Dam slope BDS / GNSS reference station stability analysis method and system

Abstract

The invention discloses a stability analysis method and system for a BDS / GNSS reference station of a dam slope. The invention discloses a method for analyzing stability of GNSS reference stations in a dam and a surrounding area by using a GNSS station coordinate time sequence, and belongs to the field of GNSS precision positioning and engineering monitoring interdiscipline. According to the method, stable GNSS reference stations in a reservoir area and around the reservoir area are selected, long-term observation data are processed through a precise point positioning (PPP) mode with fixed ambiguity, and a high-precision GNSS station coordinate time sequence is obtained. Then, through the steps of reference frame alignment, data preprocessing, environmental load and thermoelastic deformation elimination and the like, non-structural signal interference is eliminated, and a clean coordinate time sequence is obtained. On the basis, parameter estimation is carried out by adopting a mathematical model of linear speed + annual term + semi-annual term + jump, and the stability of the reservoir dam and the surrounding GNSS reference station is comprehensively evaluated in combination with a reservoir dam border deformation mechanism, deformation characteristics and the like.

Description

Technical Field

[0001] The present invention belongs to the interdisciplinary field of GNSS precise positioning and engineering monitoring, and particularly relates to the field of GNSS deformation monitoring. Specifically, it relates to a method for analyzing the stability of BDS / GNSS reference stations on the slopes of reservoirs and dams. Background Art

[0002] The basic surveying and mapping reference in the reservoir and dam area is an important infrastructure for dam safety monitoring. During the processes of slope stability measurement of the dam and dam safety monitoring, it is the base point for traditional surveying work such as total station and level. Due to geological activity changes caused after the construction of the reservoir, such as valley width deformation and local fault movement, these reference points will be affected, resulting in difficulty in maintaining the reference for dam area deformation monitoring. How to accurately evaluate the stability of the surveying and mapping reference points in the dam area has always been an important part of the operation and maintenance of hydropower projects. Summary of the Invention

[0003] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for analyzing the stability of BDS / GNSS reference stations on the slopes of reservoirs and dams. Based on the coordinate time series of BDS / GNSS reference stations, it analyzes the stability of BDS / GNSS reference stations in the reservoir and dam and surrounding areas, aiming to solve the above technical problems through a systematic data processing and analysis process.

[0004] According to one aspect of the specification of the present invention, there is provided a method for analyzing the stability of BDS / GNSS reference stations on the slopes of reservoirs and dams, including: Based on the observation data of the selected BDS / GNSS reference stations around and within the reservoir area, using the precise point positioning mode with ambiguity fixing for data processing to obtain the coordinate time series of BDS / GNSS reference stations; When the obtained coordinate time series of BDS / GNSS reference stations is based on a unified framework, removing non-constructive signals to obtain a "clean" coordinate time series of BDS / GNSS reference stations; Based on the obtained "clean" coordinate time series of BDS / GNSS reference stations, performing time series analysis to obtain the residual RMS, linear velocity, seasonal variation, and non-seasonal variation; Based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation, performing stability analysis of the reference stations within the reservoir area.

[0005] As a further technical solution, the method further includes: When there are different frames in the obtained coordinate time series of BDS / GNSS reference stations, performing coordinate reference frame alignment.

[0006] As a further technical solution, for performing coordinate reference frame alignment, it further includes: The reference station in the reservoir area only has GPS observation data: Select IGS stations evenly distributed around the reservoir area, and add NNR+NNT constraints based on the selected IGS stations, and constrain them to the specified coordinate reference frame or the latest version of the ITRF frame; When the reference station in the reservoir area has BDS observation data and BDS data is required to be the main data for dam deformation monitoring: Select IGS stations evenly distributed around the reservoir area and add NNR+NNT constraints, constrain all GPS solution results to the specified coordinate reference frame or the latest version of the ITRF frame, and use the NNR+NNT constraint to constrain the BDS solution results in the reservoir area to the GPS solution.

[0007] As a further technical solution, to eliminate non-constructive signals, it also includes: Convert the space rectangular coordinate system XYZ to the X1Y1H direction coordinates parallel and perpendicular to the river flow direction, eliminate the error signals, and obtain the BDS / GNSS reference station coordinate time series with outliers and jumps removed.

[0008] As a further technical solution, to eliminate non-constructive signals, it also includes: Based on the BDS / GNSS reference station coordinate time series with outliers and jumps removed, calculate the environmental load model and thermo-elastic deformation model to obtain the "clean" BDS / GNSS reference station coordinate time series with environmental load and thermo-elastic deformation removed.

[0009] As a further technical solution, perform time series analysis, including: Based on the obtained "clean" BDS / GNSS reference station coordinate time series, use the mathematical model of linear velocity + annual and semi-annual terms + jumps + post-seismic deformation for estimation, and assume the stochastic model as WN+PL.

[0010] As a further technical solution, based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation, conduct stability analysis of the reference stations in the reservoir area, including: Based on the residual RMS, divide the stations into near-field stations and far-field stations for overall stability analysis; Compare the linear velocities of the stations in the reservoir area in the horizontal and vertical directions. When the velocity difference exceeds the expectation, make a judgment by combining the linear velocities in the horizontal and vertical directions of the surrounding stable BDS / GNSS reference stations; Compare the amplitudes and phases of the seasonal deformations of the stations in the reservoir area. When the difference exceeds the expectation, make a judgment by combining the seasonal deformations of the surrounding stable BDS / GNSS reference stations; Conduct non-seasonal deformation analysis based on the time series with linear velocity and seasonal variation removed.

[0011] According to one aspect of the present invention, a dam slope BDS / GNSS reference station stability analysis system is provided, comprising: The first main module is used to process the observation data of the BDS / GNSS reference stations selected around and within the reservoir area using the precise single point positioning mode with fixed ambiguity to obtain the BDS / GNSS reference station coordinate time series; The second main module is used to remove non-constructive signals and obtain a "clean" BDS / GNSS reference station coordinate time series based on a unified framework; The third main module is used to perform time series analysis based on the obtained “clean” BDS / GNSS reference station coordinate time series to obtain residual RMS, linear velocity, seasonal changes and non-seasonal changes; The fourth main module is used to perform stability analysis of the reference stations in the reservoir area based on the obtained residual RMS, linear velocity, seasonal changes and non-seasonal changes.

[0012] According to one aspect of the present invention, a reservoir dam slope BDS / GNSS reference station stability analysis device is provided, comprising a memory and a processor, wherein the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the reservoir dam slope BDS / GNSS reference station stability analysis method.

[0013] According to one aspect of the present specification, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to execute the reservoir dam slope BDS / GNSS reference station stability analysis method.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a method for analyzing the stability of BDS / GNSS reference stations in the reservoir dam and surrounding areas based on the coordinate time series of BDS / GNSS reference stations, aiming to solve the problem of accurate evaluation of the stability of surveying and mapping reference points in the dam area through a systematic data processing and analysis process. Specifically, the present invention first selects stable BDS / GNSS reference stations and in-station survey stations in the reservoir area to ensure the reliability of data quality and observation conditions; secondly, processes long-term observation data using the precise point positioning (PPP) mode with ambiguity fixing to obtain high-precision BDS / GNSS reference station coordinate time series; then, eliminates non-constructive signals through steps such as coordinate frame alignment, data preprocessing, and environmental load model calculation; finally, based on the estimation results of linear velocity, seasonal terms, and other deformation parameters, combined with the data of surrounding stable survey stations, consistency analysis is carried out to achieve a comprehensive evaluation of the stability of GNSS reference stations in the reservoir dam and surrounding areas. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings used in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 Schematic diagram of the process for analyzing the stability of BDS / GNSS reference stations on the slope of the reservoir dam provided by the embodiment of the present invention.

[0017] Figure 2 Schematic diagram of the residual RMS distribution provided by the embodiment of the present invention. Detailed Embodiment

[0018] Based on the current situation that accurately evaluating the stability of surveying and mapping reference points in the dam area has always been an important part of the operation and maintenance of hydropower projects, considering that the GNSS precise point positioning technology is based on satellite precise orbits, clock differences and other products, and can directly obtain the absolute coordinate time series results of the measurement points without using a reference station for differential, and has the advantages of all-weather, high precision, and high degree of automation, and can provide continuous time series data, providing a new solution for deformation monitoring in the reservoir dam and surrounding areas. Therefore, the present invention provides a method for analyzing the stability of GNSS reference stations in the reservoir dam and surrounding areas based on the GNSS station coordinate time series, aiming to solve the problem of accurate evaluation of the stability of surveying and mapping reference points in the dam area through a systematic data processing and analysis process.

[0019] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. In addition, the technical features in each embodiment or individual embodiment provided by the present invention can be combined with each other arbitrarily to form a new technical solution. Such combination is not restricted by the order of steps and / or the structural composition mode, but must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0020] Please refer to Figure 1 , the present invention provides a method for analyzing the stability of the BDS / GNSS reference station on the reservoir dam slope, including the following steps: Step 1: Selection of BDS / GNSS stations for the reservoir area monitoring network Station selection (stations within the reservoir area and surrounding stations): For stations within the reservoir area, BDS / GNSS reference stations with continuous observation periods and good observation conditions should be selected, especially at key locations such as the main body of the dam and landslide bodies in the reservoir area; several stable BDS / GNSS reference stations should be selected around the reservoir area, avoiding tectonic activity zones, as the reference benchmark for dam deformation analysis.

[0021] The present invention selects the data of 17 GNSS reference stations in a certain reservoir area from 2021 to 2023 (about 2.6 years), and the time accumulation of the data is greater than the shortest time span (2.5 years) for separating the long-term trend term and annual term in the GNSS coordinate sequence.

[0022] Step 2: High-precision PPP solution for dam deformation Using the observation data of the surrounding stable BDS / GNSS stations and BDS / GNSS stations within the reservoir area selected in Step 1, perform 24-hour solution processing in the PPP mode with ambiguity fixing. To focus on improving the monitoring accuracy of the vertical deformation in the reservoir area, the tropospheric correction model uses the VMF3 projection function + PWC residual delay estimation to specifically weaken the influence of local meteorological conditions in the reservoir area on the PPP elevation solution.

[0023] Static single-day solutions are performed using the PRIDE software. This software conducts precise point positioning based on the undifferenced ionosphere-free combination model, using the L1 and L2 frequencies of GPS, with an elevation cut-off angle of 7 degrees and a sampling rate of 30 seconds. Among them, the prior values of ZHD and ZWD in the tropospheric delay model are sourced from VMF3-OP (operational VMF3) grid data. The residual tropospheric delay estimation is set to piecewise constants over 60 minutes, with the process noise parameter unit of 0.02 m / sqrt(h), and the mapping function is VMF3. The satellite orbits and clock biases are fixed to the rapid products provided by Wuhan University (WHU). Meanwhile, the ambiguity is fixed using the code-phase bias products provided by WHU. The receiver antenna model selects the igs14.atx or igs20.atx absolute antenna phase center correction model according to the reference frame of the orbit products in different periods. The receiver clock bias is estimated according to the white noise model. The ocean tide correction adopts the FES2014b model; the solid tide and polar tide corrections adopt the IERS2010 protocol.

[0024] Step 3: Coordinate frame alignment The BDS / GNSS station coordinate time series required for the reservoir area are obtained from Step 2. If there are cases of different frames in the time series, coordinate frame alignment is required. There are the following two cases: (1) Only GPS observation data are available for the reference stations in the reservoir area: Select IGS stations evenly distributed around the reservoir area, and impose NNR+NNT constraints based on these stations, constrained to the specified reference frame or the latest version of the ITRF frame.

[0025] (2) When there is BDS observation data for the reference stations in the reservoir area and BDS data are mainly required for dam deformation monitoring: First, select IGS stations evenly distributed around the reservoir area and impose NNR+NNT constraints, and constrain all GPS solution results to the specified reference frame or the latest version of the ITRF frame. Then, use the NNR+NNT constraints to constrain the BDS solution results in the reservoir area to the GPS solutions, ensuring the benchmark consistency of BDS data in dam deformation analysis.

[0026] The coordinate time series of the stations in the reservoir area obtained from Step 2 are in the IGS14 frame before November 26, 2022 (including November 26, 2022), and in the IGS20 frame after that. Using the stable surrounding IGS stations, calculate the transformation parameters for converting the IGS station coordinate time series to the IGS20 frame, and then uniformly transform the case station coordinate time series to the IGS20 frame.

[0027] Step 4: Data preprocessing The BDS / GNSS coordinate time series under the unified framework is obtained from Step 3. The preprocessing steps of GNSS data in the reservoir area are very important, which seriously affect the estimation of station signals in the reservoir area. To better monitor the valley amplitude deformation and the deformation of the reservoir area, the XYZ-direction coordinates are converted into the X 1 Y 1 H-direction coordinates parallel and perpendicular to the river flow direction. Then, the error signals are eliminated, including the following two types of methods: (1) Automatic screening: The Hector / CATS software is used to eliminate the gross errors in the coordinate series of the stations in the reservoir area, and the jumps caused by artificial activities such as dam construction and equipment maintenance are highlighted, and other jumps are automatically detected. (2) Manual intervention: Visual inspections are carried out on the key stations of the dam (such as the dam crest and the stations in the gallery), and the abnormal data (such as the mutations during the impoundment period and the vibrations of the instruments) are corrected in combination with the dam safety logs.

[0028] The Hector software is used to analyze the GNSS station coordinate time series obtained from Step 3. In the data preprocessing stage, the interquartile range (IQR) method is first used to eliminate the outliers in the ENU series. And jumps are detected based on the PL+WN background noise model.

[0029] Step 5: Eliminate the surface deformation in the reservoir area caused by environmental loading and thermo-elastic deformation Eliminate the surface deformation in the BDS / GNSS coordinate time series caused by the environmental loading and thermo-elastic deformation in the reservoir area. Among them, the global grid models of non-tidal atmosphere, ocean and terrestrial water provided by GFZ are used for the environmental loading in the reservoir area. If there is a refined surface mass grid model in this area, then a new regional grid model is formed by using the regional grid model and the global grid models of other regions to calculate the environmental loading in the reservoir area. The thermo-elastic deformation model simultaneously considers the surface deformation in the reservoir area caused by the thermal expansion and contraction of the bedrock and the observation piers. After obtaining the coordinate series with gross errors and jumps eliminated from Step 4, subtract the deformation in the reservoir area caused by environmental loading and thermo-elastic deformation. The specific formula is as follows:

[0030] In the above formula, t is the deformation time, 、 and are the coordinate series after removing the surface deformation caused by environmental loading and thermo-elastic deformation; 、 and are the coordinate series with only gross errors and jumps eliminated; 、 and are the total environmental loading deformations in three directions; 、 and The thermo-elastic deformation of bedrock in three directions; , and are the thermo-elastic deformations of observation piers in three directions.

[0031] Step 6: Extraction of deformation characteristics in the reservoir area Use the "clean" BDS / GNSS reference station coordinate time series obtained in Step 5. An estimation is carried out using a mathematical model of linear velocity (reflecting the long-term deformation trend in the reservoir area) + annual and semi-annual terms (reflecting the periodic changes in the reservoir area, mainly the water level changes in the reservoir area) + jumps (special events or artificial intervention events in this area) + post-seismic deformation (if an earthquake occurred in this area). The noise model is assumed to be WN + PL (white noise + power-law noise).

[0032] It should be noted that using a mathematical model for time series analysis is a mature technology in this field and will not be elaborated here.

[0033] Step 7: Stability assessment of GNSS stations in the reservoir area Use the residual RMS and the change parameters of linear velocity and seasonal terms to analyze the stability of reference stations in the reservoir area.

[0034] (1) Residual RMS Use the residual sequence RMS after removing the linear velocity and annual and semi-annual terms to divide the stations into near-field stations and far-field stations for overall stability assessment.

[0035] The RMS of all stations in the ENU directions in this area is 1.87, 1.91, and 7.24 mm on average. To analyze whether the positioning accuracy of GNSS stations is affected by the water level changes in the Jinsha River reservoir area, all stations are divided into near-field stations and far-field stations according to the distance from the Jinsha River. The six stations closest to the Jinsha River are uniformly defined as "near-field stations", namely HH01 - 06, and the remaining stations are uniformly defined as "far-field stations". In the ENU directions, the average RMS of near-field stations increases by 0.37, 0.48, and 2.93 mm compared with far-field stations, as shown in Figure 2 and Table 1. Generally, stations closer to the Jinsha River are more susceptible to the influence of the water storage process of a certain power station reservoir. Therefore, the RMS of near-field GNSS stations is larger, especially in the vertical direction, which is also susceptible to the influence of the water mass load in the reservoir. Moreover, among the near-field stations, the RMS of stations closer to the dam site is also larger. The average value of the RMS of far-field stations is comparable to the positioning accuracy of global IGS stations. Since IGS stations are relatively stable and basically not affected by regional deformations, it can be preliminarily inferred that far-field stations are relatively stable. More precisely, far-field stations are less affected by reservoir deformations.

[0036] Table 1 Comparison of RMS between near-field stations and far-field stations

[0037] In Table 1, for the first two rows: the average RMS in the ENU direction of the near-field stations and the far-field stations; for the third row: the difference between the average RMS of the near-field stations and that of the far-field stations.

[0038] (1) Linear velocity: Under normal circumstances, the linear trend in the horizontal direction of GNSS stations is mainly caused by plate movement, and the difference in plate movement speed within a small area is < 0.01 mm / yr (area is 242 square kilometers). Therefore, first, compare the magnitudes and directions of the horizontal velocities of the GNSS reference stations in the reservoir area for consistency analysis. When the horizontal velocity differences among the stations in the reservoir area are large, it can be preliminarily judged that there is dam deformation. At this time, it is necessary to combine the magnitudes and directions of the horizontal velocities of the surrounding stable GNSS reference stations for judgment; use the horizontal velocities of the surrounding stable GNSS reference stations to construct a plate movement model or a parameter fitting model, and then calculate the horizontal velocities of the GNSS reference stations in the reservoir area based on the model and compare them with the measured values. When the difference between the model fitting value and the measured value is large, it can be determined that there is deformation in the reservoir area.

[0039] Under normal circumstances, the linear velocity in the elevation direction is generally very small; when the magnitudes and directions of the elevation velocities of the reference stations in the reservoir area are inconsistent, it can be preliminarily judged that there is dam deformation. At this time, it is necessary to combine the magnitudes and directions of the elevation velocities of the surrounding stable GNSS reference stations for judgment; use the elevation velocities of the surrounding stable GNSS reference stations to construct a parameter fitting model, and then calculate the elevation velocities of the GNSS reference stations in the reservoir area based on the model and compare them with the measured values. When the difference between the model fitting value and the measured value is large, it can be determined that there is deformation in the reservoir area.

[0040] It can be obtained from step 6 that the magnitudes and directions of the horizontal velocities of each station are generally consistent, with an average of 36 mm / yr, and the average velocity uncertainty is 0.65 mm / yr. The estimation accuracy of the linear velocity in the horizontal direction of the stations in this area is relatively high. The vertical direction of the GNSS stations shows an overall upward trend, with an average velocity of 3.9 mm / yr. Generally, the velocity accuracy in the horizontal direction is good, and it can be initially considered that the stability of the stations is good.

[0041] In addition, in order to explore the influence of the reservoir on the surrounding stations, we statistically analyzed the average velocity uncertainties and their differences of the near-field and far-field stations in the ENU direction, as shown in Table 2.

[0042] Table 2 Average velocity uncertainties and their differences of the near-field and far-field stations in the ENU direction

[0043] In Table 2, the first two rows: the average velocity uncertainties of the near-field stations and far-field stations in the ENU directions; the third row: the difference between the average velocity uncertainties of the near-field stations and far-field stations.

[0044] As shown in Table 2, the average velocity uncertainties of the near-field stations in the ENU directions are 0.09, 0.36, and 1.86 mm / yr higher than those of the far-field stations respectively. This indicates that the impoundment of the Xiluodu Reservoir has a significant impact on the near-field stations, especially in the vertical direction, possibly due to the water level change leading to a decrease in the vertical velocity stability; in the horizontal direction, the impact on the N direction is greater than that on the E direction, which may be related to the river flow direction. From the results of the linear trend, there is certain deformation in the reservoir area, but the stability of the far-field stations in this area is relatively good.

[0045] (2) Seasonal deformation The estimation results in Step 6 show that in the E direction, the annual amplitudes of all stations are distributed between 0.8 - 2.2 mm. The annual phase distributions of the stations closer to the Jinsha River are relatively chaotic, while the annual phases of the remaining stations are more consistent. In the N direction, the annual amplitudes of all stations are distributed between 1.3 - 2.1 mm. Compared with the E direction, the phase distributions of each station are more consistent and are basically in the same quadrant. In the U direction, the annual amplitude range of all stations is 7 - 10 mm, and the annual phase distributions are generally more consistent. It shows that the reservoir dam has a certain impact on the seasonal signals in the east direction of the near-field stations, but overall the seasonal signals are relatively stable.

[0046] (3) Other deformations Perform non-seasonal deformation analysis on the time series after deducting the linear trend and seasonal variations. Examine whether there is still non-seasonal deformation related to the flood season. After determining the deformation in the reservoir area using parameters such as linear velocity and seasonal terms, it is best to also make a comparison and judgment in combination with the geological data of the reservoir area and the measured data of other observation techniques.

[0047] It can be seen that the method described in the present invention comprehensively and effectively evaluates the stability of the stations around the reservoir dam from the perspectives of linear trend, seasonal deformation, and other deformations, demonstrating the effectiveness of the present invention.

[0048] The implementation basis of each embodiment of the present invention is achieved through programmed processing by a device with a processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention are encapsulated into various modules. Based on this actual situation, on the basis of the above embodiments, an embodiment of the present invention provides a stability analysis system for the BDS / GNSS reference stations on the reservoir dam slope, which is used to execute the stability analysis method for the BDS / GNSS reference stations on the reservoir dam slope in the above method embodiments.

[0049] The system includes: a first main module for processing data by using the precise point positioning mode with ambiguity fixing based on the observation data of the selected BDS / GNSS reference stations around and within the reservoir area to obtain the BDS / GNSS reference station coordinate time series; a second main module for removing non-constructive signals based on the obtained BDS / GNSS reference station coordinate time series under a unified framework to obtain a "clean" BDS / GNSS reference station coordinate time series; a third main module for performing time series analysis based on the obtained "clean" BDS / GNSS reference station coordinate time series to obtain the residual RMS, linear velocity, seasonal variation, and non-seasonal variation; and a fourth main module for performing stability analysis of the reference stations within the reservoir area based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation.

[0050] A stability analysis system for BDS / GNSS reference stations on the reservoir dam slope provided by an embodiment of the present invention, aiming at the current situation of accurate assessment of the stability of surveying and mapping reference points in the dam area, adopts the foregoing several modules to perform stability analysis on the BDS / GNSS reference stations in the reservoir dam and surrounding areas based on the BDS / GNSS reference station coordinate time series, aiming to solve the above technical problems through the data processing and analysis process of the system.

[0051] It should be noted that the system embodiment provided by the present invention, in addition to being used to implement the method in the above method embodiment, is also used to implement the method in other method embodiments provided by the present invention. The difference is only in setting corresponding functional modules, and its principle is basically the same as that of the above system embodiment provided by the present invention. As long as those skilled in the art, based on the above system embodiment, refer to the specific technical solutions in other method embodiments, obtain corresponding technical means by combining technical features, and the technical solutions constituted by these technical means, and on the premise of ensuring the practicability of the technical solutions, improve the modules in the above system embodiment to obtain corresponding system-like embodiments for implementing the methods in other method-like embodiments.

[0052] Based on the same inventive concept as the foregoing embodiment, an embodiment of the present invention further provides a stability analysis device for BDS / GNSS reference stations on the reservoir dam slope, including a memory and a processor. The memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the stability analysis method for BDS / GNSS reference stations on the reservoir dam slope.

[0053] In an embodiment of the present invention, the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), etc., or may also be a volatile memory, such as a random-access memory (RAM). The memory is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in the embodiment of the present invention may also be a circuit or any other device capable of implementing a storage function, for storing program instructions and / or data.

[0054] In an embodiment of the present invention, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed by a hardware processor, or executed by a combination of hardware and software modules in the processor.

[0055] Based on the same inventive concept as the foregoing embodiments, an embodiment of the present invention further provides a non-transitory computer-readable storage medium, and the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the method for analyzing the stability of the BDS / GNSS reference station on the reservoir dam slope as follows: Based on the observation data of the selected BDS / GNSS reference stations around and within the reservoir area, use the precise point positioning mode with ambiguity fixing to process the data to obtain the BDS / GNSS reference station coordinate time series; When the obtained BDS / GNSS reference station coordinate time series is based on a unified framework, remove non-constructive signals to obtain a "clean" BDS / GNSS reference station coordinate time series; Based on the obtained "clean" BDS / GNSS reference station coordinate time series, perform time series analysis to obtain the residual RMS, linear velocity, seasonal variation and non-seasonal variation; Based on the obtained residual RMS, linear velocity, seasonal variation and non-seasonal variation, perform stability analysis on the reference stations within the reservoir area.

[0056] In summary of the above embodiments, the present invention discloses a method for analyzing the stability of GNSS reference stations in a reservoir dam and its surrounding areas using GNSS station coordinate time series, belonging to the interdisciplinary field of GNSS precise positioning and engineering monitoring. This method selects stable GNSS reference stations in and around the reservoir area, processes long-term observation data using the precise point positioning (PPP) mode with ambiguity fixing to obtain high-precision GNSS station coordinate time series. Subsequently, through steps such as reference frame alignment, data preprocessing, and elimination of environmental load and thermoelastic deformation, non-constructive signal interference is eliminated to obtain a "clean" coordinate time series. On this basis, a mathematical model of linear velocity + annual term + semi-annual term + jump is used for parameter estimation, and combined with the deformation mechanism and deformation characteristics of the reservoir dam edge area, the stability of the reservoir dam and its surrounding GNSS reference stations is comprehensively evaluated.

[0057] As used in the description and claims of the present invention and the above drawings, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. And these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing the stability of a BDS / GNSS reference station on the slope of a reservoir dam, characterized in that, Including: Based on the observation data of BDS / GNSS reference stations selected around and within the reservoir area, using the precise point positioning mode with ambiguity fixing for data processing to obtain the BDS / GNSS reference station coordinate time series; When the obtained BDS / GNSS reference station coordinate time series is based on a unified framework, removing non-constructive signals to obtain a "clean" BDS / GNSS reference station coordinate time series; Based on the obtained "clean" BDS / GNSS reference station coordinate time series, performing time series analysis to obtain the residual RMS, linear velocity, seasonal variation, and non-seasonal variation; Based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation, performing stability analysis of the reference stations within the reservoir area.

2. The method for analyzing the stability of a BDS / GNSS reference station on the slope of a reservoir dam according to claim 1, wherein The method further includes: When there are different coordinate reference frameworks in the obtained BDS / GNSS reference station coordinate time series, performing coordinate reference framework alignment.

3. The method for analyzing the stability of a BDS / GNSS reference station on the slope of a reservoir dam according to claim 2, wherein, Performing coordinate reference framework alignment further includes: If there is only GPS observation data for the reference stations within the reservoir area: Select IGS stations evenly distributed around the reservoir area, and add NNR+NNT constraints based on the selected IGS stations, and constrain them to the specified coordinate reference framework or the latest version of the ITRF framework; If there is BDS observation data for the reference stations within the reservoir area and it is necessary to mainly use BDS data for dam deformation monitoring: Select IGS stations evenly distributed around the reservoir area and add NNR+NNT constraints, constrain all GPS solution results to the specified coordinate reference framework or the latest version of the ITRF framework, and use the NNR+NNT constraints to constrain the BDS solution results within the reservoir area to the GPS solution.

4. The method for analyzing the stability of a BDS / GNSS reference station on the slope of a reservoir dam according to claim 1, characterized in that, Removing non-constructive signals further includes: Convert the space rectangular coordinate system XYZ to the X 1 1 Y 1 H-direction coordinates, eliminate the error signals, and obtain the BDS / GNSS reference station coordinate time series with outliers and jumps removed.

5. The stability analysis method of a BDS / GNSS reference station on the slope of a reservoir dam according to claim 4, wherein Removing non-constructive signals further includes: Based on the BDS / GNSS reference station coordinate time series after eliminating gross errors and jumps, calculating the environmental load model and thermo-elastic deformation model to obtain a "clean" BDS / GNSS reference station coordinate time series after eliminating environmental load and thermo-elastic deformation.

6. The stability analysis method of the BDS / GNSS reference station on the reservoir dam slope according to claim 1, wherein, Performing time series analysis includes: Based on the obtained "clean" BDS / GNSS reference station coordinate time series, using a mathematical model of linear velocity + annual and semi-annual terms + jumps + post-seismic deformation for estimation, and assuming the stochastic model as WN+PL.

7. The stability analysis method of the BDS / GNSS reference station on the slope of the reservoir dam according to claim 1, characterized in that Based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation, performing stability analysis of the reference stations within the reservoir area, including: Based on the residual RMS, dividing the stations into near-field stations and far-field stations for overall stability analysis; Comparing the linear velocities of the stations within the reservoir area in the horizontal and vertical directions, and when the velocity difference exceeds the expectation, making a judgment in combination with the linear velocities of the surrounding stable BDS / GNSS reference stations in the horizontal and vertical directions; Comparing the amplitudes and phases of the seasonal deformations of the stations within the reservoir area, and when the difference exceeds the expectation, making a judgment in combination with the seasonal deformations of the surrounding stable BDS / GNSS reference stations; Performing non-seasonal deformation analysis based on the time series after removing linear velocity and seasonal variation.

8. A stability analysis system for a BDS / GNSS reference station on the slope of a reservoir dam, characterized in that, Including: The first main module is used to process the observation data of the BDS / GNSS reference stations selected around and within the reservoir area using the precise single point positioning mode with fixed ambiguity to obtain the BDS / GNSS reference station coordinate time series; The second main module is used to remove non-constructive signals and obtain a "clean" BDS / GNSS reference station coordinate time series based on a unified framework; The third main module is used to perform time series analysis based on the obtained "clean" BDS / GNSS base station coordinate time series to obtain residual RMS, linear velocity, seasonal changes and non-seasonal changes; The fourth main module is used to perform stability analysis of the reference stations in the reservoir area based on the obtained residual RMS, linear velocity, seasonal changes and non-seasonal changes.

9. An equipment for analyzing the stability of a BDS / GNSS reference station on the slope of a reservoir dam, characterized in that, It comprises a memory and a processor, wherein the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the reservoir dam slope BDS / GNSS reference station stability analysis method as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the reservoir dam slope BDS / GNSS reference station stability analysis method as described in any one of claims 1 to 7.

Images