invention, the large plane magnetic field value of the magnetic ore at a certain height or depth obtained by measurement is used as input, and the magnetic parameters (magnetization intensity, magnetic permeability and other magnetic parameters) that generate magnetic field anomaly are inverted and calculated by using the optimization algorithm. The optimization algorithm adopts the differential evolution algorithm. In the initial case, the population size, scaling factor and hybridization probability, the range of the required optimization parameters and the number of iterations need to be set. The range of the optimization parameters and the number of iterations directly affect the accuracy of the optimization parameters and the time of the optimization algorithm. After the initial conditions are set, the residual magnetization intensity is optimized by using the measurement data of the ore sample and the subdivision grid fitted with the ore sample. The measurement data of the ore sample is compared with the data generated by the subdivision grid in the same measurement plane, and the optimal solution is continuously iterated to find the optimal solution. The optimized residual magnetization intensity is corresponded to each subdivision grid. The residual magnetization intensity of adjacent grids has continuity. According to the mapping relationship between the subdivision grid of the ore sample and the magnetic rock mass, the position correspondence between the optimized residual magnetization intensity and the subdivision grid of the magnetic rock mass is obtained.

[0061] Step 3: Use the JA hysteresis model to establish and optimize the hysteresis loop.

[0062] The JA hysteresis model is based on the energy conservation principle of magnetic materials during the magnetization process, and derives a hysteresis model in the form of a first-order ordinary differential equation. The model separates the reversible magnetization component and the irreversible magnetization component in the magnetic material, and comprehensively considers factors such as the magnetic field intensity, magnetization intensity, and the average field parameter of the coupling within the magnetic domain to simulate the hysteresis characteristics. It is a hysteresis model based on the motion law of the magnetic domain wall under the pinning effect and the principle of energy conservation. The model decomposes the magnetization intensity M into the reversible magnetization intensity M rev and irreversible magnetization M irr The sum is:

[0063] M=M rev +M irr

[0064] Among them, M rev represents the reversible magnetization intensity under the action of an external magnetic field, M irr It represents the irreversible magnetization intensity component in the magnetization process, corresponding to the defective magnetic domain part in the soft magnetic material, M rev With M irr The relationship between them is expressed as:

[0065] M rev =c(M an -M irr )

[0066]

[0067] Where M an , H eThey represent the hysteresis-free magnetization intensity and the effective magnetic field intensity, c is the reversibility coefficient, 0 <c<1;δ M is a restriction factor introduced to prevent non-physical solution. k is the pinning coefficient, which is related to the energy loss in the magnetization process. δ is the direction coefficient. When dH / dt>0, δ=1; when dH / dt<0, δ=-1, which ensures that the defective magnetic domain consumes energy when it is magnetized. an , H e and δ M Respectively expressed as:

[0068]

[0069] H e =H+αM

[0070]

[0071] Where M s is the saturation magnetization intensity; α is the coupling mean field parameter within the magnetic domain, which characterizes the degree of magnetic field interaction between magnetic domains; a is the shape parameter of the hysteresis-free magnetization curve, which characterizes the degree of magnetic field interaction between magnetic domains.

[0072] The energy conservation formula during magnetization is as follows:

[0073]

[0074] The JA model is derived as follows:

[0075]

[0076] In the embodiment of the present invention, the ore sample is subjected to impacts of magnetic field attenuation of different amplitudes and magnetic field magnetization of different sizes, so as to obtain magnetic parameters under different states, and the drawing of some points in the hysteresis loop can be realized. However, the hysteresis loop is not complete at this time, but only a distribution diagram of some measuring points. Therefore, it is necessary to use the JA model for supplementation and optimization. By calculating the impact magnetic field value by calculating the surrounding coil current, the magnetization intensity M under any impact magnetic field can be found; Ms (i.e., saturation magnetization intensity) in the experiment is known, α, c, k, δ (α is the coupling mean field parameter within the magnetic domain, c is the reversible coefficient, k is the pinning coefficient, and δ is the directional coefficient) has been determined in the experiment, and M is calculated by function interpolation of the measured magnetic parameters and the known M and H (external magnetic field strength). an , H e ,δ M (respectively, the hysteresis-free magnetization intensity, the effective magnetic field intensity, and the restriction coefficient introduced to prevent non-physical solutions), and the hysteresis loop is obtained. The first-order differential equation can be used to forward model the JA model and form a complete hysteresis loop that can conform to each measuring point, making the hysteresis loop more complete and smooth; its streamlined parameter configuration effectively reduces the complexity of model implementation and improves calculation efficiency. The hysteresis loops under different magnetization states can fully display the physical properties of ore samples. At the same time, with the support of a large amount of data, the magnetic parameters can be optimized, which is more accurate and reliable.

[0077] Different JA model parameters represent hysteresis loops of different shapes. In a specific embodiment of the present invention, the model parameters of the material can be calculated by a particle swarm algorithm. The JA model is based on the principle of conservation of energy and the microscopic physical mechanism of magnetic materials. It deeply describes the hysteresis phenomenon through mathematical equations and can accurately reflect the physical behavior of magnetic materials under any magnetization state, so that the model has high credibility and a solid theoretical foundation in theory. In addition, the number of parameters in the JA model is relatively small, and each parameter has a clear physical meaning. These parameters can be identified through experimental data or intelligent optimization algorithms, thereby achieving a high degree of adaptability to diverse magnetic materials and changing working environments. The streamlined parameter configuration effectively reduces the computational burden of the model, reduces the complexity of model implementation, improves computational efficiency, and promotes its widespread adoption in theoretical analysis and practical applications.

[0078] After establishing the hysteresis loops under different magnetization states, the magnetic parameters inverted by the optimization algorithm are re-optimized to obtain the optimal magnetic parameters. According to the grid size and position, a mapping relationship is used to correspond the magnetic parameters to the grid of the magnetic rock mass and strata. Since the optimization data come from different ore samples, the corresponding magnetic rock sampling locations are also different, so the mapping relationship used on the JA model is also different.

[0079] Step 4: Calculate the magnetic field.

[0080] The embodiment of the present invention uses the integral equation method to set the measurement plane of the target magnetic rock mass, sets the coefficient matrix according to the positional relationship between the subdivision grid of the magnetic rock layer and the measurement plane, corresponds the optimized magnetic parameters to the coefficient matrix, and obtains the calculated magnetic field on the set measurement plane after matrix operation.

[0081] Step 5: Carry out forward calculation and evaluation on the additional magnetic field generated when the magnetic rock mass is subjected to a strong alternating attenuated pulse magnetic field.

[0082] According to the requirements of ship magnetic treatment, the present invention considers the influence of magnetic field changes of magnetic rock mass on magnetic treatment when a strong alternating attenuated pulse magnetic field is applied. Since the magnetic permeabilities of various regions of the magnetic rock mass are different, the present invention uses the JA model to set the expansion coefficient χ of the magnetic rock mass when the magnetic permeability is a change, considering that all magnetic rock masses use the maximum magnetic permeability. The size of magnetic anomalies under extreme conditions can be obtained, providing a construction reference for magnetic control areas under the worst conditions for engineering construction, and providing a guarantee for construction efficiency. The expansion coefficient in the present invention represents the change of magnetic field size with magnetic parameters, that is, the ratio of the magnetic field size per unit magnetic parameter change to the initial magnetic field size.

[0083] Step 6: Map the magnetic anomaly area.

[0084] By drawing the divided grid and the measurement plane, the positional relationship between the measurement plane and the magnetic rock mass can be clearly obtained. By drawing the distribution diagram of the size of the calculated magnetic field of each component, the magnetic field distribution trend can be intuitively analyzed. In the embodiment of the present invention, contour drawing is used to analyze the relationship between the measurement point and the magnetic field distribution. A three-dimensional magnetic field distribution diagram is drawn according to the magnetic field distribution of different measurement planes. The magnetic anomaly situation is observed more intuitively and systematically for analysis and decision-making, so as to analyze the influencing factors and degree and then put forward construction suggestions and plans to implement the engineering requirements.

[0085] In another specific embodiment of the present invention, in order to verify the implementation effect of the present invention, a magnetic rock sample of a certain place is selected for measurement. During the exploration and construction of the magnetic control area of ​​the place, it is found that there are several magnetic rock masses, whose magnetism is much greater than that of rocks in other positions; under the action of the magnetic field of the demagnetization working coil, the magnetic rock mass will produce a variable additional magnetic field, which will cause great interference to the magnetic control of the magnetic control area, and will lead to the serious consequence that the magnetic field measurement system cannot measure the magnetic field normally. In order to eliminate the interference of the additional magnetic field of the magnetic rock mass, its spatial distribution must be analyzed.

[0086] First, this embodiment detects the magnetic state parameters of the magnetic rock sample, and analyzes the magnetic field distribution generated by the demagnetization working coil in the periphery (i.e., in the magnetic rock), thereby determining the state parameters of the additional magnetism of the magnetic rock. According to the determined state parameters of the additional magnetism of the magnetic rock, the numerical calculation technology of the magnetic field is used to analyze the spatial distribution of the additional magnetic field of the magnetic rock, including the spatial distribution of the additional magnetic field of the magnetic rock at different excavation depths. On the basis of comprehensive calculation and analysis, a technical suggestion is proposed to partially excavate the magnetic rock to eliminate the interference of the additional magnetic field of the magnetic rock, and technical parameters such as the excavation depth are given, which specifically include the following contents:

[0087] In step one, the magnetic rock sample is magnetized in a magnetizing device, and the external magnetic field of the magnetic rock sample is measured before and after being magnetized in the magnetizing device.

[0088] Step 2: Measure the initial magnetic permeability, residual magnetization and coercive force of the magnetic rock samples. According to the measurement of the external magnetic field of the magnetic rock samples before and after magnetization in the magnetization device, the magnetic rock samples are divided into three groups: strong magnetism, medium magnetism and weak magnetism. Three samples are selected from each group, and three samples are made from each sample, for a total of 27 samples. The initial magnetic permeability, residual magnetization and coercive force of the samples are measured with a magnetometer. Draw the hysteresis loop based on the measured magnetic parameters and optimize it using the JA model.

[0089] Step 3: Analyze the magnetic field in the space surrounding the demagnetization working coil. Calculate the distribution of the magnetic field of the demagnetization working coil in the space surrounding it (i.e., in the magnetic rock mass).

[0090] Step 4: Analysis of additional magnetic field in magnetic rock space. Based on the measured values ​​of initial magnetic permeability, residual magnetization and coercive force of magnetic rock sample optimized by JA hysteresis model, and the peripheral spatial distribution of magnetic field of demagnetizing working coil, the change of additional magnetic state caused by magnetization of magnetic rock by demagnetizing working coil is analyzed. Based on the change of additional magnetic state parameters of magnetic rock, the calculation technology of three-dimensional static magnetic field integral equation method is used to calculate and analyze the distribution of additional magnetic field in magnetic rock space.

[0091] Step 5: Technical suggestions for eliminating the additional magnetic field interference in the magnetic rock mass space. Based on the analysis results of the additional magnetic field in the magnetic rock mass space, technical suggestions for eliminating the additional magnetic field interference in the magnetic rock mass space are proposed.

[0092] like Figures 2 to 6 As shown in the figure, a schematic diagram of the structure of magnetic rock mass subdivision units and calculation points when digging down to different depths is given. Figure 7 The change of the material magnetization curve of rock material under the external attenuated magnetic field is calculated by using the JA model. The magnetization curve assigned to the simulation model is determined according to the position of the magnetization state after the demagnetization field is reduced to zero. Figure 8 As shown in the figure, based on this simulation, the spatial distribution characteristics of the magnetic field of the rock are simulated; further, uniform magnetic fields with magnetic induction intensities of 1mT, 2mT, and 3mT are applied to the outside of the sample to magnetize the sample, simulating the influence of different magnetic field magnetization on the spatial magnetic field distribution of the sample. The simulation results are shown in Figures 9 to 11 As shown, it can be seen that as the magnetizing magnetic field increases from 1mT to 3mT, the magnetic induction intensity distributed around the sample also increases accordingly.

[0093] The schematic diagram of the spatial additional magnetic field distribution (taking the magnetic field in the middle of the working coil as an example) obtained by digging out magnetic rock at different depths is shown in the figure below: Figures 12 to 16As shown, Figure A shows the longitudinal distribution characteristics of the additional magnetic field of the magnetic rock mass in the middle of the coil; Figure B shows the lateral distribution characteristics of the additional magnetic field of the magnetic rock mass in the middle of the coil; after comprehensive calculation and analysis, it is found that in order to better eliminate the interference of the additional magnetic field in the space of the magnetic rock mass, it is necessary to dig the magnetic rock mass down from the bottom of the pit by at least 3.2m; if the magnetic rock mass is very thin, the digging depth can be appropriately reduced, but it must not be less than 2.0m.

[0094] From the above analysis and conclusions, it can be seen that this is the minimum requirement. Below this standard, the interference caused by the additional magnetic field of the magnetic rock mass to the magnetic control area is likely to be unable to be eliminated, causing irreparable losses. After detailed comprehensive calculations and in-depth analysis, in order to effectively and significantly eliminate the additional magnetic field interference generated by the magnetic rock mass in space, it is necessary to ensure that the magnetic rock mass is at least 3.2 meters from the bottom of the pit; this depth is determined based on multiple considerations of the magnetic field distribution characteristics, the magnetic strength of the rock, and the influence of the surrounding geological structure on the magnetic field. At the same time, for magnetic rock areas with relatively small thickness, although the excavation depth can be appropriately reduced to save cost and time, this reduction must be strictly controlled above the lower limit of 2.0 meters to ensure that the weakening effect of the magnetic field interference can still reach an acceptable level.

[0095] It is worth noting that the above-mentioned excavation depth is the minimum necessary condition to eliminate or significantly reduce the additional magnetic field interference of magnetic rock mass. Any excavation operation below this standard may not be able to fully isolate the interference of magnetic rock mass to the surrounding magnetic control area, thereby affecting the accuracy and reliability of high-precision magnetic exploration. It may even mislead geological interpretation due to the residual magnetic field interference, leading to misjudgment in mineral exploration, engineering construction or other related fields, and ultimately causing irreparable losses such as waste of resources, project delays and even safety accidents. Therefore, when planning and executing relevant excavation operations, this depth standard must be strictly observed. At the same time, combined with field survey data, a scientific excavation plan must be formulated to ensure that the additional magnetic field interference of magnetic rock mass is effectively controlled, laying a solid foundation for subsequent exploration, development or construction activities.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating magnetic anomalies in magnetically controlled areas based on inversion of magnetic rock mass parameters, characterized in that: include: Sampling the target magnetic rock mass to obtain measurement data and magnetic parameters of the target magnetic rock mass; Inverting the magnetic parameters of the target magnetic rock mass using a differential evolution algorithm to obtain optimized magnetic parameters; Establishing the hysteresis loop of the target magnetic rock mass according to the optimized magnetic parameters; The optimized magnetic parameters are re-optimized using the JA hysteresis model of the target magnetic rock mass to obtain the optimal magnetic parameters; Establishing a coefficient matrix according to the measurement data of the target magnetic rock mass, and calculating the magnetic field of the target magnetic rock mass in combination with the optimal magnetic parameters; The magnetic field of the target magnetic rock mass is forward calculated to obtain the magnetic anomaly area of ​​the target magnetic rock mass for evaluation.

2. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The measurement data and magnetic parameters of the target magnetic rock mass include: Sampling the target magnetic rock mass to obtain the collected ore, wherein the measurement data includes: ore size, ore shape parameters, ore position parameters in the vein, and position parameters of each measurement point on the measurement plane; The magnetic parameters include: magnetization intensity, magnetic permeability and coercive force.

3. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The magnetic parameters of the target magnetic rock mass are inverted using a differential evolution algorithm, including: The inversion model of the target magnetic rock mass is established using the differential evolution algorithm, and the magnetic data of the magnetic ore is used as the input of the inversion model; Gridding the target ore, and obtaining the magnetization intensity of the target magnetic rock mass corresponding to the fitted grid according to the magnetic data of the target magnetic rock mass and the inversion model; The magnetization intensity of the fitted grid is iteratively optimized according to the magnetic data of the target magnetic rock mass to obtain the optimized magnetic parameters.

4. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The JA hysteresis model expression of the target magnetic rock mass is: Where M is the magnetization intensity, M an is the hysteresis-free magnetization, H e is the effective magnetic field strength, δ M is the confinement coefficient, α is the coupling mean field parameter within the magnetic domain, c is the reversibility coefficient, k is the pinning coefficient, δ is the direction coefficient, represents the first-order differential equation about the hysteresis loop.

5. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The optimized magnetic parameters are optimized again, including: The target magnetic rock mass is subjected to multiple amplitude magnetic field attenuation impacts and corresponding magnetic field magnetization treatments of multiple magnitudes to obtain optimized magnetic parameters under different magnetization states; Establishing a plurality of corresponding hysteresis loops according to the optimized magnetic parameters under different magnetization states, and re-optimizing the optimized magnetic parameters according to the established plurality of hysteresis loops to obtain the optimal magnetic parameters; The optimal magnetic parameters are mapped to each fitting grid of the target magnetic rock mass using a mapping relationship.

6. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The method for calculating the magnetic field of the target magnetic rock mass is: The measurement plane is set for the target magnetic rock mass by using the integral equation method, and a coefficient matrix is ​​established according to the positional relationship between the fitted grid of the target magnetic rock mass and the set measurement plane. A matrix operation is performed on the optimal magnetic parameters and the coefficient matrix to obtain the magnetic field of the target magnetic rock mass.

7. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: The magnetic field of the target magnetic rock mass is forward calculated, including: When the target magnetic rock mass uses the maximum magnetic permeability, an expansion coefficient of the magnetic rock mass is set when the magnetic permeability is a variable; the expansion coefficient represents the proportion of the magnetic rock in the total magnetic rock mass and the setting range of the magnetic parameters of the magnetic rock; According to the expansion coefficient and the forward calculation model, the magnetic anomaly area of ​​the target magnetic rock mass is obtained.

8. The method for evaluating magnetic anomaly in a magnetically controlled area based on magnetic rock mass parameter inversion according to claim 1, characterized in that: Obtain the magnetic anomaly area of ​​the target magnetic rock mass for evaluation, specifically: The magnetic anomaly area, the measurement plane and the fitting grid of the target magnetic rock mass are respectively mapped, and the magnetic field distribution map of the target magnetic rock mass is established according to the positional relationship between the magnetic anomaly area and the fitting grid; According to each measuring point in the measuring plane of the target magnetic rock mass and the magnetic field distribution map, a three-dimensional magnetic field distribution map of the target magnetic rock mass is established by using a contour drawing method; The magnetic anomaly area is observed and evaluated based on the three-dimensional magnetic field distribution map.

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