Plane network building and re-building and re-measurement stability evaluation method based on known system

Abstract

The application discloses a kind of plane network construction and reconstruction and re-measurement stability evaluation method based on known system, including using total station to obtain total station result;GNSS receiver is used to obtain the first two periods of GNSS network result of continuous observation;GNSS network result is translated, and the GNSS network-CGCS2000 result of two periods is obtained;GNSS network-CGCS2000 result is projected as Gauss plane coordinate, and average value is taken as GNSS network average result;Scaling factor, rotation parameter and displacement parameter between total station result and GNSS network average result are calculated;Total station result is reduced to the result of consistent scale with GNSS network average result, and the engineering coordinate system network construction result of plane network construction is obtained.The application makes full use of the respective advantages of total station angle network and GNSS network, and establishes the plane network construction of scale precision, point precision uniformity and high relative accuracy.Meanwhile, after the construction of control network, the post-earthquake control network can be reconstructed according to the number of stable points after the earthquake.

Description

Technical Field

[0001] This invention relates to the field of surveying and mapping technology, specifically to a method for evaluating the stability of planar network construction, reconstruction, and re-measurement based on a known system. Background Technology

[0002] With the continuous development of total station monitoring technology and GNSS monitoring technology, and the successful networking of my country's Beidou navigation satellite system, there are more and more cases of combined application of total station measurement method and GNSS measurement method in engineering safety monitoring. However, there are still some areas that need improvement in specific applications.

[0003] Since the devastating Wenchuan earthquake of May 12, seismic activity has become increasingly frequent. In particular, after a perceptible earthquake, the control points that serve as safety monitoring benchmarks will inevitably experience some degree of displacement. If the displacement of the control points cannot be accurately determined, the conclusions obtained from the monitoring will be unreliable.

[0004] Existing planar network construction methods and their respective advantages and disadvantages:

[0005] 1. Advantages and disadvantages of total station corner network construction method

[0006] 1) Advantages

[0007] (1) High accuracy in angle and side length measurement;

[0008] (2) It can perform automated data collection;

[0009] (3) The relationship is close and the results are highly accurate.

[0010] 2) Disadvantages

[0011] (1) Points must be able to see each other;

[0012] (2) The redundant observations at each point are not completely consistent, so the accuracy of each point is not uniform;

[0013] (3) Due to the influence of instrument replacement, calibration and environmental factors, there are systematic errors in scale, orientation and position among the measurement results of different periods;

[0014] (4) If all control points are displaced after an earthquake, the control network cannot be restored to the baseline at the time of network establishment.

[0015] 2. Advantages and disadvantages of GNSS static measurement network establishment methods

[0016] 1) Advantages

[0017] (1) No inter-point visibility is required;

[0018] (2) It can perform automated data collection;

[0019] (3) Using the same number of GNSS receivers as the control network points for simultaneous observation can ensure that each point has the same redundant observation. When the observation conditions are basically the same, the point accuracy is basically the same.

[0020] (4) High accuracy of scale reference.

[0021] 2) Disadvantages

[0022] (1) Due to the different locations of each point and the different influences of environmental factors, the accuracy of GNSS measurement adjustment results is usually very high, but there are often inconsistencies with reality, that is, the GNSS results are inconsistent with the total station results.

[0023] (2) If all control points are displaced after an earthquake, the control network cannot be restored to the baseline at the time of network establishment.

[0024] 3. Advantages and disadvantages of the network construction method combining total station corner network and GNSS static survey.

[0025] 1) Advantages

[0026] (1) There are many redundant observations;

[0027] (2) Multiple data processing solutions;

[0028] (3) The results can corroborate each other.

[0029] 2) Disadvantages

[0030] (1) The types of observations are inconsistent, and there is a problem of difficulty in determining weights;

[0031] (2) The results obtained from the independent data processing mode often differ significantly;

[0032] (3) Although the joint processing method yields only one set of results and there is no difference problem, the weighting of the observation data may be unreasonable, so the results obtained from the adjustment may not be consistent with the actual situation.

[0033] (4) If all control points are displaced after an earthquake, the control network cannot be restored to the baseline at the time of network establishment. Summary of the Invention

[0034] The purpose of this invention is to provide a method for evaluating the stability of planar network construction, reconstruction, and retesting based on a known system.

[0035] The technical problem that this invention aims to solve is:

[0036] (1) How to build a planar network with accurate scale, uniform point accuracy and high relative accuracy.

[0037] (2) After an earthquake occurs in the engineering monitoring area, the problem of the reconstruction of the plane network and the inheritance of the known network construction benchmark system.

[0038] To achieve the above objectives, one embodiment of the present invention provides a method for building a planar network based on a known system, comprising the following steps:

[0039] Step (A1) Set up several control points with forced centering devices within the stable range of the engineering monitoring area;

[0040] Step (A2) Set up a total station at a control point with a forced centering device and complete two measurements. The first result of the total station measurement is the known system result. At the same time, based on the first result, use a two-dimensional four-parameter transformation model to reduce the second result of the total station measurement to obtain the second reduced result of the total station. Take the average of the first result of the total station measurement and the second reduced result as the total station result.

[0041] Step (A3) Use network RTK to obtain the CGCS2000 results for each control point;

[0042] Step (A4) Set up GNSS receivers at the control points and continuously observe data for two 24-hour periods to obtain the GNSS network results for the first two periods;

[0043] Step (A5) translates the GNSS network results so that the centroid of the geocentric coordinates in the translated GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the GNSS network-CGCS2000 results for two time periods.

[0044] Step (A6) Obtain the maximum and minimum longitudes of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gaussian projection surface.

[0045] The GNSS network-CGCS2000 results are projected onto Gaussian plane coordinates, with the Gaussian plane coordinates of the first time period being the known system results. Simultaneously, using the Gaussian plane coordinates of the first time period as a reference, a two-dimensional four-parameter transformation model is used to reduce the GNSS network-CGCS2000 results of the second time period, resulting in the reduced GNSS network-CGCS2000 results for the second time period. The average of the known system results of the first time period and the reduced GNSS network-CGCS2000 results of the second time period is taken as the GNSS network mean result.

[0046] Step (A7) uses the GNSS network mean results from step (A6) as known system results, and employs a two-dimensional four-parameter plane coordinate transformation model to calculate the scaling factor, rotation parameter, and displacement parameter between the total station results and the GNSS network mean results;

[0047] Step (A8) uses the starting point of the total station adjustment as the fixed point, and the scaling factor, rotation parameter and displacement parameter obtained in step (A7) as the reference, to reduce the total station results to the same scale as the GNSS network mean results, and obtain the engineering coordinate system network construction results of the plane network construction.

[0048] In a preferred embodiment of the present invention, in step (A2), the nominal accuracy of the total station is not less than: 0.5″ for angle measurement and 1mm+1ppm for distance measurement; after measuring with the total station, the data measured by the total station is checked for tolerances. After the check is passed, the side-angle network adjustment calculation method is used to adjust the fixed single-point coordinates and fixed single-direction values ​​to obtain two independent measurement results of the total station, namely the first result and the second result.

[0049] In a preferred embodiment of the present invention, step (A2) further includes determining whether the difference in planar position between the first result and the second calculated result is greater than the standard limit. If it is not greater than the standard limit, the average of the first result and the second calculated result measured by the total station is taken as the total station result. The standard limit is 4 mm.

[0050] Preferably, in step (A4), the static plane accuracy of the GNSS receiver is not less than ±3mm+1ppm, and the static elevation accuracy is not less than ±5mm+1ppm.

[0051] Preferably, in step (A6) of this invention, the method further includes determining whether the difference in planar position between the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is greater than the standard limit. If it is not greater than the standard limit, the average value of the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is taken as the GNSS network average value. The standard limit is 4 mm.

[0052] This invention also discloses a method for post-earthquake reconstruction after the establishment of a planar network based on a known system, comprising the following steps:

[0053] Step (B) Within the engineering monitoring area, the engineering coordinate system network construction results are obtained using the planar network construction method based on a known system; these engineering coordinate system network construction results are the pre-earthquake engineering coordinate system network construction results; after the earthquake, the engineering coordinate system network construction results of the engineering monitoring area are reconstructed according to the following method:

[0054] Step (B1) involves restoring and reconstructing the control network points within the engineering monitoring area. A total station is set up at each control network point to complete two measurements. The first measurement result from the total station is the known system result. Simultaneously, based on the first result, a two-dimensional four-parameter transformation model is used to reduce the second measurement result from the total station to obtain the second reduced result from the total station. The average of the first measurement result from the total station and the second reduced result is taken as the post-earthquake total station result.

[0055] Step (B2) Use network RTK to obtain the CGCS2000 results for each control point;

[0056] Step (B3) Set up GNSS receivers at the control points and continuously observe data for two 24-hour periods to obtain the GNSS network results for the two periods after the earthquake. Take the average of the GNSS network results for the two periods as the post-earthquake GNSS network results.

[0057] Step (B4) translates the post-earthquake GNSS network results so that the centroid of the geocentric coordinates in the translated post-earthquake GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the post-earthquake GNSS network-CGCS2000 results.

[0058] Step (B5) Obtain the maximum and minimum longitudes of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gaussian projection surface; project the post-earthquake GNSS network-CGCS2000 results into Gaussian plane coordinates;

[0059] Step (B6) Determine the number of stable points in the post-earthquake GNSS network results;

[0060] When there are no fewer than 3 stable points, the average GNSS network results at the time of control network establishment are used as known system results. Based on the average GNSS network results at the time of control network establishment, the post-earthquake GNSS network results are reduced using a two-dimensional four-parameter transformation model to obtain the post-earthquake GNSS network reduced results. The post-earthquake GNSS network reduced results are used as new known system results.

[0061] When the number of stable points is less than 3, obtain the mean GNSS network results and the engineering coordinate system network results of the plane network during the construction of the control network; establish a two-dimensional four-parameter transformation model between the mean GNSS network results and the engineering coordinate system network results; use this two-dimensional four-parameter transformation model to import the post-earthquake GNSS network results to obtain the post-earthquake engineering coordinate system network results.

[0062] Preferably, the planar position difference of the stable point is no greater than the standard limit value, which is 4.0 mm.

[0063] This invention discloses a method for evaluating the stability of planar network construction based on a known system, comprising the following steps:

[0064] S1. Collect data for planar network construction.

[0065] S2. Collect the first two sets of measurement data to establish the initial results;

[0066] S3. Obtain the results of the retest of the free network.

[0067] S4. Using the analysis and judgment of the stable point, the results of the remeasured free network are converted into the results of the known system in the previous period through a two-dimensional four-parameter transformation model.

[0068] S5. Calculate the remeasurement results and weights of the stable points, the remeasurement results and weights of the displacement points, and the displacement amount and direction of the displacement points.

[0069] In summary, the present invention has the following advantages:

[0070] This invention fully utilizes the advantages of both total station corner networks and GNSS networks to establish a planar network with precise scale, uniform point accuracy, and high relative precision. Furthermore, based on the control network, it enables the reconstruction of the control network after an earthquake, according to the number of stable points. Attached Figure Description

[0071] Figure 1 This is a diagram of the corner grid of a total station for constructing a planar network, as shown in one embodiment of the present invention.

[0072] TN01 to TN08 are control points, and the lines connecting the points are the observation edges and observation directions.

[0073] Figure 2 This is a GNSS network diagram for planar network construction in one embodiment of the present invention. Detailed Implementation

[0074] This invention provides a method for building a planar network based on a known system, comprising the following steps:

[0075] Step (A1) Set up several control points with forced centering devices within the stable range of the engineering monitoring area.

[0076] Step (A2) Set up a total station at a control point with a forced centering device and complete two measurements. The first result of the total station measurement is the known system result. At the same time, based on the first result, use a two-dimensional four-parameter transformation model to reduce the second result of the total station measurement to obtain the second reduced result of the total station. Take the average of the first result of the total station measurement and the second reduced result as the total station result.

[0077] The nominal accuracy of the total station of this invention is no less than: 0.5″ for angle measurement and 1mm+1ppm for distance measurement. After measurement with the total station, the data measured by the total station is checked for tolerances. After the check is passed, the angle-side network adjustment calculation method is used to adjust the data according to the fixed single-point coordinates and fixed single-direction values ​​to obtain two independent measurement results of the total station, namely the first result and the second result.

[0078] Step (A2) also includes determining whether the difference in planar position between the first result and the second calculated result is greater than the standard limit. If it is not greater than the standard limit, the average of the first result and the second calculated result measured by the total station is taken as the total station result; the standard limit is 4mm.

[0079] Step (A3) Use network RTK to obtain the CGCS2000 results for each control point.

[0080] Step (A4) involves setting up GNSS receivers at the control points and continuously observing data for two 24-hour periods. Using GNSS data processing software, the GNSS observation data undergoes standard tolerance checks. Once the data passes these checks, the initial GNSS network results for the two time periods are obtained. In step (A4), the static plane accuracy of the GNSS receiver should be no less than ±3mm + 1ppm, and the static elevation accuracy should be no less than ±5mm + 1ppm.

[0081] Step (A5) translates the GNSS network results so that the centroid of the geocentric coordinates in the translated GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the GNSS network-CGCS2000 results for two time periods.

[0082] Step (A6) Obtain the maximum and minimum longitudes of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gaussian projection surface.

[0083] The GNSS network-CGCS2000 results are projected onto Gaussian plane coordinates, with the Gaussian plane coordinates of the first time period being the known system results. Simultaneously, using the Gaussian plane coordinates of the first time period as a reference, a two-dimensional four-parameter transformation model is used to reduce the GNSS network-CGCS2000 results of the second time period, resulting in the reduced GNSS network-CGCS2000 results for the second time period. The average of the known system results of the first time period and the reduced GNSS network-CGCS2000 results of the second time period is taken as the GNSS network mean result.

[0084] Step (A7) uses the GNSS network mean results from step (A6) as known system results, and employs a two-dimensional four-parameter plane coordinate transformation model to calculate the scaling factor, rotation parameter, and displacement parameter between the total station results and the GNSS network mean results.

[0085] Step (A8) uses the starting point of the total station adjustment as the fixed point, and the scaling factor, rotation parameter and displacement parameter obtained in step (A7) as the reference, to reduce the total station results to the same scale as the GNSS network mean results, and obtain the engineering coordinate system network construction results of the plane network construction; the engineering coordinate system network construction results are the control network construction results.

[0086] In the optimized embodiment of the present invention, step (A6) further includes determining whether the difference in planar position between the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is greater than the standard limit. If it is not greater than the standard limit, the average value of the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is taken as the GNSS network average value result; the standard limit is 4mm.

[0087] After the control network is established, if no earthquake or other severe geological disaster occurs, the established control network does not need to be rebuilt. However, after an earthquake or severe geological disaster occurs, the control network points may shift, therefore, the results of the control network need to be rebuilt for verification and calibration. Based on the above-mentioned control network establishment method, this invention also discloses a method for post-earthquake reconstruction of a planar network based on a known system, including the following steps:

[0088] Step (B) Within the engineering monitoring area, the engineering coordinate system network construction results are obtained using the planar network construction method based on a known system; these engineering coordinate system network construction results are the pre-earthquake engineering coordinate system network construction results; after the earthquake, the engineering coordinate system network construction results of the engineering monitoring area are reconstructed according to the following method:

[0089] Step (B1) involves restoring and reconstructing the control network points within the engineering monitoring area. A total station is set up at each control network point to complete two measurements. The first measurement result from the total station is the known system result. Simultaneously, based on the first result, a two-dimensional four-parameter transformation model is used to reduce the second measurement result from the total station to obtain the second reduced result from the total station. The average of the first measurement result from the total station and the second reduced result is taken as the post-earthquake total station result.

[0090] Step (B2) Use network RTK to obtain the CGCS2000 results for each control point;

[0091] Step (B3) Set up GNSS receivers at the control points and continuously observe data for two 24-hour periods to obtain the GNSS network results for the two periods after the earthquake. Take the average of the GNSS network results for the two periods as the post-earthquake GNSS network results.

[0092] Step (B4) translates the post-earthquake GNSS network results so that the centroid of the geocentric coordinates in the translated post-earthquake GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the post-earthquake GNSS network-CGCS2000 results.

[0093] Step (B5) Obtain the maximum and minimum longitudes of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gaussian projection surface; project the post-earthquake GNSS network-CGCS2000 results into Gaussian plane coordinates;

[0094] Step (B6) Determine the number of stable points in the post-earthquake GNSS network results; the difference in the plane position of the stable points should not exceed the standard tolerance value, which is 4.0 mm.

[0095] When there are no fewer than 3 stable points, the average GNSS network results at the time of control network establishment are used as known system results. Based on the average GNSS network results at the time of control network establishment, the post-earthquake GNSS network results are reduced using a two-dimensional four-parameter transformation model to obtain the post-earthquake GNSS network reduced results. The post-earthquake GNSS network reduced results are used as new known system results.

[0096] When the number of stable points is less than 3, obtain the mean GNSS network results and the engineering coordinate system network results of the plane network during the construction of the control network; establish a two-dimensional four-parameter transformation model between the mean GNSS network results and the engineering coordinate system network results; use this two-dimensional four-parameter transformation model to import the post-earthquake GNSS network results to obtain the post-earthquake engineering coordinate system network results.

[0097] Example 1:

[0098] Taking a certain engineering monitoring area as an example, the monitoring was carried out according to the method of this invention.

[0099] Step (1) Set up 8 observation piers with forced centering devices in the engineering monitoring area, that is, set up 8 control points;

[0100] Step (2) Set up the TM50 total station and TM30 total station on the observation pier, and follow the instructions. Figure 1 The network configuration requires the collection of corner and edge data. Two total stations each collect data once, gathering 48 directional values ​​and 24 forward and backward edge length values. Simultaneously, using the first result TM50 as a benchmark, a two-dimensional four-parameter transformation model is used to reduce the second result TM30 obtained from the total station measurements, resulting in the second reduced result of the total station. The average of the first and second reduced results from the total station measurements is taken as the total station result.

[0101] The monitoring results and calculation results of the two total stations are shown in the table below:

[0102] Table 1. TM50 Results

[0103]

[0104] Table 2. TM30 Results

[0105]

[0106] Direct comparison of results in Tables 3, 1, and 2

[0107]

[0108] Table 3 shows that a direct comparison is clearly incorrect, as the control points observed during the same period could not have shifted. This indicates a systematic error between the observation results of the two instruments. Therefore, using the TM50 engineering coordinate system results as the known system, a two-dimensional four-parameter plane coordinate transformation model is employed to convert the TM30 results into known system results based on the TM50 results for comparison.

[0109] Table 4. Calculation Table for Known System Conversion Model of TM30 Results to TM50 Results

[0110]

[0111]

[0112] As can be seen from Table 4, the TM30 results have a large scale of 4.7354 mm / km, the internal consistency error of the transformation model is 0.5 mm, and the direction rotation is 0.0442″. This indicates that apart from the large difference in scale, the internal consistency accuracy of the two sets of results is very high.

[0113] Table 5. Comparison of TM30 and TM50 Results

[0114]

[0115] As can be seen from Table 5, when comparing the results of TM30 and TM50, all points are within the tolerance limit. Therefore, the average of the results of TM30 and TM50 is taken as the total station result.

[0116] Table 6. Total Station Results

[0117]

[0118] Step (3) Use network RTK to obtain the CGCS2000 results for each control point. The results are shown below:

[0119] Table 7. Results of CGCS2000 network construction based on known systems (planar network).

[0120]

[0121]

[0122] Step (4) Set up I90 Huace GNSS receivers at the control points and continuously observe data for two 24-hour periods. Use GNSS data processing software to perform various limit checks on the GNSS observation data as required by the specifications. After passing the checks, adjust the data to obtain the GNSS network results for the first two periods. The GNSS network results for the two periods are shown in the table below:

[0123] Table 8. Results of the first 24-hour period

[0124]

[0125] Table 9. Results of the second 24-hour period

[0126]

[0127] Step (5) translate the GNSS network results so that the centroid of the geocentric coordinates in the translated GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the GNSS network-CGCS2000 results for two time periods; the results are shown in the table below:

[0128] Table 10. Original results and GNSS network-CGCS2000 results for the first time period

[0129]

[0130] Table 11. Original results and GNSS network-CGCS2000 results for the second time period

[0131]

[0132] Step (6) Obtain the maximum and minimum longitude of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gauss projection surface;

[0133] The GNSS network-CGCS2000 results are projected onto Gaussian plane coordinates, with the Gaussian plane coordinates of the first time period being the known system results. Simultaneously, using the Gaussian plane coordinates of the first time period as a reference, a two-dimensional four-parameter transformation model is used to reduce the GNSS network-CGCS2000 results of the second time period, resulting in the reduced GNSS network-CGCS2000 results for the second time period. The average of the known system results of the first time period and the reduced GNSS network-CGCS2000 results of the second time period is taken as the GNSS network mean result.

[0134] Table 12, Gaussian projection coordinates of 91°52′51″ central meridian / geodetic height 3859.7m

[0135]

[0136] Table 13. Comparison of results between the two 24-hour periods

[0137]

[0138] As shown in Table 13, although the difference between the results of the two heat exchange periods did not exceed the limit, there was one point that was consistent with the limit, indicating that there was also a certain systematic error between the two periods. Therefore, the Gaussian plane coordinates of the first heat exchange period were taken as the known systematic results, and the results of the second period were converted into the known systematic results based on the first period according to the two-dimensional four-parameter transformation model for comparison.

[0139] Table 14. Calculation of the known system conversion model for the results of the second phase – results of the first phase

[0140]

[0141]

[0142] As shown in Table 14, the scale difference between the two time periods is only 0.3860 mm / km, the mean square error of the conversion model is 1.0 mm, and the direction rotation is 0.0921″, indicating that the scale difference between the GNSS time period results is not significant.

[0143] Table 15. Calculation results of the known system in the second time period and their difference from the results in the first heat exchange period.

[0144]

[0145] This shows that the difference between the results of the second time period and the results of the first time period is less than the limit of 4.0 mm.

[0146] Table 16 shows the average values ​​of the GNSS network over two time periods.

[0147]

[0148] In a specific embodiment of the present invention, the GNSS network mean value results in step (A6) are used as known system results, and a two-dimensional four-parameter plane coordinate transformation model is used to calculate the scaling factor, rotation parameter and displacement parameter between the total station results and the GNSS network mean value results.

[0149] Table 17. Calculation of GNSS Network Result Scale from Total Station Results

[0150]

[0151]

[0152] As shown in Table 17, the total station result scale is 3.0943 mm / km smaller than the GNSS result scale.

[0153] Step (8) uses the starting point of the total station adjustment as a fixed point, and the scaling factor, rotation parameter, and displacement parameter obtained in step (A7) as a reference, to reduce the total station results to a scale consistent with the GNSS network mean results, thus obtaining the engineering coordinate system network construction results for the plane network. In this invention, the starting point for the total station adjustment can be a control point on the edge network, for example, a control point on the edge network can be selected as the starting point. Figure 1 or Figure 2 TN05 is used as the starting point, and the coordinates of this point are used as fixed values.

[0154] Table 18. Results of Coordinate System Construction for Planar Network Construction

[0155]

[0156] In a specific embodiment of the present invention, step (9) uses the network construction results in Table 18 of step (8) as known system results and calculates a two-dimensional four-parameter conversion model between the mean GNSS network results and the network construction results. This model serves as the conversion model between the post-earthquake reconstruction GNSS network results and the network construction results when there are fewer than 3 stable control network points after the earthquake, thereby ensuring that the pre-earthquake and post-earthquake systems remain consistent.

[0157] Table 19. Calculation of Known System Transformation Model for GNSS Network Mean Value Results - Engineering Coordinate System Network Establishment Results

[0158]

[0159]

[0160] As can be seen from Table 19, the scale difference between the GNSS mean results and the engineering coordinate system network results is negligible, and the mean square error of the conversion model is 1.7 mm.

[0161] Conversion formula between GNSS network mean values ​​and engineering coordinate system network establishment results:

[0162] X=(0.999952047583179).x+(-0.00979287780776686).y+(3625.58180701621)(1)

[0163] Y=(0.00979287780776686).x+(0.999952047583179).y+(-140491.345034089)(2)

[0164] In the formula: x and y are the mean values ​​of the GNSS network;

[0165] X and Y represent the results of the total station's engineering coordinate system.

[0166] Formulas (1) and (2) are the conversion models for the post-earthquake reconstruction GNSS results to the known system when there are fewer than 3 stable control network points after an earthquake.

[0167] Example 2: Post-earthquake reconstruction

[0168] Step (B1) Set up the TM60 total station, according to... Figure 1 The mesh shape requires the collection of edge and corner data, with each edge being collected once, and 48 directional values ​​and 24 round trip edge length values ​​being collected.

[0169] Two measurements were completed using a total station at the control points. The first measurement by the total station was the known system result. At the same time, based on the first result, the second measurement by the total station was reduced using a two-dimensional four-parameter transformation model to obtain the second reduced result of the total station. The average of the first measurement result and the second reduced result was taken as the post-earthquake total station result.

[0170] Using the same edge-angle network data processing software as the network construction, the total station observation data was checked against the standard requirements for various tolerance limits. After passing the checks, the data was adjusted using fixed single-point coordinates and fixed single-direction values ​​to obtain two independent results of the post-earthquake re-measurement.

[0171] Table 20. Average values ​​of two total station measurements during post-earthquake reconstruction.

[0172]

[0173] Step (B2) Use network RTK to obtain the CGCS2000 results for each control point.

[0174] Table 21. CGCS2000 data collected using RTK method during post-earthquake reconstruction.

[0175]

[0176] Step (B3) involves setting up GNSS receivers at control points and continuously observing data for two 24-hour periods to obtain the GNSS network results for the two post-earthquake periods. The average of the GNSS network results for the two periods is taken as the post-earthquake GNSS network result. This invention can use the same GNSS data processing software as the network construction software. After the GNSS observation data passes the required tolerance checks according to the specifications, unconstrained adjustment is performed to obtain the results for the two post-earthquake periods. The difference between the results of the two periods meets the tolerance limits specified in the specifications. The median of the results of the two periods is taken as the post-earthquake reconstructed GNSS network result.

[0177] Table 22. Average values ​​of the GNSS network during two time periods in the post-earthquake reconstruction.

[0178]

[0179] Step (B4) translates the post-earthquake GNSS network results so that the centroid of the geocentric coordinates in the translated post-earthquake GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the post-earthquake GNSS network-CGCS2000 results.

[0180] Table 23. Results of Post-Earthquake Reconstruction of GNSS Network CGCS2000

[0181]

[0182] Step (B5) Obtain the maximum and minimum longitudes of the engineering monitoring area, and use the average of the maximum and minimum longitudes of the engineering monitoring area as the central meridian; use the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark to obtain the geodetic height of the projection surface as the Gaussian projection surface; project the post-earthquake GNSS network-CGCS2000 results into Gaussian plane coordinates.

[0183] Table 24. Gaussian projection coordinates of the CGCS2000 GNSS network for post-earthquake reconstruction

[0184]

[0185]

[0186] Step (B6) Determine the number of stable points in the post-earthquake GNSS network results;

[0187] When there are no fewer than 3 stable points, the average GNSS network results at the time of control network establishment are used as known system results. Based on the average GNSS network results at the time of control network establishment, the post-earthquake GNSS network results are reduced using a two-dimensional four-parameter transformation model to obtain the post-earthquake GNSS network reduced results. The post-earthquake GNSS network reduced results are used as new known system results.

[0188] When the number of stable points is less than 3, obtain the mean GNSS network results and the engineering coordinate system network results of the plane network during the construction of the control network; establish a two-dimensional four-parameter transformation model between the mean GNSS network results and the engineering coordinate system network results; use this two-dimensional four-parameter transformation model to import the post-earthquake GNSS network results to obtain the post-earthquake engineering coordinate system network results.

[0189] Table 25. Gaussian projection coordinates of the CGCS2000 GNSS network for post-earthquake reconstruction

[0190]

[0191] As shown in Table 25, two points experienced displacement after the earthquake. Based on the transformation model calculated from the six stable points, the post-earthquake reconstruction result is 0.3274 mm / km, with an internal consistency error of 1.8 mm, indicating that the stable points have a good relationship and very small scale difference.

[0192] Table 26. Results of converting post-earthquake GNSS network reconstruction into network establishment.

[0193]

[0194]

[0195] The results in Table 26 are converted into engineering coordinate system network results (known system results) using formulas (1) and (2).

[0196] Table 27. Results of the Coordinate System Establishment for the Post-Earthquake Reconstruction GNSS Network (Results of Known Systems)

[0197]

[0198] In a specific embodiment of the present invention, step (7) uses the engineering coordinate system network construction results of the GNSS network in Table 27 of step (6) as the known system results, and converts the post-earthquake results of the total station into the engineering coordinate system network construction results (known system results) according to the two-dimensional four-parameter transformation model.

[0199] Table 28. Total Station Results for Post-Earthquake Reconstruction – Transformation Model of Known System Results for Post-Earthquake Reconstruction GNSS Network Engineering Coordinate System

[0200]

[0201] As shown in Table 28, the scale of the total station results from the post-earthquake reconstruction is 8.5837 mm / km larger than the scale of the engineering coordinate results from the post-earthquake reconstruction GNSS network. The mean square error of the two results in the conversion model is 0.5 mm. This shows that the accuracy of both the total station results and the GNSS results from the post-earthquake reconstruction is very high, but the scale difference between the two results is relatively large.

[0202] Total station results for post-earthquake reconstruction – Conversion formula for GNSS engineering coordinate results for post-earthquake reconstruction:

[0203] X=(0.999991416265417).x+(-4.40783953156237E-06).y+(30.1994909793592)(3)

[0204] Y=(4.40783953156237E-06).x+(0.999991416265417).y+(-11.2469762429828)(4)

[0205] In the formula: x and y are the results of the total station used for post-earthquake reconstruction;

[0206] X and Y represent the coordinate results of the post-earthquake reconstruction GNSS project.

[0207] The total station results are converted into post-earthquake reconstruction total station engineering coordinate results according to formulas (3) and (4), and compared with the network construction results to obtain the displacement of the post-earthquake plane network construction.

[0208] Table 29. Comparison of coordinate results and network establishment results from total station engineering during post-earthquake reconstruction.

[0209]

[0210] Table 29 shows that two points on the plane network were displaced after the earthquake: TN02 with a displacement of 9.8 mm and TN05 with a displacement of 11.2 mm.

[0211] As can be seen from the results of the specific embodiments of the present invention above, the total station results have high accuracy in each period, but the scale difference between the results in each period is large; the scale difference between the GNSS results in each period is very small. Although in this case, after the scale of the GNSS results and the total station results are unified, the difference in the plane position is less than 4mm, there are usually a few outliers with large differences. Therefore, it is necessary to adopt the method of building a network and post-earthquake reconstruction by combining the total station corner network and the GNSS network to solve the problem of the present invention.

[0212] Because the results obtained from total station edge-angle networks using different instruments or different periods of instrument calibration parameters for the same observation data have significant scale differences, the data from total station edge-angle networks should be converted into results with consistent scale.

[0213] This invention discloses a method for evaluating the stability of planar network construction based on a known system, comprising the following steps:

[0214] S1. Collect data for planar network construction.

[0215] S2. Collect the first two sets of measurement data to establish the initial results;

[0216] S3. Obtain the results of the retest of the free network.

[0217] S4. Using the analysis and judgment of the stable point, the results of the remeasured free network are converted into the results of the known system in the previous period through a two-dimensional four-parameter transformation model.

[0218] S5. Calculate the remeasurement results and weights of the stable points, the remeasurement results and weights of the displacement points, and the displacement amount and direction of the displacement points.

[0219] Specifically, the stability evaluation method includes the following steps:

[0220] Step 1: Collect relevant information for planar network construction.

[0221] Step 2: Calculation of initial results;

[0222] Step 2.1 The first phase of the planar network construction is the first measurement. The scale, direction and position benchmarks of the planar network construction are established by adjusting the single-point and single-direction free network, which is the first result of the first phase.

[0223] Step 2.2 adopts a two-dimensional four-parameter transformation model. Based on the results of the first free network in the first phase, the parameters of the two-dimensional four-parameter plane coordinate transformation model between the results of the second free network in the first phase and the results of the first free network are calculated. According to this model, the results of the second free network in the first phase are converted into known system results, and the difference between the converted results and the results of the first phase is compared.

[0224] Step 2.3 Remove points whose difference exceeds the stability judgment limit, recalculate the transformation model parameters, use the new transformation model to reduce the results of the second measurement of the free network in the first phase to the new known system results, and recalculate the difference between the reduced results and the first results in the first phase.

[0225] Step 2.4 Repeat steps 2.2-2.3 until all points with differences greater than the stability judgment limit are removed. Calculate the final two-dimensional four-parameter plane coordinate transformation model parameters and use the final two-dimensional four-parameter plane coordinate transformation model to reduce the first phase of the second phase results to known system results.

[0226] Step 2.5 Regulations for the Values ​​of Initial Results:

[0227] (1) Stable point

[0228] a) Initial results = (First phase results + Second phase settlement results) / 2;

[0229] b) The initial achievement rights = 1 + 1 = 2;

[0230] (2) Displacement point

[0231] a) Initial results = Initial second settlement results;

[0232] b) Initial achievement rights = 1;

[0233] Step 3: Calculation of the results of this retest;

[0234] Step 3.1 Perform free network adjustment on the current period's remeasured observations, starting from a single point and a single direction, to obtain the current period's remeasured free network results with a plane network.

[0235] Step 3.2 Based on the previous results, calculate the two-dimensional plane coordinate transformation model parameters between the current remeasurement of the free network and the previous results. According to this model, the current remeasurement of the free network is converted into known system results, and the difference between the converted results and the previous results is compared.

[0236] Step 3.3 Remove points whose difference exceeds the stability judgment limit, recalculate the transformation model parameters, use the new transformation model to reduce the results of the current remeasurement of the free network to the new known system results, and recalculate the difference between the reduced results and the previous results.

[0237] Step 3.4 Repeat steps 3.2-3.3 until all points with differences greater than the stability judgment limit are removed. Calculate the final two-dimensional four-parameter plane coordinate transformation model parameters and use the final transformation model to convert the results of this remeasurement of the free network into known system results.

[0238] Step 3.5 Regulations for determining the value of this period's results:

[0239] (1) Stable point

[0240] a) Current period result = (Previous period result × Previous period result weight + Current period result) / (Previous period result weight + 1);

[0241] b) Current period's performance weight = Previous period's performance weight + 1;

[0242] (2) Displacement point

[0243] a) Current period results = Current period settlement results;

[0244] b) The current period's performance weight = 1;

[0245] (3) Displacement amount and displacement direction

[0246] a) Displacement during the period = Previous period's result - Current period's result; Displacement direction is represented by the azimuth angle of the displacement vector;

[0247] b) Cumulative displacement = Initial results - Current results; Displacement direction is represented by the azimuth of the displacement vector.

[0248] In step 1, the collected data includes, but is not limited to, monitoring design documents, raw observation data, instrument calibration certificates, monitoring calculation data, and monitoring reports.

[0249] Step 2 specifically involves taking the adjustment results of the first fixed point and fixed direction of the first observation in the first phase of the planar network construction as the known system results, and using the two-dimensional four-parameter planar coordinate transformation model, reducing the adjustment results of the second fixed point and fixed direction in the first phase to the known system results based on the adjustment results of the first fixed point and fixed direction in the first phase, and determining whether there are any displacement points.

[0250] In step 2:

[0251] a) Using the results of two fixed single-point and fixed single-direction adjustments as known data, the parameters of the two-dimensional four-parameter plane coordinate transformation model are obtained by removing displacement points. At this time, there are no displacement points.

[0252] b) Using the two-dimensional four-parameter plane coordinate transformation model calculated in a), the free network results of the first phase second fixed single point and fixed single direction adjustment are reduced to known system results;

[0253] c) The known values ​​of the first phase of the system results.

[0254] Step c) includes the following steps:

[0255] (a) The stable point is taken as the average of the first result and the second known system result, and the result weight is 2;

[0256] (b) The displacement point is the known system calculation result of the free network results of the first phase second fixed single point and fixed single direction adjustment. The result weight is 1. The displacement point is the point where the difference between the known system calculation result of the first phase second free network and the first result is greater than 3 times the error of the plane network construction estimation.

[0257] In step 3, after obtaining the re-measurement observation data, the re-measurement data is first pre-processed. The pre-processing refers to obtaining the re-measurement free network results by using the adjustment method with fixed single points and fixed single directions.

[0258] After preprocessing the remeasured data, based on the previous period's results, and using the current period's remeasured free network results and the previous period's results as known data, the parameters of the two-dimensional four-parameter plane coordinate transformation model are calculated using the stable point results after removing displacement points. This transformation model is then used to reduce the current period's free network results to known system results, and values ​​are assigned to the current period's known system results.

[0259] The process of assigning values ​​to the results of this period includes the following steps:

[0260] (a) The stable point result is the weighted average of the previous period's result and the current period's settled result, with the current period's result weighted by the previous period's option + 1;

[0261] (b) The displacement point results are taken from the current period's reduction results, with a weight of 1 for the current period's results. The displacement points include: points where the difference between the current period's known system reduction results and the previous period's results is greater than 3 times the mean square error of the planar network construction estimation, and points where the difference between the current period's known system reduction results and the first period's known system results is greater than 3 times the mean square error of the planar network construction estimation.

[0262] Steps 2.4 and 3.4 of this invention, which involve eliminating all displacement points and calculating the final two-dimensional four-parameter planar coordinate transformation model parameters, specifically include the following steps:

[0263] a) Using all the results from the previous period and the current period's free network results as known data, calculate the parameters of the first two-dimensional four-parameter planar coordinate transformation model;

[0264] b) Using the transformation parameters calculated in a), the results of the current free network are reduced to the results of the previous period. The reduced results are compared with the results of the previous period, and points with a difference greater than 3 times the error of the planar network construction estimation are identified as displacement points.

[0265] c) After removing the displacement points, recalculate the parameters of the second two-dimensional four-parameter planar coordinate transformation model;

[0266] d) Repeat b) and c) until all displacement points are eliminated, and calculate the final two-dimensional four-parameter planar coordinate transformation model parameters.

[0267] Once the final two-dimensional four-parameter planar coordinate transformation model parameters are calculated, the stability analysis conclusion of the planar network can be obtained according to the provisions of steps 2.5 and 3.5 in claim 1.

[0268] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A method for building a planar net based on a known system, characterized in that, Includes the following steps: Step (A1) Set up several control points with forced centering devices within the stable range of the engineering monitoring area; Step (A2) Set up a total station at a control point with a forced centering device and complete two measurements. The first result of the total station measurement is the known system result. At the same time, based on the first result, use a two-dimensional four-parameter transformation model to reduce the second result of the total station measurement to obtain the second reduced result of the total station. Take the average of the first result of the total station measurement and the second reduced result as the total station result. Step (A3) Use network RTK to obtain the CGCS2000 results for each control point; Step (A4) Set up GNSS receivers at the control points and continuously observe data for two 24-hour periods to obtain the GNSS network results for the first two periods; Step (A5) translates the GNSS network results so that the centroid of the geocentric coordinates in the translated GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the GNSS network-CGCS2000 results for two time periods. Step (A6) Obtain the maximum and minimum longitude of the engineering monitoring area, and use the average of the maximum and minimum longitude of the engineering monitoring area as the central meridian; The geodetic height of the projection surface is obtained by taking the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark, and then using it as the Gaussian projection surface. The GNSS network-CGCS2000 results are projected onto Gaussian plane coordinates, with the Gaussian plane coordinates of the first time period being the known system results. Simultaneously, using the Gaussian plane coordinates of the first time period as a reference, a two-dimensional four-parameter transformation model is used to reduce the GNSS network-CGCS2000 results of the second time period, resulting in the reduced GNSS network-CGCS2000 results for the second time period. The average of the known system results of the first time period and the reduced GNSS network-CGCS2000 results of the second time period is taken as the GNSS network mean result. Step (A7) uses the GNSS network mean results from step (A6) as known system results, and employs a two-dimensional four-parameter plane coordinate transformation model to calculate the scaling factor, rotation parameter, and displacement parameter between the total station results and the GNSS network mean results; Step (A8) uses the starting point of the total station adjustment as the fixed point, and the scaling factor, rotation parameter and displacement parameter obtained in step (A7) as the reference, to reduce the total station results to the same scale as the GNSS network mean results, and obtain the engineering coordinate system network construction results of the plane network construction.

2. The method of claim 1, wherein: In step (A2), the nominal accuracy of the total station shall not be less than: 0.5″ for angle measurement and 1mm+1ppm for distance measurement. After measuring with the total station, the data measured by the total station shall be checked for tolerance. After the check is qualified, the side-angle network adjustment calculation method shall be used to adjust the fixed single point coordinates and fixed single direction values ​​to obtain two independent measurement results of the total station, namely the first result and the second result.

3. The method of claim 1, wherein: The step (A2) also includes determining whether the difference in planar position between the first result and the second calculated result is greater than the standard limit. If it is not greater than the standard limit, the average of the first result and the second calculated result measured by the total station is taken as the total station result. The standard limit is 4mm.

4. The method of claim 1, wherein: In step (A4), the static plane accuracy of the GNSS receiver shall not be less than ±3mm+1ppm, and the static elevation accuracy shall not be less than ±5mm+1ppm.

5. The method of claim 1, wherein: Step (A6) further includes determining whether the difference in planar position between the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is greater than the standard limit. If it is not greater than the standard limit, the average of the known system results of the first time period and the GNSS network-CGCS2000 reduction results of the second time period is taken as the GNSS network average result; the standard limit is 4mm.

6. A method for post-earthquake reconstruction based on a planar network of a known system, as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step (B) Within the engineering monitoring area, the engineering coordinate system network construction results are obtained using the planar network construction method based on a known system; these engineering coordinate system network construction results are the pre-earthquake engineering coordinate system network construction results; after the earthquake, the engineering coordinate system network construction results of the engineering monitoring area are reconstructed according to the following method: Step (B1) involves restoring and reconstructing the control network points within the engineering monitoring area. A total station is set up at each control network point to complete two measurements. The first measurement result from the total station is the known system result. Simultaneously, based on the first result, a two-dimensional four-parameter transformation model is used to reduce the second measurement result from the total station to obtain the second reduced result from the total station. The average of the first measurement result from the total station and the second reduced result is taken as the post-earthquake total station result. Step (B2) Use network RTK to obtain the CGCS2000 results for each control point; Step (B3) Set up GNSS receivers at the control points and continuously observe data for two 24-hour periods to obtain the GNSS network results for the two periods after the earthquake. Take the average of the GNSS network results for the two periods as the post-earthquake GNSS network results. Step (B4) translates the post-earthquake GNSS network results so that the centroid of the geocentric coordinates in the translated post-earthquake GNSS network results is consistent with the centroid of the CGCS2000 geocentric coordinates, thus obtaining the post-earthquake GNSS network-CGCS2000 results. Step (B5) Obtain the maximum and minimum longitude of the engineering monitoring area, and use the average of the maximum and minimum longitude of the engineering monitoring area as the central meridian; The geodetic height of the projection surface is obtained by taking the average of the maximum and minimum values ​​of the normal height of the projection surface specified by the control network points and the elevation anomaly of the engineering monitoring area as the benchmark, and then using it as the Gaussian projection surface. Project the post-earthquake GNSS network-CGCS2000 results into Gaussian plane coordinates; Step (B6) Determine the number of stable points in the post-earthquake GNSS network results; When there are no fewer than 3 stable points, the average GNSS network results at the time of control network establishment are used as known system results. The average GNSS network results at the time of control network establishment are used as a benchmark. The post-earthquake GNSS network results are reduced using a two-dimensional four-parameter transformation model to obtain the post-earthquake GNSS network reduction results. The post-earthquake GNSS network regression results were used as new known system results; When the number of stable points is less than 3, obtain the mean GNSS network results and the engineering coordinate system network results of the plane network during the construction of the control network; establish a two-dimensional four-parameter transformation model between the mean GNSS network results and the engineering coordinate system network results; use this two-dimensional four-parameter transformation model to import the post-earthquake GNSS network results to obtain the post-earthquake engineering coordinate system network results.

7. The method as described in claim 6, characterized in that: The deviation of the plane position of the stable point shall not exceed the standard tolerance value, which is 4.0 mm.

8. A method for evaluating the stability of a planar network based on a known system, according to any one of claims 1 to 5, characterized in that: Includes the following steps: S1. Collect data for planar network construction. S2. Collect the first two sets of measurement data to establish the initial results; S3. Obtain the results of the retest of the free network. S4. Using the analysis and judgment of the stable point, the results of the remeasured free network are converted into the results of the known system in the previous period through a two-dimensional four-parameter transformation model. S5. Calculate the remeasurement results and weights of the stable points, the remeasurement results and weights of the displacement points, and the displacement amount and direction of the displacement points.

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