Construction method of high-speed railway concrete prestressed cable-stayed bridge ballastless track

Abstract

This invention discloses a construction method for ballastless track on a prestressed concrete cable-stayed bridge for high-speed railways. The method includes: setting up observation points for full-bridge alignment monitoring; arranging water bags on the beams to simulate ballastless track loads; identifying the actual stiffness of the main beam and correcting the finite element model, thereby calculating and tensioning the stay cables to the final tension; measuring the elevation error under ballast and obtaining the temperature deformation coefficient through continuous temperature monitoring; calculating and constructing the base slab based on the elevation error and temperature deformation coefficient; after measuring the alignment error of the base slab, calculating the track bed slab thickness again based on the error and temperature coefficient, and simultaneously and equally unloading the water bag ballast during track bed slab pouring; finally, completing the construction of the inter-track waterproof layer. This invention achieves precise layered control of the ballastless track structure on cable-stayed bridges, effectively ensuring the high smoothness and long-term stability of high-speed railway lines.

Description

Technical Field

[0001] This invention relates to the technical field of bridge construction methods, specifically to a method for constructing ballastless track for a high-speed railway prestressed concrete cable-stayed bridge. Background Technology

[0002] Currently, cable-stayed bridges have become one of the preferred bridge types for long-span high-speed railway bridges due to their superior span capacity and structural aesthetics. However, laying ballastless track on long-span, especially prestressed concrete cable-stayed bridges with asymmetrical structural stresses, remains a significant technical challenge for the engineering community. Ballastless track is extremely sensitive to the deformation of the subfoundation, and under the action of construction and secondary dead loads (the self-weight of the track structure), the girder of a cable-stayed bridge will undergo significant downward deflection. If conventional construction methods are used, this deformation will directly lead to a serious deviation of the track alignment from the design elevation after the bridge is completed, failing to meet the stringent requirements for track smoothness and comfort for high-speed train operation.

[0003] To address this problem, various alignment control methods have been proposed in existing technologies. For example, Chinese patent document CN119711261A discloses a "multi-level graded control construction method for ballastless track of long-span cable-stayed bridges for high-speed railways." This scheme includes: collecting basic data under various working conditions before equal load loading; measuring vertical deformation through bridge deck loading to obtain the actual stiffness of the structure; measuring the alignment of the main beam under different ambient temperatures to obtain the correspondence between the temperature difference of the structural system and the deformation of the main beam, thereby obtaining a theoretical calculation model after stiffness and temperature correction; and conducting full load simulation using a two-stage loading method. The first stage of loading uses sleepers as equivalent counterweight for the base plate; the second stage of loading uses water bags as equivalent counterweight for the main span track slab and the remaining auxiliary structures, with water bags placed inside the protective wall and the already arranged sleepers for water injection; calculating the theoretical alignment before base plate laying, after base plate construction, and after all two permanent structures are completed, and comparing it with the current measured alignment. If the deviation is too large, it can be adjusted by adjusting the tension of the stay cables or the thickness of the construction structure to ensure that the theoretical alignment meets the requirements for ballastless track laying.

[0004] This technology is the first to systematically propose the concept of multi-level graded control, organically integrating stiffness identification, temperature correction, graded loading, and equivalent replacement to form a relatively complete construction process. In particular, it introduces the theoretical calculation formula for the thermal deformation of the main beam and emphasizes the principle of equivalent replacement by synchronous unloading during the pouring of the track slab, providing valuable reference for controlling the ballastless track alignment of long-span cable-stayed bridges.

[0005] However, after in-depth analysis, the following technical defects still exist in the practical application of this technical solution, which restricts the further improvement of its linear control accuracy: First, there is a lack of a quantifiable, closed-loop error decay mechanism. While the proposed solution suggests adjusting the height difference through structural thickness or cable tension and provides a formula for calculating the elevation difference, it fails to clarify how to translate these calculated deviations into specific adjustments for the actual thickness of the base slab and track bed slab. In other words, the solution only calculates and identifies the error, but does not achieve its physical absorption and closed-loop elimination. This results in alignment errors during construction (such as residual errors after cable adjustment and base slab construction errors) not being systematically consumed in subsequent processes. These errors may accumulate at each stage, ultimately requiring significant corrections through long-rail fine-tuning, increasing on-site operational difficulty and cost.

[0006] Second, the handling of temperature effects lacks a dynamic correction model based on field measurements. While the scheme provides a theoretical formula for temperature difference deformation and mentions collecting observational data under the lowest nighttime temperature conditions, its temperature correction relies primarily on theoretical calculations rather than on the temperature deformation coefficient obtained from actual monitoring of the bridge structure. Because each bridge has different structural forms, material properties, and boundary conditions, the theoretical formula cannot fully and accurately reflect the actual thermal response behavior.

[0007] Third, the stiffness identification method is relatively simple. Although the plan mentions obtaining the actual stiffness of the structure by loading the bridge deck and measuring the vertical deformation, it does not provide a specific and repeatable stiffness identification algorithm, nor does it explicitly use the identified stiffness correction coefficient in subsequent cable force calculations, pre-camber settings, and structural layer thickness adjustments.

[0008] Therefore, there is an urgent need for a construction method for ballastless tracks in cable-stayed bridges to solve the technical problems in existing technologies, such as the lack of closed-loop error control logic, reliance on theoretical models for temperature correction rather than measured data, and the disconnect between stiffness identification and subsequent adjustment, which lead to insufficient accuracy in alignment control. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a method for constructing ballastless track for high-speed railway prestressed concrete cable-stayed bridges.

[0010] The technical solution of the present invention is: a construction method for ballastless track of a high-speed railway prestressed concrete cable-stayed bridge, comprising: after the main bridge is closed, setting up CPIII control network observation points to monitor the alignment of the entire bridge; Water bags were used to weigh down the beam to simulate the load on the ballastless track. Based on the linear monitoring data, the actual stiffness of the main beam is identified and the finite element model is corrected. The final tension is calculated based on the corrected finite element model, and the stay cables are tensioned to the final tension. The height difference error between the actual elevation and the theoretical elevation of the beam surface was measured under the condition of compression, and the temperature deformation coefficient was obtained by continuous temperature monitoring. The thickness of the base plate is calculated based on the elevation error and temperature deformation coefficient, and the base plate is poured accordingly. Measure the linear error after the base plate is constructed; The thickness of the track bed slab is calculated based on the linear error, and the track bed slab is poured accordingly. During the pouring process, the water bag weight is unloaded simultaneously. Construction of the waterproof layer between the tracks was carried out, and the construction of the ballastless track for the cable-stayed bridge was completed.

[0011] The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridges provided by the present invention includes the following specific methods for identifying the actual stiffness of the main beam and correcting the finite element model: The girder transport vehicle was driven to the 1 / 4, 1 / 2, and 3 / 4 mid-span positions respectively. After stopping and stabilizing at each position, the average vertical deformation at each position was measured. The theoretical deformation value of the finite element model under load equivalent to the actual axle load and wheel position distribution of the girder transport vehicle was calculated. The stiffness ratio was calculated according to the following formula: +

[0012] in: ΔE —Stiffness ratio; H 1 —The average value of vertical deformation measurements at the 1 / 4 mid-span position; H 11 —Theoretical average value of vertical deformation at the 1 / 4 mid-span position; H 2 —The average value of vertical deformation measurements at the mid-span position (1 / 2 span); H 21 —Theoretical average value of vertical deformation at the mid-span position (1 / 2 span); H 3 —The average value of vertical deformation measurements at the 3 / 4 mid-span location; H 31 —Theoretical average value of vertical deformation at the 3 / 4 mid-span position; The elastic modulus of the material in the finite element model E 0 Revised to E = E 0 ×ΔE .

[0013] The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge provided by the present invention includes a method for applying water-filled bags to the beam body, wherein the total weight of the water-filled bags is equal to the total design weight of the track slab.

[0014] The method for constructing ballastless track for a prestressed concrete cable-stayed bridge for high-speed railway according to the present invention includes the following steps for obtaining the temperature deformation coefficient: continuously monitoring the elevation of the edge line of the beam base plate at a set time, synchronously recording the atmospheric temperature at each measurement, analyzing the elevation variation law with temperature based on the monitoring results, and determining the period of stable temperature deformation; performing linear regression analysis on the monitoring data within the stable temperature deformation period, and using the slope obtained from the regression as the elevation change per unit temperature, thereby obtaining the temperature deformation coefficient.

[0015] The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge provided by the present invention includes a method for calculating the thickness of the base plate based on elevation error and temperature deformation coefficient, comprising: calculating the thickness of the base plate according to the following formula.

[0016] in: —Thickness of the base plate; —Theoretical casting thickness of the base plate; —Elevation difference error; —Coefficient of thermal deformation; —Design reference temperature; —Ambient temperature at the construction site during the base plate installation.

[0017] The method for constructing ballastless track for high-speed railway prestressed concrete cable-stayed bridges according to the present invention includes a method for calculating the track slab pouring thickness based on alignment error, comprising: calculating the track slab pouring thickness according to the following formula.

[0018] in: —Thickness of the track bed slab; —Theoretical casting thickness of the track slab; —Base plate linearity error; —Coefficient of thermal deformation; —Design reference temperature; —Atmospheric temperature at the construction site of the track bed slab.

[0019] According to the construction method of ballastless track for high-speed railway prestressed cable-stayed bridges provided by the present invention, the method of synchronously unloading water bag ballast includes: during the pouring of track slab concrete, water in the water bag is discharged synchronously and in batches according to the pouring progress and weight, so that the weight unloaded in each batch is equal to the weight of the track slab concrete poured in that batch.

[0020] According to the construction method of ballastless track for high-speed railway prestressed concrete cable-stayed bridge provided by the present invention, the method for measuring the alignment error includes: after the base plate is constructed, a measurement section is set at a predetermined distance along the line direction, and the elevation deviation of the base plate edge line is measured on each section. The alignment error is the difference between the theoretical value of the base plate edge line elevation and the measured value.

[0021] According to the construction method of ballastless track for high-speed railway prestressed concrete cable-stayed bridge provided by the present invention, the period of stable temperature deformation refers to: in the monitoring of a set time, within a time interval of more than a set time, the absolute value of the elevation change between any two adjacent measurements within the interval is less than a preset threshold, and the change in atmospheric temperature within the interval does not exceed a preset temperature.

[0022] According to the construction method of ballastless track for high-speed railway prestressed concrete cable-stayed bridge provided by the present invention, the design reference temperature is a fixed value within a set temperature range, and the construction of the base plate and the track slab are both carried out in an environment without direct sunlight where the temperature gradient does not exceed the set gradient and the wind force does not exceed the set level.

[0023] The advantages of this invention are as follows: 1. This invention proposes a construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridges. Traditional construction of ballastless track for cable-stayed bridges often involves laying the track directly according to the design thickness after the main bridge is closed, ignoring the actual beam stiffness deviation and subsequent creep and load-induced deflection accumulation. This scheme first conducts full-bridge alignment monitoring after closure to capture the true structural state; then, a secondary dead load (the self-weight of the ballastless track) is applied in advance through counterweight simulation, forcing the beam to complete most of the elastic deflection before pouring concrete. Thus, when pouring the base slab and track bed slab, the beam surface is already in a load state close to that of the completed bridge operation. This method can control the track surface elevation accuracy to the millimeter level after the bridge is completed, completely eliminating the fatal impact of the large-span flexible structure of cable-stayed bridges on the smoothness of the ballastless track.

[0024] By simulating the load on ballastless track using water-filled ballast bags instead of directly pouring concrete, the risk is significantly reduced. If errors are found during direct pouring, the cost of demolition and reconstruction would be enormous and would damage the bridge. Water-filled ballast bags serve as a non-destructive pre-test; if structural anomalies are detected at this stage, the water can be drained and the unloading adjusted in time, eliminating the risk of structural damage.

[0025] This method decouples alignment adjustment from the main structural construction. By measuring, calculating, and pouring the compensation layer in one go under ballast, it avoids the tedious process of repeated measurement, grinding, and patching required in traditional construction when the alignment does not meet standards. In particular, the subsequent simultaneous unloading of the water bag achieves a seamless connection between ballast and structural weight increase without taking up additional construction time.

[0026] 2. This invention utilizes a beam transport vehicle as calibration weights, eliminating the need for additional ballast equipment. Measurements are limited to three key sections at the mid-span (1 / 4, 1 / 2, and 3 / 4) where deflection is greatest or controllable, comprehensively reflecting the beam's bending stiffness distribution. The calculated stiffness ratio is a weighted calibration of the overall bridge's macroscopic stiffness. The corrected material elastic modulus directly eliminates the systematic error between the actual shrinkage and creep characteristics of concrete and theoretical calculations. Due to the accurate stiffness correction, the subsequently calculated final tension cable force will better match the actual stress requirements. If the stiffness estimate is too high, the calculated cable force will be too low, leading to excessive downward deflection during ballast; if the stiffness estimate is too low, the cable force will be too high, increasing the risk of beam camber. This step is a prerequisite for ensuring the accuracy of all subsequent alignment control calculations.

[0027] 3. The accurate equivalent load simulation of this invention is crucial for the success of load pre-testing. Inequality (such as underloading) will lead to a smaller error measured under the compressive load condition, resulting in a greater-than-expected residual creep deflection after pouring; overloading will force the base plate to be thickened, increasing the secondary dead load and triggering a vicious cycle. This scheme ensures a 1:1 realistic simulation, making the deflection displacement of the beam before concrete pouring 100% consistent with that after the bridge is completed. Using water bags instead of steel ingots or precast concrete blocks has the advantage of continuous and controllable loading and unloading processes with minimal impact. If steel ingots slip during hoisting, it will cause a catastrophic impact on the bridge deck; while the water bag filling process is uniform and slow, with extremely high safety redundancy.

[0028] 4. This invention obtains the temperature deformation coefficient through continuous monitoring of elevation and temperature regression analysis. Long-span cable-stayed bridges are extremely sensitive to temperature; diurnal variations in elevation caused by sunlight can lead to centimeter-level fluctuations in the mid-span elevation. Without eliminating the influence of temperature, construction personnel cannot determine whether the currently measured elevation difference is a permanent deflection caused by the load or a temporary deformation caused by sunlight. Regression analysis identifies the stable periods of temperature deformation, and the temperature deformation coefficient is calculated in conjunction with the slope. This effectively decouples thermodynamic deformation from mechanical deformation, providing accurate physical parameters for subsequent temperature correction and avoiding misjudgments of artificially high or low elevations caused by pouring concrete during periods of high or low temperatures.

[0029] 5. This invention proposes a formula for calculating the thickness of the base plate. Traditional processes strictly require construction during a very short window of time at night with no sunlight and at the design reference temperature. With this revised formula, as long as the temperature coefficient is accurately calibrated, the construction window can be broadened, allowing construction during the day or on cloudy days. The temperature effect is directly offset by thickness calculation, significantly reducing the waiting time under special working conditions.

[0030] 6. This invention also relates to the calculation of the thickness of the ballastless track slab. The ballastless track of a cable-stayed bridge comprises two layers: a base slab and a track slab. After the base slab is poured, the bridge stiffness changes and is affected by the heat of concrete hydration, resulting in slight secondary changes in the alignment. A secondary correction is introduced. Leveling is performed based on the errors in the base slab. This is equivalent to using a thicker track slab layer as a final fine-tuning layer, completely eliminating unforeseen millimeter-level errors remaining from the base slab construction. This ensures that the final rail bearing platform elevation below the rail fasteners has extremely high smoothness, meeting the safe operation requirements of high-speed rail at speeds exceeding 350 km / h.

[0031] 7. This invention also specifies the simultaneous, batch-wise, and equal-weight unloading of water bags during the pouring of the track bed slab. This is a key measure to prevent the bridge from instantly rebounding or becoming overloaded due to sudden changes in construction load. The water bag weight simulates the secondary dead load. If water is released all at once after pouring, it is equivalent to the bridge instantly unloading hundreds of tons of weight, causing the beam to violently arch and rebound, leading to cracking and voids in the freshly poured but uncured concrete. The same weight of water is released as the weight of concrete poured. The total vertical load borne by the beam remains constant throughout the entire construction process. This completely eliminates additional secondary internal forces during construction, ensures the quality of concrete forming, and causes zero damage to the main beam structure.

[0032] 8. This invention defines a method for measuring and calculating the alignment error of the track bed. Cross-sectional measurements are conducted at predetermined intervals along the track direction, obtaining continuous spatial curve deviations rather than single-point extreme values. This provides accurate and smooth data input for alignment errors. It avoids abrupt changes in track bed thickness caused by local extreme values, ensuring that the vertical smoothness indicators during train operation meet high-speed railway acceptance standards.

[0033] 9. This invention defines the criteria for determining the stable period of temperature deformation. This step automatically selects the data segment with the smallest temperature gradient at the quasi-steady-state moment from continuous monitoring data for regression analysis by setting dual constraints of the absolute value of elevation change, a threshold, and temperature change / preset temperature. This eliminates interference noise; if drastic fluctuations in temperature during morning warming or evening cooling are used to calculate the temperature deformation coefficient, the coefficient will be distorted. This method ensures the scientific rigor of the temperature deformation coefficient in subsequent formulas and is a data cleaning guarantee for maintaining high accuracy in linear control.

[0034] 10. This invention also specifies the value of the reference temperature and the requirements for the construction environment. Setting the reference temperature as a fixed value ensures that the thickness calculations for different segments of the entire bridge are based on the same standard, avoiding uneven longitudinal slopes caused by inconsistent references. Construction is stipulated to be carried out under conditions where the temperature gradient does not exceed the set gradient and there is no direct sunlight. Even with the temperature correction formula, a uniform temperature field remains a prerequisite for the formula to hold true. This constraint further minimizes the influence of uncontrollable external variables, providing a final guarantee for high accuracy in alignment control.

[0035] This invention systematically solves the world-class problem of laying ballastless track for long-span cable-stayed bridges through a closed-loop technical system of stiffness identification and correction, load pre-simulation, temperature change decoupling, dynamic thickness compensation, and dead load replacement. From theoretical model calibration to fine-tuning of specific construction parameters, it comprehensively ensures the extreme smoothness required for high-speed rail operation. Attached Figure Description

[0036] Figure 1 Flowchart of the construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge of the present invention; Figure 2 The flowchart for determining the temperature deformation coefficient in this invention; Figure 3 : Flowchart of the track bed slab casting process of the present invention; Figure 4 : Schematic diagram of the water bag arrangement of the present invention. Detailed Implementation

[0037] Embodiments of the present invention are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0038] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] This invention addresses the challenges of prestressed concrete cable-stayed bridges, including their high flexibility and sensitivity to temperature and load. It proposes a high-precision ballastless track construction method. The method utilizes a beam transport vehicle to apply load at key mid-span locations, measuring deformation to calculate the actual stiffness ratio, and correcting the finite element model to improve the accuracy of final tension and deformation prediction. Through equivalent water bag counterweight and synchronous unloading, the weight of the water bag inside the box girder is precisely equal to the total weight of the track's secondary dead load, allowing for pre-deformation of the main beam. During track slab pouring, drainage and unloading are performed synchronously and in stages according to the concrete pouring volume, ensuring constant load and zero track alignment disturbance throughout construction. By continuously monitoring beam surface elevation and atmospheric temperature for 24 hours, regression analysis is used to derive the temperature deformation coefficient and identify stable construction windows. Temperature correction is used to dynamically compensate for the actual pouring thickness of the base plate and track slab, effectively offsetting temperature effects and cumulative errors. The control network is re-measured before and after counterweighting and after the base plate, progressively transferring and correcting alignment errors layer by layer, ultimately eliminating residual deviations through long-rail fine-tuning.

[0042] The construction method of this invention integrates bridge stiffness identification, quantitative extraction of temperature deformation coefficient, constant equivalent load maintenance and layer thickness compensation, which solves the problem of poor track smoothness caused by the traditional method due to ignoring the actual stiffness difference of flexible bridges and the influence of real-time temperature. It provides a systematic and parameterized high-precision control scheme for the construction of ballastless track for special bridge types.

[0043] Specifically, such as Figure 1 As shown, a construction method for ballastless track of a high-speed railway prestressed concrete cable-stayed bridge according to the present invention includes the following steps: Step 1: Construct the three walls of the bridge deck (crash barrier wall, wind barrier foundation wall, and cable trough wall) and cover plates. After the bridge deck ancillary structures are stable, establish the track control network CPIII and set up observation points in accordance with the high-speed railway engineering surveying specifications, and carry out full-bridge linear monitoring to obtain the initial alignment status.

[0044] Step 2: Perform stiffness identification on the bridge deck. Load tests are conducted on the main beam using known loads to identify and determine the actual stiffness of the main beam under the current state, thus eliminating the discrepancy between theoretical calculations and the actual structural condition.

[0045] Step 3: Apply counterweight inside the box girder using water bags to simulate the load of the track slab. This counterweight load simulates the weight of the subsequent concrete pouring for the track slab, aiming to induce deformation in the bridge structure beforehand that is similar to the actual state after the bridge is completed.

[0046] Step 4: Based on the actual stiffness obtained in Step 2, correct the material elastic modulus parameters in the finite element model established during the design phase. Based on the corrected finite element model, which is closer to the actual state, recalculate and determine the final tension and corresponding deformation. Subsequently, tension the stay cables to the recalculated final tension to establish an accurate benchmark for the completed bridge alignment.

[0047] Step 5: After the load-bearing condition stabilizes, re-measure the CPIII control network. Use the re-measured CPIII points to measure the elevation of the predetermined base plate edge position on the beam surface after load-bearing, and calculate the elevation difference error of the base plate edge. This step aims to accurately correlate the theoretical design alignment with the actual beam surface alignment after load-bearing.

[0048] Step 6: Conduct 24-hour continuous monitoring of the elevation points along the edge of the beam base plate, simultaneously recording the atmospheric temperature at each measurement. Based on the monitoring data, analyze the elevation variation pattern with temperature to determine the period when temperature deformation is stable and suitable for construction, and calculate the linear change.

[0049] Step 7: Construct the base plate within the determined stable period. Calculate the base plate pouring thickness based on elevation error and temperature deformation coefficient, and pour the base plate accordingly.

[0050] Step 8: After the base plate construction is completed, due to the change in the self-weight of the structural system, CPIII needs to be remeasured to obtain a new elevation benchmark.

[0051] Step 9: Measure the elevation of the completed base plate edge line using the CPIII point after the remeasurement in Step 8, thereby obtaining the actual alignment error after the base plate construction is completed.

[0052] Step 10: Construct the track bed slab. Calculate the thickness of the track bed slab based on the alignment error, and pour the track bed slab accordingly, while simultaneously unloading the water bag weight during the pouring process.

[0053] Step 11: Construct the waterproof layer between the tracks. At this point, the main structure construction of the ballastless track of the cable-stayed bridge is complete.

[0054] The core principle of the construction method of this invention lies in establishing a dynamic control system of identification, prediction, compensation, and synchronization. First, the true stiffness of the structure is identified through loading tests, correcting the calculation model and ensuring the accuracy of subsequent predictions. Next, water-filled ballast is used to apply the later-stage dead load in advance, causing most of the main beam to deform beforehand. Then, temperature monitoring quantifies the temperature deformation pattern, and temperature is incorporated as a key variable into the thickness calculation formula, achieving precise compensation for the influence of temperature. Finally, the pouring of the track slab and the unloading of the water-filled ballast are carried out simultaneously, ensuring that the total load acting on the bridge remains essentially constant throughout the construction process, avoiding new alignment disturbances caused by sudden load changes.

[0055] The construction method of this invention avoids deviations between theoretical parameters and actual conditions by identifying actual stiffness and correcting with a finite element model, making cable force adjustment and alignment prediction more accurate. By incorporating temperature changes into thickness calculations, it solves the problem of the adverse effects of diurnal and seasonal temperature differences on the thickness and smoothness of the track slab in cable-stayed bridges. The use of water-filled ballast bags for ballast and simultaneous unloading during track slab pouring ensures a constant load on the bridge during the track structure construction phase, preventing secondary deformation and guaranteeing the final smoothness of the track. This construction method tightly couples measurement, calculation, monitoring, and construction, forming a scientific track construction method specifically for flexible bridges.

[0056] In some embodiments of the present invention, the above-described stiffness identification method is specifically defined, providing an efficient and accurate method for testing using existing beam transport equipment.

[0057] In the stiffness identification process of step 2 in Example 1, the following operations are specifically performed: Loading Test: The girder transport vehicle, which was already operating on the bridge during construction, was used as the load source. The girder transport vehicle was scheduled to travel back and forth on the bridge at least 40 times to eliminate any potential initial nonlinearities and gap effects in the structure. During the final few travels, the girder transport vehicle was precisely controlled to stop and stabilize at three key cross-sections: 1 / 4 of the mid-span, 1 / 2 of the mid-span, and 3 / 4 of the mid-span. After each stop, the vertical deformation of the main girder at each location was measured and recorded using a high-precision level or hydrostatic leveling system. The average value of the multiple measurements was taken to obtain the load. H 1 , H 2 and H 3 .

[0058] Using the uncorrected initial finite element model, the same load conditions as the beam transport vehicle were applied, and the theoretical vertical deformation values ​​of the main beam at the same three locations were calculated. H 11 , H21 and H 31 .

[0059] The stiffness ratio, which reflects the difference between actual and theoretical stiffness, is calculated using the following formula. ΔE : +

[0060] in: ΔE —Stiffness ratio; H 1 —The average value of vertical deformation measurements at the 1 / 4 mid-span position; H 11 —Theoretical average value of vertical deformation at the 1 / 4 mid-span position; H 2 —The average value of vertical deformation measurements at the mid-span position (1 / 2 span); H 21 —Theoretical average value of vertical deformation at the mid-span position (1 / 2 span); H 3 —The average value of vertical deformation measurements at the 3 / 4 mid-span location; H 31 —Theoretical average value of vertical deformation at the 3 / 4 mid-span position; The elastic modulus of the material in the finite element model E 0 Revised to E = E 0 ×ΔE .like ΔE If the value is greater than 1, it means the actual stiffness is greater than the theoretical value; if ΔE If the value is less than 1, it means that the actual stiffness is less than the theoretical value.

[0061] This embodiment is based on the principles of mechanics of materials and structural mechanics. For linear elastic structures, under a constant load, the deformation of the structure is inversely proportional to the elastic modulus of the material. Therefore, the ratio of measured deformation to theoretical deformation can reflect the ratio of actual elastic modulus to theoretical elastic modulus. The 1 / 4, 1 / 2, and 3 / 4 span positions were chosen because the deformation at these points is sensitive to the overall stiffness of the beam and can reflect different responses under symmetrical or asymmetrical loads. Taking the average value can reduce the random error of a single measuring point. A beam transport vehicle was used as the load, utilizing existing on-site equipment, which is economical and efficient.

[0062] This embodiment effectively eliminates test noise and accurately identifies the overall stiffness of the structure by averaging multiple loading tests and measurements at key sections. It eliminates the need for additional configuration or rental of specialized loading equipment, directly utilizing the construction beam transport vehicle, thus saving significant costs and time. The total weight of the beam transport vehicle is comparable to the live load borne by the bridge during the beam transport and erection stages, and the deformation under its action fully reflects the mechanical behavior of the structure under actual operational loads. The model corrected accordingly has greater engineering guidance value.

[0063] In other embodiments of the present invention, this embodiment refines the above-described method for establishing the CPIII network and setting up observation points.

[0064] In step 1 of Example 1, when establishing the CPIII network and setting up observation points, the following requirements must be strictly followed: Along the direction of the bridge route, pairs of CPIII control point markers are set up at fixed intervals of 60m to 80m.

[0065] The plane coordinates of the CPIII control network are measured using the free-station corner intersection method. This method does not rely on station centering; it forms a corner intersection network by observing multiple CPIII points at multiple free-station sites, and then calculates the coordinates through rigorous adjustment.

[0066] The elevation measurement of CPIII control points must be based on the national second-order leveling benchmarks laid out along the line, and the measurement must be conducted by a precision digital level instrument according to the technical requirements of second-order leveling.

[0067] The CPIII control network serves as the benchmark for surveying during the construction of ballastless track for high-speed railways. A spacing of 60m-80m is the optimal range verified through engineering practice, ensuring both the accuracy of track slab fine-tuning and controlling the workload of network construction. The free-station corner intersection method offers advantages such as flexible station placement and high relative accuracy between adjacent points (up to ±1mm), making it ideal for precision control network surveying in linear projects. Elevation is determined and closed at second-order leveling benchmarks, ensuring the uniformity, accuracy, and traceability of the entire project's elevation benchmark. This is fundamental to ensuring the long-wave irregularity of the track.

[0068] This embodiment strictly follows the CPIII network established by this method, providing a high-precision spatial reference at the sub-millimeter level for all subsequent layout and measurement work. Both horizontal and vertical measurements employ the highest-level national or industry standards, ensuring the authority and reliability of the measurement results and avoiding track irregularities caused by reference errors. The free-station method is particularly suitable for bridges spanning rivers and canyons, eliminating the need for fixed stations on the bridge, reducing interference with construction, and improving work efficiency and safety.

[0069] In a further embodiment of the present invention, the weight requirements for the water bag's compressive strength are clearly defined.

[0070] A water bag system is installed inside the box girder, such as Figure 4 As shown, water bag (such as Figure 4 A) The load is distributed in transverse compartments to ensure uniform load distribution. Water is injected into the water bags using a flow meter until the total mass of water injected is exactly equal to the design total weight of the track slab concrete given in the design drawings. The loading process is carried out in stages, and the beam deformation is monitored in real time. After confirming that there are no abnormalities, the load is maintained until subsequent construction is carried out.

[0071] The water-bag ballast method in this embodiment aims to achieve an equivalent substitution of the load effect. As a track component directly bearing train loads, the concrete self-weight of the track slab is a significant secondary dead load. In the bridge's mechanical system, the timing of the secondary dead load application results in different internal forces and deformations. This method applies an equal weight of water load before track structure construction, ensuring that the main beam has already completed all instantaneous elastic deformation and most of the initial creep deformation caused by the track slab's self-weight before the track slab is poured. The subsequently poured track slab merely replaces the water-bag load without causing additional structural deflection changes.

[0072] This embodiment achieves construction operations with zero additional deformation, ensuring that the bridge's alignment is identical to the designed completed bridge state after the water bags are removed and the track is laid. This avoids uncontrollable elevation settlement caused by subsequent loads during conventional construction. Pre-loading was used to verify the stress safety and stability of the main beam under the final dead load, serving as a pre-stressing test for the completed bridge. Water was used as the ballast medium, which is widely available, extremely low in cost, and allows for flexible control of loading and unloading through water injection and drainage. Furthermore, the water resources can be reused after construction, resulting in no environmental pollution.

[0073] In a preferred embodiment of the present invention, such as Figure 2 As shown in the figure, this embodiment specifies the method for analyzing the change of elevation with temperature in step 6.

[0074] In step 6, when analyzing the elevation data (dependent variable) measured within 24 hours and the corresponding synchronously recorded atmospheric temperature data (independent variable), a linear regression analysis method is used. Specifically: Atmospheric temperature T The x-axis represents the elevation of the measuring point. H Using the vertical axis as the ordinate, multiple sets of data within 24 hours ( T i , H i The data pairs are plotted in a coordinate system.

[0075] Using the principle of least squares, a best-fitting straight line is calculated. H = k - T + b .

[0076] The slope of the line kThis represents the average change in beam elevation at the measuring point when the temperature changes by 1℃. The slope... k Temperature deformation coefficient used in the calculations of steps 7 and 10 Δh 2 .

[0077] For a concrete cable-stayed bridge in normal service, within a certain temperature range, its temperature response can be approximated as linear elastic behavior. That is, there is an approximate linear relationship between the change in beam elevation and the change in temperature. Linear regression analysis is a standard and mature statistical method that can find the most likely linear relationship between variables from discrete monitoring data containing small measurement errors, thereby obtaining a reliable and statistically significant average rate of change (i.e., slope).

[0078] This embodiment, based on statistical methods, avoids the subjectivity and randomness of estimations based on experience or a few data points. It effectively filters out individual abnormal fluctuations caused by factors such as wind vibration, uneven sunlight, and brief cloud cover during the measurement process, obtaining a stable value that reflects the overall temperature deformation trend of the structure. This provides crucial and accurate input parameters for subsequent thickness compensation calculations. Δh 2 This is a prerequisite for ensuring the accuracy of formula calculations.

[0079] In some embodiments of the present invention, this embodiment further defines the above-described method for calculating the casting thickness of the base plate based on elevation error and temperature deformation coefficient.

[0080] Before constructing the base plate, calculate the actual pouring thickness of the base plate section by section using the following formula:

[0081] in: —Thickness of the base plate; —Theoretical casting thickness of the base plate; —Elevation difference error; —Coefficient of thermal deformation; —Design reference temperature; —Ambient temperature at the construction site during the base plate installation.

[0082] The core idea of ​​this formula is to actively compensate for all sources of deviation affecting the elevation of the track top surface by adjusting the thickness of the track structure layer itself. In the formula... This compensates for static elevation errors caused by non-temperature factors such as deviations in the actual stiffness of the main beam and differences in shrinkage and creep. This item involves dynamic temperature compensation. For example, when the construction temperature... T 1 Below the reference temperature T 0 At that time, the beam was in a relatively "descended" state, and the calculated compensation amount The result is positive, therefore the pouring thickness needs to be increased. H α This is to raise the top surface of the track so that when the temperature returns to the reference temperature, the top surface of the track will be exactly at the design elevation.

[0083] The calculation method in this embodiment achieves integrated correction of static and dynamic deviations. It integrates structural stiffness error compensation and on-site temperature effect compensation into a simple linear formula, making it easy for operators to understand and implement. It effectively solves the technical challenge of uniformly controlling the track alignment of long-span cable-stayed bridges due to long construction periods and large temperature differences across different seasons. It provides precise and quantifiable calculation basis for adjusting the base plate thickness, avoiding the uncertainty and quality risks associated with relying on empirical estimations.

[0084] In some embodiments of the present invention, this embodiment further defines the method for measuring linear error described above.

[0085] After the base plate concrete reaches its design strength, measurement sections are laid out along the centerline of the track at predetermined intervals (e.g., every 5 or 10 meters). On each measurement section, a precision level or track geometry measuring instrument is used to measure the elevation at the edges of the base plate on both sides. The measured actual elevation values ​​are compared with the theoretical elevation values ​​of the base plate edges on the design drawings, and the difference is calculated. The aforementioned alignment error... Δh 3 The value is equal to the theoretical elevation value minus the measured elevation value. This data will serve as a key input parameter for calculating the thickness of the track slab.

[0086] As the supporting layer in the ballastless track structure, the top surface alignment of the base plate directly determines the reference for the upper track bed slab. By setting measurement sections at intervals along the track direction and measuring the edge elevation, the longitudinal alignment smoothness of the base plate can be accurately captured. The error is defined as the theoretical value minus the measured value, meaning that when the measured elevation is lower than the theoretical elevation (i.e., the beam surface is locally lower), the error value... Δh 3 If the error is positive, the thickness of the track slab needs to be increased in subsequent construction to compensate for it, and vice versa. This definition method makes the error sign and the compensation direction intuitive and consistent.

[0087] This embodiment employs high-precision instruments for grid-based measurement, comprehensively understanding the spatial morphology data of the base plate. It provides quantified linear deviation values, enabling targeted adjustments to the track bed thickness, and serves as a necessary data foundation for achieving the ultimate goal of high smoothness.

[0088] In a further embodiment of the present invention, this embodiment further defines the above-described method for calculating the casting thickness of the track bed slab based on linear error.

[0089] After the base plate is constructed and reaches its strength, the actual pouring thickness of the track bed slab is calculated section by section according to the following formula:

[0090] in: —Thickness of the track bed slab; —Theoretical casting thickness of the track slab; —Base plate linearity error; —Coefficient of thermal deformation; —Design reference temperature; —Atmospheric temperature at the construction site of the track bed slab.

[0091] The calculation of the track bed slab thickness is a precise correction and closed-loop control of the errors from the previous stage (base slab construction). Although thickness compensation was performed during the base slab pouring, certain errors in construction alignment are still unavoidable in actual construction. Δ h 3 As the superstructure, the track slab itself has the capability for final adjustment in thickness. The track slab thickness calculated using this formula essentially utilizes this layer to eliminate all residual errors accumulated in the early stages and the temperature effects at the current construction moment. This embodies the core control strategy of layered construction of the track structure, progressing layer by layer, ultimately approaching the ideal design alignment.

[0092] This embodiment achieves precise control of the final alignment by calculating the thickness of the track slab. The residual error after the base slab construction is used as input for the track slab thickness calculation, serving as a secondary correction and maximizing the smoothness of the final track structure's top surface (i.e., the rail support surface). This layer-by-layer adjustment mechanism tolerates certain errors during the base slab construction stage, remedying them through the track slab, thus reducing the difficulty of construction control and the risk of rework throughout the process. Consistent with the base slab calculation principle, the on-site temperature is further corrected to a unified reference temperature. T 0 This ensures that the final alignment of the track remains physically consistent after construction at different times.

[0093] In other embodiments of the present invention, this embodiment specifically defines the criteria for determining the period of stable temperature deformation in step 6.

[0094] In the 24-hour monitoring data analysis in step 6, the criteria for identifying periods of stable temperature deformation are as follows: In a 24-hour monitoring data sequence, if there exists a continuous time interval of no less than 3 hours, and the following two conditions are met within this interval: Deformation stability conditions: The change in elevation between any two adjacent measurements is less than a preset threshold (for example, for a 250km / h line, the threshold can be set to 0.5mm; for a 350km / h line, the threshold can be set to 0.3mm), and the time interval between two adjacent measurements is no more than 2 hours.

[0095] Temperature stability condition: During this time interval, the change in atmospheric temperature does not exceed 2℃.

[0096] The time interval that meets the above conditions is determined to be the period of stable temperature deformation. The concrete pouring construction in steps 7 and 10 should preferably be carried out within these periods.

[0097] The alignment of a cable-stayed bridge is significantly affected by changes in sunlight and temperature throughout the day. From sunrise to morning, and from afternoon to sunset, the bridge structure undergoes rapid heating and cooling, resulting in large temperature differences between different components (such as the main girder, stay cables, and towers), leading to rapid and uneven deformation rates. During these periods, construction can easily introduce uncontrollable alignment errors. At night (especially in the early morning) or on cloudy days, the structural temperature tends to be uniform, and the deformation rate is extremely low, placing the bridge in a quasi-static stable state. This embodiment scientifically defines this stable construction window through continuous monitoring and the setting of quantitative thresholds.

[0098] This embodiment ensures that quantitative criteria for selecting the timing of construction are clearly defined, rather than relying on experience or intuition, guaranteeing that the beam is in its most stable state during track slab construction. Concrete poured during a stable period is not affected by drastic external temperature deformation during its solidification and hardening process, effectively reducing the risk of concrete cracking. The beam alignment during construction is predictable and repeatable, enabling thickness compensation calculations based on monitoring data (…). Δh 2 The items are more targeted and accurate.

[0099] In a further embodiment of the present invention, this embodiment specifies the design reference temperature in steps 7 and 10. T 0 In addition, optimal requirements were put forward for construction environment conditions.

[0100] During steps 7 and 10: Design reference temperature T 0 The value is uniformly set to a fixed value between 20℃ and 25℃. For example, 22℃ is taken as the design reference temperature for this bridge, and this value is always used in all thickness compensation calculations.

[0101] Construction environment conditions selection: When pouring concrete for the base plate and track slab, the following environmental conditions must be met: The temperature difference (i.e., temperature gradient) between the top and bottom surfaces of the beam shall not exceed 2℃ / m.

[0102] The wind force on the bridge surface is no greater than level 3.

[0103] Avoid carrying out the work when the work surface is directly exposed to sunlight. It is advisable to carry out the work at night, on cloudy days, or after using sunshades or other shielding measures.

[0104] 20℃~25℃ is the suitable temperature range for ballastless track locking in most parts of my country. The design reference temperature... T 0 Setting it to a fixed value within this range means that the goal of the method of this invention is to make the alignment of the track structure at this temperature perfectly match the design alignment. The compensation term in the thickness calculation formula is to correct the pouring thickness at any construction temperature to the thickness required to achieve the target alignment at this reference temperature.

[0105] Temperature gradients (temperature difference between the top and bottom surfaces of the beam) will cause additional bending deformation of the main beam. This nonlinear deformation is difficult to address with a single temperature coefficient. Δh 2 To ensure precise compensation. Limiting the temperature gradient simplifies the structural deformation pattern to primarily axial expansion and contraction and vertical deflection caused by overall temperature rise and fall. Limiting wind and sunlight ensures the stability and accuracy of the measurement and construction process.

[0106] This embodiment clearly defines the design reference temperature, giving the temperature compensation calculation a clear physical meaning and a unified objective. By strictly controlling environmental conditions, secondary but complex interfering factors such as temperature gradients, wind vibration, and uneven solar radiation deformation are eliminated, ensuring the linear temperature compensation model upon which this method relies (…). Δh 2 (Item) is more precise and effective. Pouring in a mild and stable environment helps ensure the quality of concrete pouring and curing, and reduces early cracking.

[0107] In a preferred embodiment of the present invention, such as Figure 3 As shown in the figure, this embodiment elaborates on the specific operation method of equivalent synchronous unloading in step 10.

[0108] When performing the concrete pouring of the track bed slab in step 10, the coordinated operation with the unloading of the water bag ballast should be carried out precisely according to the following procedure: Zoning planning: The track slab to be poured is divided into several pouring sections along the track direction. At the same time, the water bags inside the box girder are also divided into several groups accordingly.

[0109] Establish weight relationships: accurately calculate the design weight of the track bed concrete in each pouring section.

[0110] Synchronous operation: When the concrete pouring of a certain pouring section begins, the drainage valves of the corresponding water bags are opened simultaneously according to the real-time pouring volume of concrete (or the pump truck flow meter reading) to carry out graded and continuous drainage.

[0111] Weight matching: By controlling the opening of the drainage valve and the drainage time, ensure that at any given time, the weight of the poured concrete is basically equal to the weight of the drained water (the error is controlled within a certain range, such as ±5%).

[0112] Process monitoring: Deformation monitoring points are set up on the bridge deck to monitor changes in the beam's alignment in real time. If abnormal upward or downward cambering of the beam is detected due to mismatch between loading and unloading, the concrete pouring rate or drainage rate is adjusted promptly.

[0113] The core of this method is to maintain a constant load on the bridge during construction. If the entire track slab is poured before the water bags are unloaded, or vice versa, the bridge will undergo a significant loading or unloading process, resulting in additional, irreversible deformation and rendering the precise alignment established through ballast and measurement useless. Synchronous unloading allows the weight of the poured concrete to seamlessly replace the weight of the water bags, ensuring that the total load and its distribution on the bridge remain almost constant throughout the track slab construction, and the beam alignment remains static.

[0114] This embodiment minimizes secondary load variations caused by construction procedures, ensuring that the calibrated alignment after the base plate is completed is not disrupted during track bed construction. It avoids significant additional stress at critical locations such as the bridge tower roots and main beam spans due to sudden load changes, thus contributing to structural safety.

[0115] In other embodiments of the present invention, this embodiment provides supplementary details regarding some aspects of steps 7 and 9.

[0116] Base plate flatness inspection: After the base plate concrete is poured and reaches a certain strength, the flatness of the top surface is inspected. Use a 3m or 4m straightedge to check along the longitudinal and transverse directions of the track. The gap must not exceed the requirements of the corresponding technical specifications (e.g., 5mm / 3m). Any protrusions or depressions exceeding the allowable range must be ground or filled to ensure the flatness of the base for the track bed slab.

[0117] Base plate linearity error Δh 3 Measurement: Using the CPIII point remeasured in step 8, the elevation of the top edge of the completed base plate is measured. During the measurement, a measurement section is set every 5m to 10m along the line direction. The measured elevation of each section is compared with the corrected theoretical elevation; the difference is the base plate alignment error of that section. Δh 3 .Should Δh 3 This is a value that varies with mileage; in the thickness calculation of step 10, the value of the corresponding cross-section should be used. Δh 3 The value is calculated.

[0118] The flatness of the top surface of the base plate is a crucial factor affecting the uniformity of the track bed slab thickness and its support conditions. Failure to address this can lead to localized stress concentration and even cracking of the track bed slab. Measurements are taken at intervals of 5m to 10m. Δh 3 This is to accurately capture the long-wave and short-wave irregularities left after the base plate construction. Because Δh 3 It is an important basis for the later compensation of track bed thickness. If the measurement points are too sparse, short-wave error will be missed, and if they are too dense, unnecessary workload will be increased.

[0119] This embodiment refines the control precision from layers to points and cross-sections, strictly controlling every aspect that might affect the final accuracy. Cross-sectional measurement data with reasonable spacing can be used to draw a continuous curve reflecting the actual shape of the base plate, providing high-resolution input data for subsequent track slab thickness calculations, making compensation more accurate. Pre-processing the base plate flatness issue prevents defects from being passed on to the next process, improving the construction quality of the track slab.

[0120] In a further embodiment of the invention, a subsequent fine-tuning step is added.

[0121] After step 11 is completed, i.e., the waterproof layer between tracks is finished and the main structure of the ballastless track is completed, an additional step 12 is added: fine-tuning of the long rails of the entire bridge. Specifically: The long steel rails are laid and locked onto the sleepers.

[0122] Using a track geometry measuring instrument based on the CPIII control network, absolute and relative measurements are performed on the laid rails.

[0123] Based on the measurement data, the geometric parameters of the rail, such as height, alignment, level, gauge, and torsion, are finely adjusted by replacing the height adjustment pads of different thicknesses under the rail.

[0124] The goal of fine-tuning is to ensure that all track geometry parameters meet the high standards required for static acceptance of high-speed railways, thereby eliminating any minor, residual alignment errors that may remain from the aforementioned procedures.

[0125] Despite achieving high-precision alignment control during the construction of the base plate and track slab, the complexity of construction, materials, and environment means that residual errors at the millimeter level may still exist on the final track surface. Long rail fine-tuning is the final and most delicate polishing process in high-speed railway track construction. Utilizing the inherent fine-tuning capabilities of the rail fastening system to ultimately correct these residual errors is the ultimate technology for achieving millimeter-level or even sub-millimeter-level smoothness.

[0126] This embodiment, as the final closed-loop link in the entire construction system, ensures that the track delivered for operation meets the highest smoothness standards required by the design, guaranteeing driving safety and passenger comfort. It effectively mitigates the unavoidable systematic and random errors accumulated from previous steps. By combining the high-precision foundation construction method of this invention with mature long-rail fine-tuning technology, a complete, reliable, high-quality track construction solution is formed, from foundation to surface.

[0127] The present invention discloses a construction method for ballastless track of a high-speed railway prestressed concrete cable-stayed bridge, specifically comprising: Step 1: Preliminary preparation and initial state calibration Complete the construction of the bridge deck's "three walls" and cover plates according to the design requirements.

[0128] The CPIII control network was set up at intervals of 60m to 80m. The plane was measured using the free station corner intersection method, and the elevation was set off from and closed at the second-order leveling benchmark to complete the initial network construction.

[0129] Initial alignment monitoring of the entire bridge was conducted, and the elevations of each control point were recorded as a benchmark for subsequent analysis.

[0130] Step 2: Structural stiffness identification and finite element model correction Using a girder transport vehicle as a load, the girder was driven 40 times on the bridge, and then placed at the mid-span positions of 1 / 4, 1 / 2, and 3 / 4 respectively. The vertical deformation of the main girder was measured, and the average value was obtained. H 1 , H 2 , H 3 .

[0131] The theoretical deformation value under the same load was calculated using the initial finite element model. H 11 , H 21 , H 31 .

[0132] Calculate stiffness ratio + .

[0133] The elastic modulus of the material in the finite element model E 0 Revised to E = E 0 ×ΔE Complete the model correction.

[0134] Step 3: Final tension adjustment and equivalent counterweight Water bags are placed inside the box girder, and the total water volume is precisely equal to the design weight of the track slab, thus achieving equivalent counterweight.

[0135] Based on the revised finite element model, the final tension and target alignment were recalculated and determined, and the cable-stayed cables were tensioned accordingly.

[0136] Step 4: Measurement and analysis of temperature deformation patterns after loading After the pressure stabilizes, the CPIII control network is retested.

[0137] Using the remeasured CPIII point, measure the elevation of the predetermined base plate edge of the beam surface. h 1 Calculate the elevation difference error Δh 1 =h- h 1 .

[0138] The elevation points on the beam surface were continuously monitored for 24 hours, with atmospheric temperature recorded simultaneously. Linear regression analysis was performed on the monitoring data to obtain the regression slope, which represents the linear change in temperature for every 1°C change. Δh 2 .

[0139] Based on the monitoring data, stable periods that meet the conditions of "deformation less than a preset threshold and temperature change ≤2℃ for 3 consecutive hours" are identified as candidate windows for subsequent construction.

[0140] Step 5: High-precision construction of the base plate Construction should be carried out during a stable period when the temperature gradient is ≤2℃ / m, the wind force is ≤3, and there is no direct sunlight.

[0141] According to the formula Calculate the actual casting thickness of each section of the base plate. Use 22℃ (a fixed value between 20℃ and 25℃).

[0142] After pouring the base plate concrete, the flatness of the top surface is checked and treated.

[0143] After the base plate reaches the required strength, CPIII is measured for the third time.

[0144] Step 6: Simultaneous construction of track slabs and unloading of water bags Using the CPIII point measured for the third time, the elevation of the top edge of the base plate was measured every 5m to 10m to obtain the linear error Δh3 of the base plate for each section.

[0145] Construction was again scheduled to take place during a stable period that met environmental conditions (temperature gradient ≤ 2℃ / m, wind force ≤ level 3, no sunshine).

[0146] According to the formula Calculate the actual pouring thickness of each section of the track bed slab.

[0147] The concrete for the track bed slab is poured. During the pouring process, the drainage valves of the water bags in the corresponding areas are opened synchronously and in stages according to the progress and weight of the concrete pouring, so as to achieve equivalent synchronous unloading.

[0148] Step 7: Finishing Touches and Fine-tuning After the track bed slabs have reached sufficient strength, the waterproof layer between the tracks will be constructed.

[0149] Long rails were laid, and fine-tuning of the entire bridge's long rails was carried out based on the CPIII control network. Finally, all residual alignment errors were eliminated using the fastening system.

[0150] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for ballastless track of a high-speed railway prestressed concrete cable-stayed bridge, characterized in that, include: After the main bridge was closed, observation points were set up to monitor the alignment of the entire bridge. Water bags were used to weigh down the beam to simulate the load on the ballastless track. Based on the linear monitoring data, the actual stiffness of the main beam is identified and the finite element model is corrected. The final tension is calculated based on the corrected finite element model, and the stay cables are tensioned to the final tension. The height difference error between the actual elevation and the theoretical elevation of the beam surface was measured under the condition of compression, and the temperature deformation coefficient was obtained by continuous temperature monitoring. The thickness of the base plate is calculated based on the elevation error and temperature deformation coefficient, and the base plate is poured accordingly. Measure the linear error after the base plate is constructed; The thickness of the track bed slab is calculated based on the linear error, and the track bed slab is poured accordingly. During the pouring process, the water bag weight is unloaded simultaneously. Construction of the waterproof layer between the tracks was carried out, and the construction of the ballastless track for the cable-stayed bridge was completed.

2. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1, characterized in that, Specific methods for identifying the actual stiffness of the main beam and correcting the finite element model include: The girder transport vehicle was driven to the 1 / 4, 1 / 2, and 3 / 4 mid-span positions respectively. After stopping and stabilizing at each position, the average vertical deformation at each position was measured. The theoretical deformation value of the finite element model under load equivalent to the actual axle load and wheel position distribution of the girder transport vehicle was calculated. The stiffness ratio was calculated according to the following formula: + in: ΔE —Stiffness ratio; H 1 —The average value of vertical deformation measurements at the 1 / 4 mid-span position; H 11 —Theoretical average value of vertical deformation at the 1 / 4 mid-span position; H 2 —The average value of vertical deformation measurements at the mid-span position (1 / 2 span); H 21 —Theoretical average value of vertical deformation at the mid-span position (1 / 2 span); H 3 —The average value of vertical deformation measurements at the 3 / 4 mid-span location; H 31 —Theoretical average value of vertical deformation at the 3 / 4 mid-span position; The elastic modulus of the material in the finite element model E 0 Revised to E = E 0 ×ΔE .

3. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1, characterized in that, The method of applying water bag weights to the beam includes: the total weight of the water bag weights is equal to the total design weight of the track bed slab.

4. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1, characterized in that, The method for obtaining the temperature deformation coefficient includes: continuously monitoring the elevation of the edge line of the beam base plate for a set time, synchronously recording the atmospheric temperature at each measurement, analyzing the change law of elevation with temperature based on the monitoring results, and determining the period of stable temperature deformation; performing linear regression analysis on the monitoring data within the stable temperature deformation period, and using the slope obtained from the regression as the elevation change per unit temperature, thus obtaining the temperature deformation coefficient.

5. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1 or 4, characterized in that, The method for calculating the casting thickness of the base plate based on elevation error and temperature deformation coefficient includes: calculating the casting thickness of the base plate according to the following formula. in: —Thickness of the base plate; —Theoretical casting thickness of the base plate; —Elevation difference error; —Coefficient of thermal deformation; —Design reference temperature; —Ambient temperature at the construction site during the base plate installation.

6. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1 or 4, characterized in that, The method for calculating the track bed slab casting thickness based on linear error includes: calculating the track bed slab casting thickness according to the following formula. in: —Thickness of the track bed slab; —Theoretical casting thickness of the track slab; —Base plate linearity error; —Coefficient of thermal deformation; —Design reference temperature; —Atmospheric temperature at the construction site of the track bed slab.

7. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1, characterized in that, The method for synchronously unloading the water bag weight includes: during the concrete pouring process of the track bed slab, water is discharged from the water bag synchronously and in batches according to the pouring progress and weight, so that the weight unloaded in each batch is equal to the weight of the track bed slab concrete poured in that batch.

8. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 1, characterized in that, The method for measuring alignment error includes: after the base plate is constructed, a measurement section is set at a predetermined distance along the line direction, and the elevation deviation of the base plate edge line is measured on each section. The alignment error is the difference between the theoretical value of the base plate edge line elevation and the measured value.

9. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 4, characterized in that, The period of stable temperature deformation refers to: during monitoring over a set time period, within a time interval of more than a preset duration, the absolute value of the elevation change between any two adjacent measurements within that interval is less than a preset threshold, and the atmospheric temperature change within that interval does not exceed a preset temperature.

10. The construction method for ballastless track of high-speed railway prestressed concrete cable-stayed bridge according to claim 5 or 6, characterized in that, The design reference temperature is a fixed value within the set temperature range, and the construction of the base plate and the track bed plate are both carried out in an environment without direct sunlight where the temperature gradient does not exceed the set gradient and the wind force does not exceed the set level.

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