Construction linear control technology for large-span cable-stayed bridge of high-speed railway

Abstract

The invention relates to a linear control technology for construction of a large-span cable-stayed bridge of a high-speed railway, relates to the technical field of construction technologies of constructional engineering, and is suitable for monitoring construction of a ballastless track of the large-span cable-stayed bridge of the high-speed railway and linear control of a finished bridge. Comprising the following steps of S1, initial line shape and cable force measurement, S2, second-phase dead load accounting, S3, vertical rigidity and temperature change correction, S4, initial line shape evaluation and adjustment and S5, ballastless track laying. The stress and line shape of the cable-stayed bridge under different load and temperature working conditions are monitored, actual line shape data of the cable-stayed bridge are collected, modeling analysis is conducted through finite elements, the rigidity of a steel beam is verified, the temperature change rule of the steel beam is analyzed, and the construction theoretical line shape of each part of a full-bridge ballastless track is fitted. According to the technology, the bridge forming linear error of the large-span ballastless track is controlled within a standard allowable range, the fastener adjusting amount is greatly reduced, the track laying precision is improved, the engineering quality is guaranteed, and good economic and social benefits are generated.

Description

Technical Field

[0001] The present application relates to the technical field of building engineering construction technology, and in particular to the construction line control technology of a large-span cable-stayed bridge on a high-speed railway. Background Art

[0002] With the rapid development of China's high-speed railway network, my country's high-speed railway ballastless track laying technology has reached the world's leading level. High-quality ballastless tracks can be laid for different landforms and geological conditions. However, this is limited to ordinary bridges, roadbeds, tunnels and other areas. The laying of ballastless tracks for large-span high-speed railway cable-stayed bridges is still rare at home and abroad, and track line shape control is still the key and difficult point in the construction of high-quality ballastless tracks.

[0003] The prior art (CN107059628A) discloses a BIM-based linear control technology for monorail track beam bridges. The method includes the following steps: visually designing the linear shape of the track beam bridge through BIM, optimizing the linear shape of the track beam bridge in combination with a given monorail line, including the horizontal curve linear shape and the vertical curve linear shape, and finally determining the optimal linear shape of the track beam bridge. BIM is used to conduct a construction roaming simulation test on the track beam bridge to check the deviations in the assembly process of the track beam bridge; for unreasonable linear design and construction plans, timely solutions are proposed. The linear simulation model of the monorail track beam bridge formed based on BIM can check the adverse effects of uneven settlement of piers, uneven temperature deformation and various accidental factors on the linear shape of the monorail track beam bridge on the monorail line, and timely maintain and manage the system, greatly improving the operational maintenance efficiency in the linear control of the track beam bridge. However, the study found the following technical problems: large-span ballastless track cable-stayed bridges have high requirements for the alignment accuracy of the completed bridge, the smoothness of the ballastless track and operational safety. The alignment deviation at each construction stage will affect the alignment and internal force distribution of the completed bridge. The cables and steel beams are highly sensitive to ambient temperature. At the same time, the alignment control will also be affected by multiple factors such as the temporary load on the bridge surface, concrete shrinkage and creep, construction organization, and measurement methods.

[0004] In view of the above-mentioned related technologies, a solution is now proposed. Summary of the invention

[0005] The purpose of this application is to provide a construction line control technology for a large-span cable-stayed bridge on a high-speed railway to solve the technical problems in the prior art that the cable-stayed cables and steel beams are highly sensitive to the ambient temperature, and the line control is also affected by multiple factors such as the temporary load on the bridge surface, concrete shrinkage and creep, construction organization, and measurement methods.

[0006] The construction alignment control technology of the high-speed railway large-span cable-stayed bridge provided in this application adopts the following technical solutions: The construction alignment control technology of a high-speed railway large-span cable-stayed bridge includes the following steps: S1. Initial alignment and cable force measurement: Conduct multiple measurements of the main bridge deck alignment and cable force, observe and record the initial alignment of the main beam bridge deck and measure the cable force, monitor and analyze the changes of CPⅢ measuring points, deck alignment and cable force with temperature; S2. Phase II dead load calculation: According to different on-site working conditions, accurately calculate the residual loads of the constructed and unconstructed parts. The residual loads include but are not limited to rails and fasteners, ballast plates, base plates, protective layers, and cables; S3, vertical stiffness, temperature change correction: by preloading, correct the vertical stiffness of the theoretical model of the main bridge structure, and continuously monitor the temperature change, and obtain the theoretical calculation model after stiffness and temperature correction according to the correction calculation of the stiffness and temperature; S4. Initial alignment assessment and adjustment: Initial alignment assessment mainly includes theoretical alignment calculation. By comparing theoretical and measured alignments, three technical indicators, namely, cable force adjustment value, base plate height value, and ballast plate thickness value, are obtained to verify whether they meet the specification requirements. S5. Ballastless track laying: Repeated measurement and collection of main bridge alignment data and basic information under corresponding working conditions. Through long-term observation, the preset nighttime construction temperature T1 and the measured elevation H1 of the measuring point under the corresponding working conditions were obtained. The thickness of the base plate was adjusted to make the top surface line of the base plate as close to the theoretical line as possible. The water bag on the base plate was used for secondary loading to simulate the main span 330m section of the trackbed and the remaining auxiliary engineering loads, and basic data was observed and collected.

[0007] By adopting the above technical scheme, the ballastless track laying process should include three stages: basic data collection, initial alignment evaluation and adjustment, and ballastless track laying. The basic data collection includes S1 initial alignment and cable tension measurement, S2 second-phase constant load calculation, S3 vertical stiffness, and temperature change correction. Through these steps, a theoretical calculation model with stiffness and temperature correction is obtained, which is used for initial alignment evaluation in S4 and after adjustment with the actual situation, it guides the ballastless track laying construction in S5. Through the alignment and temperature monitoring during multi-layer graded regulation during the ballastless track construction process, the corresponding relationship between the temperature difference of the structural system and the deformation of the main beam is obtained through analysis and calculation of the basic data, and the stiffness, temperature and other parameters in the structural calculation model are corrected. The subsequent added constant load weight parameters are calculated, and finally the alignment control of the ballastless track of the high-speed railway large-span cable-stayed bridge is completed quickly, efficiently and accurately.

[0008] Preferably, in step S1, a pair of CPⅢ control points is generally arranged at about 60m. The overall stability of the cable-stayed bridge is poor, and the spacing between control points can be appropriately increased, but should not be greater than 80m. The CPⅢ network on the main bridge has 13 pairs of 26 CPⅢ points in total, and the CPⅢ points are arranged according to the following principles and methods: First, on both sides of the main bridge, a pair of bidirectional (longitudinal and vertical) stable CPⅢ points are arranged on the top surface of the protective wall directly above the fixed bearing of the approach bridge; Second, a pair of vertically stable CPⅢ points are arranged on the top surface of the protective wall directly above the auxiliary pier support; Third, a pair of vertically stable CPⅢ points are arranged on the top surface of the first transition pier protection wall close to the main tower; Fourth, a pair of bidirectional stable CPⅢ points are arranged on the inner side of the main tower and the protective wall. The CPⅢ points here can share piles with the CPⅡ points and leveling base points also arranged at the same position, so that the three types of control points share one point position; Fifth, a pair of CPⅢ points are arranged at intervals of 55m at six equal parts of the middle span. These CPⅢ points are unstable in both directions.

[0009] By adopting the above scheme, the CPⅢ points on the main bridge can have as good stability as possible. Some positions on the bridge are stable in both longitudinal and vertical directions, such as the inner side of the tower column where the main tower and the main beam are roughly at the same height; some positions on the main beam are also stable in the vertical direction, such as the top surface of the protective wall on the top of each transition pier. The CPⅢ points are arranged according to the above principles and methods. They have good stability and can be measured as they are used, which is convenient for staff to operate. The location of the measuring point should be considered together with the subsequent working conditions to facilitate observation and not easily damaged, so as to shorten the observation time in the same period as much as possible.

[0010] Preferably, in step S1, the monitoring points are mainly arranged on the main span, and the measuring points are arranged according to the main beam structure form, segment length, and combined with the linear design and monitoring requirements. The longitudinal bridge-direction measuring points of the steel box girder are arranged on the left and right protective walls at the diaphragm of each section of the steel box girder, that is, 3 pairs of 6 points are arranged every 10m, and the basic spacing of the points is 2.5m+5m+2.5m, with a total of 190 points. The longitudinal bridge-direction measuring points of the concrete beam are arranged at the diaphragm where the inclined cable is anchored, and the pier top, the negative bending moment area outside the tower, and the sudden change in stiffness need to be appropriately encrypted.

[0011] By adopting the above scheme, the effective use period and re-measurement frequency of CPⅢ data on the day are determined, and measurements are carried out as they are used, so that the large-span ballastless track cable-stayed bridge can achieve millimeter-level control accuracy. At the same time, by pre-loading the entire bridge load, the track smoothness is guaranteed to meet the design and specification requirements, and the linear error of the large-span ballastless track bridge is controlled within the allowable range of the specification, greatly reducing the amount of fastener adjustment.

[0012] Preferably, in step S1, basic data collection mainly includes temperature monitoring, linear monitoring, cable tension monitoring, beam end and tower top displacement monitoring. All monitoring needs to be performed simultaneously, and the collected data are recorded in a table and submitted to the monitoring and design units in a timely manner.

[0013] By adopting the above scheme, all monitoring needs to be carried out synchronously, and the collected data are recorded in tables and submitted to the monitoring and design units in a timely manner for comprehensive analysis of stiffness and temperature effects. There is a temperature lag effect on air temperature, cable temperature, and steel beam temperature. Through comparative analysis of multi-period data, the stable period of temperature change is determined to conduct fine-tuning of the roadbed plate and eliminate the influence of other factors, so that the completed bridge line shape is consistent with the designed line shape.

[0014] Preferably, in step S1, the linear control conditions are: bridge deck completion, off-line ancillary projects completion, secondary tensioning completion, primary preloading, secondary preloading, secondary unloading, primary unloading, base plate completion, roadbed plate completion, and inter-line ancillaries. When measuring, a time period is selected at night when the temperature is relatively stable, there is no rain, and the wind speed is low, that is, 00:00-06:00 at night, and the wind speed is <5m / s to monitor the main bridge surface linear shape, cable tension, air temperature, cable temperature, steel beam top surface temperature, steel beam box indoor temperature, and beam seam spacing, record the original data and organize them into a spreadsheet.

[0015] By adopting the above scheme, graded regulation and graded verification, the base plate line shape is controlled by relative thickness, the track line shape is controlled by absolute elevation, and the track line shape is refined and highly precise controlled, and it is very close to the theoretical line shape.

[0016] Preferably, in step S2, during preloading and unloading, the loaded counterweight must be checked several times, that is, the weight of each counterweight sleeper must be weighed to determine the weight.

[0017] By adopting the above scheme, the accuracy of the counterweight quantity is ensured, thereby improving the accuracy of construction. By accurately loading the counterweight, the alignment of the bridge can be better controlled to ensure that the alignment of the bridge during construction meets the design requirements and reduce the need for later adjustments. At the same time, through accurate counterweight verification, material waste and rework caused by inaccurate counterweights can be avoided, thereby reducing construction costs.

[0018] Preferably, in step S3, the specific steps of correcting the vertical stiffness of the theoretical model of the main bridge structure are as follows: First, load the entire bridge with a uniform load, observe and record the main beam deck line shape at the same temperature before and after preloading, and measure the cable tension of the inclined cable; Second, the measured and theoretical linear shapes and cable forces are analyzed, and the stiffness of the theoretical model is corrected. The continuous monitoring time for the temperature deformation correction is not less than 2 weeks, and the relationship between the main beam elevation and the atmospheric temperature is observed from 0:00 to 6:00 every morning. The temperature monitoring includes the normal temperature and extreme temperature before the middle span of the main bridge is closed and the influence law on the bridge deck line shape. According to the correction calculation of the stiffness and temperature, a theoretical calculation model after stiffness and temperature correction is obtained. The theoretical calculation model is: in, is the main span length; is the side span length; is the height of the bridge tower above the bridge deck; is the height of the bridge tower below the bridge deck; is the length of the mid-span cable; is the length of the side span cable; is the linear expansion coefficient of concrete; is the actual variation of the average temperature of the bridge tower.

[0019] By adopting the above scheme, according to the correction calculation of stiffness and temperature, a theoretical calculation model after stiffness and temperature correction is obtained, which can optimize the design parameters, such as the main span length, side span length, bridge tower height, etc., to meet the actual engineering needs. In the theoretical calculation model, when the bridge tower heats up, the cable anchor point on the tower will increase with the increase of tower height, causing the bridge deck in the middle of the span to rise; and the vertical constraint at the beam end will also cause the side span cable to pull the bridge tower outward and drive the bridge deck in the middle of the span to rise further. According to the precise stiffness and temperature correction, the safety and stability of the bridge structure can be improved, and the potential risks caused by stiffness or temperature changes can be reduced.

[0020] Preferably, in step S4, the verification step of the initial linear assessment and adjustment is: First, the calculation model with stiffness and temperature correction is used to calculate the target alignment before the base plate is laid, after the base plate is constructed, and after all the second-phase dead loads are completed in the current state; Second, compare the target line shape before the base plate is laid in the current state with the current measured line shape; Third, verify whether the base plate height and the roadbed plate thickness meet the requirements of the track professionals. The base plate and roadbed plate height and requirements are determined by the track professionals. If not, the thickness of the concrete to be constructed or the cable tension can be adjusted. In principle, the cable tension adjustment value should not exceed ±5% of the theoretical cable tension. Fourth, if the above adjustments still do not meet the relevant requirements, the line professionals need to adjust the longitudinal section and re-evaluate the initial alignment; Fifth, after the initial alignment assessment, if cable tension adjustment is required, make adjustments according to the calculated values ​​until the measured main beam alignment meets the requirements for ballastless track laying.

[0021] By adopting the above scheme and the calculation model corrected for stiffness and temperature, the target alignment before the base plate is laid, after the base plate is constructed, and after the completion of the second phase constant load can be accurately calculated in the current state to ensure the accuracy of the design. By comparing the target alignment before the base plate is laid in the current state with the current measured alignment, deviations in actual construction can be discovered and resolved in a timely manner, and it can be verified whether the base plate height value and the roadbed plate thickness value meet the track professional requirements, thereby ensuring the stability and safety of the bridge structure.

[0022] Preferably, in step S5, before the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate at the temperature T1, and obtains the height difference ΔH1=H1-H2 between the elevation of the observation point and the elevation of the top of the base plate; the alignment of the main bridge is reviewed, and the preset construction temperature T2 and the measured elevation H3 of the observation point are obtained, and modeling analysis is performed to determine the track design alignment data H4 under the corresponding working conditions, and obtain the height difference ΔH2=H3-H4 between the elevation of the observation point and the track control elevation. The relative height ΔH2 is used for coarse control and temporary elevation review.

[0023] By adopting the above scheme, the bridge line elevation data H2 of the top surface of the base plate at the temperature T1 provided by the design can accurately control the accuracy of the base plate during construction, and obtain the height difference ΔH1=H1-H2 between the elevation of the observation point and the elevation of the top of the base plate, which can ensure the consistency and accuracy of the observation data. At the same time, the relative height ΔH2 can be roughly controlled and the elevation can be temporarily reviewed. The temporary review is not affected by temperature, which can improve the flexibility and adaptability of construction.

[0024] Preferably, in step S5, the plane coordinates and elevation of the CPⅢ control point are updated every 1.5 hours, and the station is re-set to start the relevant track fine-tuning work. After the total station completes the free station measurement, the polar coordinate method should be used to measure and record the plane coordinates and elevation of the two CPⅢ control points. After the measurement is completed, the plane coordinates and elevation of the CPⅢ control point are measured again, and the difference should not be greater than 3mm. After the station is replaced, there are no less than 2 pairs of CPⅢ control points overlapped by adjacent stations, and the difference in the re-measured data of the previous station should not be greater than 2mm.

[0025] By adopting the above scheme, the polar coordinate method is used to measure and record the plane coordinates and elevations of two CPⅢ control points to ensure the high accuracy of the measured data. After the measurement is completed, the plane coordinates and elevation of the CPⅢ control point are measured again, and the error should not be greater than 3mm to ensure the accuracy and consistency of the data. After the station location is replaced, there are no less than 2 pairs of CPⅢ control points overlapping in adjacent stations, and the error of the re-measured data of the previous station should not be greater than 2mm to ensure the continuity and reliability of the measurement. The above measures are helpful to optimize the management and monitoring during the bridge construction process and ensure the control of construction quality and progress.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. Based on the previous monitoring results, the variation law of CPⅢ control network with temperature is obtained, and the effective use period and re-test frequency of CPⅢ data on the day are determined, so that the data can be measured as needed, so that the large-span ballastless track cable-stayed bridge can achieve millimeter-level control accuracy; 2. There is a temperature hysteresis effect in air temperature, cable temperature and steel beam temperature. Through comparative analysis of multiple periods of data, the stable period of temperature change is determined to fine-tune the roadbed plate, eliminate the influence of other factors, and make the completed bridge line shape consistent with the designed line shape; 3. Gradual regulation and verification, control the base plate line shape by relative thickness, control the track line shape by absolute elevation, fine and high-precision control, and the track line shape is close to the theoretical line shape; 4. Preload the full bridge load to eliminate the impact of the negative bending moment area on the track line shape, ensuring that the track smoothness meets the design and specification requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the construction process flow chart of the steel box girder erection using linear control technology in this application. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1 , further details of this application are given.

[0029] The embodiments of the present application disclose a construction alignment control technology for a large-span cable-stayed bridge on a high-speed railway.

[0030] Reference Figure 1 , the construction alignment control technology of a high-speed railway large-span cable-stayed bridge includes the following steps: S1. Initial alignment and cable force measurement: Conduct multiple measurements of the main bridge deck alignment and cable force, observe and record the initial alignment of the main beam bridge deck and measure the cable force, monitor and analyze the changes of CPⅢ measuring points, deck alignment and cable force with temperature; S2. Phase II dead load calculation: According to different on-site working conditions, accurately calculate the residual loads of the constructed and unconstructed parts. The residual loads include but are not limited to rails and fasteners, ballast plates, base plates, protective layers, and cables; S3, vertical stiffness, temperature change correction: by preloading, correct the vertical stiffness of the theoretical model of the main bridge structure, and continuously monitor the temperature change, and obtain the theoretical calculation model after stiffness and temperature correction according to the correction calculation of the stiffness and temperature; S4. Initial alignment assessment and adjustment: Initial alignment assessment mainly includes theoretical alignment calculation. By comparing theoretical and measured alignments, three technical indicators, namely, cable force adjustment value, base plate height value, and ballast plate thickness value, are obtained to verify whether they meet the specification requirements. S5. Ballastless track laying: Repeated measurement and collection of main bridge alignment data and basic information under corresponding working conditions. Through long-term observation, the preset nighttime construction temperature T1 and the measured elevation H1 of the measuring point under the corresponding working conditions were obtained. The thickness of the base plate was adjusted to make the top surface line of the base plate as close to the theoretical line as possible. The water bag on the base plate was used for secondary loading to simulate the main span 330m section of the trackbed and the remaining auxiliary engineering loads, and basic data was observed and collected.

[0031] Specifically, in order to better control the laying accuracy of ballastless track, the linear control technology collects basic data after the completion of bridge deck ancillary projects such as vertical walls, protective walls, cover plates, railings, cables and contact network columns to monitor the force and line shape of the cable-stayed bridge under different load and temperature conditions, collects actual line shape data of the cable-stayed bridge, uses finite element modeling and analysis, verifies the stiffness of steel beams, analyzes the temperature change law of steel beams, and fits the theoretical line shape of each part of the ballastless track of the entire bridge. This technology controls the line shape error of the large-span ballastless track bridge within the allowable range of the specification, greatly reduces the adjustment amount of fasteners, improves the track laying accuracy, ensures the quality of the project, and produces good economic and social benefits.

[0032] Reference Figure 1 In step S1, CPⅢ control points are generally arranged in pairs at about 60m. The overall stability of the cable-stayed bridge is poor, and the control point spacing can be appropriately increased, but it should not be greater than 80m. The CPⅢ network on the main bridge has 13 pairs of 26 CPⅢ points in total. The CPⅢ points are arranged according to the following principles and methods: First, on both sides of the main bridge, a pair of bidirectional (longitudinal and vertical) stable CPⅢ points are arranged on the top surface of the protective wall directly above the fixed bearing of the approach bridge; Second, a pair of vertically stable CPⅢ points are arranged on the top surface of the protective wall directly above the auxiliary pier support; Third, a pair of vertically stable CPⅢ points are arranged on the top surface of the first transition pier protection wall close to the main tower; Fourth, a pair of bidirectional stable CPⅢ points are arranged on the inner side of the main tower and the protective wall. The CPⅢ points here can share piles with the CPⅡ points and leveling base points also arranged at the same position, so that the three types of control points share one point position; Fifth, a pair of CPⅢ points are arranged at intervals of 55m at six equal parts of the middle span. These CPⅢ points are unstable in both directions.

[0033] Specifically, after the post-construction settlement deformation and creep deformation observation and evaluation of the main bridge meet the requirements of the specifications, the temporary load on the bridge face is cleared, and when the wind speed at the main beam height is less than 5m / s and the climate environment is relatively stable, generally from 02:00 to 06:00 in the morning, the main bridge deck alignment and cable tension are measured multiple times, the initial alignment of the main beam deck is observed and recorded, and the cable tension is measured, and the changes of CPⅢ measuring points, bridge deck alignment and cable tension with temperature are monitored and analyzed. The location of the CPⅢ measuring point should be considered together with subsequent working conditions to facilitate observation and not easily damaged, so as to shorten the observation time in the same period as much as possible.

[0034] Reference Figure 1In step S1, the monitoring points are mainly arranged on the main span. The monitoring points are arranged according to the main beam structure form, segment length, linear design and monitoring requirements. The longitudinal bridge-direction measuring points of the steel box girder are arranged on the left and right protective walls at the transverse diaphragm of each steel box girder, that is, 3 pairs of 6 points are arranged every 10m, and the basic spacing of the points is 2.5m+5m+2.5m, with a total of 190 points. The longitudinal bridge-direction measuring points of the concrete beam are arranged at the transverse diaphragm where the cable is anchored. The pier top, the negative bending moment area outside the tower and the sudden change of stiffness need to be appropriately encrypted.

[0035] Specifically, a track trolley is used to accurately measure the geometric state of the track, and a total station is used for monitoring and rail position measurement to ensure high precision and consistency of the measurement. An electronic level is used for beam surface monitoring and track surface elevation review to improve measurement accuracy and reliability. The Leica TS60 fully automatic measuring robot is used for linear monitoring to provide continuous and high-precision measurement data. The cable force test system is used for cable force monitoring to ensure the stability of the inclined cable under various working conditions. The radar remote sensing equipment QY-CG-XBL-W01 is used to accurately measure the plane coordinates and elevation of the CPⅢ control points to ensure data consistency and accuracy. The measurement points are arranged according to the main beam structure and segment length, combined with the linear design and monitoring requirements, which can better guide the construction process and improve management efficiency.

[0036] Reference Figure 1 ,In step S1, the collection of basic data mainly includes temperature ,monitoring, linear monitoring, cable force monitoring, beam end and tower top displacement monitoring. ,All monitoring needs to be carried out simultaneously. The collected data are ,recorded in a table and submitted to the monitoring and ,design units in a timely manner.

[0037] Specifically, the temperature monitoring is to use automatic temperature measuring instruments, comprehensive testers and other instruments to continuously collect and record the ambient temperature, steel beam top temperature, steel box beam middle box temperature, concrete beam box temperature, test cable temperature, main tower large and small mileage side inner and outer wall temperature, etc. Temperature monitoring should be carried out simultaneously with linear measurement; The linear monitoring is to collect the beam surface elevation under different temperatures and working conditions. The measurement is divided into CPⅢ closed loop and 1-6# monitoring point closed loop with a period of 2 hours. The CPⅢ closed loop uses the CPⅢ point at the P5 main tower as the starting point, and the monitoring point closed loop uses the adjacent CPⅢ point as the starting point. The linear monitoring adopts a 0.5″ fully automatic measuring robot or an electronic level for monitoring according to different working conditions. A total of 9 people in 4 groups monitor in the same period. 3 people in group 1 use the second-class leveling method to conduct closed measurement of 14 CPⅢ points in the main span to obtain the actual elevation of the CPⅢ points in this period. 2 people in group 2 use the intermediate point method to simultaneously conduct 1-2#, a total of 62 points; 2 people in group 3, The middle point method was used to measure 3-4# simultaneously, for a total of 66 points; 2 people in group 4# used the middle point method to measure the closed loop of monitoring points 5-6# simultaneously, for a total of 62 points. The height difference between each monitoring point and the CPⅢ starting point in this period was obtained, and finally the elevation of the monitoring point was corrected according to the actual elevation of the CPⅢ point to obtain the actual elevation of the beam surface monitoring point. This cycle was repeated for 3 periods to obtain 3 sets of elevation data. At the same time, it should be noted that during linear monitoring, there will be a deviation of about 2mm in the manual measurement of the elevation, and the longer the line, the greater the deviation. This deviation requires a large amount of data to be averaged to reduce the error. The stiffness and temperature corrections obtained in this way can be used for roadbed slab construction with little impact. The temperature gradient data should increase the temperature difference to reduce the impact of errors; The cable force monitoring is to use the cable force test system and radar telemetry technology to measure the vibration frequency of the inclined cable under various working conditions, convert it into fundamental frequencies of various orders by a dynamic data acquisition instrument, and substitute the fundamental frequencies into the steel string vibration equation to solve the cable force; The beam end and tower top displacement monitoring: on the premise that the temperature boundary conditions are roughly equivalent to the working conditions, the displacement data of the main beam and the bridge tower under various working conditions are continuously monitored.

[0038] Reference Figure 1 In step S1, the linear control conditions are: bridge deck completed, off-line auxiliary projects completed, secondary tensioning completed, primary preloading, secondary preloading, secondary unloading, primary unloading, base plate completed, roadbed plate completed, and line auxiliary projects. When measuring, a time period of relatively stable temperature, no rain, and low wind speed at night is selected, that is, 00:00-06:00 at night, when the wind speed is <5m / s, the main bridge surface linear shape, cable tension, air temperature, cable temperature, steel beam top surface temperature, steel beam box indoor temperature, and beam seam spacing are monitored, and the original data are recorded and organized into a spreadsheet.

[0039] Specifically, the measurement is carried out during the night when the temperature is relatively stable, there is no rain, and the wind speed is low, that is, from 00:00 to 06:00 at night, and the wind speed is less than 5m / s, to monitor the main bridge surface line shape, cable tension, air temperature, cable temperature, steel beam top surface temperature, steel beam box indoor temperature, and beam seam spacing. This can ensure the accuracy and reliability of the measurement data. These measures help to optimize the management and monitoring of the bridge construction process and ensure the control of construction quality and progress.

[0040] Reference Figure 1 In step S2, during preloading and unloading, the loaded counterweight must be checked several times, that is, the weight of each car counterweight sleeper must be weighed to determine the weight.

[0041] Specifically, during preloading and unloading, the loaded counterweight must be reviewed several times, that is, the sleepers used for counterweighting each vehicle must be weighed to determine the weight to ensure the accuracy of the counterweight quantity. The water bag counterweight must be double-calibrated with a measuring water meter. First, use a square bucket to hold it and check whether the water flow through the water meter is accurate; then place the preloaded water bag on the scale, fill it with water through the water meter, check whether the water flow is consistent with the weight measured on the scale, and perform a second calibration.

[0042] Reference Figure 1 In step S3, the specific steps of correcting the vertical stiffness of the theoretical model of the main bridge structure are as follows: First, load the entire bridge with a uniform load, observe and record the main beam deck line shape at the same temperature before and after preloading, and measure the cable tension of the inclined cable; Second, the measured and theoretical linear shapes and cable forces are analyzed, and the stiffness of the theoretical model is corrected. The continuous monitoring time for the temperature deformation correction is not less than 2 weeks, and the relationship between the main beam elevation and the atmospheric temperature is observed from 0:00 to 6:00 every morning. The temperature monitoring includes the normal temperature and extreme temperature before the middle span of the main bridge is closed and the influence law on the bridge deck line shape. According to the correction calculation of the stiffness and temperature, a theoretical calculation model after stiffness and temperature correction is obtained. The theoretical calculation model is: in, is the main span length; is the side span length; is the height of the bridge tower above the bridge deck; is the height of the bridge tower below the bridge deck; is the length of the mid-span cable; is the length of the side span cable; is the linear expansion coefficient of concrete; is the actual variation of the average temperature of the bridge tower.

[0043] Specifically, the correction is made by combining the measured theoretical values ​​with simulations, and the formula It can be obtained that under the same temperature change, the relative influence of cable temperature and main beam average temperature on the vertical displacement of the mid-span of the cable-stayed bridge depends on the tower height-span ratio, the side-to-mid-span ratio and the main beam linear expansion coefficient; there is no monotonic change relationship between the vertical displacement of the mid-span of the cable-stayed bridge caused by temperature and the ambient temperature or a certain structural temperature; within the normal temperature range, it basically conforms to the linear superposition principle with four temperature effects, namely cable temperature, main beam average temperature, main beam top and bottom plate temperature difference and bridge tower average temperature; compared with the thermal expansion and contraction effect of temperature, the influence of material elastic modulus changing with temperature on the vertical displacement of the mid-span of the cable-stayed bridge can be ignored. The above corrections are helpful to eliminate this part of the normal displacement from the measured total displacement, so as to highlight the changes in displacement indicators caused by structural damage or extreme events, thereby more sensitively discovering abnormalities in the structural health status.

[0044] Reference Figure 1 In step S4, the verification steps of the initial linear assessment and adjustment are: First, the calculation model with stiffness and temperature correction is used to calculate the target alignment before the base plate is laid, after the base plate is constructed, and after all the second-phase dead loads are completed in the current state; Second, compare the target line shape before the base plate is laid in the current state with the current measured line shape; Third, verify whether the base plate height and the roadbed plate thickness meet the requirements of the track professionals. The base plate and roadbed plate height and requirements are determined by the track professionals. If not, the thickness of the concrete to be constructed or the cable tension can be adjusted. In principle, the cable tension adjustment value should not exceed ±5% of the theoretical cable tension. Fourth, if the above adjustments still do not meet the relevant requirements, the line professionals need to adjust the longitudinal section and re-evaluate the initial alignment; Fifth, after the initial alignment assessment, if cable tension adjustment is required, make adjustments according to the calculated values ​​until the measured main beam alignment meets the requirements for ballastless track laying.

[0045] Specifically, the calculation model with stiffness and temperature correction can be used to accurately calculate the target alignment before the base plate is laid, after the base plate is constructed, and after the completion of all second-phase constant loads in the current state, thereby ensuring the accuracy of the design. By comparing the target alignment before the base plate is laid in the current state with the current measured alignment, deviation problems in actual construction can be discovered and resolved in a timely manner. After the initial alignment evaluation, if cable tension adjustment is required, it is adjusted according to the calculated value until the measured main beam alignment meets the requirements for ballastless track laying. This ensures high precision and high quality during the construction process. Through these steps, the overall quality of the bridge project can be significantly improved, ensuring its performance and stability in actual use.

[0046] Reference Figure 1In step S5, before the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate at temperature T1, and obtains the height difference ΔH1=H1-H2 between the elevation of the observation point and the elevation of the top of the base plate; the alignment of the main bridge is reviewed, and the preset construction temperature T2 and the measured elevation H3 of the observation point are obtained, and modeling analysis is performed to determine the track design alignment data H4 under the corresponding working conditions, and the height difference ΔH2=H3-H4 between the elevation of the observation point and the track control elevation is obtained. The relative height ΔH2 is used for coarse control and temporary elevation review.

[0047] Specifically, before the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate at temperature T1, and obtains the height difference ΔH1=H1-H2 between the elevation of the observation point and the elevation of the top of the base plate. Considering the changes in working conditions such as ambient temperature during the elevation positioning process, the measuring point is used as the benchmark, and the height difference ΔH1 of the same cross section is used as the basis for formwork setting, that is, the base plate is controlled by relative thickness, double lines are synchronized, and symmetrical construction from the side span to the middle span; when the strength of the base plate is not less than 75%, the water bag on the base plate is used for secondary loading to simulate the main span 330m section of the track bed plate and the remaining auxiliary engineering loads, observe and collect basic data, and verify the alignment of the main bridge to obtain the preset construction temperature T2 and the actual elevation H3 of the observation point. The monitoring and design units conduct modeling analysis to determine the track design alignment data H4 under the corresponding working conditions, and obtain the height difference ΔH2=H3-H4 between the observation point elevation and the track control elevation. The relative height ΔH2 is used for coarse control and temporary elevation review. The temporary review is not affected by temperature. During the track bed construction, due to the influence of temperature stabilization time, the time for fine adjustment and concrete pouring is short. Four groups of fine adjustment personnel work together to shorten the fine adjustment time and make extra time for concrete pouring, avoiding each pouring section being too short and multiple broken line points in the track line.

[0048] Reference Figure 1 In step S5, the plane coordinates and elevation of the CPⅢ control point are updated every 1.5 hours, and the station is re-set to start the relevant track fine-tuning work. After the total station completes the free station measurement, the polar coordinate method should be used to measure and record the plane coordinates and elevation of the two CPⅢ control points. After the measurement is completed, the plane coordinates and elevation of the CPⅢ control point are measured again, and the difference should not be greater than 3mm. After the station is replaced, there are no less than 2 pairs of CPⅢ control points overlapped by adjacent stations, and the difference in the re-measured data of the previous station should not be greater than 2mm.

[0049] Specifically, due to the large deformation of large-span bridges under the action of temperature loads, the CPⅢ control network often has large differences from the original measurement results and exceeds the limit when used. In view of the objective existence of its deformation, CPⅢ data should be used as soon as it is measured. During the construction of the roadbed slab, the CPⅢ elevation data needs to be measured after the temperature is stable and measured as it is used. During the construction of the roadbed slab in the bid section, an average of 1 to 1.5 hours of measurement can meet the needs of fine-tuning. Several groups should not be measured in advance for use during construction, because it is impossible to determine whether the elevation value is applicable to the current situation.

[0050] The implementation principle of the embodiment of the present application is: the whole bridge line shape is fitted by using rail sleepers + water bags to simulate the whole bridge base plate, the main span 330M roadbed plate and the second phase constant load counterweight of the remaining ancillary facilities. Through graded simulated constant load tests, the temperature and linear change data of the characteristic points of the main beam structure under various construction conditions are collected, the stiffness and temperature change laws of the steel beam are analyzed, the accuracy of the bridge model is verified, and the correction parameters of the main bridge ballastless track construction are determined to guide the implementation of the ballastless track and ensure that the accuracy and smoothness of the bridge line shape meet the requirements of the specifications.

[0051] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. High-speed railway long-span cable-stayed bridge construction line shape control technology, characterized by: The following steps are involved: S1. Initial alignment and cable force measurement: Conduct multiple measurements of the main bridge deck alignment and cable force, observe and record the initial alignment of the main beam bridge deck and measure the cable force, monitor and analyze the changes of CPⅢ measuring points, deck alignment and cable force with temperature; S2. Phase II dead load calculation: According to different on-site working conditions, accurately calculate the residual loads of the constructed and unconstructed parts. The residual loads include but are not limited to rails and fasteners, ballast plates, base plates, protective layers, and cables; S3, vertical stiffness, temperature change correction: by preloading, correct the vertical stiffness of the theoretical model of the main bridge structure, and continuously monitor the temperature change, and obtain the theoretical calculation model after stiffness and temperature correction according to the correction calculation of the stiffness and temperature; S4. Initial alignment assessment and adjustment: Initial alignment assessment mainly includes theoretical alignment calculation. By comparing theoretical and measured alignments, three technical indicators, namely, cable force adjustment value, base plate height value, and ballast plate thickness value, are obtained to verify whether they meet the specification requirements. S5. Ballastless track laying: Repeated measurement and collection of main bridge alignment data and basic information under corresponding working conditions. Through long-term observation, the preset nighttime construction temperature T1 and the measured elevation H1 of the measuring point under the corresponding working conditions were obtained. The thickness of the base plate was adjusted to make the top surface line of the base plate as close to the theoretical line as possible. The water bag on the base plate was used for secondary loading to simulate the main span 330m section of the trackbed and the remaining auxiliary engineering loads, and basic data was observed and collected.

2. The high-speed railway long-span cable-stayed bridge construction alignment control technology according to claim 1 is characterized in that: In step S1, CPⅢ control points are generally arranged in pairs at about 60m. The overall stability of the cable-stayed bridge is poor, and the control point spacing can be appropriately increased, but it should not be greater than 80m. The CPⅢ network on the main bridge has 13 pairs of 26 CPⅢ points in total. The CPⅢ points are arranged according to the following principles and methods: First, on both sides of the main bridge, a pair of bidirectional (longitudinal and vertical) stable CPⅢ points are arranged on the top surface of the protective wall directly above the fixed bearing of the approach bridge; Second, a pair of vertically stable CPⅢ points are arranged on the top surface of the protective wall directly above the auxiliary pier support; Third, a pair of vertically stable CPⅢ points are arranged on the top surface of the first transition pier protection wall close to the main tower; Fourth, a pair of bidirectional stable CPⅢ points are arranged on the inner side of the main tower and the protective wall. The CPⅢ points here can share piles with the CPⅡ points and leveling base points also arranged at the same position, so that the three types of control points share one point position; Fifth, a pair of CPⅢ points are arranged at intervals of 55m at six equal parts of the middle span. These CPⅢ points are unstable in both directions.

3. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S1, the monitoring points are mainly arranged on the main span. The monitoring points are arranged according to the main beam structure, segment length, linear design and monitoring requirements. The longitudinal bridge-direction measuring points of the steel box girder are arranged on the left and right protective walls at the transverse diaphragm of each steel box girder, that is, 3 pairs of 6 points are arranged every 10m, and the basic spacing of the points is 2.5m+5m+2.5m, with a total of 190 points. The longitudinal bridge-direction measuring points of the concrete beam are arranged at the transverse diaphragm where the inclined cable is anchored. The pier top, the negative bending moment area outside the tower and the sudden change of stiffness need to be appropriately encrypted.

4. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S1, the basic data collection mainly includes temperature monitoring, linear monitoring, cable tension monitoring, beam end and tower top displacement monitoring. All monitoring needs to be carried out simultaneously, and the collected data is recorded in a table and submitted to the monitoring and design units in a timely manner.

5. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S1, the linear control conditions are: bridge deck completion, off-line auxiliary projects completion, secondary tensioning completion, primary preloading, secondary preloading, secondary unloading, primary unloading, base plate completion, roadbed plate completion, and inter-line auxiliary projects. When measuring, a time period of relatively stable temperature, no rain, and low wind speed at night is selected, that is, 00:00-06:00 at night, when the wind speed is <5m / s, the main bridge surface linear shape, cable tension, air temperature, cable temperature, steel beam top surface temperature, steel beam box indoor temperature, and beam seam spacing are monitored, and the original data is recorded and organized into a spreadsheet.

6. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S2, during preloading and unloading, the loaded counterweight must be checked several times, that is, the weight of each counterweight sleeper must be weighed to determine the weight.

7. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S3, the specific steps of correcting the vertical stiffness of the theoretical model of the main bridge structure are as follows: First, load the entire bridge with a uniform load, observe and record the main beam deck line shape at the same temperature before and after preloading, and measure the cable tension of the inclined cable; Second, the measured and theoretical linear shapes and cable forces are analyzed, and the stiffness of the theoretical model is corrected. The continuous monitoring time for the temperature deformation correction is not less than 2 weeks, and the relationship between the main beam elevation and the atmospheric temperature is observed from 0:00 to 6:00 every morning. The temperature monitoring includes the normal temperature and extreme temperature before the middle span of the main bridge is closed and the influence law on the bridge deck line shape. According to the correction calculation of the stiffness and temperature, a theoretical calculation model after stiffness and temperature correction is obtained. The theoretical calculation model is: in, is the main span length; is the side span length; is the height of the bridge tower above the bridge deck; is the height of the bridge tower below the bridge deck; is the length of the mid-span cable; is the length of the side span cable; is the linear expansion coefficient of concrete; is the actual variation of the average temperature of the bridge tower.

8. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S4, the verification steps of the initial linear assessment and adjustment are: First, the calculation model with stiffness and temperature correction is used to calculate the target alignment before the base plate is laid, after the base plate is constructed, and after all the second-phase dead loads are completed in the current state; Second, compare the target line shape before the base plate is laid in the current state with the current measured line shape; Third, verify whether the base plate height and the roadbed plate thickness meet the requirements of the track professionals. The base plate and roadbed plate height and requirements are determined by the track professionals. If not, the thickness of the concrete to be constructed or the cable tension can be adjusted. In principle, the cable tension adjustment value should not exceed ±5% of the theoretical cable tension. Fourth, if the above adjustments still do not meet the relevant requirements, the line professionals need to adjust the longitudinal section and re-evaluate the initial alignment; Fifth, after the initial alignment assessment, if cable tension adjustment is required, make adjustments according to the calculated values ​​until the measured main beam alignment meets the requirements for ballastless track laying.

9. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S5, before the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate at temperature T1, and obtains the height difference ΔH1=H1-H2 between the elevation of the observation point and the elevation of the top of the base plate; the alignment of the main bridge is reviewed, and the preset construction temperature T2 and the measured elevation H3 of the observation point are obtained, and modeling analysis is performed to determine the track design alignment data H4 under the corresponding working conditions, and the height difference ΔH2=H3-H4 between the elevation of the observation point and the track control elevation is obtained. The relative height ΔH2 is used for coarse control and temporary elevation review.

10. The construction alignment control technology for a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S5, the plane coordinates and elevation of the CPⅢ control point are updated every 1.5 hours, and the station is re-set to start the relevant track fine-tuning work. After the total station completes the free station measurement, the polar coordinate method should be used to measure and record the plane coordinates and elevation of the two CPⅢ control points. After the measurement is completed, the plane coordinates and elevation of the CPⅢ control point are measured again, and the difference should not be greater than 3mm. After the station is replaced, there are no less than 2 pairs of CPⅢ control points overlapped by adjacent stations, and the difference in the re-measured data of the previous station should not be greater than 2mm.

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