Methods for reducing abnormal difference in elevation measurement in mining areas

Abstract

The present application discloses a method for reducing the abnormal difference of elevation measurement in a mining area, comprising the following steps: Step S1: removing the model gravity anomaly Δg from the observed gravity anomaly Δg GM and topographic gravity effect δN T Obtain the residual gravity anomaly, substitute the residual gravity anomaly into the Stokes formula, and calculate the residual geoid δN as follows r :Step S2: In the absence of gravity data, the geoid height N is decomposed according to the spectral structure characteristics of the elevation anomaly; Step S3: At the unknown point, the model elevation anomaly of the unknown point is calculated by the EGM2008 earth gravity field model, and the residual elevation anomaly ξ of the unknown point is added to the result C , get the final elevation anomaly value of the unknown point, and find the normal height of the unknown point. Through practice, the multifaceted function fitting method based on the "remove-restore" method has a good fitting effect in the Dahongshan copper mine area, and the normal height accuracy after fitting can reach the requirement of ±2cm.

Description

Technical Field

[0001] The present application relates to the field of surveying and mapping engineering technology, and in particular to a method for reducing abnormal elevation differences in mining area measurements. Background Art

[0002] As a representative technology of modern space geodesy, GPS technology has the characteristics of high precision, low cost, speed and flexibility. GPS measurement needs to be combined with a high-precision, high-resolution (quasi-)geoid model to accurately determine the orthometric height or normal height.

[0003] The relative position relationship between the existing quasi-geoid model and the ground and the reference ellipsoid is as follows: Figure 1 As shown. At present, GPS positioning technology can accurately and quickly measure the three-dimensional coordinates of points. However, the elevation measured by GPS is the geodetic height of the station relative to the WGS-84 ellipsoid, while the elevation system used in my country is the normal height system relative to the quasi-geoid.

[0004] Normal height is the distance h from a ground point to the quasi-geoid along the plumb line, while geoid height is the distance H0 from a ground point to the reference ellipsoid along the normal line. The difference between H0 and h is the elevation anomaly.

[0005] If the elevation anomaly value ξ of the ground point is known, then the earth height H 大地 Normal high H 正常 The relationship is:

[0006] H 大地 =H 正常 +ξ

[0007] How to convert geodetic height into normal height has become an important issue in GPS elevation application under specific geographical environment. The existing methods to solve the elevation conversion problem are mainly:

[0008] 1. Comprehensively utilize GPS measurement data and elevation anomaly data to determine the elevation of the point;

[0009] 2. Comprehensively utilize GPS measurement data and leveling measurement data to determine the elevation of the quasi-geoid.

[0010] The first method requires sufficient gravity measurement data. However, due to the severe shortage of gravity measurement data and the difficulty and accuracy of gravity measurement, the second method is used in more cases: combining GPS measurement data with leveling data, selecting a suitable mathematical model, and obtaining the required normal height through fitting methods.

[0011] The basic idea of ​​the elevation fitting method is to measure some leveling points in the GPS network, and then use the orthometric height and geoid height at these points to find the elevation anomaly values ​​of these points. Then, based on the relationship between the elevation anomaly values ​​and the coordinates of these points, use the least squares method to calculate the quasi-geoid of the survey area. Use the fitted quasi-geoid to interpolate the elevation anomalies of other GPS points, so as to find the normal height of each unknown point.

[0012] The second method has been effectively applied in survey areas with flat or simple terrain and has obtained satisfactory results.

[0013] In areas such as the Dahongshan Copper Mine, where the terrain is complex or the terrain of adjacent areas varies greatly, the national C-level GPS control point is used as the starting reference point, and points and networks are reasonably selected and laid out in the center and edge of the mining area. Eleven control points are evenly buried to form a plane control network. The national first-class leveling point is used as the starting reference point, and the leveling route is laid along the mining area road. The third-class leveling measurement is carried out using an electronic level, and the high-precision leveling elevation is introduced into the mining area to the GPS control point involved in the calculation of the level surface model. At GPS points with large height differences and difficult to reach geometric leveling routes, electromagnetic wave ranging elevation traverses are used for measurement.

[0014] A GPS C-level control network consisting of 11 points including HZ01, HL (Hengli), HP (Hongpo), HZ12, 3521, HZ04, G1, DHS5, 35182, 3508, and HZ02-1 was laid out. The highest point (HL) elevation is 1230m; the lowest point (35182) elevation is 695m; the average elevation is 970m. The shortest side is 620m; the longest side is 4659m; the average side length is 2135m. The Gaussian plane coordinates of each control point in the CGCS2000 coordinate system (central meridian east longitude 102°) and the normal height in the 1985 national datum framework were calculated by adjustment using the third-class leveling method. The 11 selected points form the basis for the construction of the geoid model of the mining area. The CGCS2000 plane coordinates, CGCS2000 geodetic coordinates, geodetic height, and normal height provided by the mine are used as known data for geodetic leveling refinement in the mining area. These data are used to construct a model to establish the geoid datum of the Dahong Copper Mine. The result data are shown in Table 1.

[0015] Table 1 GPS control network and elevation control measurement results

[0016]

[0017] In order to conduct field inspection and testing of the established geoid model in the mining area, 23 representative points were selected and arranged as test points in view of the large height difference in the mining area. The GCS2000 plane coordinates, CGCS2000 geodetic coordinates and geodetic height of each point were determined mainly by using GPS static positioning post-processing technology (some points used GPS RTK technology). The normal height of the 23 test points was measured and calculated using the third-class leveling method, and the elevation anomaly of each point was calculated. The results of the test points are shown in Table 2.

[0018] Table 2 Test point results table

[0019]

[0020]

[0021] It can be seen from the elevation anomaly items in Table 2 that the elevation anomaly values ​​of each detection point are all greater than 35m, indicating that the geoid model of the mining area obtained by using the existing benchmark points according to the existing technology is quite different from the actual elevation of the complex geographical environment, and the obtained model cannot be used directly. If the existing method is not improved and the model results obtained by the above method are directly used, the reference planes of each region will deviate from the normal value, resulting in a serious loss of accuracy in the conversion from GPS geoid height to normal height, and the elevation of the point cannot be solved with the corresponding accuracy. Especially in mountainous areas with large elevation differences, the impact of geoid elevation anomalies is particularly obvious, resulting in low accuracy of elevation information. Affecting the normal operation of mining production. Summary of the invention

[0022] The present application provides a method for reducing the abnormal difference in elevation measurement in mining areas, which is used to solve the technical problem that in mining areas with large elevation fluctuations and drastic terrain cutting, the GPS control points obtained by directly using the national first-class leveling points as the starting reference points can produce elevation abnormal values ​​of more than 35m in the detection results, resulting in the inability to use GPS technology for accurate positioning in areas with complex terrain.

[0023] The present application provides a method for reducing the abnormal difference of elevation measurement in a mining area, comprising the following steps:

[0024] Step S1: Remove the model gravity anomaly Δg from the observed gravity anomaly Δg GM and topographic gravity effect δN T Obtain the residual gravity anomaly, substitute the residual gravity anomaly into the Stokes formula, and calculate the residual geoid δN as follows r :

[0025]

[0026] Where π is a constant, G is the observed gravity anomaly, and h is pis the topographic height of the calculation point, γ is the average normal gravity, l is the distance from the calculation point to the flow point, ρ is the crust density,;

[0027] To restore the geoid, calculate N GM and δN T , where N GM Calculated from the bit coefficients;

[0028] Step S2: In the absence of gravity data, according to the spectral structure characteristics of elevation anomaly, the geoid height N is decomposed into:

[0029] ξ=ξ GM +ξ ΔG +ξ T Formula (2)

[0030] Among them, ξ is the anomaly of the Earth's gravity model, ξ GM is the elevation anomaly of the long-wave model, ξ ΔG is the residual elevation anomaly of the medium wave part, ξ T For shortwave part of the terrain is high and positive;

[0031] In the absence of digital elevation model data, ΔG and T The parts are combined and characterized by the method of mathematical model approximation;

[0032] The elevation anomaly of the GPS point is divided into two parts according to the following formula, namely:

[0033] ξ=ξ GM +ξ C Formula (3)

[0034] Among them, ξ C is the residual elevation anomaly.

[0035] Step S3: At the unknown point, the model elevation anomaly of the unknown point is calculated using the EGM2008 Earth gravity field model, and the residual elevation anomaly of the unknown point is added to the result C , get the final elevation anomaly value of the unknown point and find the normal height of the unknown point.

[0036] Preferably, step S1 comprises the following steps:

[0037] The gravity anomaly observation value can also be decomposed into three corresponding parts, namely the model gravity anomaly calculated by the potential model, the terrain gravity effect and the residual gravity anomaly. If the influence of terrain is not considered, the above decomposition can also be divided into two parts, namely the part determined by the potential model and the residual part. These two decompositions can be expressed as:

[0038] N=N GM +δNT +δN r

[0039] Δg=Δg GM +δΔg T +δΔg r

[0040] Step S11: Removal process, i.e., the model gravity anomaly Δg GM and topographic gravity effect δN T The residual gravity anomaly is obtained by removing the observed gravity anomaly Δg:

[0041] δΔg r =Δg-Δg GM -δg T

[0042] In the formula, Δg GM The bit coefficient is calculated using the following formula:

[0043]

[0044] In the above formula, ψ, λ are the latitude and longitude of the calculation point, GM is the gravitational constant, R is the average radius of the earth, is the fully normalized bit coefficient, is the fully normalized associated Legendre function, N is the maximum order of the spherical harmonic expansion of the potential model;

[0045] δΔg r is the gravitational force of the terrain mass on the calculation point, and only the influence of the local terrain undulation relative to the Bouguer patch can be considered, that is, the local terrain correction δΔg TC , the influence of terrain undulation relative to the geoid can be considered, and the calculation formula is:

[0046]

[0047] Step S12: Substitute the residual gravity anomaly into the Stokes formula to calculate the residual geoid δN r .

[0048]

[0049] Step S13: restore the geoid and calculate N GM and δN T , where N GM Still calculated by the bit coefficient:

[0050]

[0051] Where ρ is the distance from the center of the earth to the calculation point, and γ is the average normal gravity.T The calculation can be calculated using the following formula:

[0052]

[0053] Here δN T is the influence of local terrain. Where ρ is the crust density, hp is the terrain height of the calculation point, h is the terrain height of the flow point, and l is the distance from the calculation point to the flow point.

[0054] Preferably, step S2 comprises the following steps:

[0055] In the absence of gravity data, according to the spectral structure characteristics of elevation anomaly, the geoid height N can be decomposed into:

[0056] ξ=ξ GM +ξ ΔG +ξ T

[0057] ξ GM —— represents the long wave part, called model elevation anomaly, which can be calculated by the EGM2008 gravity field model:

[0058]

[0059] ξ ΔG —— represents the medium wave part, called the residual elevation anomaly, which can be obtained by solving the edge value of the residual gravity anomaly:

[0060]

[0061] ξ T ——represents the shortwave part, which is obtained by solving the terrain height:

[0062]

[0063] Similarly, in the absence of digital elevation model data, ΔG and T The parts are combined and characterized by mathematical model approximation. The elevation anomaly of the GPS point is divided into two parts for solution, namely:

[0064] ξ=ξ GM +ξ C

[0065] In the formula, ξ GM ——Height anomaly obtained from gravity field;

[0066] ξ C ——Residual elevation anomaly.

[0067] In the absence of gravity and digital terrain data, the elevation anomaly of other unknown points is obtained by using the "remove-restore" method through several known GPS / leveling points, and finally the normal height of the unknown point is obtained.

[0068] Preferably, step S3 comprises the following steps:

[0069] Combined with the CGCS2000 coordinate values ​​of each known point, the residual elevation anomaly values ​​are taken as known values ​​and substituted into the weighted average model, polynomial curve model, plane model, quadratic surface model, cubic surface model, moving surface model and multifaceted function model respectively, and a function model of residual elevation anomaly values ​​of each unknown point is established with CGCS2000 coordinate values ​​as parameters. Based on the EGM2008 model, the model elevation anomaly of each unknown point is calculated, and finally the elevation anomaly value of each unknown point is obtained. The calculation formula is as follows:

[0070]

[0071] In the formula, ξ(x i ,y i )——elevation anomaly value of unknown point;

[0072] ξ C (x i ,y i )——Interpolation of residual elevation anomaly of unknown points based on function model;

[0073] ξ GM (x i ,y i )——Model elevation anomaly of unknown points based on EGM2008;

[0074] F fit (x i ,y i )——remaining elevation anomaly interpolation function;

[0075] F EGM2008 (x i ,y i )——EGM2008 model elevation anomaly interpolation function.

[0076] In order to test the effect of each model, the elevation anomaly of the EMG2008 model was calculated using the above method and the residual elevation anomaly of each detection point was obtained.

[0077] The beneficial effects of this application include:

[0078] 1) The method for reducing the difference in elevation anomaly measured in the mining area provided by this application, combined with the actual situation of the large elevation difference and drastic terrain changes in the Dahongshan Copper Mine, calculates and compares the data of known common points and check points. Based on the superposition of elevation anomalies, the "remove-restore" method is used. First, the medium and long wave parts of the elevation anomaly calculated by the gravity field model are removed, and the short wave part is obtained. Then, a mathematical model is selected to fit the remaining residual elevation anomaly. Through practice, the multifaceted function fitting method based on the "remove-restore" method has a good fitting effect in the Dahongshan Copper Mine area, and the normal high precision after fitting can reach the requirement of ±2cm.

[0079] 2) The method provided in this application for reducing the abnormal difference in elevation measurement in the mining area, the GPS height measurement in the Dahongshan Copper Mine is based on the established mining area geoid model to meet the dual needs of engineering site data collection and internal batch data processing. The GPS technology is used to indirectly determine the normal height of any site in the area, comprehensively improve the technical conditions for elevation measurement in various types of engineering construction, and realize the three-dimensional positioning function of GPS technology. The multi-faceted function fitting method based on the "remove-restore" method has a good fitting effect in the Dahongshan Copper Mine area, and the normal height accuracy after fitting can reach the requirement of ±2cm.

[0080] 3) The method provided in the present application for reducing the difference in elevation anomaly measured in a mining area adopts the EGM2008 gravity geoid model and the high-precision geometric geoid for fitting. The removal-recovery method uses a mathematical model to first remove the medium and long wave parts of the elevation anomaly calculated using the gravity field model before elevation conversion; then fit and interpolate the remaining elevation anomaly; and then use the gravity field model to restore the removed part at the interpolation point, and finally obtain the elevation anomaly of the point.

[0081] 4) The method provided in this application for reducing the difference in elevation anomaly measured in mining areas adopts the "remove-restore" method of the EGM2008 model to improve the height measurement accuracy and applicability in the application of geoid refinement in mining areas with large elevation differences, realizes the calculation of elevation anomaly values ​​of the earth gravity field model in mining areas supported by the EGM2008 model, and proposes a model and method for establishing a centimeter-level quasi-geoid in mining areas based on the geometric and physical characteristics of elevation anomalies in mining areas, replacing conventional geometric leveling technology in mountainous areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 Schematic diagram of the "remove-restore" method based on the Earth's gravity field model provided for this application;

[0083] Figure 2 Schematic diagram of the "remove-restore" method provided for this application taking into account the Earth's gravity field model;

[0084] Figure 3Global error distribution map of the EGM2008 model provided for this application;

[0085] Figure 4 To check the data residual graph based on the “removal recovery” method of the EGM2008 model; Specific implementation methods

[0086] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0087] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0088] The technical means that are not described in detail in this application and are not used to solve the technical problems of this application are all set according to the common knowledge in the field, and can be implemented in a variety of common knowledge settings.

[0089] See also Figure 1 , the present invention will be further described below in conjunction with the accompanying drawings:

[0090] Step S1: The gravity anomaly observation value is decomposed into: model gravity anomaly calculated by the potential model, terrain gravity effect and residual gravity anomaly. If the influence of terrain is not considered, the above decomposition can also be divided into two parts, namely the model gravity anomaly part calculated by the potential model and the residual part. These two decomposition methods can be expressed as:

[0091] Δg=Δg GM +δΔg T +δΔg r

[0092] Where Δg is the observed gravity anomaly, Δg GM is the model gravity anomaly, δΔg T is the local terrain correction value, δΔg r is the gravitational force of the terrain mass on the calculation point;

[0093] N=N GM +δN T +δN r

[0094] Among them, N is the observed value of gravity anomaly, N GM is the model gravity anomaly, δN T is the terrain gravity effect, δN r is the residual gravity anomaly;

[0095] Step S11: Removal process: the model gravity anomaly Δg is calculated as follows: GM and topographic gravity effect δN T The residual gravity anomaly δΔg is obtained by removing the observed gravity anomaly Δg. r :

[0096] δΔg r =Δg-Δg GM -δg T

[0097] Where, the model gravity anomaly Δg GM The coefficient method is used to calculate the following formula:

[0098]

[0099] In the above formula, ψ, λ are the latitude and longitude of the calculation point, GM is the gravitational constant, R is the average radius of the earth, is the fully normalized bit coefficient, is the fully normalized associated Legendre function, N is the maximum order of the spherical harmonic expansion of the potential model; a is the fitting coefficient;

[0100] δΔg r is the gravitational force of the terrain mass on the calculation point, and only the influence of the local terrain undulation relative to the Bouguer patch can be considered, that is, the local terrain correction δΔg TC , the influence of terrain undulation relative to the geoid can be considered, and the calculation formula is:

[0101]

[0102] Among them, δN total is the influence value of geoid terrain fluctuation, G ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity, h p is the terrain height of the calculation point,

[0103] Step S12: Substitute the residual gravity anomaly into the Stokes formula and calculate the residual geoid δN as follows: r :

[0104]

[0105] Where R is the average radius of the Earth, γ is the average normal gravity, Δg ris the gravitational force of the terrain mass on the calculation point, S(ψ) is the latitude of the calculation point;

[0106] Step S13: restore the geoid and calculate N GM and δN T , where N GM Calculated from the bit coefficients:

[0107]

[0108] Where ρ is the distance from the center of the earth to the calculation point, and γ is the average normal gravity;

[0109] δN T Calculate as follows:

[0110]

[0111] Among them, δN T is the influence of local terrain, ρ is the crust density, h p is the terrain height of the calculation point, h is the terrain height of the flow point, l is the distance from the calculation point to the flow point, and G is the distance from the center of the earth.

[0112] Step S2: In the absence of gravity data, the geoid height N is decomposed into:

[0113] ξ=ξ GM +ξ ΔG +ξ T

[0114] Among them, ξ ΔG is the medium wave part, called residual elevation anomaly, ξ T The terrain is high in the short-wave part; GM The long-wave part is called model elevation anomaly. The EGM2008 gravity field model is used to calculate ξ GM :

[0115]

[0116] Among them, ψ, λ are the latitude and longitude of the calculation point, GM is the gravitational constant, R is the average radius of the earth, is the fully normalized bit coefficient, is the fully normalized associated Legendre function, N is the maximum order of the spherical harmonic expansion of the potential model; a is the fitting coefficient; ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity,

[0117] ξ ΔG Represents the mid-wave part, called the residual elevation anomaly, which is obtained by solving the edge value of the residual gravity anomaly:

[0118]

[0119] Where R is the average radius of the Earth, γ is the average normal gravity, To calculate the latitude, longitude and geocentric distance of the point, It is elevation anomaly; is the latitude of the point;

[0120] ξ T ——represents the shortwave part, which is obtained by solving the terrain height:

[0121]

[0122] Among them, ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity, and h p is the terrain height of the calculation point, l is the distance from the calculation point to the flow point, h is the terrain height of the flow point, and G is the distance from the center of the earth to the point;

[0123] Similarly, in the absence of digital elevation model data, ΔG and T After partial merging, the mathematical model approximation method is used to characterize the elevation anomaly of the GPS point, which is divided into two parts for solution, namely:

[0124] ξ=ξ GM +ξ C

[0125] In the formula, ξ GM ——Height anomaly obtained from gravity field;

[0126] ξ C ——Residual elevation anomaly.

[0127] Step S3: The residual value after removing the EGM2008 model geoid height from the elevation anomaly is considered as the residual elevation anomaly value ξ C . Based on the elevation anomaly values ​​of the EGM2008 model, the difference between the normal height obtained by GPS geodetic height and the third-order leveling measurement is used to obtain the true elevation anomaly values ​​of each known point. The residual elevation anomaly values ​​are obtained by subtracting the model elevation anomaly values ​​from the true elevation anomaly values, and are considered to be the true residual elevation anomaly values ​​of each known point. Combined with the CGCS2000 coordinate values ​​of each known point, the residual elevation anomaly values ​​are taken as known values ​​and substituted into the weighted average model, polynomial curve model, plane model, quadratic surface model, cubic surface model, moving surface model and polyhedral function model respectively, and a function model of the residual elevation anomaly values ​​of each unknown point is established with the CGCS2000 coordinate values ​​as parameters. Based on the EGM2008 model, the model elevation anomaly of each unknown point is calculated, and finally the elevation anomaly values ​​of each unknown point are obtained. The calculation formula is as follows:

[0128]

[0129] In the formula, ξ(x i ,y i )——elevation anomaly value of unknown point;

[0130] ξ C (x i ,y i )——Interpolation of residual elevation anomaly of unknown points based on function model;

[0131] ξ GM (x i ,y i )——Model elevation anomaly of unknown points based on EGM2008;

[0132] F fit (x i ,y i )——remaining elevation anomaly interpolation function;

[0133] F EGM2008 (x i ,y i )——EGM2008 model elevation anomaly interpolation function.

[0134] In order to test the effect of each model, the elevation anomaly of the EMG2008 model was calculated using the above method and the residual elevation anomaly of each detection point was obtained. Example

[0135] In the Dahongshan copper mine area, 11 known GPS / leveling points were obtained through static GPS observation and third-order geometric leveling. The point elevations were calculated according to step S1 and step S2.

[0136]

[0137] Among them, δN T is the influence of local terrain, ρ is the crust density, h p is the terrain height of the calculation point, h is the terrain height of the flow point, l is the distance from the calculation point to the flow point, and G is the distance from the center of the earth to the point.

[0138] ξ=ξ GM +ξ C

[0139] In the formula, ξ GM ——Height anomaly obtained from gravity field;

[0140] ξ C ——Residual elevation anomaly.

[0141] Then the elevation anomaly of these 11 points can be obtained k=h k -H k (k=1,2…11). At these points, the elevation anomaly ξ is calculated using the Earth gravity field model. GM , and finally get the remaining elevation anomaly ξ C The calculation results are shown in Table 3.

[0142] Table 3 Elevation anomaly calculation table of 11 known points

[0143]

[0144] The residual elevation anomaly of 11 known points is C As known data, the fitting coefficients of the fitting model are calculated using conventional fitting methods, and then the residual elevation anomaly ξ of the unknown point is interpolated. C The fitting function is the function fitting model as mentioned above, which are quadratic surface fitting, cubic surface fitting, multi-faceted function (positive hyperboloid) fitting, multi-faceted function (inverse hyperboloid) fitting, multi-faceted function (conical surface function) fitting, and multi-faceted function (cubic surface) fitting.

[0145] According to step S3 process,

[0146]

[0147] In the formula, ξ(x i ,y i )——elevation anomaly value of unknown point;

[0148] ξ C (x i ,y i )——Interpolation of residual elevation anomaly of unknown points based on function model;

[0149] ξ GM (x i ,y i )——Model elevation anomaly of unknown points based on EGM2008;

[0150] F fit (x i ,y i )——remaining elevation anomaly interpolation function;

[0151] F EGM2008 (x i ,y i )——EGM2008 model elevation anomaly interpolation function.

[0152] At the unknown point, the model elevation anomaly of the unknown point is calculated by the EGM2008 Earth gravity field model, and the residual elevation anomaly of the unknown point is added. C, and obtain the final elevation anomaly value of the unknown point, thereby obtaining the normal height of the unknown point.

[0153] In order to test the effect of each model, 23 detection points were set up in the mining area, and the elevation anomaly of the EMG2008 model was calculated using the above method to obtain the residual elevation anomaly of each detection point. The calculation results are shown in Table 4.

[0154] Table 4 Elevation anomaly calculation table of 23 detection points

[0155]

[0156]

[0157] 23 points evenly distributed in the Dahongshan Copper Mine were selected for actual testing. The geodetic height and normal height of the checkpoints were obtained by direct measurement, and the elevation anomaly ξ of the checkpoints was obtained by difference. i Then, the above-mentioned “remove-restore” method based on the EGM2008 model is used to calculate the elevation anomaly fitting value ξ′ of the check point. i , and calculate the difference to get the residual value of each function. The residual statistics of the external verification data based on the "removal and restoration" method of the EGM2008 model are shown in Table 5 below. The EGM2008 gravity field model is combined with GPS / leveling data, and the removal-restoration method is selected to determine the geoid, usually when the elevation anomaly changes are complex and the number of GPS / leveling points is sufficient. The method of combining the gravity field model with GPS / leveling to determine the local quasi-geoid can truly reflect the accuracy of the geoid and has achieved good results. The residual graph of the external verification data based on the "removal and restoration" method of the EGM2008 model is as follows Figure 4 shown.

[0158] Depend on Figure 4 It can be seen that after being processed by the method provided by this application, the geographical location results gradually approached..., indicating that this method can effectively correct the errors of each test point, especially suitable for the Dahongshan mining area, where the elevation difference fluctuates too much. Combined with the actual situation of the Dahongshan copper mine area with large elevation difference and drastic terrain changes, the known common points and check point data were calculated and compared, and the normal high accuracy after fitting can reach the requirement of ±2cm.

[0159] Table 5 Statistics of residual errors of data verified by the “removal and recovery” method based on the EGM2008 model

[0160]

[0161] It can be seen from Tables 3 to 5 that based on the “remove-restore” method of the EGM2008 model, the quadratic surface fitting, the polyhedral function fitting with the positive hyperboloid as the kernel function, the polyhedral function fitting with the cone function as the kernel function, and the polyhedral function fitting method with the cubic surface as the kernel function have better fitting effects in the Dahongshan copper mine area. After fitting, the normal high precision can reach the requirement of ±2cm.

[0162] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for reducing abnormal differences in elevation measurements in a mining area, characterized in that: The following steps are involved: Step S1: The gravity anomaly observation value is decomposed into: model gravity anomaly calculated by the potential model, terrain gravity effect and residual gravity anomaly. Without considering the influence of terrain, the above decomposition can be divided into two parts, namely the model gravity anomaly part calculated by the potential model and the residual part. These two decomposition methods can be expressed as: Δg=Δg GM +δΔg T +δΔg r Where Δg is the observed gravity anomaly, Δg GM is the model gravity anomaly, δΔg T is the local terrain correction value, δΔg r is the gravitational force of the terrain mass on the calculation point; N=N GM +δN T +δN r Among them, N is the observed value of gravity anomaly, N GM is the model gravity anomaly, δN T is the terrain gravity effect, δN r is the residual gravity anomaly; Step S11: Removal process: the model gravity anomaly Δg is calculated as follows: GM and topographic gravity effect δN T The residual gravity anomaly δΔg is obtained by removing the observed gravity anomaly Δg. r : δΔg r =Δg-Δg GM -δg T Where, the model gravity anomaly Δg GM The coefficient method is used to calculate the following formula: In the above formula, ψ, λ are the latitude and longitude of the calculation point, GM is the gravitational constant, R is the average radius of the earth, is the fully normalized bit coefficient, is the fully normalized associated Legendre function, N is the maximum order of the spherical harmonic expansion of the potential model; a is the fitting coefficient; δΔg r is the gravitational force of the terrain mass on the calculation point, considering only the influence of the local terrain undulation relative to the Bouguer patch, that is, the local terrain correction δΔg TC , considering the influence of terrain undulation relative to the geoid, the calculation formula is: Among them, δN total is the influence value of geoid terrain fluctuation, G ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity, h p is the terrain height of the calculation point, Step S12: Substitute the residual gravity anomaly into the Stokes formula and calculate the residual geoid δN as follows: r : Where R is the average radius of the Earth, γ is the average normal gravity, Δg r is the gravitational force of the terrain mass on the calculation point, S(ψ) is the latitude of the calculation point; Step S13: Restore the geoid and calculate N GM and δN T , where N GM Calculated from the bit coefficients: Where ρ is the distance from the center of the earth to the calculation point, and γ is the average normal gravity; δN T Calculate as follows: Among them, δN T is the influence of local terrain, ρ is the crust density, h p is the terrain height of the calculation point, h is the terrain height of the flow point, l is the distance from the calculation point to the flow point, and G is the distance from the center of the earth; Step S2: In the absence of gravity data, the geoid height N is decomposed into: ξ=ξ GM +ξ ΔG +ξ T Among them, ξ ΔG is the medium wave part, called residual elevation anomaly, ξ T The terrain is high in the short-wave part; GM The long-wave part is called model elevation anomaly. The EGM2008 gravity field model is used to calculate ξ GM : Among them, ψ, λ are the latitude and longitude of the calculation point, GM is the gravitational constant, R is the average radius of the earth, is the fully normalized bit coefficient, is the fully normalized associated Legendre function, N is the maximum order of the spherical harmonic expansion of the potential model; a is the fitting coefficient; ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity, ξ ΔG Represents the mid-wave part, called the residual elevation anomaly, which is obtained by solving the edge value of the residual gravity anomaly: Where R is the average radius of the Earth, γ is the average normal gravity, To calculate the latitude, longitude and geocentric distance of the point, It is elevation anomaly; is the latitude of the point; ξ T ——represents the shortwave part, which is obtained by solving the terrain height: Among them, ρ is the distance from the center of the earth to the calculation point, γ is the average normal gravity, and h p is the terrain height of the calculation point, l is the distance from the calculation point to the flow point, h is the terrain height of the flow point, and G is the distance from the center of the earth to the point; In the absence of digital elevation model data, ξ ΔG and T After partial merging, the mathematical model approximation method is used to characterize the elevation anomaly of the GPS point, which is divided into two parts for solution, namely: ξ=ξ GM +ξ C In the formula, ξ GM ——Height anomaly obtained from gravity field; ξ C ——Residual elevation anomaly; Step S3: The residual value after removing the EGM2008 model geoid height from the elevation anomaly is considered as the residual elevation anomaly value ξ C ; Based on the elevation anomaly value of the EGM2008 model, the difference between the normal height obtained by GPS geodetic height and the third-order leveling measurement is used to obtain the true elevation anomaly value of each known point. The residual elevation anomaly value is obtained by subtracting the model elevation anomaly value from the true elevation anomaly value, and is considered to be the true residual elevation anomaly value of each known point; combined with the CGCS2000 coordinate values ​​of each known point, the residual elevation anomaly value is used as a known value and substituted into the weighted average model, polynomial curve model, plane model, quadratic surface model, cubic surface model, moving surface model and polyhedral function model respectively, and a residual elevation anomaly function model is established with the CGCS2000 coordinate value as a parameter to solve the residual elevation anomaly value function model of each unknown point; based on the EGM2008 model, the model elevation anomaly of each unknown point is calculated, and finally the elevation anomaly value of each unknown point is obtained; the calculation formula is as follows: In the formula, ξ(x i ,y i )——elevation anomaly value of unknown point; ξ C (x i ,y i )——Interpolation of residual elevation anomaly of unknown points based on function model; ξ GM (x i ,y i )——Model elevation anomaly of unknown points based on EGM2008; F fit (x i ,y i )——Interpolation function of residual elevation anomaly; F EGM2008 (x i ,y i )——EGM2008 model elevation anomaly interpolation function; Find the normal height of the unknown point.

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