A method for monitoring and positioning installation of a top-supported steel pipe arch

Abstract

The application provides a kind of upper bearing type steel pipe arch installation monitoring positioning method, belongs to steel pipe arch installation monitoring positioning technical field, the method comprises the following steps: step 1: the overall temperature data of arch rib linear is monitored all-weather continuously by mathematical statistics and comparative analysis method;Step 2: the accuracy of primary control network is analyzed, and the accuracy meets the installation requirements;Step 3: the encryption control network is established, and the accuracy of encryption control network is optimized;Step 4: the automatic collection of arch rib linear three-dimensional coordinates is realized through encryption control network;Step 5: the collected data is transmitted, stored and displayed on cloud platform.The application realizes the automatic monitoring method of arch rib installation linear by laying encryption and accuracy analysis of arch bridge construction control network, and realizes the automatic monitoring of arch rib installation linear by taking high-precision independent control network as the benchmark and matching cloud platform, analyzes the influence of structural temperature change on arch rib three-dimensional linear by automatically collecting, storing and displaying monitoring data, realizes the automatic monitoring of arch bridge main arch linear, realizes high-precision detection, avoids deviation, and provides high-precision data support for steel pipe arch installation.

Description

Technical Field

[0001] This invention relates to the field of monitoring and positioning technology for steel pipe arch installation, and in particular to a method for monitoring and positioning the installation of an upper-bearing steel pipe arch. Background Technology

[0002] Arch rib alignment control surveying is an important part of the main arch installation process of arch bridges. It requires high positioning accuracy, is difficult to construct, and has high safety risks. In the arch rib installation construction control surveying, it is necessary to study the actual terrain and geomorphological characteristics of different projects, construction conditions, and the impact of the external environment on the measurement accuracy.

[0003] For steel pipe arch bridges, the alignment of the main arch rib has a decisive influence on the stress state of the bridge structure. Since adjusting the alignment after the main arch rib is closed is extremely difficult, alignment control during the installation process is crucial. Among these, the cable tension and the pre-lift value of the arch rib control nodes are two important indicators for controlling the alignment during main arch rib installation. Currently, the optimization calculation of cable tension mainly uses methods such as the moment balance method, zero displacement method, zero bending moment method, fixed-length cable method, elastic-rigid support method, and influence matrix method. In engineering practice, these methods calculate the cable tension and arch rib pre-lift value based on the ideal closure temperature, and the on-site control is also based on the indicators corresponding to the ideal state. The cable tension optimization calculation process and the on-site construction process are relatively independent. However, because the installation of the main arch of an arch bridge requires extremely high precision, a real-time positioning and detection method during installation needs to be designed. Summary of the Invention

[0004] The purpose of this invention is to provide a monitoring and positioning method for the installation of upper-bearing steel pipe arches, which solves the technical problems of difficult positioning and easy deviation in the existing steel pipe arch installation process.

[0005] It achieved accurate installation positioning between arch rib segments, pre-positioning technology for the arch foot of the steel pipe arch head segment, and detection of relative displacement during arch rib assembly.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for monitoring and positioning the installation of an upper-bearing steel pipe arch, the method comprising the following steps:

[0008] Step 1: Utilize mathematical statistics and comparative analysis methods to continuously monitor the overall temperature data of the arch rib line around the clock;

[0009] Step 2: Accuracy analysis of the primary control network to determine if the accuracy meets installation requirements;

[0010] Step 3: Establish an encrypted control network and optimize its accuracy;

[0011] Step 4: Automatically acquire the three-dimensional coordinates of the arch rib line through an encrypted control network;

[0012] Step 5: Transmit, store, and display the collected data on the cloud platform.

[0013] Furthermore, the specific process of step 1 is as follows:

[0014] The temperature of the arch ribs was monitored and analyzed. During the day, from 6:00 am to 2:00 pm, the temperature of the arch ribs gradually increased, reaching its peak between 2:00 pm and 6:00 pm, with an average temperature between 30°C and 50°C. The linear variation was large. The longitudinal X value of the monitoring point gradually shifted towards the middle of the span and reached its peak at 2:00 pm. The transverse Y value shifted more towards the left side of the route. The elevation Z value gradually decreased.

[0015] The temperature gradually decreased from 6 pm to midnight, and was lowest from 1 am to 6 am the next day, averaging between 24°C and 26°C. The longitudinal X-axis deviation of the arch rib monitoring point shifted towards the side span and returned to positive, reaching its peak at midnight. The elevation Z-axis increase gradually returned to positive, and the transverse Y-axis deviation of the right lane returned to positive.

[0016] The fine-tuning and measurement of the main arch installation should be controlled during the period of no sunlight and uniform component temperature, which is 22:00-6:00 in the evening. This avoids the impact of temperature gradient load caused by sunlight on the transverse Y value of the main bridge, and the impact of overall temperature changes on the longitudinal X and elevation Z values, thus effectively improving the quality and efficiency of arch rib positioning.

[0017] Furthermore, the specific process of step 2 is as follows:

[0018] The primary control network of the bridge consists of eight control points: D021, WJ02, WJ03, WJ04, D032, WJ05, WJ06, and WJ08. All horizontal and vertical control points are classified as Class III highway control points. A construction coordinate system is established using D021 as a fixed point and D032 as an orientation point. Due to limited visibility between the primary control points caused by the special terrain across the river, and to avoid errors from multiple observation points using the corner observation method and to achieve the same observation accuracy under the same conditions, a GPS control survey method is used for resurveying. In the adjustment and accuracy evaluation of the control network, considering factors such as the main arch design location, control network level, and corner shape, three control points (D021, D032, and WJ08) are selected as starting points. The remaining five control points serve as check points.

[0019] The control network was measured using GPS control with an iRTK2 instrument. The weakest side error was calculated to be 0.8 mm using 2D constrained adjustment. The nominal accuracy of the iRTK2 instrument is static (±2.5+1ppm*D) mm, where D is the distance between measured points. The positional error of the weakest point was 0.8 mm, and the relative error of the weakest side was 1 / 477718, which is less than the third-order satellite positioning technical indicator of a relative error of 1 / 70000 for the weakest side. The elevation control network was measured using a DiNi03 electronic level for third-order leveling. The nominal accuracy of the electronic level is ±0.3 mm per kilometer of forward and backward measurement with an invar steel tape. A precise cross-river trigonometric leveling method was used for the joint measurement. The total measured section length was 5.87 km. After rigorous adjustment calculations, the total closure error was 3.8 mm, which is less than the allowable error of 29.1 mm.

[0020] Furthermore, the specific process of step 3 is as follows:

[0021] After verifying the accuracy of the primary plane control network, a high-precision interpolation method was used to densify the control points based on the primary control network shape. A total of four points were densified, namely WJ0A, WJ0C, WJ0D, and WJ0F. All the newly added control points adopted forced centering observation piers. The control network was set up as a triangular network combining long and short sides. Planar control measurements of the densified points were carried out through a GPS static module. During the static data processing of the densified control points, the baseline vectors in the network shape were refined by combining the baseline residual sequence diagram. The variance ratio of each baseline was controlled to determine the reliability of the integer ambiguity of each baseline. The root mean square error (RMS) was controlled to ensure that the quality of the baseline data observation values ​​was qualified and the spatial position accuracy factor (PDOP) met the requirements. The densified plane control network was continuously observed according to the technical indicators of the third-order effective observation period. The mean square error of the weakest side of the densified control network was 0.7 mm, the mean square error of the weakest point was 1.2 mm, and the relative error of the weakest side was 1 / 86764, obtained by 2D constrained adjustment.

[0022] Considering the projection distortion from the geodetic coordinate system to the actual local engineering coordinate system, the multipath effect of GPS in static surveying across the river, the error caused by the non-linear propagation of GPS signals in mountainous terrain, and the differences in the length and short sides of the densified control network, based on the GPS control survey scheme, the coordinate results of the densified points were verified using the total station corner observation method. Automatic corrections for temperature, air pressure, distance projection, and spherical atmospheric difference were set. Field side length observations were corrected using additive constants, multiplicative constants, and meteorological corrections. The adjustment calculation selected the minimum constraint adjustment for one point and one direction, forming four triangles for the control network. After adjustment, the angular mean square error was 0.89″. During the installation and positioning of the main arch rib using the densified control points, the maximum slope distance did not exceed 470m, and the maximum vertical angle did not exceed 30°, according to the distance measurement accuracy formula...

[0023] (1.1)

[0024] In the formula, mD, a, b, and D are the distance measurement error, the nominal distance measurement fixed error of the total station, the nominal distance measurement proportional error coefficient of the total station, and the distance measurement length, respectively. By performing comprehensive adjustment analysis on the total station's side-angle network measurement data and GPS side measurement data, the densified plane control network can achieve the designed measurement accuracy.

[0025] Furthermore, the specific process of step 4 is as follows:

[0026] 360MiNi small prisms are installed on the arch rib line. A new spot analysis method is used to optimize and verify the prisms. The 360MiNi small prisms are automatically identified. In the case of poor visibility or strong light, the prisms are locked to complete the measurement. Continuous absolute encoding combined with ATR plus technology enables efficient data transmission. An independent coordinate system is established with the center line of the arch axis as the X-axis and the vertical and horizontal as the Y-axis. The coordinates of the primary control point WJ04 and the azimuth of the straight lines WJ04 and WJ05, given by the design unit, are used as the coordinates and azimuth references for the control network adjustment calculation.

[0027] Coordinate transformation between the geodetic coordinate system and the independent coordinate system is performed according to equations (1.2) to (1.5).

[0028] (1.2)

[0029] (1.3)

[0030] (1.4)

[0031] (1.5)

[0032] In the formula, , Let P be the coordinates of point P in the geodetic coordinate system. , Let P be the coordinates of point P in an independent coordinate system. , The coordinates of the origin of the independent coordinate system in the geodetic coordinate system are given by α, and the coordinate azimuth angle of the X-axis of the independent coordinate system in the geodetic coordinate system is given by α. The results of the transformation of the independent coordinate system are used to automatically collect the monitoring point data of the arch rib.

[0033] The present invention, by adopting the above-described technical solution, has the following beneficial effects:

[0034] This invention achieves automated monitoring of the arch rib installation alignment by densifying and refining the construction control network of arch bridges, using a high-precision independent control network as a benchmark and a cloud platform. The invention analyzes the impact of structural temperature changes on the three-dimensional alignment of the arch ribs using automatically collected, stored, and displayed monitoring data, thereby realizing automated monitoring of the main arch alignment of the arch bridge, achieving high-precision detection, avoiding deviations, and providing high-precision data support for the installation of steel pipe arches. Attached Figure Description

[0035] Figure 1 This is a diagram showing the layout of control points and the shape of the control network for the bridge of this invention;

[0036] Figure 2 This is an automatic monitoring data diagram of the arch rib line shape of the present invention;

[0037] Figure 3 This is a temperature curve of the arch rib structure during the same period of the present invention;

[0038] Figure 4 This is a diagram showing the elevation layout of the bridge in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0040] like Figure 1-4 As shown, this embodiment summarizes the experience related to the establishment of a high-precision measurement and control network for arch bridges and the realization of automated monitoring of the main arch alignment of arch bridges through the installation and construction example of the main arch ribs of the bridge.

[0041] like Figure 1 As shown, the bridge is 1834m long, with the main span being a 504m long (calculated span 475m) upper-bearing steel-concrete composite variable cross-section truss arch bridge. The arch axis adopts a catenary design, with an arch axis coefficient of 2.2, a rise of 90m, and a rise-to-span ratio of 1 / 5.278, forming a rigidly integrated arch, beam, and column system. The outer diameter of the chord tube is φ1400mm, and the entire bridge consists of 60 segments, with the largest segment lifting a weight of 157.8t. The project site is a typical "U"-shaped river valley with significant elevation differences. The arch rib installation accuracy requirements are: the deviation of the segment centerline from the design axis ≤10mm, the deviation of the centerline between adjacent segments ≤5mm, and the relative elevation difference of symmetrical points ≤10mm. Before the main arch is closed, the maximum cantilever is 237m, and the alignment control is affected by multiple factors such as structural temperature; all components are bolted, requiring high installation and positioning accuracy.

[0042] Accuracy analysis of primary control network

[0043] Step 1: Using mathematical statistics and comparative analysis methods, the continuous monitoring data under all weather conditions were comprehensively analyzed. The overall shape of the arch rib exhibited the following variation pattern:

[0044] (1) During the day, from 6 am to 2 pm, the temperature of the arch rib gradually increases, reaching its peak between 2 pm and 6 pm, with an average of 30°C to 50°C. The linear variation is large. The longitudinal X value of the monitoring point deviates towards the middle of the span and reaches its peak at 2 pm. The transverse Y value deviates towards the left side of the route (the side facing away from the sun) and the elevation Z value gradually decreases.

[0045] Temperatures gradually decreased from 6 PM to around midnight, reaching their lowest point between 1 AM and 6 AM the following morning, averaging between 24°C and 26°C. The longitudinal X-axis deviation of the arch rib monitoring points shifted towards the side span and returned to positive, peaking at midnight. The elevation Z-value increment gradually returned to positive, and the lateral Y-axis deviation of the right lane also returned to positive. Figure 2-3 As shown.

[0046] The fine-tuning and measurement of the main arch installation should be controlled during a period without sunlight and when the component temperature is uniform (preferably 22:00-6:00). This avoids the impact of temperature gradient load caused by sunlight on the transverse Y value of the main bridge, and the impact of overall temperature changes on the longitudinal X and elevation Z values, which can effectively improve the quality and efficiency of arch rib positioning.

[0047] Temperature monitoring data: The bridge's temperature monitoring system mainly consists of surface-mounted temperature sensors, which are installed on the outer upper and lower chords and the arch rib fastening cables of each arch rib section, with a data collection frequency of 10 minutes per time.

[0048] The temperature changes of the arch rib and the steel strand are basically consistent, both exhibiting a periodicity approximating a cosine function. Within 24 hours, both undergo a cooling-heating-cooling process, with the maximum and minimum values ​​occurring at roughly the same times. Data comparison shows that the temperature rise and fall of the steel strand is faster than that of the arch rib, exhibiting a clear characteristic of rapid heating and cooling. According to relevant knowledge of heat transfer, temperature change is related to the relative surface area of ​​the structure; the smaller the relative surface area, the slower the temperature change. As shown in the formula for calculating the volume and surface area of ​​an object, the smaller the volume, the larger the relative surface area. Therefore, the temperature change of the steel strand is faster than that of the arch rib.

[0049] Analysis and correction of the effect of temperature on linear shape

[0050] Cause Analysis

[0051] The effects of temperature on the structure can be divided into two parts: the overall temperature effect and the temperature gradient effect. Changes in the overall temperature will cause displacement of the structure along the axial direction, while the temperature gradient will cause bending deformation. Based on temperature and alignment data, the reasons for the changes in alignment before and after the closure are analyzed.

[0052] (1) Before the closure

[0053] Regarding longitudinal displacement, from 0:00 to 7:00, the temperature decreases, causing the arch ribs to shorten and move towards the side spans; with the effect of solar radiation, the overall temperature of the arch ribs increases, so from 7:00 to 16:00, the arch ribs elongate and move towards the center of the span; after 16:00, as the effect of solar radiation weakens, the arch ribs begin to shorten.

[0054] Regarding lateral deviation, based on the geographical location of the Wujiang Bridge, the sun rises from the downstream side of the bridge, and between 7:00 and 11:00, it illuminates the downstream side of the arch rib, causing a temperature gradient from the downstream side to the upstream side of the arch rib, resulting in the arch rib deflecting upstream. As the sun moves, between 11:00 and 16:00, it illuminates the upstream side of the arch rib, causing a temperature gradient from the upstream side to the downstream side, and the arch rib deflects downstream. After 16:00, as the temperature gradient caused by solar radiation weakens, the temperature distribution on the same cross-section of the arch rib tends to be uniform, and the arch rib deflected downstream begins to rebound until the sun rises again.

[0055] Regarding elevation, both overall temperature changes and temperature gradients cause variations in the arch rib elevation. From approximately 7:00 AM to 4:00 PM, as the temperature rises, the steel strands begin to elongate. Simultaneously, due to solar radiation, a temperature gradient from top to bottom is generated, causing the arch rib elevation to decrease. From approximately 4:00 PM to 10:00 PM, as the temperature decreases, the steel strands shorten, the temperature gradient effect weakens, and the arch rib rebounds. From approximately 10:00 PM to 7:00 AM the next day, the ambient temperature changes less, and the steel strand changes tend to stabilize. However, the air temperature inside the steel pipe is higher than the external ambient temperature. On the same arch rib cross-section, hot air accumulates above the arch rib, creating a temperature gradient from top to bottom, leading to a decrease in the arch rib elevation.

[0056] (2) After the closure

[0057] After the closure, the longitudinal displacement of the arch ribs is restricted, so the displacement is almost zero. However, temperature changes will still cause contraction and expansion along the axial direction of the arch ribs. Due to the longitudinal restriction and the characteristics of the arch structure, the arch ribs expand and displace upwards when the temperature rises, and contract and displace downwards when the temperature falls. The lateral displacement follows the same trend as before the closure and will not be described further here.

[0058] Linear correction

[0059] Based on the preceding analysis, the data was processed and analyzed to obtain the correction values ​​for the alignment before and after the closure. Equation (1.0) is the principle for calculating the correction values, and its meaning is that within the time period... Within, the ratio of the linear difference between the end time and the start time to the temperature difference.

[0060]

[0061] In the formula:

[0062] — Correction value within a certain period;

[0063] , — Linear values ​​at the start and end of a certain time period;

[0064] , — Temperature values ​​at the beginning and end of a certain time period;

[0065] Step 2: The bridge project's plane coordinate system adopts the CGCS2000 ellipsoid, Gauss projection, with a central meridian of 108°00′00″, a projection surface elevation of 570m, and a geoid anomaly of -32m. The geodetic height with the ellipsoid as the elevation datum is 538m. The bridge's primary control network consists of 8 control points (i.e., D021, WJ02, WJ03, WJ04, D032, WJ05, WJ06, and WJ08). Both the plane and elevation control points are classified as Class III highway control points, with D021 as the fixed point. A construction coordinate system was established using D032 as the orientation point. Due to the limited visibility between the primary control points caused by special terrain conditions such as crossing the river, in order to avoid the multi-point observation error of the corner observation method and to achieve the same observation accuracy under the same conditions, the GPS control survey method was used for re-measurement. In the adjustment calculation and accuracy evaluation of the control network, three control point data (i.e., D021, D032, and WJ08) were selected as the starting points, taking into account factors such as the design location of the main arch, the control network level, and the shape of the corners, and the remaining five control points were used as check points.

[0066] The horizontal control network of this project was measured using an iRTK2 instrument (nominal accuracy: static (±2.5+1ppm*D) mm, where D is the distance between the measured points) via GPS control. Two-dimensional constrained adjustment calculations yielded a mean square error of 0.8 mm for the weakest side and 0.8 mm for the weakest point location. The relative mean square error of the weakest side was 1 / 477718, which is less than the third-order satellite positioning technical specification of 1 / 70000 for the relative mean square error of the weakest side. The vertical control network was measured using a DiNi03 electronic level (nominal accuracy: mean square error of ±0.3 mm per kilometer for round trip measurement with an indium steel tape) for third-order leveling. A precise cross-river trigonometric leveling method was used for the joint measurement, with a total measured section length of 5.87 km. After rigorous adjustment calculations, the total closure error was 3.8 mm, less than the allowable error of 29.1 mm. Therefore, the accuracy of the primary construction control network meets the technical requirements, as shown in Table 1.

[0067] Table 1. Results of Two-Dimensional Constraint Adjustment Calculation for the Primary Control Points of the Bridge

[0068]

[0069] Step 3: Establishment and precision optimization of the encrypted control network

[0070] To meet the surveying needs of the main arch structure construction of this project, after verifying the accuracy of the primary plane control network, and based on the specific circumstances such as the location of the main arch structure, the actual terrain, the construction site layout, and the construction operation plan, high-precision interpolation was used to densify the control points on the basis of the primary control network. A total of four additional control points were added (WJ0A, WJ0C, WJ0D, and WJ0F). All added control points used forced-centering observation piers. The control network was laid out as a triangular network combining long and short sides. The control point layout and control network shape are detailed below. Figure 1 .

[0071] Planar control surveying of densified control points was conducted using a GPS static module. During the static data processing of these densified control points, the baseline vectors in the network were refined strictly in conjunction with the baseline residual sequence diagram. The variance ratio of each baseline was controlled to determine the reliability of the integer ambiguity of each baseline. The root mean square error (RMS) was controlled to ensure the quality of the baseline data observations was up to standard, and the spatial position accuracy factor (PDOP) met the requirements. The densified plane control network was continuously observed according to the technical indicators of the third-order effective observation period. Two-dimensional constrained adjustment yielded a mean square error of 0.7 mm for the weakest side and 1.2 mm for the weakest point; the relative error of the weakest side was 1 / 86764. Meanwhile, considering the projection distortion when transforming the geodetic coordinate system CGCS2000 to the actual local engineering coordinate system, the multipath effect of GPS in static surveying in cross-river areas, the error caused by the non-linear propagation of GPS signals in mountainous terrain, and the differences in the length and short sides of the densified control network, based on the GPS control survey scheme, the total station corner observation method was used to verify the coordinate results of the densified points. This project used a Leica TS60 with an angle measurement accuracy of 0.5″ and a distance measurement accuracy of ±(0.6 +1 ppm*D) mm. The instrument's fixed module can be set to automatically correct for temperature, air pressure, distance projection, and spherical atmospheric difference. The field side length observation values ​​were corrected by additive constants, multiplicative constants, and meteorological corrections. The adjustment calculation selected the minimum constraint adjustment for one point and one direction, forming four triangles for the control network. After adjustment calculation, the angular mean square error was 0.89″. During the installation and positioning of the main arch rib using densified control points, the maximum slope distance did not exceed 470m, and the maximum vertical angle did not exceed 30°, according to the nominal distance measurement accuracy formula.

[0072] (0.1)

[0073] In the formula, mD, a, b, and D represent the distance measurement error, the nominal distance measurement error of the total station, the nominal distance measurement ratio error coefficient of the total station, and the distance measurement length, respectively. Therefore, the distance measurement error mD is 0.6 mm. This demonstrates that by combining the total station's edge-angle network measurement data with GPS edge measurement data through comprehensive adjustment analysis, the bridge's densified plane control network can achieve the designed measurement accuracy.

[0074] The elevation densification control network was constructed using third-order leveling in accordance with the technical requirements for digital leveling instruments and cross-river leveling observations in the "Engineering Surveying Standards". The total length of the survey section was 3.79 km, with a closure error of 6.2 mm. The measurement was precisely allocated according to the length of each section, meeting the technical specifications.

[0075] In this way, a construction survey control network for the bridge was established, and a three-dimensional benchmark was achieved for the automatic monitoring of the arch rib alignment by the Leica TS60.

[0076] Step 4: The Leica TS60, based on a high-precision encrypted control network, automatically acquires, stores, and displays the three-dimensional coordinates of the arch rib line on a cloud platform. A novel spot analysis method is used to optimize and verify the prism, automatically identifying 360-micro prisms (such as...). Figure 4 In situations with poor visibility (rainy or foggy weather) or strong light, the prism can be locked at a long distance to complete the measurement. Continuous absolute encoding combined with ATR plus technology enables efficient data transmission and accurate positioning.

[0077] To adapt to the platform coding and further improve the control accuracy of the main arch structure, an independent coordinate system is established with the arch axis centerline as the X-axis and the vertical and horizontal axes as the Y-axis (east is positive). The coordinates of the primary control point WJ04 and the azimuth angles of the lines WJ04 and WJ05, given by the design unit, are used as the coordinate and azimuth references for the control network adjustment calculation.

[0078] The geodetic coordinate system and the independent coordinate system are defined according to equation (1.2).

[0079] Equation (1.5) is used for coordinate transformation:

[0080] (1.2)

[0081] (1.3)

[0082] (1.4)

[0083] (1.5)

[0084] In the formula, , Let P be the coordinates of point P in the geodetic coordinate system. , Let P be the coordinates of point P in an independent coordinate system. , Let α be the coordinate value of the origin of the independent coordinate system in the geodetic coordinate system, and let α be the coordinate azimuth angle of the X-axis of the independent coordinate system in the geodetic coordinate system.

[0085] The Leica TS60 automatically collects monitoring data of the arch rib by transforming the results into an independent coordinate system.

[0086] Step 5: Platform connection and data transmission. The IDMOS platform's automated monitoring technology provides strong support in ensuring the accuracy and continuity of data, improves the control precision of the arch rib segment installation, and effectively guarantees the high-precision closure of the main arch of the Deyu Expressway Bridge in three dimensions.

[0087] Leica TS60 Automatic Data Acquisition Platform Connection and Transmission Steps:

[0088] (1) The Leica Captivate homepage website interface uses the encrypted control point selection [known backsight point] method to complete the coordinate orientation;

[0089] (2) Set a fixed frequency to accurately identify and collect effective 360MiNi prisms, and establish a target point database based on the monitoring point number of each segment;

[0090] (3) Data is transmitted to the DTU interactive system via RS-232 line, and a terminal module number is established;

[0091] (4) Create a new service port, upload the data to the IDMOS automated deformation monitoring platform, and upload it to the cloud via the communication network;

[0092] (5) Establish a dedicated account for the IDMOS platform to complete the data display.

[0093] The accuracy of the control network is an important benchmark for the measurement robot to monitor the main arch alignment of the arch bridge. The densified plane construction control network should be composed of geodetic quadrilaterals and triangles. At the same time, the basic network shape combining long and short sides should be optimized. In addition to the GPS static control measurement scheme, the accuracy of the main arch alignment monitoring can be further guaranteed by using high-precision measuring instruments in combination with conventional edge and corner network observation schemes for verification.

[0094] Taking the arch rib hoisting construction of the Deyu Expressway Bridge as an example, this paper elaborates on the method of using Leica TS60 with a high-precision independent control network and cloud platform to achieve automated monitoring of the arch rib installation alignment by analyzing the layout, density and accuracy of the arch bridge construction control network. The paper analyzes the impact of structural temperature changes on the three-dimensional alignment of the arch rib by automatically collecting, storing and displaying monitoring data, and summarizes the relevant technical experience of alignment control measurement during the main arch installation process of the arch bridge, providing a reference for similar projects.

[0095] Equipped with the IDMOS platform's automated monitoring technology, it improves the control accuracy of arch rib positioning and installation in arch bridges; it has the advantages of efficient, automatic, real-time data display, high precision, and all-weather operation. Through practical research, it can be promoted and applied in the main arch alignment control of long-span arch bridges.

[0096] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for monitoring and positioning the installation of an upper-bearing steel pipe arch, characterized in that: The method includes the following steps: Step 1: Utilize mathematical statistics and comparative analysis methods to continuously monitor the overall temperature data of the arch rib line around the clock; Step 2: Accuracy analysis of the primary control network to determine if the accuracy meets installation requirements; Step 3: Establish an encrypted control network and optimize its accuracy; Step 4: Automatically acquire the three-dimensional coordinates of the arch rib line through an encrypted control network; Step 5: Transmit, store, and display the collected data on the cloud platform; The specific process of step 2 is as follows: The primary control network of the bridge consists of eight control points: D021, WJ02, WJ03, WJ04, D032, WJ05, WJ06, and WJ08. All horizontal and vertical control points are classified as Class III highway control points. A construction coordinate system is established using D021 as a fixed point and D032 as an orientation point. Due to limited visibility between the primary control points caused by the special terrain across the river, and to avoid errors from multiple observation points using the corner observation method and to achieve the same observation accuracy under the same conditions, a GPS control survey method is used for re-measurement. In the adjustment and accuracy evaluation of the control network, considering factors such as the main arch design location, control network level, and corner shape, three control points are selected as starting points: D021, D032, and WJ08. The remaining five control points serve as check points. The control network was measured using GPS control with an iRTK2 instrument. The weakest side error was calculated to be 0.8 mm using 2D constrained adjustment. The nominal accuracy of the iRTK2 instrument is static (±2.5+1ppm*D) mm, where D is the distance between measured points. The positional error of the weakest point was 0.8 mm, and the relative error of the weakest side was 1 / 477718, which is less than the third-order satellite positioning technical indicator of a relative error of 1 / 70000 for the weakest side. The elevation control network was measured using a DiNi03 electronic level for third-order leveling. The nominal accuracy of the electronic level is ±0.3 mm per kilometer of forward and backward measurement with an invar steel tape. A precise cross-river trigonometric leveling method was used for the joint measurement. The total measured section length was 5.87 km. After rigorous adjustment calculations, the total closure error was 3.8 mm, which is less than the allowable error of 29.1 mm. The specific process of step 3 is as follows: After verifying the accuracy of the primary plane control network, a high-precision interpolation method was used to densify the control points based on the primary control network shape. A total of four points were densified, namely WJ0A, WJ0C, WJ0D, and WJ0F. All the newly added control points adopted forced centering observation piers. The control network was set up as a triangular network combining long and short sides. Planar control measurements of the densified points were carried out through a GPS static module. During the static data processing of the densified control points, the baseline vectors in the network shape were refined by combining the baseline residual sequence diagram. The variance ratio of each baseline was controlled to determine the reliability of the integer ambiguity of each baseline. The root mean square error (RMS) was controlled to ensure that the quality of the baseline data observation values ​​was qualified and the spatial position accuracy factor (PDOP) met the requirements. The densified plane control network was continuously observed according to the technical indicators of the third-order effective observation period. The mean square error of the weakest side of the densified control network was 0.7 mm, the mean square error of the weakest point was 1.2 mm, and the relative error of the weakest side was 1 / 86764, obtained by 2D constrained adjustment. Considering the projection distortion from the geodetic coordinate system to the actual local engineering coordinate system, the multipath effect of GPS in static surveying across the river, the error caused by the non-linear propagation of GPS signals in mountainous terrain, and the differences in the length and short sides of the densified control network, based on the GPS control survey scheme, the coordinate results of the densified points were verified using the total station corner observation method. Automatic corrections for temperature, air pressure, distance projection, and spherical atmospheric difference were set. Field side length observations were corrected using additive constants, multiplicative constants, and meteorological corrections. The adjustment calculation selected the minimum constraint adjustment for one point and one direction, forming four triangles for the control network. After adjustment, the angular mean square error was 0.89″. During the installation and positioning of the main arch rib using the densified control points, the maximum slope distance did not exceed 470m, and the maximum vertical angle did not exceed 30°, according to the distance measurement accuracy formula... （1.1） In the formula, mD, a, b, and D are the distance measurement error, the nominal distance measurement fixed error of the total station, the nominal distance measurement proportional error coefficient of the total station, and the distance measurement length, respectively. By performing comprehensive adjustment analysis on the total station's side-angle network measurement data and GPS side measurement data, the densified plane control network can achieve the designed measurement accuracy.

2. The method for monitoring and positioning the installation of an upper-bearing steel pipe arch according to claim 1, characterized in that: The specific process of step 1 is as follows: The temperature of the arch ribs was monitored and analyzed. During the day, from 6:00 am to 2:00 pm, the temperature of the arch ribs gradually increased, reaching its peak between 2:00 pm and 6:00 pm, with an average temperature between 30°C and 50°C. The linear variation was large. The longitudinal X value of the monitoring point gradually shifted towards the middle of the span and reached its peak at 2:00 pm. The transverse Y value shifted more towards the left side of the route. The elevation Z value gradually decreased. The temperature gradually decreased from 6 pm to midnight, and was lowest from 1 am to 6 am the next day, averaging between 24°C and 26°C. The longitudinal X-axis deviation of the arch rib monitoring point shifted towards the side span and returned to positive, reaching its peak at midnight. The elevation Z-axis increase gradually returned to positive, and the transverse Y-axis deviation of the right lane returned to positive. The fine-tuning and measurement of the main arch installation should be controlled during the period of no sunlight and uniform component temperature, which is 22:00-6:00 in the evening. This avoids the impact of temperature gradient load caused by sunlight on the transverse Y value of the main bridge, and the impact of overall temperature changes on the longitudinal X and elevation Z values, thus effectively improving the quality and efficiency of arch rib positioning.

3. The method for monitoring and positioning the installation of an upper-bearing steel pipe arch according to claim 1, characterized in that: The specific process of step 4 is as follows: 360MiNi small prisms are installed on the arch rib line. A new spot analysis method is used to optimize and verify the prisms. The 360MiNi small prisms are automatically identified. In the case of poor visibility or strong light, the prisms are locked to complete the measurement. Continuous absolute encoding combined with ATRplus technology enables efficient data transmission. An independent coordinate system is established with the center line of the arch axis as the X-axis and the vertical and horizontal as the Y-axis. The coordinates of the primary control point WJ04 and the azimuth of the lines WJ04 and WJ05, given by the design unit, are used as the coordinates and azimuth references for the control network adjustment calculation. Coordinate transformation between the geodetic coordinate system and the independent coordinate system is performed according to equations (1.2) to (1.5). （1.2） （1.3） （1.4） （1.5） In the formula, , Let P be the coordinates of point P in the geodetic coordinate system. , Let P be the coordinates of point P in an independent coordinate system. , The coordinates of the origin of the independent coordinate system in the geodetic coordinate system are given by α, and the coordinate azimuth angle of the X-axis of the independent coordinate system in the geodetic coordinate system is given by α. The results of the transformation of the independent coordinate system are used to automatically collect the monitoring point data of the arch rib.

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