A method for measuring the deformation characteristics of railway structures after an earthquake using a precise survey network system

Abstract

The present invention discloses a method for measuring the deformation characteristics of railway structures after an earthquake by using a precise survey network system. Affected by earthquakes and other factors, displacement or damage may occur to control points of different grades in railway construction. The present invention dynamically updates the coordinates of control networks of different levels step by step. Based on the control results of precise survey networks of different levels obtained through repeated surveys, the multi-directional spatial deformation characteristics of the railway are analyzed. Combining the lateral and longitudinal deformation values of the overall and local tracks, the availability assessment of the track structure affected by the earthquake is completed. The present invention makes the most of the original control results and ensures the smooth connection of the track coordinate system, providing a data benchmark for project restoration.

Description

Technical Field

[0001] The present invention belongs to the technical field of railway control measurement and deformation monitoring, and in particular relates to a method for measuring deformation characteristics of railway structures after an earthquake by using a precise measurement network system. Background Art

[0002] In high-speed railway engineering surveying, the horizontal and vertical control networks for high-speed railway surveying are divided into the survey and design control network, the construction control network, and the operation and maintenance control network, based on the surveying stage, survey objectives, and functional requirements. These three phases of survey control networks are referred to as the "three networks." The establishment of a "three-network-in-one" precision surveying network meets the needs of survey and design and construction, and also serves as a survey benchmark for line maintenance during the operational phase. Railway belt control networks are mostly laid out in a hierarchical manner, with control networks at various levels, such as CP0, CPI, CPII, and CPIII, currently established in my country's railway construction. However, earthquakes and other impacts can cause varying degrees of displacement or damage to control points at different levels. Failure to promptly update these control points will impact surveying work during the construction and operation and maintenance phases. Currently, there is a lack of case studies and technical research on the rapid restoration of railway precision surveying networks after earthquakes and the detection of deformation characteristics of railway structures after earthquakes. Summary of the Invention

[0003] In order to make up for the shortcomings of the existing technology, the present invention provides a method for measuring the deformation characteristics of railway structures after an earthquake using a precise measurement network system, which makes up for the lack of rapid recovery of the precise measurement network system and structure deformation detection technology after an earthquake, and provides a solution for post-earthquake emergency rescue of railways.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for measuring deformation characteristics of railway structures after an earthquake using a precision measurement network system, characterized by comprising the following steps:

[0006] Step 1: Post-earthquake framework control network CP0 data processing and update;

[0007] Step 2: Post-earthquake basic plane control network CPI data processing and update;

[0008] Step 3: Post-earthquake line plane control network CPII and online encrypted CPII data processing;

[0009] Step 4: Post-earthquake track control network CPⅢ re-survey;

[0010] Step 5: Analysis of overall railway deformation characteristics;

[0011] Step 6: Analysis of deformation characteristics of railway structures.

[0012] Furthermore, the step 1 specifically includes:

[0013] S1.1: Measure CP0 and CPI in multiple time periods according to the GNSS first-order network observation technical requirements and the second-order network observation technical requirements, and calculate the CP0 and CPI observation data according to the precise ephemeris and multi-baseline mode;

[0014] S1.2: Solve the CP0 baseline vector network in different time periods to generate the normal equation and the corresponding covariance matrix, check for repeated baseline errors and asynchronous loop closure errors, integrate the normal equations and covariance matrices for each time period, and input the 3D coordinates of the CP0 point farthest from the epicenter within the line control network for unconstrained adjustment.

[0015] S1.3: Analyze the stability of CP0 points, CPI points, and their relationships. Based on the CP0 point spacing and tolerance requirements, perform a two-dimensional constrained adjustment using the CP0 point with the smallest displacement change as the starting point. Update the CP0 points affected by vibration, calculate the difference between the updated control points and the original control points, and analyze the point position change and deformation direction.

[0016] Furthermore, the second step specifically includes:

[0017] S2.1: Use edge connection to construct the CPI and CPII networks, forming a ribbon network composed of triangles or geodesic quadrilaterals;

[0018] S2.2: Use the updated CP0 point and the stable CPI points at the short-mileage end and the long-mileage end as the starting point to update the entire CPI control network of the re-survey section;

[0019] Furthermore, the step three specifically includes:

[0020] S3.1: For the line plane control network CPII and online encrypted CPII within the CPI control network resurvey range, resurvey the same network in accordance with the technical requirements of the GNSS third-class network. For the online encrypted CPII at the entrance and exit of the tunnel, resurvey it in accordance with the technical requirements of the GNSS second-class network.

[0021] S3.2: Using the updated CPI coordinates as the constrained starting data, perform constrained adjustment on the CPII network and calculate the difference between the re-surveyed and original survey results of the line CPII and the online encrypted CPII control points and the coordinate differences between adjacent points;

[0022] S3.3: Using the encrypted CPII results on the entrance and exit measurement lines as the starting data, re-survey the CPII control network inside the tunnel after the earthquake using the free-station corner intersection measurement method;

[0023] S3.4: For the CPII buried during the tunnel network construction period and now destroyed, a mandatory centering mark shall be used to coincide with the CPIII track control network;

[0024] S3.5: Lay the encrypted CPII in pairs at specified positions on the top surface of the cable trench on the side wall of the tunnel or U-shaped groove at a certain interval, and there are at least two station observations for each CPII point; for adjacent tunnels, incorporate the existing tunnel traverse results into the adjustment calculation during the constrained adjustment calculation;

[0025] Further, the specific steps of Step Four include:

[0026] S4.1: Re-bury the points damaged by the earthquake and unable to be used normally. The specifications of the CPIII components used and the burial positions are the same as those of the original network;

[0027] S4.2: Use the free station method of intersection of angles and sides for the re-survey of CPIII. There are at least three station observations for each CPIII point;

[0028] S4.3: Measure the CPIII network in segments according to a certain interval length, and the overlap between adjacent segments is not less than 6 pairs of CPIII points;

[0029] S4.4: When connecting between segments, it is necessary to meet the tolerance of the coordinate difference of the overlapping points in the independent adjustment of the front and rear segments; and for the adjustment of the CPIII network in the latter segment, use the encrypted CPII control points surveyed in this segment and 1 - 3 pairs of CPIII points in the previous segment of the overlapping section as the constraint points for the adjustment calculation;

[0030] Further, the specific steps of Step Five include:

[0031] S5.1: After the re-survey of the plane control network is completed, conduct a comprehensive analysis of the re-survey results, calculate the deformation values and displacement directions of CP0, CPI, and CPII from the original control points, analyze the co-seismic rupture characteristics of the track caused by the earthquake, and draw the multi-directional spatial deformation of plane offset and torsion, longitudinal compression and tension;

[0032] S5.2: Combine the re-survey data of CPIII and convert the coordinate change values in the north and east directions of CPIII into the change values along the longitudinal and transverse directions of the line;

[0033] S5.3: Measure the track center line, fit it in segments, calculate the line spacing, evaluate the dislocation of the line position, and complete the analysis of the overall deformation characteristics of the railway;

[0034] Further, the specific steps of Step Six include:

[0035] S6.1: Use the free station resection method to measure the characteristic parts such as the crown, waist, foot of the arch, invert point, contact rod, center of the bridge pier, and platform edge of the station on the tunnel wall, conduct a clearance analysis, and complete the evaluation of the availability of the track structure;

[0036] S6.2: Conduct stepped joint detection on the deformed positions, analyze the left and right structural offsets and the extrusion values of the structures towards the large and small mileage directions, synchronously carry out the observation of cracks on the tunnel wall, obtain crack data, and complete the matching analysis of the deformation conditions of the track structure and the overall railway.

[0037] Advantages of the present invention:

[0038] 1) The present invention proposes a method for quickly restoring the post-earthquake precise survey network system of railways, dynamically updates the coordinates of control networks at different levels step by step, makes the best use of the original control results to the greatest extent, and ensures the smooth connection of the track coordinate system, providing a position reference for post-earthquake emergency rescue.

[0039] 2) Based on the control results of the resurveyed precise survey networks at different levels, the present invention analyzes the multi-faceted spatial deformation characteristics of railways, combines the lateral and longitudinal deformation values of the overall and local tracks, and completes the evaluation of the usability of the track structure affected by earthquakes, providing a data reference for project restoration. Description of the Drawings

[0040] Figure 1 is the overall operation flow chart of the present invention;

[0041] Figure 2 is the schematic diagram of the railway plane control network;

[0042] Figure 3 is the schematic diagram of the CP0 network type of a certain railway;

[0043] Figure 4 is the observation schematic diagram of the CPⅢ plane control network with a station spacing of 120m;

[0044] Figure 5 is the schematic diagram of the connection and transition between adjacent sections of the CPⅢ network;

[0045] Figure 6 is the left-side CPⅢ plane deformation diagram of a certain tunnel line;

[0046] Figure 7 is the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1965+780;

[0047] Figure 8 is the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1971+390;

[0048] Figure 9 is the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1971+400;

[0049] Figure 10 is the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1972+000;

[0050] Figure 11This is a schematic diagram of the deformation of points before and after the misalignment in the mileage range of K1971+377 to K1971+497. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to a specific implementation of measuring the deformation characteristics of railway structures after an earthquake using a precise measurement network system on a railway affected by an earthquake.

[0052] like Figure 1 As shown in the overall operation flow chart of the present invention, the present invention includes the following steps:

[0053] Step 1: Post-earthquake frame control network CP0 data processing and update

[0054] S1.1: Schematic diagram of railway level control network at different levels Figure 2 As shown in the figure, after the earthquake, three CP0 points within a railway were checked for piles. The site locations were well preserved. According to the GNSS first-class network observation technical requirements, GNSS measurements were conducted on the three CP0 points for three periods. The observation time of the first period was greater than 20 hours, the observation time of the second period was greater than 14 hours, and the observation time of the third period was greater than 7 hours.

[0055] S1.2: Simultaneously with the CP0 re-survey, CPI point measurements shall be carried out simultaneously in two time periods on site according to the technical requirements of the second-order GNSS network observation. CP0 and CPI observation data shall be resolved using the precise ephemeris and multi-baseline mode.

[0056] S1.3: Solve the normal equations and corresponding covariance matrices for the CP0 baseline vector network in different time periods. After verifying that the maximum values of the repeated baseline difference and the asynchronous loop closure error meet the tolerance requirements, fuse the normal equations and covariance matrices for each time period and input the three-dimensional coordinates of the CP0 point farthest from the epicenter within the line control network for unconstrained adjustment. The three CP0 points are distributed as follows: Figure 3 As shown;

[0057] S1.4: Analysis shows that the relationship between CP0 control point G070 and the nearby CPI is relatively stable, and the relationship between CP0 control point ML1S and the nearby CPI is also relatively stable. The difference between control points G070 and ML1S can also meet the point spacing tolerance requirement. Therefore, control points G070 and ML1S are determined as CP0 starting points with smaller displacement changes, and two-dimensional constrained adjustment is performed; the CP0 control point IZQ6 affected by vibration is updated, and the difference between the updated control point and the original control point coordinate value is calculated, and the point position change and deformation direction are analyzed; this step determines the position benchmark and maximizes the use of the original control results, reducing the amount of repair and adjustment to the railway track structure.

[0058] Step 2: Post-earthquake foundation plane control network CPI data processing and update

[0059] S2.1: Use edge connection to construct the CPI and CPII (including online encrypted CPII) networks, forming a strip network composed of triangles or geodesic quadrilaterals;

[0060] S2.2: Use the updated CP0 point and the stable CPI points at the short-mileage end and the long-mileage end as the starting point to update the entire CPI control network of the re-survey section (including the newly built points). This step ensures the connection between the CPI control network of the re-survey section and the original CPI control network, ensuring the relative accuracy of the control network and the smoothness of the existing control network.

[0061] Step 3: Post-earthquake line plane control network CPII and online encrypted CPII data processing

[0062] S3.1: For the line plane control network CPII and online encrypted CPII within the CPI control network resurvey range, resurvey the same network according to the technical requirements of the GNSS third-order network. For the online encrypted CPII at the entrance and exit of the tunnel, resurvey it according to the technical requirements of the GNSS second-order network to improve the measurement accuracy of the tunnel entrance.

[0063] S3.2: Using the updated CPI coordinates as the constrained starting data, perform constrained adjustment on the CPII network and calculate the difference between the re-surveyed and original survey results of the line CPII and the online encrypted CPII control points and the coordinate differences between adjacent points;

[0064] S3.3: Using the encrypted CPII results on the entrance and exit measurement lines as the starting data, re-survey the CPII control network inside the tunnel after the earthquake using the free-station corner intersection measurement method;

[0065] S3.4: For the CPII buried during the tunnel network construction period and now destroyed, a mandatory centering mark shall be used to coincide with the CPIII track control network;

[0066] S3.5: Encrypted CPIIs are arranged in pairs, with a pair spaced about 200m apart. They are located 30-50cm above the top of the cable trough on the tunnel sidewall or the U-shaped trough sidewall, and each CPII point has at least two observation station values. For adjacent tunnels, the existing tunnel conductor results are included in the constraint adjustment calculation to ensure smooth connection of the conductor results.

[0067] Step 4: Post-earthquake track control network CPⅢ re-survey

[0068] S4.1: Rebury points damaged by the earthquake and unusable points, using the same CPIII component specifications and burying locations as the original network;

[0069] S4.2: Use the corner intersection free station method to conduct CPIII re-survey. Each CPIII point has at least three station observation values, such as Figure 4As shown;

[0070] S4.3: The CPIII network shall be measured in sections with a length of 2 km to 10 km. Adjacent sections shall overlap by no less than 6 pairs of CPIII points, e.g. Figure 5 As shown;

[0071] S4.4: When connecting between sections, the coordinate difference of the overlapping points of the independent adjustment of the previous and next sections is ≤±3mm. After meeting this condition, the CPIII network adjustment of the latter section is carried out, and the encrypted CPII control points of the joint measurement of this section and 1 to 3 pairs of CPIII points of the previous section of the overlapping section are used as constraint points for adjustment calculation to achieve smooth overlap in measurement.

[0072] Step 5: Analysis of overall railway deformation characteristics

[0073] S5.1: After the resurvey of the plane control network is completed, a comprehensive analysis of the resurvey results is conducted to calculate the deformation values and displacement directions of CP0, CPI, and CPII relative to the original control points, analyze the coseismic rupture characteristics of the track caused by the earthquake, and plot the plane offset torsion, longitudinal compression and tension multi-directional spatial deformation;

[0074] S5.2: Combined with the CPIII re-survey data, the CPIII north and east direction coordinate change values are converted into longitudinal and transverse change values along the line, which can intuitively reflect the track deformation value and direction, such as Figure 6 The horizontal and vertical deviation values of the left line of a tunnel after being affected by an earthquake are shown;

[0075] S5.3: Measure the track centerline, perform segmented fitting, calculate track spacing, assess track displacement, and complete overall railway deformation analysis;

[0076] Step 6: Analysis of deformation characteristics of railway structures

[0077] S6.1: After the re-measurement is completed, the data must be compared with the structural deformation observation data to comprehensively analyze the stability of the structure. In areas with abnormal data, the cause must be identified and supplementary measurements must be conducted. Once the measurement is confirmed to be correct, an immediate warning should be issued and structural deformation observations should be strengthened in the relevant areas.

[0078] S6.2: Use free station intersection to measure the characteristic parts of the tunnel wall, such as the arch crown, arch haunch, arch foot, invert arch point, contact rod, bridge pier center, and station platform edge, to conduct clearance analysis and complete the track structure availability assessment; for example, within the range of K1965+530 to K1971+385 at the entrance of a tunnel, Figure 7As shown in the schematic diagram of the secondary lining deformation of the section at mileage K1965+780, due to the influence of the earthquake, the absolute position of the tunnel structure has shifted. The lateral offset gradually increases, and the displacement direction is to the right facing the large mileage. However, the inner contour of the tunnel is intact, and no obvious deformation has occurred in the lining. Starting from mileage K1971+386, the secondary lining of the tunnel has been significantly deformed due to the earthquake, and the lining has been damaged to varying degrees. The secondary lining on the left side of the tunnel is well preserved, while the secondary lining on the right side is severely deformed and damaged. The lateral displacement direction is to the right facing the large mileage, as Figure 8 shown in the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1971+390; as the mileage increases, within the mileage range of K1971+399 - K1971+408, the secondary linings on both the left and right sides of the tunnel are severely deformed, as Figure 9 shown in the arch and sidewall collapse, lining tension crack and shear break at the section of mileage K1971+400. A bench step has occurred within this mileage range, with obvious lateral and vertical misalignments, which is the boundary position between the upper and lower plates. The absolute deformation direction of the tunnel has changed, from to the right facing the large mileage to to the left facing the large mileage; from mileage K1971+480 to the tunnel exit section, the secondary lining is basically intact, the inner contour has no significant deformation, and the tunnel as a whole has shifted. The horizontal displacement direction is to the left facing the large mileage, as Figure 10 shown in the schematic diagram of the secondary lining deformation of the tunnel section at mileage K1972+000;

[0079] S6.3: Conduct bench step detection on the deformed positions, analyze the structural breakage on the left and right sides and the extrusion amounts of the structure towards the large and small mileage. For example, a bench step has occurred on the plane near the section of mileage K1971+377 - K1971+497. There are cracks opened longitudinally in the tunnel at the bench step, and the structure has formed a certain extrusion towards the large and small mileage; there are also large bench step amounts in the secondary linings on the left and right sides of the tunnel. The deformation characteristics here indicate that the tunnel has undergone tensile shear failure at this mileage; and within the range from the bench step to the tunnel exit, the longitudinal change of the points is displaced towards the large mileage direction, and the lateral change is displaced towards the northwest direction, as Figure 11 shown; simultaneously conduct crack observation on the tunnel wall to obtain crack data. The crack data includes crack position, width, length, and depth, and complete the matching analysis of the track structure and the overall deformation of the railway.

[0080] In the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "link", "fix" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] The content of the present invention is not limited to the examples listed. Any equivalent transformation of the technical solution of the present invention made by those of ordinary skill in the art by reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. A method for measuring the deformation characteristics of railway structures after an earthquake using a precise survey network system, characterized in that: It includes the following steps: Step 1: Data processing and update of the post-earthquake frame control network CP0; Step 2: Data processing and update of the post-earthquake basic plane control network CPI; Step 3: Data processing of the post-earthquake line plane control network CPII and the on-line encrypted CPII; Step 4: Re-measurement of the post-earthquake track control network CPIII; Step 5: Analysis of the overall deformation characteristics of the railway; Step 6: Analysis of the deformation characteristics of railway structures; The specific content of Step 4 includes: S4.1: Re-bury the points damaged by the earthquake and unable to be used normally. The specifications of the CPIII components used and the burial positions are the same as those of the original network; S4.2: Adopt the free station method of angle-side intersection for CPIII re-measurement, and at least three station observation values are required for each CPIII point; S4.3: Segmentally measure the CPIII network according to a certain interval length, and the overlap between adjacent sections is not less than 6 pairs of CPIII points; S4.4: When connecting between sections, it is necessary to meet the tolerance of the coordinate difference of the overlapping points of the independent adjustment of the front and rear sections; and for the adjustment of the CPIII network in the latter section, the encrypted CPII control points measured in this section and 1-3 pairs of CPIII points in the overlapping section of the previous section are used as constraint points for adjustment calculation; The specific content of Step 5 includes: S5.1: After the re-measurement of the plane control network is completed, comprehensively analyze the re-measurement results, calculate the deformation values and displacement directions of CP0, CPI, CPII and the original control points, analyze the co-seismic rupture characteristics of the track caused by the earthquake, and draw the multi-directional spatial deformation of plane offset and torsion, longitudinal compression and tension; S5.2: Combine the CPIII re-measurement data and convert the coordinate change values in the north and east directions of CPIII into the longitudinal and transverse change values along the line; S5.3: Measure the track center line, fit it segment by segment, calculate the line spacing, evaluate the line dislocation, and complete the analysis of the overall deformation characteristics of the railway.

2. A method for measuring the deformation characteristics of post-earthquake railway structures using a precise survey network system according to claim 1, characterized in that: The specific content of Step 1 includes: S1.1: Conduct multi-period measurements on CP0 according to the observation technical requirements of GNSS first-class network and on CPI according to the observation technical requirements of second-class network, and solve the observation data of CP0 and CPI according to precise ephemeris and multi-baseline mode; S1.2: Solve the normal equations and the corresponding covariance matrices of the CP0 baseline vector network in different periods, check the repeat baseline difference and the asynchronous loop closure difference, fuse the normal equations and covariance matrices of each period, and input the three-dimensional coordinates of the CP0 point farthest from the epicenter within the line control network range for unconstrained adjustment; S1.3: Analyze the stability of CP0 points, CPI points and their mutual relationships, and combine the CP0 point spacing and tolerance requirements. Take the CP0 point with the smallest displacement change as the starting point for two-dimensional constrained adjustment; update the CP0 points affected by vibration, and calculate the difference between the coordinates of the updated control points and the original control points, and analyze the point position change amount and deformation direction.

3. A method for measuring the deformation characteristics of post-earthquake railway structures using a precise survey network system according to claim 2, characterized in that: The specific content of Step 2 includes: S2.1: Structure the CPI and CPII networks in an edge connection manner to form a strip network composed of triangles or geodetic quadrilaterals; S2.2: Use the updated CP0 points and the stable CPI points at the small mileage end and the large mileage end as the combined starting points to update the entire network of the re-measured section of the CPI control network.

4. A method for measuring the deformation characteristics of railway structures after an earthquake using a precise survey network system, characterized in that: The specific content of Step 3 includes: S3.1: For the line plane control network CPII and online encrypted CPII within the CPI control network resurvey range, resurvey the same network in accordance with the technical requirements of the GNSS third-class network. For the online encrypted CPII at the entrance and exit of the tunnel, resurvey it in accordance with the technical requirements of the GNSS second-class network. S3.2: Using the updated CPI coordinates as the constrained starting data, perform constrained adjustment on the CPII network and calculate the difference between the post-earthquake re-measured coordinates and the pre-earthquake original measured coordinates of the CPII and the encrypted CPII control points on the line plane control network after adjustment, as well as the difference between the coordinate differences between adjacent points before the earthquake and those after the earthquake. S3.3: Using the encrypted CPII results on the entrance and exit measurement lines as the starting data, re-survey the CPII control network inside the tunnel after the earthquake using the free-station corner intersection measurement method; S3.4: For the CPII in the tunnel that was buried during the tunnel network construction period and is now destroyed, a mandatory centering mark shall be used to coincide with the CPIII track control network; S3.5: The encrypted CPIIs shall be arranged in pairs at a certain interval on the tunnel side wall or the top surface of the cable trough on the U-shaped trough side wall, and each CPII point shall have at least two observation station values; for adjacent tunnels, the results of the existing tunnel conductors shall be included in the adjustment calculation when constraining the adjustment calculation.

5. A method for measuring the deformation characteristics of post-earthquake railway structures using a precise survey network system, characterized in that: The step six specifically includes: S6.1: Using free station intersection, measure the tunnel wall arch crown, arch haunch, arch foot, invert point, contact rod, bridge pier center, and station platform edge feature locations, conduct clearance analysis, and complete the track structure availability assessment; S6.2: Conduct misalignment detection at the deformation location, analyze the left and right structural misalignment and the extrusion value of the structure to the large and small mileages, and simultaneously carry out tunnel wall crack observation to obtain crack data, and complete the matching analysis of the track structure and the overall deformation of the railway.

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