A construction control method applicable to ballastless track laying on medium-span bridges

Abstract

This invention discloses a construction control method applicable to the laying of ballastless track on medium-span bridges, comprising the following steps: establishing a finite element model of the bridge; monitoring the deformation data of the bridge during the pouring and tensioning processes, and correcting the finite element model; calculating the pre-camber of the ballastless track base plate at the design temperature; after the entire bridge is closed, setting CPIII measuring points on the bridge deck, carrying out the pouring construction of the base plate, and correcting the finite element model again; after completing the construction of the entire bridge base plate, re-measuring the CPIII points on the beam surface for the first time; dividing the entire bridge track slab into three sections; carrying out three pouring constructions on the three sections of track slab, and determining the optimal length; laying the sleeper elevations of the side spans and part of the middle span; laying the remaining sleeper elevations in the middle span, and pouring the remaining middle span track slab in place; and fine-tuning the rail elevation using rail fasteners. This invention avoids large errors between the actual construction and the designed track elevation, which could affect project acceptance, and can simplify construction process measures, reduce construction costs, and improve construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of railway construction technology, specifically relating to a construction control method applicable to the laying of ballastless track on medium-span bridges. Background Technology

[0002] Ballastless track construction is a relatively advanced track laying technology that uses a monolithic foundation such as concrete or asphalt mixture to replace the traditional loose gravel track bed, thereby improving the stability and smoothness of the track.

[0003] Chinese patent CN202311241088.1 discloses a method for constructing ballastless track on a long-span bridge with dynamic correction. The core drawback is in step S2, where sandbags or water bags are used to weigh the track during construction. The sandbags or water bags simulate the load of the ballastless track, and the track is constructed span by span. The sandbags or water bags corresponding to the weight of the track structure are unloaded during construction to ensure that the load on the bridge is constant and to avoid the load changes affecting the bridge deformation.

[0004] However, this method has the following drawbacks:

[0005] Firstly, it requires a large number of temporary engineering measures. Taking the CRTS double-block ballastless track as an example, it requires approximately 7.5 tons of weight per linear meter. For a rigid frame continuous beam with a span of (88+160+88)m and a total length of 336m, it requires approximately 2520 tons of sandbags or water bags. The larger the bridge span, the more expensive it becomes, often costing hundreds of thousands to millions of yuan. Therefore, the cost investment is enormous.

[0006] Secondly, the working surface on the bridge deck is very limited when laying ballastless track. If water bags of 7.5t per linear meter are used, and assuming a 2m space is reserved on the bridge deck, a water tank 3.75m high would be required. This is not only difficult to implement, but it would also affect existing construction techniques and negatively impact the quality of track construction. Therefore, weighting measures are not only difficult to implement, but also cannot guarantee the quality of the project. Summary of the Invention

[0007] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a construction control method suitable for laying ballastless track on medium-span bridges.

[0008] The technical solution of this invention is: a construction control method applicable to the laying of ballastless track on medium-span bridges, comprising the following steps:

[0009] A. Establish a finite element model of the bridge based on its design parameters;

[0010] B. Monitor the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and correct the finite element model to obtain the corrected finite element model after the first correction.

[0011] C. Using the modified finite element model, calculate the precamber of the ballastless track base plate at the design temperature;

[0012] D. After the entire bridge is closed, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the load weight is monitored, and the finite element model is corrected again to obtain the second corrected finite element model.

[0013] E. After the completion of the entire bridge base plate construction, the first re-measurement of point CPIII on the beam surface;

[0014] F. Divide the entire bridge's track bed into three sections;

[0015] G. The track bed slab, divided into three sections, is poured three times, and the optimal section length is determined.

[0016] H. According to the design elevation, lay the sleeper elevations for both side spans and part of the middle span, and then cast-in-place the corresponding track bed slabs.

[0017] I. Lay the remaining sleeper elevation at the mid-span according to the design elevation, and then cast in place the remaining mid-span track slab;

[0018] J. Based on the design elevation, the elevation of the rails across the entire bridge is finely adjusted using rail fasteners.

[0019] Furthermore, step B monitors the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and corrects the finite element model to obtain the first corrected finite element model, which includes the layout of linear monitoring points and temporary measurement points.

[0020] Furthermore, linear monitoring points are deployed, and the specific process is as follows:

[0021] First, five measuring points are set up on one beam segment of the beam surface, and the five measuring points are in a straight line;

[0022] Then, five measuring points were set up on the other beam segments, with each measuring point corresponding to the previous one.

[0023] Furthermore, temporary measurement points were set up, and the specific process is as follows:

[0024] First, set up measuring point No. 1 on the side wall of the top slab of the beam;

[0025] Then, measuring point No. 2 is set up at the transition between the top plate and the web of the beam;

[0026] Next, measuring point No. 3 was set up on the bottom plate of the beam;

[0027] Finally, the remaining three measuring points are symmetrical to measuring points 1, 2, and 3 along the centerline of the beam.

[0028] Furthermore, step C uses a modified finite element model to calculate the precamber of the ballastless track base plate at the design temperature. The specific process is as follows:

[0029] First, based on the final target alignment of the track surface and the subsequent load on the upper bridge of the track slab, calculate the top elevation of the base plate point by point;

[0030] Then, the top surface elevation G of the i control point on the base plate i The following relationship must be satisfied:

[0031] G i =S i +Y i

[0032] In the formula: S i —Design elevation of control points;

[0033] Y i —Calculation of deflection at control point i;

[0034] Finally, calculate the deflection Y. i The calculation considers the remaining load on the entire bridge deck, including the track slab / double-block sleeper, ballast slab / self-compacting concrete, rails, fasteners, and contact wire, after the base plate is constructed.

[0035] Furthermore, after the entire bridge is closed in step D, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the loaded weight is monitored, and the finite element model is revised again to obtain the second revised finite element model. The specific process is as follows:

[0036] First, after the entire bridge is closed, CPIII measuring points are set on the bridge deck to carry out the pouring of the base plate;

[0037] Then, during the pouring process, the relationship between the bridge alignment and the loaded weight was monitored, and the finite element model was revised again to obtain the second revised finite element model.

[0038] Subsequently, the revised items included the elastic modulus of bridge concrete and the unit weight of the foundation slab concrete.

[0039] Finally, if the ambient temperature during the casting of the base plate differs significantly from the design temperature, the influence of temperature should be eliminated using a modified finite element model, while avoiding construction of the base plate in strong winds.

[0040] Furthermore, after the completion of the entire bridge base plate construction in step E, the first re-measurement of point CPIII on the beam surface was conducted. The specific process is as follows:

[0041] After the construction of the bridge's base plate was completed, the bridge deck gained additional weight, and the beam's alignment changed. The first remeasurement of point CPIII on the beam surface was conducted.

[0042] Furthermore, step F divides the entire bridge's track bed slab into three sections, as detailed below:

[0043] First, the entire bridge track bed slab is divided into three sections: left section A, section B, and right section A.

[0044] Then, the left A section track bed slab includes the left side span track bed slab and part of the middle span track bed slab; the right A section track bed slab includes the right side span track bed slab and part of the middle span track bed slab.

[0045] Finally, the track bed slab for section B is the mid-span track bed slab.

[0046] Furthermore, in step G, the track slab, divided into three sections, undergoes three pouring processes, as detailed below:

[0047] First, the cast-in-place track slab of the entire bridge was divided into three sections and poured in three stages.

[0048] Then, during the pouring process, after the left A section and right A section of the track bed slab were poured, the B section of the track bed slab with the largest deflection was adjusted again according to the design elevation. In fact, the B section of the track bed slab was raised once, reducing its final deflection on the rail surface.

[0049] Furthermore, in step G, the optimal segment length is determined, and the specific process is as follows:

[0050] First, in the first revised finite element model, the weight of the cast-in-place track slab was simulated by a uniformly distributed load. The weight of the double-track track slab of the CRTS double-block track structure was 31.2 kN / m, and the weight of the self-compacting layer of the CRTSⅢ type slab was 12.4 kN / m. The revised finite element model was used to set up two construction steps to simulate the segmented construction of the track slab. Step 1: Activate the uniformly distributed load of section A. Step 2: Activate the uniformly distributed load of section B, and calculate the changes in the structural alignment during the two construction processes.

[0051] Then, after the track bed slab construction of the entire bridge is completed, the track surface alignment A at each location in section A will be determined. i for:

[0052] A i =A si +C Ai +C Bi

[0053] In the formula: A i —Elevation of control point i within segment A;

[0054] A si —Design elevation of control point i within segment A;

[0055] C Ai —The linear change of control point i within section A during construction of section A;

[0056] C Bi —The linear changes of control point i within section A during the construction of section B;

[0057] Then, the track surface alignment B at various locations in section B. i for:

[0058] B i =B si +C Bi

[0059] In the formula: A i —Elevation of control point i within segment B;

[0060] B si —Design elevation of control point i within segment B;

[0061] C Bi —Linear changes of control point i within section B during construction of section B;

[0062] Finally, by adjusting the lengths of segments A and B, A is made... i Or B i The optimal lengths of segments A and B are found when the maximum value of the two linear shapes is minimized.

[0063] The beneficial effects of this invention are as follows:

[0064] This invention solves the problem that when laying ballastless track on bridges, the deformation of the bridge can cause changes in the track alignment, resulting in low track laying accuracy. It avoids large discrepancies between the actual construction and the designed track elevation, which could affect project acceptance. At the same time, it simplifies the construction process, reduces construction costs, and improves construction efficiency and quality. Attached Figure Description

[0065] Figure 1 This is a schematic diagram showing the layout of monitoring points during the construction processes of bridge cantilever casting and tensioning in this invention;

[0066] Figure 2 This is a schematic diagram of the casting construction of the base plate in this invention;

[0067] Figure 3 This is a schematic diagram of the bed slab division in this invention;

[0068] Figure 4 This is a construction schematic diagram of the side span track bed slab in this invention;

[0069] Figure 5 This is a construction schematic diagram of part of the mid-span track bed slab in this invention;

[0070] Figure 6 This is a construction schematic diagram of the remaining middle span track slab in this invention;

[0071] Figure 7 This is a segmentation diagram in an embodiment of the present invention;

[0072] Figure 8 This is a view of the rail surface profile in an embodiment of the present invention; Detailed Implementation

[0073] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0074] like Figures 1 to 8 As shown, a construction control method applicable to ballastless track laying on medium-span bridges includes the following steps:

[0075] A. Establish a finite element model of the bridge based on its design parameters;

[0076] B. Monitor the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and correct the finite element model to obtain the corrected finite element model after the first correction.

[0077] C. Using the modified finite element model, calculate the precamber of the ballastless track base plate at the design temperature;

[0078] D. After the entire bridge is closed, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the load weight is monitored, and the finite element model is corrected again to obtain the second corrected finite element model.

[0079] E. After the completion of the entire bridge base plate construction, the first re-measurement of point CPIII on the beam surface;

[0080] F. Divide the entire bridge's track bed into three sections;

[0081] G. The track bed slab, divided into three sections, is poured three times, and the optimal section length is determined.

[0082] H. According to the design elevation, lay the sleeper elevations for both side spans and part of the middle span, and then cast-in-place the corresponding track bed slabs.

[0083] I. Lay the remaining sleeper elevation at the mid-span according to the design elevation, and then cast in place the remaining mid-span track slab;

[0084] J. Based on the design elevation, the elevation of the rails across the entire bridge is finely adjusted using rail fasteners.

[0085] Furthermore, step B monitors the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and corrects the finite element model to obtain the first corrected finite element model, which includes the layout of linear monitoring points and temporary measurement points.

[0086] Furthermore, linear monitoring points are deployed, and the specific process is as follows:

[0087] First, five measuring points are set up on one beam segment of the beam surface, and the five measuring points are in a straight line;

[0088] Then, five measuring points were set up on the other beam segments, with each measuring point corresponding to the previous one.

[0089] Furthermore, temporary measurement points were set up, and the specific process is as follows:

[0090] First, set up measuring point No. 1 on the side wall of the top slab of the beam;

[0091] Then, measuring point No. 2 is set up at the transition between the top plate and the web of the beam;

[0092] Next, measuring point No. 3 was set up on the bottom plate of the beam;

[0093] Finally, the remaining three measuring points are symmetrical to measuring points 1, 2, and 3 along the centerline of the beam.

[0094] Furthermore, step C uses a modified finite element model to calculate the precamber of the ballastless track base plate at the design temperature. The specific process is as follows:

[0095] First, based on the final target alignment of the track surface and the subsequent load on the upper bridge of the track slab, calculate the top elevation of the base plate point by point;

[0096] Then, the top surface elevation G of the i control point on the base plate i The following relationship must be satisfied:

[0097] G i =S i +Y i

[0098] In the formula: S i —Design elevation of control points;

[0099] Y i —Calculation of deflection at control point i;

[0100] Finally, calculate the deflection Y. i The calculation considers the remaining load on the entire bridge deck, including the track slab / double-block sleeper, ballast slab / self-compacting concrete, rails, fasteners, and contact wire, after the base plate is constructed.

[0101] Furthermore, after the entire bridge is closed in step D, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the loaded weight is monitored, and the finite element model is revised again to obtain the second revised finite element model. The specific process is as follows:

[0102] First, after the entire bridge is closed, CPIII measuring points are set on the bridge deck to carry out the pouring of the base plate;

[0103] Then, during the pouring process, the relationship between the bridge alignment and the loaded weight was monitored, and the finite element model was revised again to obtain the second revised finite element model.

[0104] Subsequently, the revised items included the elastic modulus of bridge concrete and the unit weight of the foundation slab concrete.

[0105] Finally, if the ambient temperature during the casting of the base plate differs significantly from the design temperature, the influence of temperature should be eliminated using a modified finite element model, while avoiding construction of the base plate in strong winds.

[0106] Furthermore, after the completion of the entire bridge base plate construction in step E, the first re-measurement of point CPIII on the beam surface was conducted. The specific process is as follows:

[0107] After the construction of the bridge's base plate was completed, the bridge deck gained additional weight, and the beam's alignment changed. The first remeasurement of point CPIII on the beam surface was conducted.

[0108] Furthermore, step F divides the entire bridge's track bed slab into three sections, as detailed below:

[0109] First, the entire bridge track bed slab is divided into three sections: left section A, section B, and right section A.

[0110] Then, the left A section track bed slab includes the left side span track bed slab and part of the middle span track bed slab; the right A section track bed slab includes the right side span track bed slab and part of the middle span track bed slab.

[0111] Finally, the track bed slab for section B is the mid-span track bed slab.

[0112] Furthermore, in step G, the track slab, divided into three sections, undergoes three pouring processes, as detailed below:

[0113] First, the cast-in-place track slab of the entire bridge was divided into three sections and poured in three stages.

[0114] Then, during the pouring process, after the left A section and right A section of the track bed slab were poured, the B section of the track bed slab with the largest deflection was adjusted again according to the design elevation. In fact, the B section of the track bed slab was raised once, reducing its final deflection on the rail surface.

[0115] Furthermore, in step G, the optimal segment length is determined, and the specific process is as follows:

[0116] First, in the first revised finite element model, the weight of the cast-in-place track slab was simulated using a uniformly distributed load. The weight of the double-track track slab of the CRTS double-block track structure was 31.2 kN / m, and the weight of the self-compacting layer of the CRTSⅢ type slab was 12.4 kN / m. The revised finite element model was used to set up two construction steps to simulate the segmented construction of the track slab. Step 1: Activate the uniformly distributed load of section A. Step 2: Activate the uniformly distributed load of section B, and calculate the changes in the structural alignment during the two construction processes.

[0117] Then, after the track bed slab construction of the entire bridge is completed, the track surface alignment A at each location in section A will be determined. i for:

[0118] A i =A si +C Ai +C Bi

[0119] In the formula: A i —Elevation of control point i within segment A;

[0120] A si —Design elevation of control point i within segment A;

[0121] C Ai —The linear change of control point i within section A during construction of section A;

[0122] C Bi —The linear changes of control point i within section A during the construction of section B;

[0123] Then, the track surface alignment B at various locations in section B. i for:

[0124] B i =B si +C Bi

[0125] In the formula: A i —Elevation of control point i within segment B;

[0126] B si —Design elevation of control point i within segment B;

[0127] C Bi —Linear changes of control point i within section B during construction of section B;

[0128] Finally, by adjusting the lengths of segments A and B, A is made... i Or B i The optimal lengths of segments A and B are found when the maximum value of the two linear shapes is minimized.

[0129] Specifically, step B involves monitoring the deformation data of the bridge during the pouring and tensioning process, and then correcting the finite element model to obtain the first corrected finite element model. The main items corrected include the elastic modulus of concrete, unit weight, and weight of the formwork.

[0130] Specifically, in step C, when calculating the precamber of the ballastless track base plate under the design temperature using a modified finite element model, the spacing between the elevation control points on the top surface of the base plate along the bridge direction should generally not exceed 6m.

[0131] Specifically, step H involves laying the sleeper elevations for both side spans and part of the middle span according to the design elevation. The specific process is as follows:

[0132] First, using the re-measured CPIII point, according to the design elevation, the elevations of the sleepers on both side spans and part of the middle span were laid. The track bed slabs for the two side spans were then cast in place, and the track bed slabs for part of the middle span were constructed.

[0133] Then, after the construction was completed, the alignment of the bridge changed due to the added weight on the bridge deck, and the CPIII point was remeasured for the second time.

[0134] Specifically, in step I, according to the design elevation, the remaining sleepers at the mid-span elevation are laid, and the remaining mid-span track slab is cast in place. The specific process is as follows:

[0135] First, using the CPIII point after the second remeasurement, the remaining sleeper elevation in the middle of the span was laid according to the design elevation, and the remaining middle span track slab was cast in place.

[0136] Then, due to the added weight on the bridge deck, the alignment changed, and point CPIII was remeasured for the third time.

[0137] Specifically, step J involves fine-tuning the rail elevation using rail fasteners based on the design elevation. The specific process is as follows:

[0138] Using the CPIII point after the third remeasurement, the rail elevation was finely adjusted based on the design elevation using rail fasteners.

[0139] Example 1

[0140] Laying ballastless track on medium-span bridges by segmenting the ballast slab and coordinating with CPIII measuring points for re-measurement can reduce the deviation of the track surface alignment and improve the quality of track laying without increasing engineering costs.

[0141] The specific implementation effect is illustrated using an example of an (88+160+88)m rigid frame continuous beam in a certain project, which is equipped with CRTS double-block track slabs. The bridge elevation layout is shown in [reference needed]. Figure 7 The bridge has a single-box, single-cell cross-section, with reinforced concrete piers 47.5m high. The beams are made of C60 concrete, the pier body within 4m of the pier top is made of C60 concrete, and the rest of the body is made of C40 concrete.

[0142] Using the modified finite element model, the reasonable lengths of sections A and B were calculated and determined. The schemes for segmented construction of the track slab and the track surface alignment for conventional track laying were calculated. Three schemes for the segment lengths of the track slab were developed: Scheme 1 (section A + section B + section A) lengths are (143 + 50 + 143) m; Scheme 2: (147 + 42 + 147) m; and Scheme 3: (151 + 34 + 151) m. In the conventional track laying scheme, the maximum deflection of the main span track surface was -12.4 mm, occurring at the mid-span, exceeding the "High-Speed ​​Railway Track Engineering Construction Quality Acceptance Standard" (TB). According to the requirement of -10mm limit in 10754-2018, in the segmented casting scheme, Scheme 1 has a maximum rail surface deflection of -8.5mm, which also occurs at the mid-span of the main span, and -6.5mm at the A and B segment junctions on both sides. Scheme 2 has a maximum rail surface deflection of -7.8mm, which occurs at the A and B segment junctions on both sides, and -7.3mm at the mid-span of the main span. Scheme 3 has a maximum rail surface deflection of -8.5mm, which occurs at the A and B segment junctions on both sides, and -6.1mm at the mid-span of the main span. Scheme 2 has the smallest deflection and is the optimal solution for the segmented calculation length. All three track slab segmentation schemes can reduce the maximum rail surface deflection, ensuring that the maximum deflection meets the limit requirement. The rail surface elevation can be achieved to the design elevation through track fine-tuning.

[0143] This invention solves the problem that when laying ballastless track on bridges, the deformation of the bridge can cause changes in the track alignment, resulting in low track laying accuracy. It avoids large discrepancies between the actual construction and the designed track elevation, which could affect project acceptance. At the same time, it simplifies the construction process, reduces construction costs, and improves construction efficiency and quality.

Claims

1. A construction control method applicable to ballastless track laying on medium-span bridges, characterized in that: Includes the following steps: A. Establish a finite element model of the bridge based on its design parameters; B. Monitor the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and correct the finite element model to obtain the corrected finite element model after the first correction. C. Using the modified finite element model, calculate the precamber of the ballastless track base plate at the design temperature; D. After the entire bridge is closed, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the load weight is monitored, and the finite element model is corrected again to obtain the second corrected finite element model. E. After the completion of the entire bridge base plate construction, the first re-measurement of point CPIII on the beam surface; F. Divide the entire bridge's track bed into three sections; G. The track bed slab, divided into three sections, is poured three times, and the optimal section length is determined. H. According to the design elevation, lay the sleeper elevations for both side spans and part of the middle span, and then cast-in-place the corresponding track bed slabs. I. Lay the remaining sleeper elevation at the mid-span according to the design elevation, and then cast in place the remaining mid-span track slab; J. Based on the design elevation, the rail elevation of the entire bridge is finely adjusted using rail fasteners; Step G involves determining the optimal segment length, and the specific process is as follows: First, in the first revised finite element model, the weight of the cast-in-place track slab was simulated by a uniformly distributed load. The weight of the double-track track slab of the CRTS double-block track structure was 31.2 kN / m, and the weight of the self-compacting layer of the CRTSⅢ type slab was 12.4 kN / m. The revised finite element model was used to set up two construction steps to simulate the segmented construction of the track slab. Step 1: Activate the uniformly distributed load of section A. Step 2: Activate the uniformly distributed load of section B, and calculate the changes in the structural alignment during the two construction processes. Then, after the track bed slab construction of the entire bridge is completed, the track surface alignment at each location in section A is determined. for: ； In the formula: ——In paragraph A Elevation of control points; ——In paragraph A Design elevation of control points; ——Section A construction within Section A Linear variation of control points; —Section B construction within Section A Linear changes of control points; Next, the track surface alignment at various locations in section B. for: (Equation 6-2) In the formula: B i —Section B Elevation of control points; —Section B Design elevation of control points; —Construction of Section B within Section B Linear changes of control points; Finally, by adjusting the lengths of segments A and B, the following was achieved: or The optimal lengths of segments A and B are found when the maximum value of the two linear shapes is minimized.

2. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: Step B involves monitoring the deformation data of the bridge during the pouring and tensioning process in the cantilever construction, and then correcting the finite element model to obtain the first corrected finite element model, which includes the layout of linear monitoring points and temporary measurement points.

3. The construction control method for laying ballastless track on medium-span bridges according to claim 2, characterized in that: The specific process for setting up linear monitoring points is as follows: First, five measuring points are set up on one beam segment of the beam surface, and the five measuring points are in a straight line; Then, five measuring points were set up on the other beam segments, with each measuring point corresponding to the previous one.

4. The construction control method for laying ballastless track on medium-span bridges according to claim 2, characterized in that: The specific process for setting up temporary measurement points is as follows: First, set up measuring point No. 1 on the side wall of the top slab of the beam; Then, measuring point No. 2 is set up at the transition between the top plate and the web of the beam; Next, measuring point No. 3 was set up on the bottom plate of the beam; Finally, the remaining three measuring points are symmetrical to measuring points 1, 2, and 3 along the centerline of the beam.

5. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: Step C uses a modified finite element model to calculate the precamber of the ballastless track base plate at the design temperature. The specific process is as follows: First, based on the final target alignment of the track surface and the subsequent load on the upper bridge of the track slab, calculate the top elevation of the base plate point by point; Then, the base plate Top surface elevation of control points The following relationship must be satisfied: ； In the formula: —— Design elevation of control points; —— Calculate the deflection of the control points; Finally, calculate the deflection. The calculation considers the remaining load on the entire bridge deck, including the track slab / double-block sleeper, ballast slab / self-compacting concrete, rails, fasteners, and contact wire, after the base plate is constructed.

6. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: After the entire bridge is closed in step D, CPIII measuring points are set on the bridge deck for the pouring of the base plate. During the pouring process, the relationship between the bridge alignment and the loaded weight is monitored, and the finite element model is revised again to obtain the second revised finite element model. The specific process is as follows: First, after the entire bridge is closed, CPIII measuring points are set on the bridge deck to carry out the pouring of the base plate; Then, during the pouring process, the relationship between the bridge alignment and the loaded weight was monitored, and the finite element model was revised again to obtain the second revised finite element model. Subsequently, the revised items included the elastic modulus of bridge concrete and the unit weight of the foundation slab concrete. Finally, if the ambient temperature during the casting of the base plate differs significantly from the design temperature, the influence of temperature should be eliminated using a modified finite element model, while avoiding construction of the base plate in strong winds.

7. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: After completing the construction of the entire bridge base plate in step E, the first re-measurement of point CPIII on the beam surface was carried out. The specific process is as follows: After the construction of the bridge's base plate was completed, the bridge deck gained additional weight, and the beam's alignment changed. The first remeasurement of point CPIII on the beam surface was conducted.

8. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: Step F divides the entire bridge's track bed slab into three sections, as detailed below: First, the entire bridge track bed slab is divided into three sections: left section A, section B, and right section A. Then, the left A section track bed slab includes the left side span track bed slab and part of the middle span track bed slab; the right A section track bed slab includes the right side span track bed slab and part of the middle span track bed slab. Finally, the track bed slab for section B is the mid-span track bed slab.

9. The construction control method for laying ballastless track on medium-span bridges according to claim 1, characterized in that: Step G involves three pours of concrete for the track slab, which is divided into three sections. The specific process is as follows: First, the cast-in-place track slab of the entire bridge was divided into three sections and poured in three stages. Then, during the pouring process, after the left A section and right A section of the track bed slab were poured, the B section of the track bed slab with the largest deflection was adjusted again according to the design elevation. In fact, the B section of the track bed slab was raised once, reducing its final deflection on the rail surface.

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