A method and system for analyzing the stability of a dam slope BDS / GNSS reference station

Abstract

A kind of library dam slope BDS / GNSS reference station stability analysis method and system.The present application discloses a kind of method for analyzing the stability of GNSS reference station in library dam and surrounding area using GNSS station coordinate time series, belong to the cross-disciplinary field of GNSS precise positioning and engineering monitoring.The method is by selecting the stable GNSS reference station in library area and surrounding area, using the precise point positioning (PPP) mode of ambiguity fixing to process long-term observation data, obtain high-precision GNSS station coordinate time series.Subsequently, by reference frame alignment, data preprocessing and environmental load and thermal elastic deformation elimination etc., eliminate non-structural signal interference, obtain the "clean" coordinate time series.On this basis, using linear velocity+annual term+half-yearly term+jump mathematical model is estimated, and combined with the deformation mechanism of library dam side area, deformation characteristics etc., the stability of library dam and surrounding GNSS reference station is comprehensively evaluated.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of GNSS precision positioning and engineering monitoring, and particularly relates to the field of GNSS deformation monitoring. Specifically, it relates to a method for stability analysis of reservoir and dam slopes using BDS / GNSS reference stations. Background Technology

[0002] Basic surveying benchmarks in the reservoir dam area are crucial infrastructure for dam safety monitoring. They serve as the baseline for traditional surveying work, including total stations and levels, during dam slope stability measurements and dam safety monitoring. However, geological changes caused by reservoir construction, such as valley deformation and local fault movement, can affect these benchmarks, making it difficult to maintain accurate benchmarks for dam area deformation monitoring. Therefore, accurately assessing the stability of dam area surveying benchmarks has always been a critical aspect of hydropower project operation and maintenance. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention provides a method for stability analysis of reservoir dam slopes using BDS / GNSS reference stations. This method analyzes the stability of BDS / GNSS reference stations in the reservoir dam and surrounding areas based on the time series of BDS / GNSS reference station coordinates. The aim is to solve the aforementioned technical problems through a systematic data processing and analysis process.

[0004] According to one aspect of the present invention, a method for stability analysis of reservoir dam slopes using a BDS / GNSS reference station is provided, comprising:

[0005] Based on the observation data of selected BDS / GNSS reference stations around and within the reservoir area, the data is processed using a precise single-point positioning mode with fixed ambiguity to obtain the time series of BDS / GNSS reference station coordinates.

[0006] With the obtained BDS / GNSS reference station coordinate time series based on a unified framework, non-structural signals are removed to obtain a "clean" BDS / GNSS reference station coordinate time series.

[0007] Based on the obtained "clean" BDS / GNSS reference station coordinate time series, time series analysis was performed to obtain residual RMS, linear velocity, seasonal variation and non-seasonal variation;

[0008] Based on the obtained residual RMS, linear velocity, seasonal and non-seasonal variations, stability analysis of the benchmark stations in the reservoir area is conducted.

[0009] As a further technical solution, the method also includes:

[0010] When different frames exist in the obtained BDS / GNSS reference station coordinate time series, coordinate reference frame alignment is performed.

[0011] As a further technical solution, aligning the coordinate reference frame also includes:

[0012] The reference stations in the reservoir area only have GPS observation data: IGS stations that are evenly distributed around the reservoir area are selected, and NNR+NNT constraints are added based on the selected IGS stations, which are constrained to the specified coordinate reference frame or the latest version of the ITRF frame.

[0013] When BDS observation data is available at the base station in the reservoir area, and dam deformation monitoring is to be based primarily on BDS data: 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 NNR+NNT constraints to constrain the BDS solution results in the reservoir area to the GPS solution.

[0014] As a further technical solution, eliminating unstructured signals also includes:

[0015] The spatial rectangular coordinate system XYZ is transformed to X1Y1H coordinates that are parallel and perpendicular to the river flow direction. Error signals are then eliminated to obtain the BDS / GNSS reference station coordinate time series with gross errors and jumps removed.

[0016] As a further technical solution, eliminating unstructured signals also includes:

[0017] Based on the BDS / GNSS reference station coordinate time series with gross errors and jumps eliminated, environmental load model and thermoelastic deformation model calculations are performed to obtain a "clean" BDS / GNSS reference station coordinate time series with environmental load and thermoelastic deformation eliminated.

[0018] As a further technical solution, time series analysis is performed, including:

[0019] Based on the obtained "clean" BDS / GNSS reference station coordinate time series, a mathematical model of linear velocity + annual and semi-annual terms + jump + post-earthquake deformation is used for estimation, and the stochastic model is assumed to be WN+PL.

[0020] As a further technical solution, based on the obtained residual RMS, linear velocity, seasonal and non-seasonal variations, stability analysis of the benchmark stations within the reservoir area is conducted, including:

[0021] Based on residual RMS, the stations are divided into near-field stations and far-field stations for overall stability analysis.

[0022] Compare the linear velocities of the monitoring stations within the reservoir area in the horizontal and vertical directions. If the velocity difference exceeds expectations, make a judgment based on the linear velocities of the surrounding stable BDS / GNSS reference stations in the horizontal and vertical directions.

[0023] By comparing the amplitude and phase of seasonal deformation at stations within the reservoir area, and when the difference exceeds expectations, a judgment is made in conjunction with the seasonal deformation of surrounding stable BDS / GNSS reference stations.

[0024] Non-seasonal deformation analysis was performed based on time series data after removing linear velocity and seasonal variations.

[0025] According to one aspect of the present invention, a BDS / GNSS reference station stability analysis system for reservoir dam slopes is provided, comprising:

[0026] The first main module is used to process the observation data of selected BDS / GNSS reference stations around and within the reservoir area using a precise single-point positioning mode with fixed ambiguity to obtain the time series of BDS / GNSS reference station coordinates.

[0027] The second main module is used to remove non-structural signals from the obtained BDS / GNSS reference station coordinate time series based on a unified framework, so as to obtain a "clean" BDS / GNSS reference station coordinate time series.

[0028] The third main module is used to perform time series analysis based on the obtained "clean" BDS / GNSS reference station coordinate time series, and to obtain residual RMS, linear velocity, seasonal variation and non-seasonal variation;

[0029] The fourth main module is used to perform stability analysis of the benchmark stations within the reservoir area based on the obtained residual RMS, linear velocity, seasonal variation and non-seasonal variation.

[0030] According to one aspect of the present invention, a stability analysis device for a reservoir / dam slope BDS / GNSS reference station is provided, comprising a memory and a processor. The memory stores program instructions that are executed by the processor, and the processor invokes the program instructions to execute the stability analysis method for the reservoir / dam slope BDS / GNSS reference station.

[0031] According to one aspect of the present invention, a non-transitory computer-readable storage medium is provided, the non-transitory computer-readable storage medium storing computer instructions that cause the computer to execute the described method for stability analysis of reservoir / dam slope BDS / GNSS reference station.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention proposes a method for stability analysis of BDS / GNSS reference stations in and around reservoir dam areas based on BDS / GNSS reference station coordinate time series. The aim is to solve the problem of accurate stability assessment of mapping reference points in the dam area through a systematic data processing and analysis process. Specifically, this invention first selects stable BDS / GNSS reference stations and stations within the reservoir area to ensure data quality and the reliability of observation conditions. Second, it uses a precise point positioning (PPP) mode with fixed ambiguity to process long-term observation data, obtaining high-precision BDS / GNSS reference station coordinate time series. Then, through steps such as coordinate frame alignment, data preprocessing, and environmental load model calculation, non-structural signals are eliminated. Finally, based on the estimation results of linear velocity, seasonal terms, and other deformation parameters, and combined with data from stable surrounding stations, a consistency analysis is performed, thereby achieving a comprehensive assessment of the stability of GNSS reference stations in and around the reservoir dam area. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the process for stability analysis of reservoir dam slope using BDS / GNSS reference stations provided in this embodiment of the invention.

[0036] Figure 2 This is a schematic diagram of the residual RMS distribution provided in an embodiment of the present invention. Detailed Implementation

[0037] This invention addresses the ongoing challenge of accurately assessing the stability of dam area mapping benchmarks, a crucial aspect of hydropower project operation and maintenance. Considering that GNSS precise point positioning technology, based on satellite precise orbits and clock differences, can directly obtain the absolute coordinate time series results of measurement points without the need for differential analysis using reference stations, and boasts advantages such as all-weather operation, high precision, and high automation, providing continuous time series data, this invention offers a new solution for deformation monitoring of reservoirs, dams, and surrounding areas. Therefore, this invention provides a method for stability analysis of GNSS reference stations in reservoirs, dams, and surrounding areas based on GNSS station coordinate time series, aiming to solve the problem of accurately assessing the stability of dam area mapping benchmarks through a systematic data processing and analysis workflow.

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0039] Please see Figure 1 This invention provides a method for stability analysis of reservoir dam slopes using BDS / GNSS reference stations, comprising the following steps:

[0040] Step 1: Selection of BDS / GNSS stations for reservoir area monitoring network

[0041] Station selection (stations within the reservoir area and surrounding areas): Stations within the reservoir area should be BDS / GNSS reference stations with continuous observation periods and good observation conditions, especially in 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 reference benchmarks for dam deformation analysis.

[0042] This invention selected data from 17 GNSS reference stations in a certain reservoir area from 2021 to 2023 (approximately 2.6 years). The time accumulation of the data is greater than the shortest time span (2.5 years) of the long-term trend term and annual term in the separated GNSS coordinate sequence.

[0043] Step 2: High-precision PPP calculation of dam deformation

[0044] Using observational data from the selected stable BDS / GNSS stations in the surrounding area and within the reservoir area, as described in Step 1, a 24-hour solution processing was performed using a PPP model with fixed ambiguity. To significantly improve the accuracy of vertical deformation monitoring in the reservoir area, the tropospheric correction model employed the VMF3 projection function combined with PWC residual delay estimation to specifically mitigate the impact of local meteorological conditions in the reservoir area on the PPP elevation solution.

[0045] PRIDE software was used for single-day static calculations. This software performs precise single-point positioning based on a non-differential ionospheric composite model, using GPS frequencies L1 and L2, an altitude cutoff angle of 7 degrees, and a sampling rate of 30 seconds. In the tropospheric delay model, the prior values ​​for ZHD and ZWD are derived from VMF3-OP (operational VMF3) grid data. The residual tropospheric delay estimate is set to a piecewise constant of 60 minutes. The process noise parameter is in units of 0.02 m / sqrt(h), and the mapping function is VMF3. Satellite orbits and clock biases are fixed to the fast product provided by Wuhan University (WHU). Ambiguity is fixed using the code phase deviation product provided by WHU. The receiver antenna model uses either igs14.atx or igs20.atx based on the reference frame of the orbit product for different periods. The absolute antenna phase center correction model uses a white noise model to estimate the receiver clock bias. Tidal correction uses the FES2014b model; solid tide and polar tide corrections use the IERS2010 protocol.

[0046] Step 3: Align the coordinate frame

[0047] Step 2 yields the required BDS / GNSS station coordinate time series for the reservoir area. If the time series contains different frames, coordinate frame alignment is necessary. This can be done in two cases:

[0048] (1) The reference stations in the reservoir area only have GPS observation data: IGS stations that are evenly distributed around the reservoir area are selected, and NNR+NNT constraints are added based on these stations, and the constraints are applied to the specified reference frame or the latest version of the ITRF frame.

[0049] (2) When there is BDS observation data at the benchmark station in the reservoir area and it is necessary to use BDS data as the main data for dam deformation monitoring: First, select IGS stations evenly distributed around the reservoir area and add NNR+NNT constraints to constrain all GPS calculation 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 solution to ensure the benchmark consistency of BDS data in dam deformation analysis.

[0050] The time series of station coordinates within the reservoir area obtained in step 2 is in IGS14 frame before November 26, 2022 (including November 26, 2022), and in IGS20 frame thereafter. Using stable IGS stations in the surrounding area, the transformation parameters for converting their IGS station coordinate time series to the IGS20 frame are calculated, and then the time series of the case station coordinates are uniformly converted to the IGS20 frame.

[0051] Step 4: Data Preprocessing

[0052] Step 3 yields the BDS / GNSS coordinate time series based on a unified framework. The GNSS data preprocessing step in the reservoir area is crucial, significantly impacting the estimation of signals from monitoring stations within the reservoir. To better monitor valley deformation and reservoir deformation, the XYZ coordinates are transformed to X coordinates parallel and perpendicular to the river flow direction. 1 Y 1 H-direction coordinates. Then, error signals are eliminated, including the following two methods: (1) Automated screening: Hector / CATS software is used to eliminate gross errors in the coordinate sequence of reservoir area stations, with a focus on marking jumps caused by human activities such as dam construction and equipment maintenance, and other jumps are automatically detected. (2) Manual intervention: Visual inspection is carried out on key dam stations (such as stations on the dam crest and in the corridor), and abnormal data (such as sudden changes during the water storage period, instrument vibration, etc.) are corrected in conjunction with the dam safety log.

[0053] The GNSS station coordinate time series obtained in step 3 was analyzed using Hector software. In the data preprocessing stage, outliers in the ENU series were first eliminated using the Interquartile Range (IQR) method. Then, abrupt changes were detected based on the PL+WN background noise model.

[0054] Step 5: Eliminate surface deformation in the reservoir area caused by environmental load and thermoelastic deformation.

[0055] The surface deformation caused by environmental load and thermoelastic deformation in the BDS / GNSS coordinate time series is eliminated. The environmental load of the reservoir area is calculated using a global grid model of non-tidal atmosphere, ocean, and terrestrial water provided by GFZ. If a refined surface quality grid model exists for the region, a new regional grid model is constructed using the regional grid model and global grid models from other regions to calculate the environmental load within the reservoir area. The thermoelastic deformation model simultaneously considers the surface deformation of the reservoir area caused by the thermal expansion and contraction of bedrock and observation piers. After obtaining the coordinate series from step 4, which eliminates gross errors and jumps, the reservoir area deformation caused by environmental load and thermoelastic deformation is subtracted, using the following formula:

[0056]

[0057] In the above formula, t is the deformation time. , and The coordinate sequence after removing surface deformation caused by environmental load and thermoelastic deformation; , and For coordinate sequences that only eliminate gross errors and jumps; , and The total environmental load deformation in three directions; , and The bedrock undergoes thermoelastic deformation in three directions; , and The thermoelastic deformation of the observation pier in three directions.

[0058] Step 6: Extraction of reservoir deformation features

[0059] The "clean" BDS / GNSS reference station coordinate time series is obtained from step 5. A mathematical model is used for estimation, which is linear velocity (reflecting the long-term deformation trend of the reservoir area) + annual and semi-annual terms (reflecting the periodic changes in the reservoir area, mainly the changes in the reservoir water level) + jump (special events in the region, or artificial intervention events) + post-earthquake deformation (if an earthquake has occurred in the region). The noise model is assumed to be WN+PL (white noise + power-law noise).

[0060] It should be noted that using mathematical models for time series analysis is a mature technology in this field, and will not be elaborated upon here.

[0061] Step 7: Stability assessment of GNSS stations in the reservoir area

[0062] Stability analysis of the benchmark station in the reservoir area was conducted using residual RMS, linear velocity, and seasonal variation parameters.

[0063] (1) Residual RMS

[0064] By using the residual sequence RMS after removing linear velocity and annual and semi-annual terms, the stations are divided into near-field stations and far-field stations for overall stability assessment.

[0065] The average RMS in the ENU direction for all stations in the area was 1.87, 1.91, and 7.24 mm, respectively. To analyze whether the positioning accuracy of the GNSS stations was affected by the water level changes in the Jinsha River reservoir, all stations were divided into near-field and far-field stations according to their distance from the Jinsha River. The six stations closest to the Jinsha River were uniformly defined as "near-field stations," namely HH01-06, and the remaining stations were uniformly defined as "far-field stations." In the ENU direction, the average RMS of the near-field stations increased by 0.37, 0.48, and 2.93 mm compared to the far-field stations, respectively, as shown in Figure 2 and Table 1. Overall, stations closer to the Jinsha River are more susceptible to the impact of the reservoir impoundment process of a certain power station, thus the RMS of near-field GNSS stations is larger, especially in the vertical direction, where they are also more susceptible to the influence of reservoir water mass load. Moreover, among the near-field stations, those closer to the dam site also have larger RMS. The average RMS of far-field stations is comparable to the positioning accuracy of global IGS stations. Since IGS stations are relatively stable and largely unaffected by regional deformation, it can be preliminarily inferred that far-field stations are relatively stable. More precisely, far-field stations are less affected by reservoir deformation.

[0066] Table 1. Comparison of RMS between near-field and far-field stations.

[0067]

[0068] In Table 1, the first two rows show the average RMS values ​​of near-field and far-field stations in the ENU direction; the third row shows the difference between the average RMS values ​​of near-field and far-field stations.

[0069] (1) Linear velocity:

[0070] Typically, the linear trend in the horizontal direction of GNSS stations is mainly caused by plate tectonics, with differences in plate velocity within a small area (area of ​​242 square kilometers) of less than 0.01 mm / yr. Therefore, the first step is to compare the magnitude and direction of the horizontal velocities of GNSS reference stations within the reservoir area to conduct a consistency analysis. When there are significant differences in the horizontal velocities of stations within the reservoir area, it can be preliminarily determined that dam deformation exists. At this point, it is necessary to combine the magnitude and direction of the horizontal velocities of surrounding stable GNSS reference stations for further judgment. A plate tectonics model or a parameter fitting model is constructed using the horizontal velocities of surrounding stable GNSS reference stations. Then, the horizontal velocities of GNSS reference stations within the reservoir area are calculated based on the model and compared with the measured values. When the model-fitted values ​​differ significantly from the measured values, it can be determined that reservoir area deformation exists.

[0071] Normally, linear velocities along the elevation direction are very small. When the magnitude and direction of the elevation velocities at reference stations within the reservoir area are inconsistent, it can be preliminarily determined that dam deformation exists. In this case, it is necessary to combine the magnitude and direction of the elevation velocities of surrounding stable GNSS reference stations for judgment. A parameter fitting model is constructed using the elevation velocities of surrounding stable GNSS reference stations, and then the elevation velocities of GNSS reference stations within the reservoir area are calculated based on the model and compared with the measured values. When the model-fitted values ​​differ significantly from the measured values, it can be determined that reservoir area deformation exists.

[0072] Step 6 shows that the horizontal velocity magnitude and direction are generally consistent across all stations, averaging 36 mm / yr, with an average velocity uncertainty of 0.65 mm / yr. This indicates relatively high accuracy in estimating the horizontal linear velocity of the stations in this area. The vertical velocity of the GNSS stations generally shows an upward trend, with an average velocity of 3.9 mm / yr. Overall, the horizontal velocity accuracy is good, suggesting that the stations have good stability.

[0073] In addition, to investigate the impact of the reservoir on surrounding stations, we statistically analyzed the average velocity uncertainty and its difference between near-field and far-field stations in the ENU direction, as shown in Table 2.

[0074] Table 2. Mean velocity uncertainty and its difference between near-field and far-field stations in the ENU direction.

[0075]

[0076] In Table 2, the first two rows show the average velocity uncertainty in the ENU direction for near-field and far-field stations; the third row shows the difference between the average velocity uncertainty of near-field and far-field stations.

[0077] Table 2 shows that the average velocity uncertainty of the near-field stations is 0.09, 0.36, and 1.86 mm / yr higher in the ENU direction than that 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, where the vertical velocity stability may be reduced due to water level changes. In the horizontal direction, the impact is greater in the N direction than in the E direction, which may be related to the river flow direction. The linear trend results indicate that there is some deformation in the reservoir area, but the stability of the far-field stations in this region is better.

[0078] (2) Seasonal deformation

[0079] The estimation results from step 6 show that, in the E direction, the annual amplitude distribution of all stations ranges from 0.8 to 2.2 mm. The annual phase distribution of stations closer to the Jinsha River is more chaotic, while the annual phase distribution of the remaining stations is relatively consistent. In the N direction, the annual amplitude distribution of all stations ranges from 1.3 to 2.1 mm. Compared to the E direction, the phase distribution of each station is more consistent and generally falls within the same quadrant. In the U direction, the annual amplitude range of all stations is 7-10 mm, and the annual phase distribution is generally consistent. This indicates that while the reservoir and dam have some influence on the seasonal signal in the east direction from near-field stations, the overall seasonal signal is relatively stable.

[0080] (3) Other deformations

[0081] Non-seasonal deformation analysis was conducted using time series data that had been adjusted for linear trends and seasonal variations. The analysis examined whether non-seasonal deformation related to the flood season still existed. After estimating the presence of deformation in the reservoir area using parameters such as linear velocity and seasonal terms, it is best to compare and confirm this with geological data of the reservoir area and measured data from other observation techniques.

[0082] It can be seen that the method described in this invention comprehensively and effectively evaluates the stability of the monitoring stations around the reservoir and dam from the perspectives of linear trends, seasonal deformation, and other deformations, demonstrating the effectiveness of this invention.

[0083] The implementation of the various embodiments of the present invention is based on programmed processing by a device with processor functionality. Therefore, in practical engineering, the technical solutions and functions of the various embodiments of the present invention are encapsulated into various modules. Based on this reality, and building upon the above embodiments, the embodiments of the present invention provide a reservoir dam slope BDS / GNSS reference station stability analysis system, which is used to execute the reservoir dam slope BDS / GNSS reference station stability analysis method in the above method embodiments.

[0084] The system comprises: a first main module, used to process data from selected BDS / GNSS reference stations around and within the reservoir area using a precise single-point positioning mode with fixed ambiguity, to obtain BDS / GNSS reference station coordinate time series; a second main module, used to remove non-structural signals from the obtained BDS / GNSS reference station coordinate time series within a unified framework, to obtain a "clean" BDS / GNSS reference station coordinate time series; a third main module, 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 variation, and non-seasonal variation; and a fourth main module, used to perform stability analysis of reference stations within the reservoir area based on the obtained residual RMS, linear velocity, seasonal variation, and non-seasonal variation.

[0085] This invention provides a BDS / GNSS reference station stability analysis system for reservoir dam slopes. Addressing the current state of accurate stability assessment of surveying reference points in the dam area, the system employs several modules to perform stability analysis on BDS / GNSS reference stations in the reservoir dam and surrounding areas based on BDS / GNSS reference station coordinate time series. The aim is to solve the aforementioned technical challenges through the system's data processing and analysis workflow.

[0086] It should be noted that the system embodiments provided by the present invention are used not only to implement the methods in the above method embodiments, but also to implement the methods in other method embodiments provided by the present invention. The only difference is that corresponding functional modules are set. The principle is basically the same as that of the above system embodiments provided by the present invention. As long as those skilled in the art can improve the modules in the above system embodiments by referring to the specific technical solutions in other method embodiments and combining technical features to obtain corresponding technical means and technical solutions composed of these technical means, on the basis of the above system embodiments, and on the premise of ensuring the practicality of the technical solutions, they can obtain corresponding system-like embodiments for implementing the methods in other method-like embodiments.

[0087] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a reservoir dam slope BDS / GNSS reference station stability analysis device, including a memory and a processor. The memory stores program instructions that are executed by the processor, and the processor calls the program instructions to execute the reservoir dam slope BDS / GNSS reference station stability analysis method.

[0088] In embodiments of the present invention, the memory can be non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), or it can be volatile memory, such as random-access memory (RAM). Memory is any other medium capable of carrying or storing desired program code having an instruction or data structure form and accessible by a computer, but is not limited thereto. The memory in embodiments of the present invention can also be a circuit or any other device capable of implementing a storage function for storing program instructions and / or data.

[0089] In this embodiment of the invention, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components, capable of implementing or executing the methods, steps, and logic block diagrams disclosed in this embodiment of the invention. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in this embodiment of the invention can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0090] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a non-transitory computer-readable storage medium storing computer instructions. These computer instructions instruct the computer to execute the following method for analyzing the stability of the reservoir / dam slope using a BDS / GNSS reference station:

[0091] Based on the observation data of selected BDS / GNSS reference stations around and within the reservoir area, the data is processed using a precise single-point positioning mode with fixed ambiguity to obtain the time series of BDS / GNSS reference station coordinates.

[0092] With the obtained BDS / GNSS reference station coordinate time series based on a unified framework, non-structural signals are removed to obtain a "clean" BDS / GNSS reference station coordinate time series.

[0093] Based on the obtained "clean" BDS / GNSS reference station coordinate time series, time series analysis was performed to obtain residual RMS, linear velocity, seasonal variation and non-seasonal variation;

[0094] Based on the obtained residual RMS, linear velocity, seasonal and non-seasonal variations, stability analysis of the benchmark stations in the reservoir area is conducted.

[0095] In summary, this invention discloses a method for analyzing the stability of GNSS reference stations in and around reservoir dams 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 within and around the reservoir area, and processes long-term observation data using a precise point positioning (PPP) mode with fixed ambiguity to obtain a high-precision GNSS station coordinate time series. Subsequently, through steps such as reference frame alignment, data preprocessing, and removal of environmental loads and thermoelastic deformations, non-structural signal interference is eliminated, resulting in a "clean" coordinate time series. Based on this, 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 periphery, a comprehensive evaluation of the stability of the reservoir dam and surrounding GNSS reference stations is conducted.

[0096] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions 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 stability of a reservoir dam slope BDS / GNSS reference station, characterized in that, The method comprises the following steps: Based on the observation data of the selected BDS / GNSS reference stations in the periphery of the reservoir area and in the reservoir area, data processing is performed by using the precise point positioning mode with ambiguity fixed to obtain the time series of the coordinates of the BDS / GNSS reference stations; In the case that the obtained time series of the coordinates of the BDS / GNSS reference stations are based on a unified frame, non-constructive signals are removed to obtain the "clean" time series of the coordinates of the BDS / GNSS reference stations; Based on the obtained "clean" time series of the coordinates of the BDS / GNSS reference stations, time series analysis is performed 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, stability analysis of the reference stations in the reservoir area is performed, which comprises the following steps: based on the residual RMS, the stations are divided into near-field stations and far-field stations for overall stability analysis; the linear velocities of the stations in the horizontal direction and the elevation direction in the reservoir area are compared, and when the velocity difference exceeds the expectation, the linear velocities of the stations in the horizontal direction and the elevation direction of the stable BDS / GNSS reference stations in the periphery are combined for judgment; the amplitudes and phases of the seasonal deformations of the stations in the reservoir area are compared, and when the difference exceeds the expectation, the seasonal deformations of the stable BDS / GNSS reference stations in the periphery are combined for judgment; non-seasonal deformation analysis is performed based on the time series from which the linear velocity and the seasonal variation are removed.

2. The method according to claim 1, wherein, The method further comprises the following steps: In the case that the obtained time series of the coordinates of the BDS / GNSS reference stations are in different frames, coordinate reference frame alignment is performed.

3. The method according to claim 2, wherein, The coordinate reference frame alignment further comprises the following steps: When the reference stations in the reservoir area only have GPS observation data: IGS stations uniformly distributed in the periphery of the reservoir area are selected, and based on the selected IGS stations, NNR+NNT constraints are added to constrain the stations to a specified coordinate reference frame or the latest version of the ITRF frame; When the reference stations in the reservoir area have BDS observation data and need to mainly use the BDS data for dam deformation monitoring: IGS stations uniformly distributed in the periphery of the reservoir area are selected, and NNR+NNT constraints are added to constrain all GPS solution results to a specified coordinate reference frame or the latest version of the ITRF frame, and the BDS solution results in the reservoir area are constrained to the GPS solution by using the NNR+NNT constraints.

4. The method according to claim 1, wherein, The non-constructive signal removal further comprises the following steps: The spatial rectangular coordinate system XYZ is converted to X 1 Y 1 H direction coordinates, the error signal is removed, and the BDS / GNSS reference station coordinate time sequence eliminating gross errors and jumps is obtained.

5. The method according to claim 4, wherein, The non-constructive signal removal further comprises the following steps: Based on the BDS / GNSS reference station coordinate time series from which the gross errors and jumps are removed, environmental load model and thermal elastic deformation model calculations are performed to obtain the "clean" BDS / GNSS reference station coordinate time series from which the environmental load and thermal elastic deformation are removed.

6. The method according to claim 1, wherein, The time series analysis comprises the following steps: Based on the obtained "clean" BDS / GNSS reference station coordinate time series, a mathematical model of linear velocity + annual semi-annual term + jump + post-seismic deformation is used for estimation, and the random model is assumed to be WN+PL.

7. A reservoir dam slope BDS / GNSS reference station stability analysis system, characterized in that, The method comprises the following steps: The first main module is used for obtaining a time series of BDS / GNSS reference station coordinates by using a precise point positioning mode with ambiguity fixed based on observation data of selected BDS / GNSS reference stations in the periphery of the reservoir area and in the reservoir area; The second main module is used for eliminating non-constructive signals based on the obtained time series of BDS / GNSS reference station coordinates based on a unified framework to obtain a "clean" time series of BDS / GNSS reference station coordinates; The third main module is used for performing time series analysis based on the obtained "clean" time series of BDS / GNSS reference station coordinates to obtain residual RMS, linear velocity, seasonal variation and non-seasonal variation; The fourth main module is used for performing stability analysis of reference stations in the reservoir area based on the obtained residual RMS, linear velocity, seasonal variation and non-seasonal variation, 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 in the horizontal direction and the elevation direction in the reservoir area, and when the velocity difference exceeds the expectation, combining the linear velocities of the stations in the horizontal direction and the elevation direction of the surrounding stable BDS / GNSS reference stations for judgment; comparing the amplitude and phase of the seasonal deformation of the stations in the reservoir area, and when the difference exceeds the expectation, combining the seasonal deformation of the surrounding stable BDS / GNSS reference stations for judgment; and performing non-seasonal deformation analysis based on the time series from which the linear velocity and the seasonal variation are removed.

8. A reservoir dam slope BDS / GNSS reference station stability analysis device, characterized in that, The memory stores program instructions executed by the processor, and the processor invokes the program instructions to perform the reservoir dam slope BDS / GNSS reference station stability analysis method of any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium, comprising: The non-transitory computer readable storage medium stores computer instructions, and the computer instructions cause the computer to perform the reservoir dam slope BDS / GNSS reference station stability analysis method of any one of claims 1 to 6.

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