Construction method of large-span cable-stayed bridge ballastless track

Abstract

The application relates to a construction method of a large-span cable-stayed bridge ballastless track, which comprises the following steps: before track construction on a bridge deck, monitoring temperature and linear change of the bridge deck to calculate temperature pre-camber of the bridge deck linear; establishing a finite element model of the cable-stayed bridge, constructing auxiliary facilities, monitoring linear change of the bridge deck before and after construction, correcting the stiffness of the finite element model based on the linear change of the bridge deck to calculate construction pre-camber of subsequent load after the construction stage; adjusting cable force of a stay cable to adjust the bridge deck linear to a first target linear; performing base plate lofting, and constructing the base plate; laying track plates to adjust the bridge deck linear to a second target linear; performing concrete construction, and laying steel rails to complete the construction. The application provides a construction method of a large-span cable-stayed bridge ballastless track, abandons a pre-loading process, corrects a finite element model according to actual construction conditions, simplifies a process, guarantees that the laying precision of the ballastless track meets a standard, and greatly saves a construction period.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge construction, in particular to a construction method of a large-span cable-stayed bridge CRTS III type ballastless track. BACKGROUND

[0002] The cable-stayed bridge is a kind of bridge in which the main beam is directly pulled on the bridge tower by many cables, and is a structural system composed of a pressure bearing tower, a tension cable and a bending main beam. It can be regarded as a multi-span elastic support continuous beam in which the piers are replaced by cables. It can reduce the bending moment in the beam body, reduce the building height, reduce the structure weight, save the material, and has a larger span than the beam bridge, and is the main bridge type of large-span bridges.

[0003] As of the end of 2020, the operating mileage of high-speed railways in China was nearly 37,900 kilometers, and the main line mainly used ballastless tracks. Compared with ballasted tracks, ballastless tracks are stable, accurate, comfortable to run, can effectively improve the track smoothness and line utilization rate, and have a relatively long maintenance cycle. It is the main track type used in high-speed railways in China.

[0004] The CRTS III type ballastless track is a ballastless track system that adopts technical standards and design concepts of the China Railway Track System (CRTS) series and is used in the fields of high-speed railways and urban rail transit.

[0005] The CRTS III type ballastless track uses prestressed concrete components and uses special connecting devices to fix the track on the foundation without traditional sleepers and ballast beds. The construction process of the ballastless track has high laying precision requirements, and the large-span cable-stayed bridge is relatively flexible and has obvious temperature effects. Therefore, when the CRTS III type ballastless track is applied to the large-span cable-stayed bridge, the laying precision of the ballastless track is difficult to meet the standards, and the overall process is relatively complex. For example, in related technologies, when establishing and correcting the finite element model, the commonly used method is to pre-load the bridge deck, obtain the correspondence between the bridge deck load and the preliminary deformation of the main beam of the cable-stayed bridge through the deformation of the main beam during the pre-loading process, and then correct the finite element model. The overall pre-loading process is relatively tedious, and the load quality accuracy is difficult to control. Even a small flow error can cause a significant difference in the deformation of the bridge deck, and the construction period is long. SUMMARY

[0006] The embodiments of the present application provide a construction method of a large-span cable-stayed bridge ballastless track to solve the technical problems of the laying precision of the CRTS III type ballastless track being difficult to meet the standards and the long construction period when the CRTS III type ballastless track is applied to the large-span cable-stayed bridge in related technologies.

[0007] The embodiment of the present application provides a construction method of a large-span cable-stayed bridge ballastless track, and the construction method of the large-span cable-stayed bridge ballastless track comprises the following steps:

[0008] Before track construction of a bridge deck, temperature and linear variation of the bridge deck are monitored to calculate temperature pre-camber of the bridge deck linear;

[0009] A finite element model of the cable-stayed bridge is established, auxiliary facilities are constructed, linear variation of the bridge deck before and after construction is monitored, the finite element model is corrected in stiffness based on the linear variation of the bridge deck, and construction pre-camber of subsequent load after the construction stage is calculated;

[0010] Cable force of a stay cable is adjusted to adjust the bridge deck linear to a first target linear, and the first target linear is a sum of a final bridge linear, a first construction pre-camber and a temperature pre-camber;

[0011] Setting-out of a base plate is performed, and the base plate is constructed;

[0012] Track slabs are laid to adjust the bridge deck linear to a second target linear, and the second target linear is a sum of the final bridge linear, a second construction pre-camber and the temperature pre-camber;

[0013] Concrete construction is performed, and rails are laid to complete the construction of the large-span cable-stayed bridge ballastless track.

[0014] In some embodiments, when the temperature and the linear variation of the bridge deck are monitored, measurement components are embedded on the bridge deck as linear observation points.

[0015] In some embodiments, the measurement components are measuring nails.

[0016] In some embodiments, the measuring nails are embedded on both sides of the bridge deck at a setting-out section of the base plate.

[0017] In some embodiments, the auxiliary facilities are auxiliary facilities with low precision requirements and uniform load.

[0018] In some embodiments, physical parameters of construction materials are detected to optimize the finite element model.

[0019] In some embodiments, the physical parameters comprise any one or more of a concrete elastic modulus, a unit weight, a compressive strength and a Poisson's ratio.

[0020] In some embodiments, when the base plate is set out, the measuring nails serve as setting-out reference points, and the height difference between the measuring nails and the base plate is used for setting-out.

[0021] In some embodiments, the laying of the track slabs comprises:

[0022] The track slabs are laid to a predetermined position;

[0023] According to the finite element model, the linear of the track slab is calculated, and the position of the track slab is fine-tuned according to the calculation result of the track slab linear.

[0024] In some embodiments, the linear of the track slab is detected before laying the steel rail, and whether it meets the linear error range is confirmed.

[0025] The technical scheme provided by the application has the beneficial effects including:

[0026] The application provides a construction method of a large-span cable-stayed bridge ballastless track. The temperature and the linear change of the bridge deck are monitored, and the temperature pre-camber of the bridge deck linear is calculated. Then, the stiffness of the finite element model is corrected by monitoring the linear change of the bridge deck before and after construction, and the subsequent construction such as adjustment of the cable force of the stay cable and the base plate is performed. Compared with the related art, the construction method provided in the embodiments of the application discards the preloading process and the linear control mode of equivalent load replacement, corrects the finite element model according to the actual construction condition, simplifies the process, corrects the finite element model more accurately, ensures that the laying precision of the ballastless track meets the standard, and especially, the preloading process may cause the preloading quality precision control problem and the related material equipment procurement and arrangement process, which are not needed in the embodiments of the application, thereby greatly saving the construction period. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The step flow chart of the construction method of the large-span cable-stayed bridge ballastless track in an embodiment of the application.

[0029] Figure 2 The structural schematic diagram of the ballastless track in an embodiment of the application.

[0030] Reference signs:

[0031] 1, base plate; 2, track slab; 3, concrete; 4, steel rail. DETAILED DESCRIPTION

[0032] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0033] As shown in Figure 1 and Figure 2 , wherein, Figure 1 is a step flow chart of a construction method of a ballastless track of a long-span cable-stayed bridge in an embodiment of the present application. Figure 2 is a structural schematic diagram of a ballastless track in an embodiment of the present application.

[0034] The embodiments of the present application provide a construction method of a ballastless track of a long-span cable-stayed bridge, which is especially suitable for a CRTS III type ballastless track.

[0035] A construction method of a ballastless track of a long-span cable-stayed bridge comprises the following steps:

[0036] In step S1, before track construction of a bridge deck, temperature and linear changes of the bridge deck are monitored to calculate a temperature camber of the linear shape of the bridge deck;

[0037] In step S2, a finite element model of the cable-stayed bridge is established, auxiliary facilities are constructed, changes of the linear shape of the bridge deck before and after construction are monitored, and the finite element model is corrected in stiffness based on the changes of the linear shape of the bridge deck to calculate a construction camber of subsequent loads after construction;

[0038] In step S3, cable forces of the stay cables are adjusted to adjust the linear shape of the bridge deck to a first target linear shape, and the first target linear shape is a sum of a final bridge completion linear shape, a first construction camber and a temperature camber;

[0039] In step S4, lofting of a base plate is performed, and the base plate 1 is constructed;

[0040] In step S5, track slabs 2 are laid to adjust the linear shape of the bridge deck to a second target linear shape, and the second target linear shape is a sum of the final bridge completion linear shape, a second construction camber and the temperature camber;

[0041] In step S6, concrete 3 construction is performed, and steel rails 4 are laid to complete the construction of the ballastless track of the long-span cable-stayed bridge.

[0042] The embodiment of the present application provides a construction method of a large-span cable-stayed bridge ballastless track, first, the temperature and the linear change of the bridge deck are monitored, and the temperature pre-camber of the bridge deck linear is calculated; then, the stiffness of the finite element model is corrected based on the linear change of the bridge deck before and after construction, and subsequent construction such as adjustment of cable force and base plate is carried out. Compared with the related art, the construction method provided by the embodiment of the present application discards the preloading process and the linear control mode of equivalent load replacement, corrects the finite element model according to the actual construction condition, simplifies the process, and makes the correction of the finite element model more accurate, thereby ensuring that the laying precision of the ballastless track meets the standard, and in particular, the preloading process, the quality precision control problem of the preloading process and the related material equipment procurement and arrangement process are not required in the embodiment of the present application, thereby greatly saving the construction period.

[0043] The following will be described in detail.

[0044] In step S1, the temperature and the linear change of the bridge deck are monitored before the construction of the bridge deck track, so as to calculate the temperature pre-camber of the bridge deck linear.

[0045] Before the construction of the bridge deck track, that is, after the completion of the main structure of the cable-stayed bridge.

[0046] In some embodiments, when the temperature and the linear change of the bridge deck are monitored, measurement components are buried on the bridge deck as linear observation points.

[0047] In some embodiments, the measurement component is a measuring nail.

[0048] In some embodiments, the measuring nail is buried on both sides of the bridge deck at the lofting section of the base plate.

[0049] Taking a large-span high-low tower cable-stayed bridge structure as an example, the main beam is a composite beam structure, the temperature sensitivity of which is relatively strong, the temperature gradient effect between the beam plates under the action of sunlight and the deformation under the action of temperature effect are relatively obvious, and the cable-stayed bridge also has the characteristics of different tower beam temperatures, different cable beam temperatures, and uneven temperature distribution of upstream and downstream cables. The calculation and analysis of the temperature sensitivity by simulation has low reliability. In the embodiment of the present application, the temperature and the measured linear change of the bridge deck are monitored through the measuring nail arranged in advance, and the temperature sensitivity data of the bridge deck linear can be obtained, and the temperature pre-camber of the bridge deck linear is calculated, which is more real and reliable.

[0050] In step S2, a finite element model of the cable-stayed bridge is established, construction auxiliary facilities are constructed, the linear change of the bridge deck before and after construction is monitored, the stiffness of the finite element model is corrected based on the linear change of the bridge deck, and the construction pre-camber of the subsequent load in the construction stage is calculated.

[0051] Through the establishment of the finite element model of the cable-stayed bridge in the construction stage, the analysis is made according to the material characteristics of the bridge structure and the construction schedule, the stiffness of the model is corrected through the implementation of part of the construction process and the construction camber is determined, and the laying accuracy of the ballastless track is improved.

[0052] In some embodiments, the accessory facility is an accessory facility with low precision requirements and uniform load, such as a crash barrier.

[0053] After the construction of the accessory facility with low precision requirements and uniform load, the bridge line shape before and after the construction is measured, the stiffness of the finite element model is corrected based on the deformation data of the main bridge, and the construction camber of each construction stage is obtained, which is more reasonable.

[0054] In some embodiments, the physical parameters of the construction material are detected to optimize the finite element model.

[0055] By detecting the physical parameters of the construction material, the accuracy of the finite element model analysis is further ensured.

[0056] In some embodiments, the physical parameters include any one or more of the elastic modulus, the unit weight, the compressive strength, and the Poisson's ratio of the concrete.

[0057] Taking a long-span high-low tower cable-stayed bridge structure as an example, the midas software is used to model the whole bridge of the cable-stayed bridge, a finite element model is established, and the stiffness of the main bridge model is corrected in combination with part of the measured data.

[0058] In order to understand the change of the main bridge line shape under the action of different static loads, the mid-span deformation of the main bridge under the action of uniform load (-35kN / m) is analyzed, wherein the value of the uniform load is the total load of the accessory facility with low precision requirements and uniform load (such as the crash barrier and other accessory facilities), the finite element model is corrected through the measured change of the main bridge line shape before and after the construction of this part of the load, and the mid-span deformation data of the main span of the main bridge under the action of the uniform load is listed in Table 1.

[0059] Table 1: Mid-span deformation of the main span of the main bridge under the action of the uniform load

[0060] Load case Calculated value / mm Measured value / mm - 35 kN / m uniform load -56.98 -55.54

[0061] According to the measured data, the stiffness correction coefficient of the finite element model is 0.975. The construction camber of the main bridge at different construction stages in the track construction process is calculated through the corrected finite element model, wherein the load required to be applied to the bridge deck in the track construction process mainly includes:

[0062] (1) Base plate (4 lines): 59.9kN / m;

[0063] (2) Waterproof layer and protective layer structure: 25.4kN / m;

[0064] (3) Self-compacting concrete between base plate and track bed plate (4 lines): 29.8 kN / m;

[0065] (4) Track plate (4 lines) (including track base): 52.7 kN / m;

[0066] (5) Others (cables, catenary, tracks, etc.): 11.6 kN / m.

[0067] The deflection of the main girder caused by the load of each stage is shown in Table 2, which lists the deformation data in the main span.

[0068] Table 2 Deformation of the main span of the main bridge under the construction load of different stages

[0069] Load type Load weight / kN / m Midspan deflection / mm Soffit 59.9 95.1 Waterproofing layer 25.4 40.3 Self-compacting concrete 29.8 47.3 Track slab 52.7 83.6 Other 11.6 18.4

[0070] Step S3, adjust the cable force of the stay cable to adjust the bridge line shape to the first target line shape, and the first target line shape is the sum of the final bridge line shape, the first construction camber and the temperature camber.

[0071] Before the construction of the base plate, the bridge line shape is adjusted to the pre-camber position by fine-tuning the cable force of the stay cable, and in the first target line shape, the first construction camber includes the construction camber of the base plate + protective layer + track plate + self-compacting concrete + other auxiliary facilities.

[0072] Step S4, perform base plate lofting, and perform construction on the base plate 1.

[0073] In some embodiments, when performing base plate lofting, the measuring nail is used as a lofting reference point, and the height difference between the measuring nail and the base plate is used for lofting.

[0074] The process of constructing the base plate 1 is a standard process, which will not be described here.

[0075] The lofting method used in the related art is to loft the base plate through CPIII control points, but in engineering examples, the cross-sectional deformation is 1.8 mm when the atmospheric temperature changes by 1℃, that is, when the temperature changes by less than 1℃, the CPIII control points on the bridge surface will be out of limits, the measurement control network cannot be adjusted, and the network needs to be determined multiple times. During the process of lofting the base plate through CPIII control points, it is necessary to perform multiple CPIII network operations.

[0076] In the embodiment of the present application, the survey pegs arranged on both sides of each lofting section in the early stage are used as the lofting reference points, and the lofting is performed according to the height difference between the survey pegs and the base plate. Since the linear shape of the same section of the beam body is the same under the action of load and environmental factors, the height difference between the survey pegs and the base plate remains unchanged. On the one hand, the influence of temperature and other environmental factors on the linear shape of the bridge deck is avoided, and the problem that the CPIII measurement control network needs to be repeatedly constructed during the construction of the base plate due to the influence of environmental factors is solved. On the other hand, the cross operation of the bridge deck during the construction of the base plate is facilitated, and the lofting process of the base plate only needs 20% of the time of the conventional lofting method, thereby further saving the construction period.

[0077] Step S5, laying the track slab 2 to adjust the linear shape of the bridge deck to a second target linear shape, which is the sum of the final bridge linear shape, the second construction camber and the temperature camber.

[0078] In some embodiments, laying the track slab 2 comprises:

[0079] Laying the track slab 2 to a predetermined position;

[0080] Calculating the linear shape of the track slab 2 according to the finite element model, and fine-tuning the position of the track slab 2 according to the calculation result of the linear shape of the track slab 2.

[0081] When laying the track slab 2 on the base plate 1, the track slab 2 is first roughly laid and then fine-tuned to the position through model calculation, which is more accurate.

[0082] In the second target linear shape, the second construction camber includes the construction camber of the self-compacting concrete and other auxiliary facilities.

[0083] Step S6, performing concrete 3 construction and laying steel rails 4 to complete the construction of the ballastless track of the long-span cable-stayed bridge.

[0084] The concrete 3 construction and the laying of the steel rails 4 are standard processes, which are not described here.

[0085] The concrete 3 and the track slab 2 are provided with an isolation layer as a waterproof layer and a protective layer.

[0086] In some embodiments, before laying the steel rails 4, the linear shape of the track slab 2 is detected to confirm whether it meets the linear error range.

[0087] If it meets the linear error range, the steel rail laying can be performed according to the standard operation process.

[0088] In the description of the present application, it should be noted that the terms "upper", "lower", and the like are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the methods or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be interpreted broadly, for example, "connecting" can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0089] It should be noted that in the present application, relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0090] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A construction method of a ballastless track of a long-span cable-stayed bridge, characterized in that, The construction method of the long-span cable-stayed bridge ballastless track comprises the following steps: Before the construction of the bridge track, the temperature and the linear change of the bridge are monitored to calculate the temperature pre-camber of the bridge linear; A finite element model of the cable-stayed bridge is established, the auxiliary facilities are constructed, the linear change of the bridge before and after the construction is monitored, the stiffness of the finite element model is corrected based on the linear change of the bridge, and the construction pre-camber of the subsequent load after the construction is calculated; The cable force of the stay cable is adjusted to adjust the linear of the bridge to the first target linear, and the first target linear is the sum of the final bridge linear, the first construction pre-camber and the temperature pre-camber; The lofting of the base plate is performed, and the base plate (1) is constructed; The track plate (2) is laid to adjust the linear of the bridge to the second target linear, and the second target linear is the sum of the final bridge linear, the second construction pre-camber and the temperature pre-camber; The concrete (3) is constructed, and the steel rail (4) is laid to complete the construction of the long-span cable-stayed bridge ballastless track; Wherein, when the temperature and the linear change of the bridge are monitored, the measuring components are buried on the bridge deck as linear observation points, and the measuring components are measuring nails; The auxiliary facilities are auxiliary facilities with low precision requirements and uniform load; When the lofting of the base plate is performed, the measuring nails are used as lofting reference points, and the lofting is performed according to the height difference between the measuring nails and the base plate (1); The laying of the track plate (2) comprises: Laying the track plate (2) to the predetermined position; According to the linear of the track plate (2) calculated by the finite element model, the position of the track plate (2) is fine-adjusted according to the calculation result of the track plate linear.

2. The construction method of a ballastless track of a long-span cable-stayed bridge according to claim 1, characterized in that, The measuring nails are buried on both sides of the bridge deck of the lofting section of the base plate.

3. The construction method of a ballastless track of a long-span cable-stayed bridge according to claim 1, characterized in that, The physical parameters of the construction materials are detected to optimize the finite element model.

4. The construction method of a long-span cable-stayed bridge ballastless track according to claim 3, characterized in that, The physical parameters include any one or more of the elastic modulus, the volume weight, the compressive strength and the Poisson's ratio of the concrete.

5. The construction method of a ballastless track of a long-span cable-stayed bridge according to any one of claims 1 to 4, characterized in that, Before laying the steel rail (4), the linear of the track plate (2) is detected to confirm whether it meets the linear error range.

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