High-speed railway large-span cable-stayed bridge ballastless track multi-layer grading regulation and control construction method

Abstract

The invention relates to a multi-layer grading regulation and control construction method for a ballastless track of a long-span cable-stayed bridge of a high-speed railway. The method comprises the following steps: S1, initial preparation; s2, collecting basic data; s3, performing initial linear evaluation and adjustment; s4, laying a ballastless track base plate; s5, ballastless track roadbed slab laying, a multi-layer grading regulation and control method is adopted, and before a ballastless track bed is implemented, the precision of a bridge model is verified through a grading simulation dead load test, and the steel beam rigidity and the temperature change rule are analyzed; a water bag is used for loading graded regulation and control counterweights, a finished bridge line shape is simulated, the corresponding counterweights are synchronously unloaded for equivalent replacement when roadbed slab concrete is to be poured, it is ensured that the internal force state of a bridge and the ballastless track line shape are consistent with the ideal finished bridge state after a main bridge is built, and the error of the large-span ballastless track finished bridge line shape is controlled within the 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, and in particular to a multi-layer graded control construction method for ballastless track of a large-span cable-stayed bridge on a high-speed railway. Background Art

[0002] In the construction of high-speed railways, the combination of long-span cable-stayed bridges and ballastless tracks is an important technological innovation. This combination not only improves the smoothness and stability of the line, but also eliminates potential speed limit points on the line, unifies track types, and reduces the operation and maintenance costs of the track line. The ballastless track construction technology for long-span cable-stayed bridges on high-speed railways is not yet mature. If conventional ballastless track construction methods are used, the smoothness and vertical deformation of the ballastless track of long-span bridges are easily exceeded due to multiple factors such as temperature effects, load changes, and concrete shrinkage creep, affecting the safety and stability of train operations. Each increase in span above 300m is a new challenge for construction. How to meet the requirements of safety and comfort while ensuring that the train passes at a speed of 350km / h is a key technical problem facing the project team.

[0003] Aiming at the above-mentioned problems that the construction technology of the double-block ballastless track cable-stayed bridge for high-speed railway with a design speed of 350km / h and a main span of more than 300m is immature and the track is very easy to exceed the limit, the present invention proposes a solution. Summary of the invention

[0004] The purpose of this application is to provide a multi-layer graded control construction method for ballastless track of a large-span cable-stayed bridge on a high-speed railway to solve the technical problems that the existing technology is immature, the track is very easy to exceed the limit, and it is difficult to ensure safety and comfort when the speed is met.

[0005] The multi-layer graded control construction method of the ballastless track of the high-speed railway long-span cable-stayed bridge provided in this application adopts the following technical scheme: The multi-layer hierarchical control construction method of the ballastless track of a high-speed railway long-span cable-stayed bridge is characterized by comprising the following steps: S1. Initial preparation: Analyze the stress of the main beam, determine the layout of CP III monitoring points and the encryption of other monitoring points, complete offline project acceptance and settlement deformation observation and evaluation; S2. Basic data collection: collect basic data under various working conditions before equal load loading, conduct full load simulation, and obtain the theoretical calculation model after stiffness and temperature correction; S3. Initial linear assessment and adjustment: Calculate the theoretical alignment before the base plate is laid, after the base plate is constructed, and after all two constants are completed. Compare the theoretical alignment before the base plate is laid with the current measured alignment to see if it meets the track requirements. After calculation and adjustment, make the theoretical alignment meet the requirements for ballastless track laying. S4. Ballastless track base plate laying: base plate setting out and pouring, and elevation re-measurement after construction to meet accuracy requirements; S5. Laying of ballastless track slab: Use water bags to load counterweights to simulate the shape of a bridge. When pouring the ballastless track slab concrete, unload the corresponding counterweights simultaneously to perform equivalent replacement and meet the accuracy requirements to lay long rails.

[0006] By adopting the above technical scheme, according to the principle of linear control as the main and cable tension control as the auxiliary, the linear shape and cable tension of the main beam are systematically adjusted. Before the implementation of the ballastless track, the bridge model accuracy is verified through graded simulated constant load tests, and the stiffness and temperature change laws of the steel beam are analyzed to guide the implementation of the ballastless track. If necessary, the cable tension is adjusted twice to make the linear shape of the main beam reach a more reasonable state; then according to the working conditions of the ballastless track implementation process, water bags are used to load counterweights to simulate the linear shape of the bridge. When pouring the ballastless track bed concrete, the corresponding counterweights are simultaneously unloaded for equivalent replacement to ensure that the internal force state of the bridge and the linear shape of the ballastless track after the main bridge is completed are consistent with the ideal bridge state.

[0007] Preferably, in step S1, the longitudinal bridge-direction measuring points of the steel box girder are arranged at the cross diaphragm of each section of the steel box girder, with 2 pairs of measuring points every 10 meters; the longitudinal bridge-direction measuring points of the concrete beam are arranged at the cross diaphragm where the inclined cable is anchored, and are densely arranged at the steel-concrete joint section. The measuring points are set on the top surface of the protective wall throughout the entire construction process, and during the construction of the ballastless track, the linear data and basic information of the main bridge under the corresponding working conditions need to be remeasured and collected. Through long-term observation, the preset night construction temperature T1 and the actual measured elevation H1 of the measuring points under the corresponding working conditions are obtained.

[0008] By adopting the above scheme, measuring points are arranged at the diaphragm of each steel box girder and the cable-anchored diaphragm of the concrete beam, ensuring the overall monitoring of the bridge structure. In particular, by densely arranging measuring points at the steel-concrete joint section, the deformation of this key part can be captured more carefully. At the same time, by setting the night construction temperature T1, measurements can be carried out under relatively stable temperature conditions, reducing the impact of temperature changes on the measurement results and improving the reliability of the data.

[0009] Preferably, in step S2, observation data under stable nighttime minimum temperature conditions are collected, and the temperature difference condition is not less than 5°C; the actual stiffness of the structure is obtained by loading the bridge deck and measuring the vertical deformation; the main beam line shape under different ambient temperatures is measured to obtain the corresponding relationship between the temperature difference of the structural system and the deformation of the main beam, and the temperature difference deformation formula of the main beam is: ; in, is the main span length; is the side span length, is the height of the Tower Bridge above the bridge deck; is the length of the mid-span cable; is the linear expansion coefficient of steel and concrete; For temperature changes.

[0010] By adopting the above scheme, the alignment of the main bridge is verified. Multi-layer graded control, loading, and continuous monitoring are adopted. The settlement deformation, creep deformation observation and settlement assessment of the main bridge after construction meet the requirements. Before equal load loading, basic data under various working conditions are collected first, including initial beam surface alignment data, cable force value, air temperature, cable temperature, steel box temperature, concrete box beam temperature, cable tower temperature, cable tower displacement, wind force, and second-phase constant load calculation. In particular, the observation data under the stable lowest temperature condition at night is collected, and the temperature difference condition is not less than 5°C; if the temperature change during the observation period is not obvious, the observation time is appropriately extended, and the influence of temperature change on the alignment of the main beam is corrected according to the theoretical calculation and the conversion relationship of the measured displacement change. The average temperature change of the main beam can indirectly affect the mid-span vertical displacement. After the main beam heats up, it will stretch to both ends. Due to the restraint of the side span cable, the bridge towers will separate from each other, and the movement of the bridge tower will pull the main beam up in the mid-span through the mid-span cable. The expression of the mid-span vertical displacement Δ22 is: In the calculation, the linear expansion coefficient of the material is introduced to simulate the thermal expansion and contraction effect, and it is assumed that the elastic modulus of steel and concrete decreases linearly with increasing temperature, and the cross-sectional temperature of the main beam and bridge tower changes linearly, thereby obtaining the corresponding relationship between the temperature difference of the structural system and the deformation of the main beam.

[0011] Preferably, in step S2, the full load simulation includes a first level of loading and a second level of loading, wherein the first level of loading is for the base plate to adopt equivalent counterweights of sleepers, and the trackbed plate structure is designed and the sleepers are arranged together in the beam, and the second level of loading is for the main span trackbed plate and the remaining accessories to adopt equivalent counterweights of water bags, and at the same time, 2.4M×1M×10M water bags are used on site to inject water on the inner side of the protective wall and the arranged sleepers, so as to equivalently load the weight of the main span trackbed plate and the remaining accessories.

[0012] By adopting the above scheme, simulating actual load conditions, verifying the accuracy of the bridge model, and analyzing the stiffness and temperature change laws of the steel beam, the implementation of the ballastless track can be guided. The line shape and deformation of the ballastless track can be controlled more accurately to ensure that the laying accuracy reaches the millimeter level requirements. The full load simulation helps to achieve highly coordinated deformation between the large-span cable-stayed bridge and the ballastless track, and avoid the problem of gaps between layers.

[0013] Preferably, in step S3, during 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 construction temperature T1, and the height difference between the elevation of the observation point and the elevation of the top of the base plate is obtained: ΔH1=H1-H2; during the construction of the roadbed plate, counterweights are set outside the protective wall and in the beam to simulate the load of the main span roadbed plate and the remaining ancillary projects, and the preset construction temperature T2 and the measured elevation H3 of the observation point are obtained. The monitoring and design units perform modeling and analysis to determine the track design alignment data H4 under the corresponding working conditions, and the height difference between the elevation of the observation point and the track control elevation is obtained: ΔH2=H3-H4, and ΔH2 is used for coarse track control and temporary elevation review.

[0014] By adopting the above scheme, the height difference between the elevation of the observation point and the elevation of the top of the base plate can be calculated. This process helps to accurately control the elevation changes during the construction process and ensure that the laying accuracy of the ballastless track reaches the millimeter level requirements. Subsequently, the monitoring and design units conduct modeling analysis to determine the track design linear data H4 under the corresponding working conditions, thereby obtaining ΔH2=H3-H4, that is, the height difference between the elevation of the observation point and the track control elevation. This process helps to achieve highly coordinated deformation between the large-span cable-stayed bridge and the ballastless track and avoid the problem of inter-layer gap separation. Using ΔH2 for track coarse adjustment control and temporary elevation review can further improve the elevation control accuracy during the construction process and ensure the laying quality of the ballastless track.

[0015] Preferably, in step S3, by comparing the theoretical and measured alignments, three technical indicators, namely the cable tension adjustment value, the base plate height value and the track bed plate height value, are obtained to verify whether they meet the requirements of the specifications. If the actual alignment deviates too much from the designed alignment, it is necessary to communicate with the design whether the alignment adjustment is required, and the monitoring unit issues a monitoring instruction to adjust the cable tension to obtain a more reasonable main beam alignment to meet the requirements for ballastless track laying.

[0016] By adopting the above scheme, the cable force adjustment value of the inclined cable, the height value of the base plate and the roadbed plate can be accurately determined. This high-precision control method ensures the laying quality of the ballastless track and achieves millimeter-level laying accuracy. Through the precise measurement and control network layout and correction technology under real-time dynamic changes, the deformation coordination problem between the long-span cable-stayed bridge and the ballastless track is solved. This method improves the overall stability and durability of the bridge and the track. At the same time, the curvature radius of the deformation curve fitting is used to evaluate the vertical and lateral stiffness of the bridge and the "60m chord vector value 7mm (high and low) / 6mm (track direction)" track line static evaluation index based on the midpoint chord measurement method, filling the gap in the design and acceptance standards of large-span ballastless track bridges.

[0017] Preferably, in step S4, the construction process flow of the base plate is: construction preparation → acceptance of foundation surface → roughening of beam surface → extension of embedded steel bars → measurement and layout → steel bar binding → installation of base plate and groove formwork → concrete pouring → concrete maintenance and demoulding → quality inspection, and the pouring of the base plate is carried out symmetrically from the side span to the middle span.

[0018] By adopting the above scheme, the quality and accuracy of the base plate can be ensured, providing a solid foundation for the subsequent laying of the roadbed plate and track. The beam surface is roughened mechanically or manually to increase the bonding force. At the same time, the embedded steel bars are extended as required to enhance the structural strength. The size and position of the base plate are accurately measured and marked, and then the steel bars are tied according to the design requirements to ensure the stability of the structure. Then the templates of the base plate and the groove are installed to ensure the shape and size are accurate. Finally, the completed base plate is fully quality checked to ensure that there are no defects. The symmetrical implementation method in the process of this construction process helps to balance the load and reduce the structural deformation caused by uneven load. In addition, this process can effectively control the bridge line error of the ballastless track of the large-span cable-stayed bridge, improve the track laying accuracy, and ensure the quality of the project.

[0019] Preferably, in step S4, the isolation layer and elastic cushion layer can be constructed only when the concrete strength of the base reaches more than 75%. The base surface and the bottom of the groove are cleaned with high-pressure water. The surface of the groove should be flat with a flatness of 10mm / 3m. At the same time, the entire bridge line shape is measured before the secondary loading to check whether the elevation deviation of the base plate construction is within the allowable range.

[0020] By adopting the above scheme, before constructing the isolation layer and elastic cushion layer, use high-pressure water to clean the base surface and the bottom of the groove to ensure good adhesion and avoid uneven support or gaps caused by dust, loose particles, etc. The flatness requirement of the groove surface is 10mm / 3m, which helps to ensure the uniform laying of the isolation layer and the elastic cushion layer, thereby ensuring the correct installation and performance of the roadbed plate. Before the secondary loading, a comprehensive bridge alignment measurement is carried out, and the base plate construction elevation deviation is reviewed to ensure that all parameters are within the design allowable range to ensure the accuracy and safety of the structure. The measurement of the entire bridge alignment and the review of the base plate elevation ensure the construction accuracy and the accuracy of the linearity and slope of the bridge, which is particularly important for high-speed railways. It is directly related to the safety and stability of train operation.

[0021] Preferably, in step S5, during the construction of the ballast slab, the principle of equivalent weight replacement is adopted to control the main bridge load to the full load under the completed bridge, and an isolation layer and ballast slab structural materials are arranged on the base plate, including elastic pads, geotextiles, steel bars, sleepers, fasteners and other structural permanent loads, and temporary loads are arranged in advance. The temporary loads include but are not limited to gantry crane running rails and tooling templates. The water bags of the main span are transferred outside the protective wall and arranged in the cable groove along the bridge direction. The counterweight load is replaced by simultaneously unloading the corresponding water bag weight when the ballast slab concrete is poured.

[0022] By adopting the above scheme, temporary loads and permanent loads are arranged in advance, which ensures the accurate arrangement and use of various materials during the construction process, improves the construction efficiency and precision, and ensures that the load of the bridge remains stable during the pouring of the ballast slab concrete through the principle of equivalent weight replacement, avoiding structural deformation and stress concentration caused by load changes. At the same time, the method of graded counterweight adjustment by loading with water bags is used to simulate the line shape of the completed bridge. When pouring the ballast slab concrete, the corresponding counterweight is simultaneously unloaded for equivalent replacement, ensuring that the internal force state of the bridge and the line shape of the ballastless track are consistent with the ideal state of the completed bridge.

[0023] Preferably, in step S5, the construction process of the ballast plate is: rail and sleeper acceptance → foundation surface acceptance → rail assembly → rail rough adjustment → grounding steel bar welding → rail fine adjustment → concrete pouring → rail fastener stress release → rail removal and data collection → concrete maintenance and demoulding.

[0024] By adopting the above scheme, the track is assembled according to the design requirements to ensure that the connection of each component during the assembly process is firm and reliable, and the welded track is finely adjusted to ensure that its geometric state meets the design requirements. After the initial setting of the concrete, the prestress of the rail fasteners is released to prevent the concrete from cracking due to excessive stress. Through the meticulous acceptance, assembly, adjustment and pouring process, it is ensured that the structural accuracy and geometric state of the track bed meet the design requirements. The method of welding grounding steel bars and fine adjustment is adopted to enhance the overall stability and durability of the track bed. At the same time, the reasonable process arrangement and fine operation methods improve the construction efficiency and shorten the construction period.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. Through full load simulation, the bridge state can be fitted in advance, and the correction of design parameters can be more accurate; 2. Through simulated load tests and long-term monitoring observations, the stiffness and temperature change laws of large-span steel beams are analyzed, and the synchronous temperature change periods of steel beams, concrete beams, and inclined cables are obtained, effectively eliminating the influence of other factors and making the construction results more consistent with the theoretical values; 3. Analyze the stress characteristics of the main bridge structure, deploy CP III measuring points in the structural transition area, negative bending moment area, and representative stress sections, and encrypt other monitoring points to accurately control the linear changes of the main bridge and ensure the correctness of the construction control direction; 4. Adopt the multi-layer graded control construction technology of ballastless track, accurately calculate the load change value of each working condition, and make the load of the whole bridge stable and the line shape remain in the preset state by equivalently replacing the construction load of ballastless track bed, so as to ensure that the internal force state of the bridge and the line shape of ballastless track after the main bridge is completed are consistent with the ideal bridge state; 5. Based on the previous monitoring results, the temperature variation pattern of the CP III control network was obtained, and the effective use period and re-measurement frequency of the CP III data on the day were determined to achieve millimeter-level control accuracy for large-span ballastless track cable-stayed bridges.

[0026] 6. The ballastless track is implemented synchronously from the side spans at both ends to the middle span, symmetrically on the left and right sides, balancing the main beam load, eliminating sudden changes, and ensuring smooth and synchronous linear changes under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the process flow chart of the multi-layer graded control process of ballastless track of the present application; Figure 2 This is a process flow chart of the ballastless track base plate construction process of the present application; Figure 3 It is a process flow chart of the ballastless track slab construction process of the present application. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1 -Attached Figure 3 , further details of this application are given.

[0029] The embodiment of the present application discloses a multi-layer graded control construction method for ballastless track of a large-span cable-stayed bridge on a high-speed railway.

[0030] Reference Figure 1 The invention discloses a multi-layer hierarchical control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge, which is characterized by comprising the following steps: S1. Initial preparation: Analyze the stress of the main beam, determine the layout of CP III monitoring points and the encryption of other monitoring points, complete offline project acceptance and settlement deformation observation and evaluation; S2. Basic data collection: collect basic data under various working conditions before equal load loading, conduct full load simulation, and obtain the theoretical calculation model after stiffness and temperature correction; S3. Initial linear assessment and adjustment: Calculate the theoretical alignment before the base plate is laid, after the base plate is constructed, and after all two constants are completed. Compare the theoretical alignment before the base plate is laid with the current measured alignment to see if it meets the track requirements. After calculation and adjustment, make the theoretical alignment meet the requirements for ballastless track laying. S4. Ballastless track base plate laying: base plate setting out and pouring, and elevation re-measurement after construction to meet accuracy requirements; S5. Laying of ballastless track slab: Use water bags to load counterweights to simulate the shape of a bridge. When pouring the ballastless track slab concrete, unload the corresponding counterweights simultaneously to perform equivalent replacement and meet the accuracy requirements to lay long rails.

[0031] Specifically, the conditions for construction are: the completion of the auxiliary projects of the main bridge, and the completion of the secondary tensioning of the cable-stayed cables according to the design requirements. S1 is mainly responsible for the preliminary preparation of the project. These works ensure the stability and reliability of the basic structure and provide a solid foundation for subsequent construction. S2 ensures the accuracy and reliability of the theoretical model through detailed data collection and analysis, providing a scientific basis for subsequent construction adjustments. S3 involves calculating the theoretical line shape before and after the laying of the base plate, and conducting comparative analysis to determine whether it meets the track requirements. If the actual line shape deviates too much from the designed line shape, it is necessary to communicate with the design whether If the line shape adjustment is needed, the monitoring unit will issue a monitoring instruction to adjust the cable tension to obtain a more reasonable main beam line shape to meet the requirements of ballastless track laying. If it does not meet the professional requirements of the track, it can be adjusted by the thickness of the construction structure or the cable tension. If it still does not meet the relevant requirements, the line professional needs to adjust the longitudinal section and re-evaluate the initial line shape. S4 is an important link to ensure the accuracy of the ballast plate laying, which directly affects the overall quality of the ballastless track and the safety of train operation. S5 ensures that the internal force state of the bridge after completion and the line shape of the ballastless track are consistent with the ideal bridge state, thereby improving the construction accuracy and project quality.

[0032] Reference Figure 1 In step S1, the longitudinal bridge measuring points of the steel box girder are arranged at the transverse diaphragm of each steel box girder, with 2 pairs of measuring points every 10 meters; the longitudinal bridge measuring points of the concrete beam are arranged at the transverse diaphragm of the inclined cable anchorage, and are densely arranged at the steel-concrete joint section. The measuring points are set on the top surface of the protective wall throughout the entire construction process, and during the construction of the ballastless track, the main bridge linear data and basic information under the corresponding working conditions need to be re-measured and collected. Through long-term observation, the preset night construction temperature T1 and the actual measured elevation H1 of the measuring point under the corresponding working conditions are obtained.

[0033] Specifically, the longitudinal bridge measuring points of the steel box girder are arranged at the transverse diaphragm of each steel box girder, and 2 pairs of measuring points are set every 10 meters. This arrangement ensures that the geometric state of each section of the steel box girder can be accurately monitored during the construction process, thereby ensuring the overall accuracy and stability of the bridge. The longitudinal bridge measuring points of the concrete beam are arranged at the transverse diaphragm where the inclined cable is anchored, and are densely arranged at the steel-concrete joint section. This arrangement can effectively monitor the stress changes at the joint between the concrete beam and the steel box girder to ensure the reliability of the structural connection. The measuring points are set on the top surface of the protective wall throughout the entire construction process. This arrangement makes it easy to monitor the key parts of the bridge in real time throughout the construction process, and to promptly discover and deal with potential problems. During the construction of ballastless track, it is necessary to re-measure and collect the main bridge line shape data and basic information under the corresponding working conditions. Through long-term observation, the preset construction temperature T1 at night and the measured elevation H1 of the measuring point under the corresponding working conditions are obtained. The collection and analysis of these data are important means to ensure the quality of bridge construction and the safety of subsequent operation.

[0034] Reference Figure 1 In step S2, the observation data under the stable minimum temperature condition at night is collected, and the temperature difference condition is not less than 5°C; the actual stiffness of the structure is obtained by loading the bridge deck and measuring the vertical deformation; the main beam line shape under different ambient temperatures is measured to obtain the corresponding relationship between the temperature difference of the structural system and the deformation of the main beam. The temperature difference deformation formula of the main beam is: ; in, is the main span length; is the side span length, is the height of the Tower Bridge above the bridge deck; is the length of the mid-span cable; is the linear expansion coefficient of steel and concrete; For temperature changes.

[0035] Specifically, during the construction process, especially under low temperature conditions at night, according to previous observation data, the temperature difference between 0:00 and 5:00 in the morning is small (≤3°C), which is suitable for linear measurement work and roadbed slab pouring work at various stages. At this time, the basic data of the bridge is collected, and the temperature difference condition is not less than 5°C to ensure the stability and reliability of the data. These data include initial beam surface linear data, cable force value, air temperature, cable temperature, steel box temperature, concrete box beam temperature, cable tower temperature, cable tower displacement, wind force, second-phase constant load calculation, etc. At the same time, a loading test is carried out on the bridge deck, and the vertical deformation caused by loading is measured. By comparing the theoretical linear shape with the measured linear shape, the actual stiffness of the bridge can be obtained. This step ensures that the geometric state of the bridge under the actual load meets the design requirements, and the main beam linear shape is measured at different ambient temperatures, and the deformation of the main beam at different temperatures is recorded. Substituted into the theoretical calculation model, the temperature difference deformation formula of the main beam is: ; in, is the main span length; is the side span length, is the height of the Tower Bridge above the bridge deck; is the length of the mid-span cable; is the linear expansion coefficient of steel and concrete; for temperature changes; The average temperature change of the main beam can indirectly affect the vertical displacement at the mid-span. When the main beam heats up, it will stretch to both ends. The bridge towers will separate from each other due to the restraint of the side span cables, and the movement of the bridge towers will pull the main beam up at the mid-span through the middle span cables. In this way, the deformation direction of the main beam under temperature changes and the influence of the deformation temperature on the main beam can be calculated, thereby obtaining the deformation law of the bridge structure system under different temperature difference conditions, which can better guide the subsequent construction adjustments and optimized design.

[0036] Reference Figure 1 In step S2, the full load simulation includes the first level loading and the second level loading. The first level loading is that the base plate adopts the equivalent counterweight of the sleeper, and the sleepers of the roadbed plate structure are arranged together in the beam. The second level loading is that the main span roadbed plate and the remaining accessories adopt the equivalent counterweight of the water bag. At the same time, on the inner side of the protective wall and the arranged sleepers, 2.4M×1M×10M water bags are used on site to inject water, and the main span roadbed plate and the remaining accessories are equivalently loaded.

[0037] Specifically, in the first level of loading, the structural deviation of the prefabricated sleepers is taken into consideration, and the weight of each sleeper used as counterweight on each vehicle must be weighed to ensure the accuracy of the counterweight quantity. In the second level of loading, in order to verify the accuracy of the water bag counterweight, the counterweight measuring water meter must be doubly calibrated. First, it is loaded in a square bucket to check whether the water flow through the water meter is accurate; then the pre-loaded water bag is placed on the scale, and water is filled in stages through the water meter to check whether the water flow is consistent with the weight measured on the scale, and a second calibration is carried out. The water bags, sleepers, and counterweights in the two-level loading must be calibrated before they can enter the site to ensure that the error between the calculated weight and the actual weight is less than 0.5%.

[0038] Reference Figure 1 In step S3, during the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate under the construction temperature T1, and obtains the height difference between the elevation of the observation point and the elevation of the top of the base plate: ΔH1=H1-H2; during the construction of the track bed plate, counterweights are set outside the protective wall and in the beam to simulate the load of the main span track bed plate and the remaining auxiliary engineering, and obtain the preset construction temperature T2 and the measured 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 between the elevation of the observation point and the track control elevation: ΔH2=H3-H4, and use ΔH2 for track coarse adjustment control and temporary elevation review.

[0039] Specifically, during the construction of the base plate, the changes in working conditions such as ambient temperature during the elevation positioning process are taken into account. Therefore, the measuring point is used as the benchmark, and the height difference ΔH1 of the same cross section is used as the basis for the layout. That is, the base plate is controlled by relative thickness, and the main span is laid once using the tool rail method to complete the main span section of the roadbed. The use of the CPⅢ data of the main bridge can only be used after the balance correction and update results on the same day, and the results will be invalidated the next day. Through continuous CPⅢ joint measurement and track alignment fine adjustment for several days, according to the deformation situation, analysis is carried out. When it is considered that the re-measurement results are in line with the deformation law and actual situation, concrete pouring can be prepared. Through the measurement of actual stiffness and deformation analysis at different temperatures, the overall stability and durability of the bridge are enhanced. During the production, the offline structure settlement deformation and CPⅢ measurement control network evaluation are carefully done, and the offline structure geometric dimensions are jointly accepted with all parties involved in the construction. For those who do not meet the requirements of ballastless track construction, there is no fluke.

[0040] Reference Figure 1 In step S3, by comparing the theoretical and measured alignments, three technical indicators, namely the cable tension adjustment value, the base plate height value, and the roadbed plate height value, are obtained to verify whether they meet the requirements of the specifications. If the actual alignment deviates too much from the designed alignment, it is necessary to communicate with the design whether the alignment adjustment is required. The monitoring unit will issue a monitoring instruction to adjust the cable tension and obtain a more reasonable main beam alignment to meet the requirements for ballastless track laying.

[0041] Specifically, through the above adjustment measures, if cable force adjustment or line shape adjustment is required, the monitoring unit will issue specific monitoring instructions, and make corresponding adjustments according to these instructions to ensure that the main beam line shape is more reasonable and finally obtain a more reasonable main beam line shape to meet the requirements of ballastless track laying. This ensures the stability and safety of the train when passing at high speed.

[0042] Reference Figure 1 and Figure 2 In step S4, the construction process of the base plate is as follows: construction preparation → acceptance of foundation surface → roughening of beam surface → extension of embedded steel bars → measurement and layout → steel bar binding → installation of base plate and groove formwork → concrete pouring → concrete maintenance and demoulding → quality inspection. The pouring of the base plate is carried out symmetrically from the side span to the middle span.

[0043] Specifically, before construction, detailed preparation work is carried out, including technical review, personnel allocation, on-site operation, etc. Ensure that all construction personnel are familiar with the specifications and technical standards, and conduct pre-job training and technical briefings. Inspect the completed foundation surface to ensure that its flatness and stability meet the design requirements. This step is an important part of ensuring the construction quality of the base plate. Then, the beam surface is roughened to increase the bonding force between the concrete and the base plate. The embedded steel bars are extended according to the design requirements to ensure that the connection of the steel bars is firm and reliable. This step provides a solid foundation for the subsequent concrete pouring. The position and size of the base plate are accurately measured and laid out to ensure that the geometric state of the base plate meets the design requirements. The steel bars are tied according to the design requirements to ensure that the steel bars are arranged reasonably and the tying is done properly. Firmly, this step improves the structural stability and seismic resistance of the base plate. Install the base plate and groove templates to ensure that the templates are accurately positioned and firmly fixed. This step ensures that the templates will not move or deform during the concrete pouring process. After completing the above work, concrete pouring is carried out. During the pouring process, it is necessary to ensure that the concrete is uniform and dense to avoid problems such as honeycomb and hemp. After pouring, the base plate is cured to maintain appropriate humidity to prevent the concrete from drying and cracking. After the concrete strength reaches the design requirements, the formwork is removed. Through detailed process flow and strict quality control measures, it is ensured that the geometric state and structural strength of the base plate meet the design requirements, thereby improving construction accuracy.

[0044] Reference Figure 1 In step S4, the isolation layer and elastic cushion layer can be constructed only when the concrete strength of the base reaches more than 75%. The base surface and the bottom of the groove are cleaned with high-pressure water. The surface of the groove should be flat with a flatness of 10mm / 3m. At the same time, the entire bridge line shape is measured before the secondary loading to check whether the elevation deviation of the base plate construction is within the allowable range.

[0045] Specifically, before the secondary loading, the entire bridge alignment is measured to verify whether the elevation deviation of the base plate construction is within the allowable range. This step ensures that the geometric state of the bridge under the actual load meets the design requirements, thereby improving the construction accuracy. The main bridge ballastless track is a cast-in-place ballast bed. The load increases gradually as the ballast bed is poured, which will cause the track alignment to change. The ballastless track construction process is always in a dynamic state of change. Preloading can more accurately understand the changes in the main bridge track construction alignment and verify the deviation between the actual alignment and the designed alignment after the track is laid. Make corrections in advance, reduce the deformation compensation value of the track fine-tuning beam surface, and improve the track alignment smoothness.

[0046] Reference Figure 1 and Figure 3In step S5, during the construction of the ballast slab, the principle of equivalent weight replacement is adopted to control the main bridge load to the full load under the completed bridge, and the isolation layer and ballast slab structural materials are arranged on the base plate, including elastic pads, geotextiles, steel bars, sleepers, fasteners and other structural permanent loads, and temporary loads are arranged in advance. The temporary loads include but are not limited to gantry crane running rails and tooling templates. The main span water bag is transferred outside the protective wall and arranged in the cable groove along the bridge direction. The counterweight load is replaced by unloading the corresponding water bag weight simultaneously when the ballast slab concrete is poured.

[0047] Specifically, during the construction of the ballast slab, the principle of equivalent weight replacement is adopted to control the load of the main bridge to the full load under the completed bridge. This step ensures that the geometric state of the ballast slab under the actual load meets the design requirements, thereby improving the construction accuracy. The water bag of the main span is transferred outside the protective wall and arranged along the bridge in the cable channel. At this time, the water injection weight is: ballast slab concrete + remaining accessories - tooling weight, and the loading weight is 1186t. At this time, the water bag on each side has a counterweight of 1.2t per linear meter, and the counterweight block in the beam has a counterweight of 1.2t per linear meter. The counterweight load is replaced by unloading the corresponding water bag weight simultaneously when the ballast slab concrete is poured.

[0048] Reference Figure 1 and Figure 3 In step S5, the construction process of the ballast plate is as follows: rail and sleeper acceptance → foundation surface acceptance → rail assembly → rail rough adjustment → grounding steel bar welding → rail fine adjustment → concrete pouring → rail fastener stress release → rail removal and data collection → concrete maintenance and demoulding.

[0049] Specifically, all tool rails, sleepers and other materials used on site must have factory quality certification materials, and the dimensions must be measured in detail to check whether they meet the requirements. They can only be used after acceptance. The completed foundation surface must be inspected to ensure that its flatness and stability meet the design requirements. This step is an important part of ensuring the quality of the track bed construction. The track is assembled according to the design requirements to ensure that the positions of each component are accurate and the connections are firm. Then the assembled track is roughly adjusted to make its geometric state meet the design requirements. The grounding steel bars are welded to ensure that the welding is firm and reliable. After the track is fine-tuned in place, the track is immediately reinforced with corresponding measures to prevent lateral displacement and floating of the track during concrete pouring. Data is collected as the final fine-tuning data. After completing the above work, concrete pouring is carried out. After pouring, the stress release of the rail fasteners is carried out to ensure that the stress distribution between the fasteners and the track is reasonable. This step improves the overall structural strength and durability of the track bed. Finally, the track is removed and data is collected to ensure that all data are accurate. The offline structure settlement deformation and CPⅢ measurement control network assessment are carefully done, and the offline structure geometric dimensions are jointly accepted with all parties involved in the construction. For those who do not meet the requirements of ballastless track construction, there is no room for luck.

[0050] The implementation principle of the embodiment of the present application is: after the bridge deck is attached, the main beam line shape and cable tension are systematically adjusted according to the principle of line shape control as the main and cable tension control as the auxiliary, the bridge model accuracy is verified through graded simulated constant load tests, the stiffness and temperature change laws of the steel beams are analyzed, and the counterweights are graded and adjusted by loading with water bags to simulate the line shape of the completed bridge. When pouring the ballast slab concrete, the corresponding counterweights are simultaneously unloaded for equivalent replacement to ensure that the internal force state of the bridge and the line shape of the ballastless track after the main bridge is completed are consistent with the ideal bridge state.

[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. A multi-layer hierarchical control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge, characterized in that: The following steps are involved: S1. Initial preparation: Analyze the stress of the main beam, determine the layout of CP III monitoring points and the encryption of other monitoring points, complete offline project acceptance and settlement deformation observation and evaluation; S2. Basic data collection: collect basic data under various working conditions before equal load loading, conduct full load simulation, and obtain the theoretical calculation model after stiffness and temperature correction; S3. Initial linear assessment and adjustment: Calculate the theoretical alignment before the base plate is laid, after the base plate is constructed, and after all two constants are completed. Compare the theoretical alignment before the base plate is laid with the current measured alignment to see if it meets the track requirements. After calculation and adjustment, make the theoretical alignment meet the requirements for ballastless track laying. S4. Ballastless track base plate laying: base plate setting out and pouring, and elevation re-measurement after construction to meet accuracy requirements; S5. Laying of ballastless track slab: Use water bags to load counterweights to simulate the shape of a bridge. When pouring the ballastless track slab concrete, unload the corresponding counterweights simultaneously to perform equivalent replacement and meet the accuracy requirements to lay long rails.

2. The multi-layer hierarchical control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S1, the longitudinal bridge-direction measuring points of the steel box girder are arranged at the cross diaphragm of each section of the steel box girder, with 2 pairs of measuring points every 10 meters; the longitudinal bridge-direction measuring points of the concrete beam are arranged at the cross diaphragm where the inclined cable is anchored, and are densely arranged at the steel-concrete joint section. The measuring points are set on the top surface of the protective wall throughout the entire construction process, and during the construction of the ballastless track, it is necessary to re-measure and collect the main bridge line shape data and basic information under the corresponding working conditions. Through long-term observation, the preset night construction temperature T1 and the actual measured elevation H1 of the measuring points under the corresponding working conditions are obtained.

3. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S2, observation data under stable nighttime minimum temperature conditions are collected, and the temperature difference condition is not less than 5°C; the actual stiffness of the structure is obtained by loading the bridge deck and measuring the vertical deformation; the main beam line shape under different ambient temperatures is measured to obtain the corresponding relationship between the temperature difference of the structural system and the deformation of the main beam. The temperature difference deformation formula of the main beam is: ； in, is the main span length; is the side span length, is the height of the Tower Bridge above the bridge deck; is the length of the mid-span cable; is the linear expansion coefficient of steel and concrete; For temperature changes.

4. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S2, the full load simulation includes the first level loading and the second level loading. The first level loading is that the base plate adopts the equivalent counterweight of the sleeper, and the sleepers of the roadbed plate structure are arranged together in the beam. The second level loading is that the main span roadbed plate and the remaining accessories adopt the equivalent counterweight of the water bag. At the same time, on the inner side of the protective wall and the arranged sleepers, 2.4M×1M×10M water bags are used on site to inject water to equivalently load the weight of the main span roadbed plate and the remaining accessories.

5. The multi-layer hierarchical control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S3, during the construction of the base plate, the design provides the bridge alignment elevation data H2 of the top surface of the base plate under the construction temperature T1, and obtains the height difference between the elevation of the observation point and the elevation of the top of the base plate: ΔH1=H1-H2; during the construction of the track bed plate, counterweights are set outside the protective wall and in the beam to simulate the load of the main span track bed plate and the remaining ancillary projects, and obtain the preset construction temperature T2 and the measured elevation H3 of the observation point. The monitoring and design units conduct modeling and analysis to determine the track design alignment data H4 under the corresponding working conditions, and obtain the height difference between the elevation of the observation point and the track control elevation: ΔH2=H3-H4, and use ΔH2 for track coarse adjustment control and temporary elevation review.

6. The multi-layer hierarchical control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S3, by comparing the theoretical and measured alignments, three technical indicators, namely the cable tension adjustment value, the base plate height value, and the track bed plate height value, are obtained to verify whether they meet the requirements of the specifications. If the actual alignment deviates too much from the designed alignment, it is necessary to communicate with the design whether the alignment needs to be adjusted. The monitoring unit will issue monitoring instructions to adjust the cable tension and obtain a more reasonable main beam alignment to meet the requirements for ballastless track laying.

7. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S4, the construction process of the base plate is as follows: construction preparation → acceptance of foundation surface → roughening of beam surface → extension of embedded steel bars → measurement and layout → steel bar binding → installation of base plate and groove formwork → concrete pouring → concrete maintenance and demoulding → quality inspection. The pouring of the base plate is carried out symmetrically from the side span to the middle span.

8. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S4, the isolation layer and elastic cushion layer can be constructed only when the concrete strength of the base reaches more than 75%. The base surface and the bottom of the groove are cleaned with high-pressure water. The surface of the groove should be flat with a flatness of 10mm / 3m. At the same time, the entire bridge line shape is measured before the secondary loading to check whether the elevation deviation of the base plate construction is within the allowable range.

9. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1 is characterized in that: In step S5, during the construction of the ballast slab, the principle of equivalent weight replacement is adopted to control the main bridge load to the full load under the completed bridge, and the isolation layer and ballast slab structural materials are arranged on the base plate, including elastic pads, geotextiles, steel bars, sleepers, fasteners and other structural permanent loads, and temporary loads are arranged in advance. The temporary loads include but are not limited to gantry crane running rails and tooling templates. The water bags of the main span are transferred outside the protective wall and arranged in the cable groove along the bridge direction. The counterweight load is replaced by simultaneously unloading the corresponding water bag weight when the ballast slab concrete is poured.

10. The multi-layer graded control construction method for ballastless track of a high-speed railway long-span cable-stayed bridge according to claim 1, characterized in that: In step S5, the construction process of the ballast plate is as follows: rail and sleeper acceptance → foundation surface acceptance → rail assembly → rail rough adjustment → grounding steel bar welding → rail fine adjustment → concrete pouring → rail fastener stress release → rail removal and data collection → concrete maintenance and demoulding.

Images