A construction method for cast-in-place beams spanning railways

Abstract

This invention discloses a construction method for cast-in-place beams spanning railways, mainly including the rotation of T-shaped cast-in-place beams and the construction of side span cast-in-place beams. The T-shaped cast-in-place beams are constructed in segments, and a pre-rotation step is set up. The monitoring data of the pre-rotation guides the formal rotation. Furthermore, the support system of the side span cast-in-place beams is constructed simultaneously with the construction of the T-shaped cast-in-place beams, which improves construction efficiency and helps ensure the overall safety of the construction of the cast-in-place beams spanning railways.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology. More specifically, this invention relates to a method for constructing a cast-in-place beam spanning a railway. Background Technology

[0002] In the construction of bridges spanning railways, due to the presence of railway traffic below and the large length of the overpass beam, the entire bridge is divided into several different parts for separate construction, which are then assembled into a complete bridge. Currently, a common construction method is to divide the bridge beam into two parts, construct them separately at the piers on both sides of the railway using the cantilever method, and then join them together above the railway. However, this method is not suitable for situations where the clearance between the beam and the catenary of the railway line is small. Furthermore, setting up rotation systems on both sides of the railway results in high construction costs, difficulty in aligning the rotation direction, and low construction efficiency. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0004] Another objective of this invention is to provide a construction method for cast-in-place beams spanning railways, in order to solve the technical problem of low overall construction efficiency in existing technologies when the clearance between bridges and railways is small, due to the lack of mature and stable construction schemes.

[0005] To achieve these objectives and other advantages according to the present invention, a method for constructing a cast-in-place beam over a railway is provided, comprising the cast-in-place construction of the rotating section of the T-beam, the rotation construction of the rotating section, and the construction of the side span cast-in-place section, specifically including the following steps:

[0006] S1 and T-shaped cast-in-place beams correspond to three adjacent piers. One transition pier is located on the north side of the railway, and another transition pier and the main rotating pier are located on the south side of the railway. The middle pier is the main rotating pier, and the other two are transition piers. First, the site is leveled and paved, and the pile foundations, abutments, pier bodies, and cap beams of these three piers are constructed simultaneously.

[0007] S2. On the south side, along the direction parallel to the railway, the T-shaped cast-in-place beam rotation section is constructed. The rotation section is divided into 4 segments and adopts a drilled pile + steel pipe column + cast-in-place beam support system. The cast-in-place beam support is composed of Bailey panels + disc buckle support frame. The concrete is poured and tensioned and grouted in sequence segment by segment. Simultaneously, the monitoring and protective ancillary facilities on both sides of the rotation section are constructed.

[0008] S3. After the two transition piers and the rotating section reach the design strength and pass the acceptance inspection, the corresponding disc buckle support frame of the rotating section is removed, the preparatory work before the rotation is completed, and a counterclockwise trial rotation is carried out. Then, the section is officially rotated to the design position within the vertical skylight point. After the beam posture is adjusted, the beam position is fixed. At the same time, the support system of the cast-in-place side spans on both sides of the rotating section is erected and pre-stressed. The support system has reserved space so as not to affect the rotation construction.

[0009] S4. After the rotation is completed, the concrete pouring of the side span cast-in-place section is carried out and the prestressing tensioning and grouting are completed.

[0010] S5. The support system of the cast-in-place section of the side span is dismantled to complete the system conversion, and the auxiliary structures of the construction of anti-collision guardrails, bridge deck paving, and bridge deck drainage are constructed.

[0011] Preferably, the foundation treatment is carried out in the area where the main pier of the rotating structure is located. There are irrigation culverts in the corresponding railway lines, and the irrigation culverts cross the cast-in-place beam support area. The cast-in-place beam support area is backfilled, and the bearing capacity of the backfill foundation is controlled to be not less than 300 kPa. The irrigation canals within the cast-in-place beam support area are relocated, and concrete circular culverts are pre-embedded in the cast-in-place beam support area.

[0012] Preferably, the cast-in-place beam support is preloaded, and the preload is 1.1 times the maximum construction load that the cast-in-place beam support can withstand. During preloading, the preloading area is divided into multiple preloading units, and the load is symmetrically distributed from the mid-span to both ends in a three-level loading sequence. The three levels of loading are 60%, 80%, and 100% of the preload value in the preloading unit, respectively. The unloading sequence follows the principle of loading first and unloading later, and unloading first after loading later, so as to unload evenly.

[0013] Preferably, during the rotation construction of the rotating section, a total of 6 monitoring points are set up at the centerline and edge line of both ends of the top surface of the beam. During the trial rotation, a high-precision automatic aiming total station is used to measure the monitoring points on the top surface of the beam. After the trial rotation, the data is analyzed to calculate the rotation speed, the horizontal chord length of the jogging cantilever rotation, the elevation change of the beam end, and the elevation difference change of the two sides of the beam, as reference technical parameters.

[0014] During the formal rotation, an automatic total station is set up on both the large and small mileage sides of the rotating pier. The station is established by resection, and the plane position of the monitoring point is measured by polar coordinate method and the elevation of the monitoring point is measured by trigonometric leveling method. The rotation angle is reported after synchronous measurement by the two stations. When the rotation enters the final jog, the measurement data of the two automatic total stations are checked against the observation points at both ends of the beam. The error is ≤2mm, and the average value is taken as the observation data until the rotation is in place.

[0015] Preferably, when constructing the support system for the cast-in-place section of the side span, a bored pile foundation is first installed on the side of the transition pier facing the rotating main pier. A set of casings is installed on the top of the bored pile foundation, and grouting holes are opened at the bottom of the side walls of the casings. Grouting pipes are connected to the grouting holes, and switch valves are installed on the grouting pipes. The support system includes steel pipe columns arranged vertically in an array. A support ring is connected to the outer side of the lower end of the steel pipe column. The support ring is used for anchoring between the steel pipe column and the top of the bored pile foundation. The inner side of the bottom of the steel pipe column is a closed structure. The bottom of each steel pipe column extends downward into a casing. The outer diameter of the steel pipe column matches the inner diameter of the casing. The position of the support ring is higher than the top of the casing. A sealing expansion membrane is connected between the top of the outer side of the sleeve and the part of the steel pipe column below the support ring. Scissor braces are connected between adjacent steel pipe columns. A pile cap is fixed on the top of each steel pipe column. A transverse distribution beam is welded together on a row of pile caps in the transverse direction. A row of longitudinal distribution beams is welded on the top surface of all transverse distribution beams in the transverse direction. A disc-lock bracket is set on the top of the row of longitudinal distribution beams. Then, longitudinal rods, small square timber, and bottom formwork bamboo plywood are set on the disc-lock bracket in sequence. One end of the longitudinal rod is supported on the top of the pier body of the transition pier. A static level is also set on the top of the pier body of the transition pier. The static level is used to monitor the height difference between the bottom of the two ends of the longitudinal rod in the longitudinal direction.

[0016] When the height difference measured by the hydrostatic level exceeds the set threshold, jacks are symmetrically installed below the support ring of the steel pipe column at the bottom of the lower end of the corresponding longitudinal rod. The jacks are used to lift the height corresponding to the height difference. Then, the grouting pipe is connected to the grouting pump, the switch valve is opened, and quick-setting cement is injected into the space at the bottom of the steel pipe column in the casing. After that, the switch valve is closed, and after the quick-setting cement reaches the setting time, the jacks are removed, and the bottom of the corresponding steel pipe column rests on the quick-setting cement.

[0017] Preferably, a plurality of stiffening ribs are connected between the surface of the support ring and the outer wall of the steel pipe column.

[0018] The present invention has at least the following beneficial effects: The construction method of the cast-in-place beam over the railway of the present invention mainly includes the rotation of the T-shaped cast-in-place beam and the construction of the side span cast-in-place beam. The T-shaped cast-in-place beam is constructed in segments, and a pre-rotation step is set. The monitoring data of the pre-rotation guides the formal rotation. At the same time as the construction of the T-shaped cast-in-place beam, the support system of the side span cast-in-place beam is constructed, which improves the construction efficiency and helps to ensure the safety of the overall construction of the cast-in-place beam over the railway.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the structure after the construction of the pile foundation, pile cap, pier body, and cap beam of the three bridge piers in step S1 of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the cast-in-place beam support for the rotating section in step S2 of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of step S3 of the present invention, after the casting of the rotating section is completed, rotating to the longitudinal direction of the bridge.

[0023] Figure 4 This is a structural schematic diagram of the side span cast-in-place section construction in step S4 of the present invention;

[0024] Figure 5 This is a schematic diagram showing the arrangement of the six monitoring points during the rotation construction of this invention;

[0025] Figure 6 This is a schematic diagram of the structure of the support system of the present invention;

[0026] Figure 7 This is a schematic diagram of the structure of the sleeve in one embodiment of the present invention;

[0027] The following are the reference numerals in the accompanying drawings: 1. Railway, 2. Main pier for rotation, 3. Transition pier, 4. Rotation section, 5. Cast-in-place section of side span, 6. Cast-in-place beam support, 7. Drilled pile foundation, 8. Sleeve, 9. Grouting pipe, 10. Support ring, 11. Steel pipe column, 12. Shear brace, 13. Pile cap, 14. Transverse distribution beam, 15. Longitudinal distribution beam, 16. Disc-type support, 17. Longitudinal bar, 18. Stiffening rib, 19. Rotation system, 20. Sealing expansion membrane. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0029] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] like Figure 1-4As shown, this invention provides a construction method for a cast-in-place beam spanning a railway, including the cast-in-place construction of the rotating section 4 of the T-beam, the rotation construction of the rotating section 4, and the construction of the side span cast-in-place section 5, specifically including the following steps:

[0031] S1 and T-shaped cast-in-place beams correspond to three adjacent piers. One transition pier (3) is located north of railway 1, another transition pier (3) and the main rotating pier (2) are located south of railway 1, and the middle pier is the main rotating pier (2). The other two are transition piers (3). On-site leveling and construction are carried out first, and the pile foundations, abutments, pier bodies, and cap beams of these three piers are constructed simultaneously. Combined with... Figure 1 As shown, from left to right, there are piers #0, #1, and #2. Pier #0 is on the back side of railway 1. Piers #0 and #2 are transition piers, and pier #1 is the main pier for rotation, pier #2.

[0032] S2. On the south side, along the direction parallel to railway 1, the cast-in-place section 4 of the T-beam is constructed. The cast-in-place section 4 is divided into 4 segments and adopts a system of bored piles + steel pipe columns 11 + cast-in-place beam support 6. The cast-in-place beam support 6 is composed of Bailey bridge panels + disc buckle support frame. The concrete is poured and tensioned and grouted in sequence for each segment. At the same time, the monitoring and protective auxiliary facilities on both sides of the cast-in-place section 4 are constructed.

[0033] The cast-in-place beam support 6 is set up for the cast-in-place construction of the corresponding rotation segment 4. Figure 2 As shown in the arrangement, the pre-rotation segment 4 follows... Figure 2 The concrete box girder is poured at a position parallel to the extension direction of railway 1, with a rotation angle of 79.5°. In this case, the single-sided rotation construction method is adopted for the section crossing railway 1. The core component of the rotation system 19, the ball joint, is located in the pier cap of the main pier 2. The rotation system 19 consists of a lower ball joint, a sliding track, an upper ball joint, a rotation traction system, and an axis fine-tuning system. It is set at the bottom of the rotation section 4 to realize the rotation construction of the main pier rotation section 4. The rotation construction generally includes the following process: completion of tensioning and grouting of concrete box girder → completion of construction of bridge deck ancillary facilities → removal of cast-in-place beam support 6 → appearance quality improvement of concrete box girder → removal of upper pier cap disc fastener support frame → cleaning of sliding track and laying of polytetrafluoroethylene plate under support feet → installation of temporary steel support for upper and lower turntables, removal of fixed steel and sand box → weighing, counterweighting, and re-weighing.

[0034] When installing the rotating system 19, the lower foundation is constructed first. The lower foundation is poured in two stages. According to the plane position of the ball joint and slide, the first stage is poured to 5cm below the bottom elevation of the ball joint and slide support. The foundation reinforcement is tied, the positioning steel plate of the ball joint support is pre-embedded, and after acceptance, concrete is poured. The slide and ball joint are installed, the remaining reinforcement of the lower turntable is tied, and the pre-embedded components such as the traction reaction seat, T-shaped box girder assembly support, and limit frame are pre-embedded. After acceptance, the second stage is poured.

[0035] After the foundation pit is excavated, the bottom elevation is measured. Once the elevation meets the requirements, the foundation layer construction begins. During foundation layer construction, the width and length are controlled in conjunction with the formwork reinforcement needs during the pile cap construction. Once the foundation layer concrete strength reaches 2.5 MPa, the pile heads can be removed. To ensure the quality of pile head treatment, the pile head is first cut along the pile perimeter with a saw to a depth of approximately 5 cm before removal. The pile head elevation is carefully controlled during removal, ensuring it is 10 cm above the bottom elevation of the pile cap. Simultaneously, the soil around the pile head extending into the pile cap is stripped until clean concrete is exposed. After completion, the pile head reinforcement is adjusted according to design requirements. If the pile head concrete is not dense and contains a lot of loose material, removal should continue until a dense concrete surface is reached. If the depression is not deep, it can be poured simultaneously with the pile cap concrete. If the depression is deep, the pile head should be filled in before reinforcement binding.

[0036] Next, the steel reinforcement is fabricated and installed, and the formwork and supports are fabricated and installed.

[0037] After S3, the two transition piers 3 and the rotating section 4 reach their design strength and pass inspection, the corresponding disc-lock support frame of the rotating section 4 is removed. Preparations for the rotation are completed, and a counter-clockwise trial rotation is performed at an angle of 3°. Then, in accordance with the Railway Bureau 1's operational line construction management regulations, a construction plan (II) is submitted. Within the vertical track maintenance window, the section is formally rotated to its designed position, reaching the desired location. Figure 3 At the indicated location, after adjusting the beam's posture, the beam's position is fixed. The turntable ball joint in the rotation system 19 is then closed. Simultaneously, the support system for the cast-in-place side spans 5 on both sides of the rotation segment 4 is erected and pre-stressed. The support system has reserved space to avoid affecting the rotation construction. During the trial rotation, the data is analyzed for comparison during the formal rotation.

[0038] The trial rotation will rotate the main bridge parallel to Railway 1 to the safety clearance boundary of Railway 1, minimizing the impact of the rotation on the operating time of Railway 1. The main purpose of the trial rotation is to test the accuracy of the theoretical traction force and to conduct two important data tests: 1. Rotation speed per minute; 2. Measurement of the horizontal arc distance rotated by the cantilever end with each jog, providing operational basis for precise positioning after the initial rotation. The trial rotation process will proceed as follows:

[0039] ① Before the test run, install polytetrafluoroethylene (PTFE) sheets under the support feet.

[0040] ② Pre-tighten the steel strands. Use a 350t jack to pre-tighten each steel strand with a force of 5-10KN. Pre-tightening should be done symmetrically and repeated several times to ensure that the force on each steel strand is uniform. During the pre-tightening process, care should be taken to ensure that the steel strands are wound parallel to each other on the upper turntable;

[0041] ③ Turn on the power to the main control console and pump station, start the pump station, and use the main control console to control both jacks to apply force and test rotation simultaneously. If they cannot rotate, further investigation and handling are required;

[0042] ④ During the trial run, two important data tests should be conducted:

[0043] ⑤ Rotation speed per minute, that is, the angle of rotation of the main bridge and the horizontal arc distance of rotation of the cantilever end per minute, should be controlled within the design requirements;

[0044] ⑤ The control is operated in a jog mode. The measurement team should measure the horizontal arc distance rotated by the cantilever end with each jog to provide an operational basis for precise positioning after the initial rotation is in place.

[0045] ⑥ During the trial rotation, the balance and stability of the rotating structure should be checked, as well as for any faults and cracks in key load-bearing areas. If any abnormalities are found, the trial rotation should be stopped, the cause identified, and appropriate corrective measures taken before the trial rotation can continue.

[0046] ⑦ Trial rotation angle: The trial rotation on both sides of railway 1 is based on the beam edge rotating to the upper space of the railway 1 wall without encroaching on the safe distance of the railway 1 contact network return line, specifically a clockwise rotation angle of 3 degrees.

[0047] ⑧ After the trial run, four 500t jacks should be used to lock the upper and lower turntables in place. At the same time, steel wedges should be inserted into the bottom of the turntable steel support feet for temporary locking. Four steel wedges should be inserted into the bottom of each steel support foot in all directions to prevent the beam from shifting.

[0048] S4, Combination Figure 4 As shown, after the rotation is completed, the concrete for the side span cast-in-place section 5 is poured and the prestressed tensioning and grouting are completed.

[0049] S5. The support system of the cast-in-place section 5 of the side span is dismantled to complete the system conversion, and the auxiliary structures of the anti-collision guardrail, bridge deck pavement, and bridge deck drainage are constructed.

[0050] The construction method of the cast-in-place beam overpass of the railway of the present invention mainly includes the rotation of the T-shaped cast-in-place beam and the construction of the side span cast-in-place beam. The T-shaped cast-in-place beam is constructed in segments, and a pre-rotation step is set up. The monitoring data of the pre-rotation guides the formal rotation. At the same time as the construction of the T-shaped cast-in-place beam, the support system of the side span cast-in-place beam is constructed, which improves the construction efficiency and helps to ensure the safety of the overall construction of the cast-in-place beam overpass of the railway.

[0051] In another technical solution, foundation treatment is carried out in the area where the main pier 2 is located. There is an irrigation culvert at the upstream and downstream lines of the corresponding railway 1. The irrigation culvert crosses the cast-in-place beam support area 6. The cast-in-place beam support area 6 is backfilled, and the bearing capacity of the backfill foundation is controlled to be not less than 300 kPa. The irrigation canal within the area of ​​the cast-in-place beam support area 6 is relocated, and a concrete circular culvert is pre-embedded in the cast-in-place beam support area 6.

[0052] In this project case, the main pier 2 of the rotating structure is located in an alluvial plain area. The bridge crosses a rural road. The terrain of the bridge site is flat with relatively developed vegetation. The ground elevation is approximately 21.45m-25.02m. The bridge piers and abutments are located in farmland and gullies. There is an irrigation culvert at K53+946m of the railway line 1 (both up and down lines). The irrigation canal runs through the support area of ​​the T-structure cast-in-place beam. According to the site survey, the highest annual water level of the irrigation canal is 21.8m. Therefore, based on the geological and hydrological conditions of this section and the construction organization arrangement, in order to ensure that the assembly area of ​​the cast-in-place beam support 6 meets the drainage requirements during the flood season, the support area will be backfilled. The backfill height is 1.5m. After backfilling, the elevation of the site is 23.3m. The bearing capacity of the backfill foundation will be controlled to be no less than 300kPa. The irrigation canal within the support area will be relocated. Three 1.5m diameter and 10cm thick concrete circular culverts will be pre-embedded in the support area.

[0053] In another technical solution, the cast-in-place beam support 6 is preloaded. The preload is 1.1 times the maximum construction load that the cast-in-place beam support 6 can withstand. During preloading, the preloading area is divided into multiple preloading units, and the load is symmetrically distributed from mid-span to both ends, with three levels of loading. The three levels of loading are 60%, 80%, and 100% of the preload value within the preloading unit, respectively. The unloading sequence follows the principle of loading before unloading and unloading the last loaded unit first, ensuring uniform unloading. Preloading ensures the support safety and stability of the cast-in-place beam support 6.

[0054] In another technical solution, such as Figure 5 As shown, during the construction of the rotating section 4, a total of 6 monitoring points were set up at the centerline and edge of both ends of the top surface of the beam. During the trial rotation, a high-precision automatic aiming total station was used to measure the monitoring points on the top surface of the beam. After the trial rotation, the data was analyzed to calculate the rotation speed, the horizontal chord length of the jogging cantilever rotation, the elevation change of the beam end, and the elevation difference change on both sides of the beam, as reference technical parameters.

[0055] During the formal rotation, an automatic total station is set up on both the large and small mileage sides of the rotating pier. The station is established by resection, and the plane position of the monitoring point is measured by polar coordinate method and the elevation of the monitoring point is measured by trigonometric leveling method. The rotation angle is reported after synchronous measurement by the two stations. When the rotation enters the final jog, the measurement data of the two automatic total stations are checked against the observation points at both ends of the beam. The error is ≤2mm, and the average value is taken as the observation data until the rotation is in place.

[0056] The overall goal of construction monitoring is to control the error between the bottom curve of the beam and the design value within ±3.0cm after the bridge is completed; control the height difference between the two ends of the closure section at the maximum cantilever within ±2.0cm; control the vertical alignment error of the main beam within ±2.0cm, and ensure smooth alignment; deviate the centerline of the bridge deck by 2.0cm; deviate the width of the bridge deck by ±1.0cm; and ensure the elevation connection error at the bridge abutments by ±0.3cm.

[0057] Before weighing, observation points on the beam are measured to obtain initial data, which is then reported to the monitoring unit. After the temporary supports for the rotating pier are removed, the observation points are measured again, and the results are reported to the monitoring unit. The monitoring unit analyzes the measurement data and determines the counterweight scheme. Our department then conducts measurements according to the requirements of the counterweight scheme, and the measurement data is promptly reported to the monitoring unit until the counterweight is completed. After weighing, a comprehensive as-built measurement of the beam is performed to confirm the beam parameters.

[0058] Preparation for measurements before rotation:

[0059] (1) Measure the monitoring points at both ends and sides of the beam as the initial observation data before rotation.

[0060] (2) Set up total stations in two groups at the major and minor mileage locations along the line. In addition to meeting the backsight requirements, the selected locations must have a wide field of view and be able to be connected between each other.

[0061] (3) It is planned to form 4 groups, with 3 people in each group. Two groups are responsible for setting up the total station, one group is responsible for observing the ball joint scale, and the other is the logistics support group, which is responsible for delivering the instruments and equipment and rotating lenses.

[0062] (4) Check whether the corner markings of the lower foundation are clear.

[0063] After setting up a total of 6 monitoring points at the centerline and edgeline of both ends of the top surface of the beam, measurements were taken during the rotation process:

[0064] (1) Lay out the angle markings on the lower turntable and extend them to the lower turntable support to provide a basis for the rotation progress;

[0065] (2) During the trial rotation, a high-precision automatic aiming total station was used to measure the monitoring points on the top surface of the beam. After the trial rotation, the data was analyzed to calculate the rotation speed, the horizontal chord length of the jogging cantilever rotation, the elevation change at the beam end, and the elevation difference between the two sides of the beam, so as to provide reliable technical parameters for the formal rotation.

[0066] (3) During the rotation process, an automatic aiming total station is set up on both the large and small mileage sides of the rotating pier. The station is established by resection, and the plane position of the monitoring point is measured by polar coordinate method and the elevation of the monitoring point is measured by trigonometric leveling method. The rotation angle is reported after the two stations measure synchronously. When the rotation enters the final jog, the observation points at both ends of the beam are measured synchronously with the jog. The measurement data of the two instruments are checked. If the error is ≤2mm, the average value is taken as the observation data until the rotation is in place.

[0067] (4) During the formal rotation, observe according to the command instructions and report the data to the commander in a timely manner;

[0068] (5) When the body rotates to the final jog, the observation points at both ends of the beam are measured simultaneously;

[0069] (6) After the rotation is completed, continue to monitor the plane and elevation at a fixed frequency. If the data exceeds the warning value, the construction supervisor should be notified in time.

[0070] After the box girder rotates, the monitoring points at the girder ends are measured again. The planar position is measured using a total station polar coordinate method, and the elevation is measured using trigonometric leveling. The measurement data is compared with the design data, and the measurement data is promptly reported to the monitoring unit. Measurements are then carried out according to the instructions of the monitoring unit. During the attitude adjustment process, the surveyors must monitor the entire process and report the data in a timely manner.

[0071] After the rotating beam is fixed, the bottom formwork edge line, etc., are laid out on the cast-in-place section support for the concrete beam. The measurement method and accuracy control for the side span cast-in-place section 5 are the same as those for the cast-in-place beam construction measurement described above. Elevation control should be carried out based on the elevation provided by the monitoring unit.

[0072] In another technical solution, such as Figure 6-7 As shown, when erecting the support system for the cast-in-place section 5 of the side span, firstly, a bored pile foundation 7 is installed on the side of the transition pier 3 facing the rotating main pier 2. A set of sleeves 8 is installed on the top of the bored pile foundation 7. A grouting hole is opened at the bottom of the side wall of the sleeve 8, and a grouting pipe 9 is connected to the grouting hole. A switch valve is installed on the grouting pipe 9. The support includes steel pipe columns 11 arranged vertically in an array. A ring 10 is connected to the outer side of the lower end of the steel pipe column 11. The ring 10 is used for anchoring between the steel pipe column 11 and the top of the bored pile foundation 7. The inner side of the bottom of the steel pipe column 11 is a closed structure. The bottom of each steel pipe column 11 extends downward into a sleeve 8. The outer diameter of the steel pipe column 11 matches the inner diameter of the sleeve 8. The position of the ring 10 is higher than the top of the sleeve 8. A sealing expansion membrane 20 is connected between the outer top and the part of the steel pipe column 11 below the support ring 10. A scissor brace 12 is connected between adjacent steel pipe columns 11. A pile cap 13 is fixed on the top of each steel pipe column 11. A transverse distribution beam 14 is welded together on a row of pile caps 13 in the transverse direction. A row of longitudinal distribution beams 15 is welded to the top surface of all transverse distribution beams 14 in the transverse direction. A disc-lock bracket 16 is set on the top of a row of longitudinal distribution beams 15. Then, a longitudinal rod 17, small square timber, and bottom formwork bamboo plywood are set on the disc-lock bracket 16 in sequence. One end of the longitudinal rod 17 is supported on the top of the pier body of the transition pier 3. A static level is also set on the top of the pier body of the transition pier 3. The static level is used to monitor the height difference between the bottom of the two ends of the longitudinal rod 17 in the longitudinal direction.

[0073] When the height difference measured by the hydrostatic level exceeds the set threshold, jacks are symmetrically installed below the support ring 10 of the steel pipe column 11 at the bottom of the lower end of the corresponding longitudinal rod 17. The jacks are used to lift the height corresponding to the height difference. Then, the grouting pipe 9 is connected to the grouting pump, the switch valve is opened, and quick-setting cement is injected into the space at the bottom of the steel pipe column 11 in the sleeve 8. After that, the switch valve is closed, and after the quick-setting cement reaches the setting time, the jacks are removed, and the bottom of the corresponding steel pipe column 11 rests on the quick-setting cement.

[0074] In response to the terrain with slightly high water content, and considering the impact of significant settlement on the structural safety of the sections erected on the top of the transition pier 3 and the support system, the use of sleeves 8 facilitates the rapid alignment and installation of the steel pipe columns 11. The longitudinal members 17 are made of large-diameter I-beams 10 steel. If a static level indicates an imbalance in the forces at both ends of the longitudinal members 17, or if the height difference or changes in height exceed the preset range, then before anchoring the steel pipe columns 11, the corresponding sections with significant settlement will be symmetrically positioned below the support rings 10. The jack applies an upward force to the steel pipe column 11, lifting it to the same height difference as measured by the corresponding static level. This creates a gap between the bottom of the steel pipe column 11 and the bottom of the casing 8. The switch valve is opened, and quick-setting cement is pumped in. After rapid solidification to meet the strength requirements, the switch valve is ensured to be completely closed and sealed. The jack is then lowered, and the foundation is anchored through the pre-embedded anchors between the support ring 10 and the top of the bored pile foundation 7. This improves installation efficiency and the safety of the support force in the early stages of installing the support system and foundation.

[0075] In another technical solution, such as Figure 7 As shown, a plurality of stiffening ribs 18 are connected between the surface of the support ring 10 and the outer wall of the steel pipe column 11. By providing stiffening ribs 18, the supporting strength of the support ring 10 structure is enhanced.

[0076] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for constructing a cast-in-place beam over a railway, characterized in that, The construction includes the cast-in-place construction of the rotating section of the T-beam, the rotation construction of the rotating section, and the construction of the side span cast-in-place section, specifically including the following steps: S1 and T-shaped cast-in-place beams correspond to three adjacent piers. One pier is located on the north side of the railway, and the other two piers are located on the south side of the railway. The middle pier is the main pier for rotation, and the other two piers are transition piers. First, the site is leveled and paved, and the pile foundations, pile caps, pier bodies, and cap beams of these three piers are constructed simultaneously. S2. On the south side, along the direction parallel to the railway, the T-shaped cast-in-place beam rotation section is constructed. The rotation section is divided into 4 segments and adopts a drilled pile + steel pipe column + cast-in-place beam support system. The cast-in-place beam support is composed of Bailey panels + disc buckle support frame. The concrete is poured and tensioned and grouted in sequence segment by segment. Simultaneously, the monitoring and protective ancillary facilities on both sides of the rotation section are constructed. S3. After the two transition piers and the rotating section reach the design strength and pass the acceptance inspection, the corresponding disc buckle support frame of the rotating section is removed, the preparatory work before the rotation is completed, and a counterclockwise trial rotation is carried out. Then, the section is officially rotated to the design position within the vertical skylight point. After the beam posture is adjusted, the beam position is fixed. At the same time, the support system of the cast-in-place side spans on both sides of the rotating section is erected and pre-stressed. The support system has reserved space so as not to affect the rotation construction. When constructing the support system for the cast-in-place section of the side span, firstly, a bored pile foundation is installed on the side of the transition pier facing the rotating main pier. A set of casings is installed upwards on the top of the bored pile foundation. Grouting holes are opened at the bottom of the side walls of the casings, and grouting pipes are connected to the grouting holes. Switch valves are installed on the grouting pipes. The support system includes steel pipe columns arranged vertically in an array. A support ring is connected to the outer side of the lower end of the steel pipe column. The support ring is used for anchoring between the steel pipe column and the top of the bored pile foundation. The inner side of the bottom of the steel pipe column is a closed structure. The bottom of each steel pipe column extends downwards into a casing, and the outer diameter of the steel pipe column matches the inner diameter of the casing. The support ring is positioned higher than the top of the sleeve. A sealing expansion membrane is connected between the top outer side of the sleeve and the part of the steel pipe column below the support ring. A pile cap is fixed at the top of each steel pipe column. A transverse distribution beam is welded together on a row of pile caps in the transverse direction. A row of longitudinal distribution beams is welded to the top surface of all transverse distribution beams in the transverse direction. A disc-lock bracket is installed on the top of the row of longitudinal distribution beams. A longitudinal rod is installed on the disc-lock bracket. One end of the longitudinal rod is supported on the top of the transition pier. A static level is also installed on the top of the transition pier. The static level is used to monitor the height difference between the bottom ends of the longitudinal rod in the longitudinal direction. When the height difference measured by the hydrostatic level exceeds the set threshold, jacks are symmetrically installed below the support ring of the lower steel pipe column. The jacks are used to lift the height corresponding to the height difference. Then, the grouting pipe is connected to the grouting pump, the switch valve is opened, and quick-setting cement is injected into the space at the bottom of the steel pipe column in the casing. After that, the switch valve is closed, and after the quick-setting cement reaches the setting time, the jacks are removed, and the bottom of the corresponding steel pipe column rests on the quick-setting cement. S4. After the rotation is completed, the concrete pouring of the side span cast-in-place section is carried out and the prestressing tensioning and grouting are completed. S5. The support system of the cast-in-place section of the side span is dismantled to complete the system conversion, and the auxiliary structures of the construction of anti-collision guardrails, bridge deck paving, and bridge deck drainage are constructed.

2. The construction method for cast-in-place beams spanning railways as described in claim 1, characterized in that, Foundation treatment was carried out in the area where the main pier of the rotating structure is located. There are irrigation culverts on the corresponding railway lines, which cross the cast-in-place beam support area. The cast-in-place beam support area was backfilled, and the bearing capacity of the backfill foundation was controlled to be no less than 300 kPa. The irrigation canals within the cast-in-place beam support area were relocated, and concrete circular culverts were pre-embedded in the cast-in-place beam support area.

3. The construction method for cast-in-place beams spanning railways as described in claim 1, characterized in that, The cast-in-place beam support is preloaded with a preload load of 1.1 times the maximum construction load that the cast-in-place beam support can withstand. During preloading, the preloading area is divided into multiple preloading units, and the load is symmetrically distributed from the mid-span to both ends in a three-level loading sequence. The three levels of loading are 60%, 80%, and 100% of the preload load value in the preloading unit, respectively. The unloading sequence follows the principle of loading first and unloading later, and unloading first, and unloading is performed evenly.

4. The construction method for cast-in-place beams spanning railways as described in claim 1, characterized in that, During the rotation construction of the rotating section, a total of 6 monitoring points were set up at the centerline and edge line of both ends of the top surface of the beam. During the trial rotation, a high-precision automatic aiming total station was used to measure the monitoring points on the top surface of the beam. After the trial rotation, the data was analyzed to calculate the rotation speed, the horizontal chord length of the jogging cantilever rotation, the elevation change of the beam end, and the elevation difference change of the two sides of the beam, as reference technical parameters. During the formal rotation, an automatic total station is set up on both the large and small mileage sides of the rotating pier. The station is established by resection, and the plane position of the monitoring point is measured by polar coordinate method and the elevation of the monitoring point is measured by trigonometric leveling method. The rotation angle is reported after synchronous measurement by the two stations. When the rotation enters the final jog, the measurement data of the two automatic total stations are checked against the observation points at both ends of the beam. The error is ≤2mm, and the average value is taken as the observation data until the rotation is in place.

5. The construction method for cast-in-place beams spanning railways as described in claim 1, characterized in that, Adjacent steel pipe columns are connected by scissor braces, and the longitudinal rods, small square timbers, and bottom formwork bamboo plywood are sequentially installed upwards on the disc-lock bracket; When the height difference measured by the static level exceeds the set threshold, the jacks are symmetrically installed below the support ring of the steel pipe column at the bottom of the lower end of the corresponding longitudinal rod.

6. The construction method for cast-in-place beams spanning railways as described in claim 5, characterized in that, Multiple stiffening ribs are connected between the surface of the support ring and the outer wall of the steel pipe column.

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