Construction method for laying ballastless track on long-span bridge

Abstract

This invention discloses a construction method for laying ballastless track on a long-span bridge, including establishing a theoretical model of the bridge and analyzing the alignment variation law; constructing the bridge deck ancillary structures and accepting the beam alignment; preloading the entire bridge, correcting the theoretical model and adjusting the cables; using relative elevation difference to control the layout of the base plate; roughly laying the track slab and conducting CPⅢ surveys, and using absolute elevation to fine-tune the track slab; pouring self-compacting concrete, and simultaneously unloading the self-compacting concrete counterweight load; laying the rails and compensating for temperature loads, and adjusting the alignment using fastener adjustment. This invention combines relative elevation difference control and absolute coordinate control during construction to precisely control each step of the process. Addressing the multi-valued coordinate problem of the CPIII control network on the bridge, new benchmark points are set up for construction control, and a rapid measurement method for the CPIII control network is proposed, ensuring that the laying of the ballastless track and the track alignment after the bridge completion meet the requirements.

Description

Technical Field

[0001] This invention relates to a construction method for laying ballastless track on long-span bridges, belonging to the field of ballastless track construction technology. Background Technology

[0002] Long-span cable-stayed bridges are flexible structures, significantly affected by bridge construction loads, environmental factors (wind, temperature variations, etc.), and construction errors. If conventional ballastless track construction methods are used, the main girder alignment will continuously change during construction, causing the coordinates of the CPⅢ track control points to also be dynamically changing, making them unsuitable for direct control of the base slab and track slab construction. Furthermore, after construction, the main girder of a low-tower cable-stayed bridge is prone to significant downward vertical displacement under secondary dead loads, deviating from the original design track elevation and affecting normal train operation. Summary of the Invention

[0003] In order to overcome the defects in the existing technology, the present invention aims to provide a construction method for laying ballastless track on long-span bridges.

[0004] The technical solution provided by this invention to solve the above-mentioned technical problems is: a construction method for laying ballastless track on a long-span bridge, comprising the following steps:

[0005] S1. Establish a theoretical model of the bridge using finite element software, conduct a preliminary analysis of the bridge structure, and obtain the theoretical alignment at each construction stage.

[0006] S2. Complete the construction of the bridge deck ancillary structures, measure the bridge deck alignment to obtain the actual alignment, compare the actual alignment with the theoretical alignment in S1, adjust the cable tension, and accept the beam alignment.

[0007] S3. Full bridge preloading: By comparing the alignment of the main bridge under different temperatures and loads, the deformation of the main bridge and the deformation of the bridge theoretical model under the corresponding construction conditions are analyzed to correct the stiffness of the bridge theoretical model. After loading, the cable force is adjusted to make the measured alignment consistent with the theoretical alignment. After the cable adjustment is completed, the cable is unloaded.

[0008] S4. Control the construction of the base plate by relative height difference. Lay out the base plate according to the elevation working benchmark on the anti-collision wall, and then pour the concrete of the base plate. After the construction is completed, measure the top surface line of the base plate and compare it with the theoretical line. Repair the base plate in the position that exceeds the limit.

[0009] S5. Lay the main span track slab of the main bridge and conduct CPⅢ survey; during the fine adjustment of the track slab, use the CPⅢ control network for construction control.

[0010] S6. Before the self-compacting concrete is poured, the load corresponding to the self-compacting concrete is preloaded between the crash barrier and the bridge railing. The corresponding counterweight load is unloaded at the same time as the self-compacting concrete is poured.

[0011] S7. Lay the rails and measure the rail surface elevation. Through temperature compensation and load compensation, convert the rail surface elevation to the design temperature and theoretical second-stage constant load state to obtain the difference between the design rail surface shape and the design rail surface shape. Adjust the rail shape using fastener adjustment to ensure that the rail surface shape after fine adjustment meets the requirements.

[0012] A further technical solution is to conduct a temperature monitoring experiment in step S3, continuously monitor the bridge deck alignment and cable force in real time, understand the changing patterns of the bridge deck alignment and cable force under temperature, and obtain temperature compensation.

[0013] A further technical solution is that, in step S3, temporary loads of construction materials and construction equipment are preloaded onto the bridge deck, while the bridge alignment is measured.

[0014] A further technical solution is that, in step S4, a fixed elevation working benchmark is set on the top surface of the protective wall according to theoretical calculations and system error control requirements; the base plate is constructed using the relative elevation difference method, that is, the elevation working benchmark of the top surface of the base plate is laid out relative to the top surface of the protective wall; the base plate is constructed using cast-in-place concrete, and its thickness is equal to the theoretical bridge elevation - the measured concrete elevation of the bridge deck protective layer + temperature load compensation.

[0015] A further technical solution is that the specific implementation method of the relative height difference method for the base plate construction in step S4 is as follows: a precision level is set up near the base plate control point p, and the design height difference H' between the base plate control point p and the elevation working benchmark point i is used as the basis for the construction. pi Vertically lay out the control point p on the base plate, and measure the actual height difference H between points p and i. pi Compare it with the design elevation difference; if H' pi ≠H pi Based on this, the elevation of the base plate control point P is finely adjusted, with a vertical fine adjustment amount of ΔH. pi =H pi -H' pi .

[0016] A further technical solution is that, in step S4, the relative height difference of the base plate is calculated as follows: through the preliminary pressure test, the 48-hour temperature deflection observation test, and the actual measurement of the elevation of the bare beam surface, the elevation of the working benchmark on the protective wall is calculated after all the second phase of dead load construction is completed and converted to the design reference temperature of 15℃. The elevation of the control point on the top surface of the base plate at the corresponding mileage position is then subtracted to obtain the height difference between the top surface of the base plate and the working benchmark.

[0017] A further technical solution is that the method for rapid measurement of the CPIII control network in step S5 is as follows:

[0018] Rapidly measure the CPIII control network laid out on the bridge. Divide the main bridge into 6 working faces with the tower location as the boundary and measure them simultaneously. The first and last two pairs of CPIII control points of each working face are stable. The elevation and plane network measurements are all closed at the first and last two pairs of CPIII control points.

[0019] A further technical solution is that, in step S6, before the self-compacting concrete is poured, the track plate is finely adjusted according to the theoretical alignment, and the actual construction thickness of the self-compacting concrete layer is determined by the elevation of the track plate and the elevation of the base plate.

[0020] The present invention has the following beneficial effects: The present invention proposes a construction method for laying ballastless track on long-span bridges. During the construction process, relative elevation difference control and absolute coordinate control are combined to accurately control each process. In view of the problem of multi-valued coordinates of the CPIII control network on the bridge, new benchmark points are set up to control the construction, and a method for rapid measurement of the CPIII control network is proposed, which can ensure that the laying of ballastless track and the track surface alignment after the bridge is completed meet the requirements. Attached Figure Description

[0021] Figure 1 This is a flowchart of the present invention;

[0022] Figure 2 This is a schematic diagram of the vertical measurement and control principle of the base plate. Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, a construction method for laying ballastless track on a long-span bridge according to the present invention includes the following steps:

[0025] S1. Establish a theoretical model of the bridge using finite element software, and conduct a preliminary analysis of the bridge structure to obtain the deformation law of the bridge structure under load and temperature, as well as the theoretical alignment at each construction stage.

[0026] S2. Complete the construction of the bridge deck ancillary structures, measure the bridge deck alignment, compare it with the theoretical alignment, adjust the cable tension of the stay cables, significantly adjust the main beam alignment to make the actual alignment match the theoretical alignment well, and accept the beam alignment.

[0027] S3. Full bridge preloading: During the loading process, the bridge is loaded in stages and the alignment is measured to correct the stiffness of the theoretical model and provide more accurate guidance for construction. After loading, the cable force is adjusted to make the measured alignment basically consistent with the theoretical alignment. After the cable adjustment is completed, the cable is unloaded.

[0028] By comparing the main bridge alignment under different temperatures and loads multiple times, the fit between the main bridge deformation and the deformation of the calculation model under the corresponding construction conditions was analyzed, and the bridge theoretical model was fine-tuned.

[0029] Specifically, temperature monitoring experiments were conducted to continuously monitor the bridge deck alignment and cable force in real time, and to understand the variation law of bridge deck alignment and cable force under the influence of temperature. If the ambient temperature during subsequent construction is different from the design reference temperature, temperature compensation should be considered.

[0030] Specifically, during the preloading of the entire bridge, it is not necessary to use a large number of water bags or buckets to simulate the subsequent second-stage dead load for preloading. Instead, it is only necessary to preload the existing construction materials, construction equipment, and other temporary loads onto the bridge deck while measuring the bridge's alignment.

[0031] S4. Control the construction of the base plate by relative height difference. Lay out the base plate according to the elevation working benchmark on the anti-collision wall and pour the concrete of the base plate. After the construction is completed, measure the top surface line of the base plate and compare it with the theoretical line. If the error is large, repair the base plate in the over-limit position.

[0032] Specifically, such as Figure 2 As shown, based on theoretical calculations and system error control requirements, a fixed elevation working benchmark is set on the top surface of the protective wall; the base plate is constructed using the relative elevation difference method, that is, the top surface of the base plate is laid out relative to the elevation working benchmark on the top surface of the protective wall; the specific implementation method is as follows: a precision level is set up near the base plate control point p, and the design elevation difference H' between the base plate control point p and the elevation working benchmark i is used as the basis for the construction. pi Vertically lay out the control point p on the base plate, and measure the actual height difference H between points p and i. pi Compare it with the design elevation difference; if H' pi ≠H pi Based on this, the elevation of the base plate control point P is finely adjusted, with a vertical fine adjustment amount of ΔH. pi =H pi -H' pi .

[0033] The calculation method for the relative height difference of the base plate construction is as follows: through the early pressure test, 48-hour temperature deflection observation test, and actual measurement of the elevation of the bare beam surface, the elevation of the working benchmark on the protective wall is calculated after all the second phase of dead load construction is completed and converted to the design reference temperature of 15℃. Subtracting the elevation of the control point on the top surface of the base plate at the corresponding mileage position, the height difference between the top surface of the base plate and the working benchmark can be obtained. This value remains unchanged under any load and temperature conditions.

[0034] S5. Lay the main bridge track slab and conduct CPⅢ survey; based on the CPⅢ survey results, monitor whether the elevation of the top surface of the track slab meets the requirements through absolute elevation measurement control;

[0035] The elevation of the top surface of the track slab = the elevation on the drawing + the deformation of the rail fasteners and protective layer, etc. + the temperature deformation correction; if the temperature during the fine-tuning construction of the track slab is inconsistent with the design reference temperature, the elevation needs to be corrected for temperature.

[0036] Specifically, the fine-tuning of the track slab is controlled by the CPIII control network. To prevent environmental factors from causing multi-valued CPIII three-dimensional control network, a rapid measurement method for the CPIII control network is adopted: First, the CPIII control network laid out on the bridge is rapidly measured. The main bridge is divided into 6 working faces with the tower location as the boundary and measured simultaneously. The first and last two pairs of CPIII control points of each working face are stable. The elevation and plane network measurements are closed at the first and last two pairs of CPIII control points.

[0037] The CPIII control network used during track slab fine-tuning adopts a "test and use" approach to ensure that atmospheric temperature changes are minimal and there is no wind load influence during measurement and use of the results.

[0038] S6. Before pouring the self-compacting concrete, preload the corresponding load of the self-compacting concrete on both sides of the contact wire column between the crash barrier and the bridge railing, and then unload the corresponding counterweight load while pouring the self-compacting concrete.

[0039] Specifically, before pouring the self-compacting concrete, the track slab is finely adjusted according to the theoretical alignment, and the actual construction thickness of the self-compacting concrete layer is determined by the elevation of the track slab and the elevation of the base plate.

[0040] S7. Lay the rails and measure the rail surface elevation. Through temperature and load compensation, convert the rail surface elevation to the design temperature and theoretical second-stage dead load state to obtain the difference between the design rail surface shape and the design rail surface shape. Adjust the rail shape using fastener adjustment to ensure that the rail surface shape after fine adjustment meets the requirements.

[0041] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of the present invention.

Claims

1. A construction method for laying ballastless track on a long-span bridge, characterized in that, Includes the following steps: S1. Establish a theoretical model of the bridge using finite element software, conduct a preliminary analysis of the bridge structure, and obtain the theoretical alignment at each construction stage. S2. Complete the construction of the bridge deck ancillary structures, measure the bridge deck alignment to obtain the actual alignment, compare the actual alignment with the theoretical alignment in S1, adjust the cable tension, and accept the beam alignment. S3. Full bridge preloading: By comparing the alignment of the main bridge under different temperatures and loads, the deformation of the main bridge and the deformation of the bridge theoretical model under the corresponding construction conditions are analyzed to correct the stiffness of the bridge theoretical model. After loading, the cable force is adjusted to make the measured alignment consistent with the theoretical alignment. After the cable adjustment is completed, the cable is unloaded. S4. Control the construction of the base plate by relative height difference. Lay out the base plate according to the elevation working benchmark on the anti-collision wall, and then pour the concrete of the base plate. After the construction is completed, measure the top surface line of the base plate and compare it with the theoretical line. Repair the base plate in the position that exceeds the limit. The specific implementation method of constructing the base plate using the relative elevation difference method in step S4 is as follows: A precision level is set up near the base plate control point p, and the design elevation difference H' between the base plate control point p and the elevation benchmark point i is used as the basis for the construction. pi Vertically lay out the control point p on the base plate, and measure the actual height difference H between points p and i. pi Compare it with the design elevation difference; if H' pi ≠H pi Based on this, the elevation of the base plate control point P is finely adjusted, with the vertical fine adjustment amount being ΔHp. i =H pi -H' pi ; In step S4, the relative height difference of the base plate is calculated as follows: through the early pressure test, 48-hour temperature deflection observation test, and actual measurement of the elevation of the bare beam surface, the elevation of the working benchmark on the protective wall is calculated after all the second phase of dead load construction is completed and converted to the design benchmark temperature of 15℃. The elevation of the control point on the top surface of the base plate at the corresponding mileage position is subtracted to obtain the height difference between the top surface of the base plate and the working benchmark. S5. Lay the main span track slab of the main bridge and conduct CPⅢ survey; during the fine adjustment of the track slab, use the CPⅢ control network for construction control. S6. Before the self-compacting concrete is poured, the load corresponding to the self-compacting concrete is preloaded between the crash barrier and the bridge railing. The corresponding counterweight load is unloaded at the same time as the self-compacting concrete is poured. S7. Lay the rails and measure the rail surface elevation. Through temperature compensation and load compensation, convert the rail surface elevation to the design temperature and theoretical second-stage constant load state to obtain the difference between the design rail surface shape and the design rail surface shape. Adjust the rail shape using fastener adjustment to ensure that the rail surface shape after fine adjustment meets the requirements.

2. The construction method for laying ballastless track on a long-span bridge according to claim 1, characterized in that, In step S3, a temperature monitoring experiment is conducted to continuously monitor the bridge deck alignment and cable force in real time, understand the changing patterns of the bridge deck alignment and cable force under the influence of temperature, and obtain temperature compensation.

3. The construction method for laying ballastless track on a long-span bridge according to claim 1, characterized in that, In step S3, construction materials and temporary loads of construction equipment are preloaded onto the bridge deck, and the bridge alignment is measured at the same time.

4. The construction method for laying ballastless track on a long-span bridge according to claim 1, characterized in that, In step S4, a fixed elevation working benchmark is set on the top surface of the protective wall according to theoretical calculations and system error control requirements; the base plate is constructed using the relative elevation difference method, that is, the elevation working benchmark of the top surface of the base plate is laid out relative to the top surface of the protective wall; the base plate is constructed using cast-in-place concrete, and its thickness is equal to the theoretical bridge elevation - the measured concrete elevation of the bridge deck protective layer + temperature load compensation.

5. The construction method for laying ballastless track on a long-span bridge according to claim 1, characterized in that, The method for rapid measurement of the CPIII control network in step S5 is as follows: Rapidly measure the CPIII control network laid out on the bridge. Divide the main bridge into 6 working faces with the tower location as the boundary and measure them simultaneously. The first and last two pairs of CPIII control points of each working face are stable. The elevation and plane network measurements are all closed at the first and last two pairs of CPIII control points.

6. The construction method for laying ballastless track on a long-span bridge according to claim 1, characterized in that, In step S6, before pouring the self-compacting concrete, the track slab is finely adjusted according to the theoretical alignment, and the actual construction thickness of the self-compacting concrete layer is determined by the elevation of the track slab and the elevation of the base plate.

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