Bridge pier column underpinning construction method for underneath crossing business line

Abstract

The invention discloses an underpinning construction method for a bridge pier column of an underneath pass business line, which comprises the following steps of: arranging gate-type pier columns on two sides of a to-be-dismantled bridge pier, and connecting two steel cross beams with the two gate-type pier columns. The horizontal sliding support and the steel cross beam form a sliding supporting system, and a sliding system is arranged on the sliding supporting system. And the sliding system is connected with the pier cap of the to-be-dismantled pier and the steel coupling beam. A temporary support beam body is installed on a steel cross beam, a pier cap of a to-be-dismantled pier is cut off, the pier cap slides out through a sliding system, and a steel coupling beam slides to a designed position. The steel coupling beam is connected with the two steel cross beams, and a bridge body is supported on the steel coupling beam mounting supports. According to the construction method, the adoption of large hoisting equipment can be avoided, the hoisting operation risk is reduced, and meanwhile, the railway driving safety and the business line equipment safety are further enhanced. Underpinning of the existing bridge pier stud is completed within a short time, the influence on railway operation is reduced to the minimum, and the economic loss of railway operation is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, specifically to a method for replacing pier columns of a bridge crossing an operational railway line. Background Technology

[0002] Due to railway planning and construction issues, it is sometimes necessary to cross existing operating railway lines during later railway construction. This is generally achieved by crossing under operating lines, which lowers the bridge deck elevation, reduces construction difficulty and safety risks, and saves investment. When new and old lines intersect, pier conflicts may occur. In such cases, the old piers can be demolished, and the load of the old bridge can be transferred to the new portal piers. That is, the new portal piers replace the old piers to support the existing railway main beams, and then the new track is constructed under the new portal piers.

[0003] Currently, the replacement of existing bridge piers on operational railway lines involves first constructing a reliable temporary support system to bear the load of the bridge beams, then dismantling the old piers, and finally constructing new portal piers to transfer the load of the bridge beams to the new piers. However, existing methods for replacing bridge piers typically employ cranes for lifting and installation. This method requires a large construction site and involves lifting operations near operational lines, significantly impacting railway traffic safety and the safety of equipment on the operational lines. It also results in long construction periods and high safety risks. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for replacing bridge piers under operating lines, which addresses the problem that existing bridge pier replacement methods result in long construction periods and make it impossible to replace bridge piers within the limited maintenance window.

[0005] A method for replacing bridge piers under an operational railway line includes the following steps: Portal pier columns are installed on both sides of the pier to be demolished, and two steel beams are connected to the two portal pier columns. The pier to be demolished is located between the two steel beams. A horizontal sliding support is installed near the pier cap. The horizontal sliding support and the steel crossbeam constitute a sliding support system. A sliding system is installed on the sliding support system. Connect the sliding system to the pier cap and steel connecting beam of the pier to be demolished; Temporary supports are installed on the steel crossbeams to bear the load of the bridge beams. The pier cap of the pier to be demolished is cut off, the sliding system lifts and suspends the pier cap, the sliding system slides the pier cap out of the operating line and the restricted hoisting area, and the steel connecting beam is slid to the design position; The steel connecting beam is connected to the two steel crossbeams, and supports are installed on the steel connecting beam to support the bridge beam.

[0006] In one embodiment, the steps for connecting the steel beam to the two portal pier columns are as follows: A lifting gantry is installed on the top of the portal pier, a sliding support is erected between the two portal piers, and an adjustment system is installed on the sliding support. The steel beam segments are lifted using the lifting gantry and then slid to the designed position using the adjustment system. All steel beam segments are connected and assembled into the steel beam.

[0007] In one embodiment, the steps of lifting the steel beam segment via the lifting gantry and sliding it to the designed position via the adjustment system are as follows: The first segment of the steel crossbeam is lifted by lifting the gantry frame and connected to one of the aforementioned portal pier columns; The middle section of the steel crossbeam is lifted by lifting the gantry and then slid to the designed position via the adjustment system. The tail section of the steel crossbeam is lifted by lifting the gantry frame and connected to another gantry pier column. The segments of the steel beam are assembled into one piece.

[0008] In one embodiment, the step of setting the adjustment system on the sliding bracket specifically involves: A track is provided on the sliding support, and a sliding beam for supporting the steel beam segment is installed on the track; A traction reaction seat is installed on the sliding bracket, and a traction rod is installed on the traction reaction seat; The traction rod is passed through the slide beam and then connected to the adjustment jack.

[0009] In one embodiment, the step of sliding the steel beam segment to the designed position via the adjustment system specifically involves: The continuous extension and retraction of the adjusting jack causes the sliding beam and steel crossbeam segments to slide. During the initial and intermediate sliding stages, the adjustment jacks automatically slide at a constant speed. When the sliding approaches the design position, the jacks switch to manual mode for inching adjustment.

[0010] In one embodiment, after the step of setting the sliding system on the sliding support system, the method further includes: A cutting line is drawn on the pier wall, with the starting end of the cutting line along the sliding direction of the pier cap being higher than the ending end.

[0011] In one embodiment, the step of drawing the cutting line on the pier wall further includes: Limiting strips are installed on both sides of the cutting line.

[0012] In one embodiment, the step of cutting off the pier cap of the pier to be demolished specifically involves: A drilling rig is used to drill a connecting hole on the pier wall along the cutting line. The wire saw is inserted through the connecting hole into the inner cavity of the pier cap and then out through another adjacent connecting hole. Multiple sets of wire saws are arranged around the circumference of the pier cap. The multiple sets of wire saws are symmetrically distributed about the plane containing the axis of the pier cap, and the multiple sets of wire saws cut the pier cap simultaneously.

[0013] In one embodiment, the specific steps of sliding the pier cap out of the operating line and the hoisting restriction area, and sliding the steel connecting beam to the design position are as follows: The traction system pulls the sliding trolley to slide on the slideway, which moves the pad beam and the spreader beam. The spreader beam suspends the pier cap and the steel connecting beam. The spreader beam moves the pier cap out of the operating line and the restricted hoisting area, and moves the steel connecting beam to the design position.

[0014] In one embodiment, when the sliding trolley slides on the slide rail, arc-shaped limiting members are provided on both sides of the sliding trolley, and a triangular correction plate is inserted between the arc-shaped limiting members and the slide rail to adjust the position of the sliding trolley on the slide rail.

[0015] The above-mentioned method for replacing bridge piers under operational railway lines has at least the following advantages: By installing temporary supports on newly constructed portal piers to support existing railway beams, the need for large scaffolding can be avoided, improving construction efficiency and reducing costs. In scenarios with limited track maintenance windows and confined space under existing railway beams, the removal of pier caps and the installation of steel connecting beams can be achieved through a sliding system, avoiding the use of large hoisting equipment, reducing the need for large construction sites, minimizing hoisting risks, and further enhancing railway traffic safety and the safety of operational line equipment. Completing the replacement of existing bridge piers in a short time minimizes the impact on railway operations, significantly reducing economic losses. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 This is a flowchart of a construction method for replacing the pier column of a bridge under an operational railway line. Figure 2 A schematic diagram of the first segment of the lifting steel crossbeam for lifting the gantry; Figure 3This is a schematic diagram showing the sliding of the middle segment of the steel crossbeam via an adjustment system. Figure 4 A schematic diagram illustrating the simultaneous lifting of the middle section of the two steel crossbeams of the gantry. Figure 5 This is a schematic diagram showing the middle segment of the steel beam supported by the adjustment system. Figure 6 A schematic diagram showing that the bottom of the sliding beam is equipped with a sliding plate and a limiting plate; Figure 7 A schematic diagram for installing the tail section of the lifting gantry; Figure 8 This is a schematic diagram showing the connection between the sliding system and the pier cap; Figure 9 This is a side view of the connection between the sliding system and the pier cap; Figure 10 This is a top view showing the connection between the sliding system and the pier cap; Figure 11 A schematic diagram of the anchor fixing device installed on the pad beam; Figure 12 This is a diagram showing the layout of the connecting holes for the pier cap. Figure 13 A schematic diagram showing the cutting lines and connecting holes on the pier cap; Figure 14 This is a schematic diagram of a steel connecting beam suspended by a sliding system. Figure 15 A schematic diagram showing temporary supports for the upper beam. Figure 16 A schematic diagram of multiple sets of wire saws symmetrically cutting the pier cap; Figure 17 A schematic diagram illustrating how the sliding system slides the steel connecting beam into place; Figure 18 This is a schematic diagram of a sliding trolley moving within a slide track. Figure 19 This is a schematic diagram of the construction of supports on a steel connecting beam; Figure 20 This is a schematic diagram after the construction equipment has been removed.

[0018] Figure label: 1-Beam body, 10-Pier to be demolished, 11-Pier cap, 12-Connecting hole, 13-Bearing pad, 14-Cutting line, 15-Connecting hole, 20-Portal pier column, 21-Steel crossbeam, 211-First end segment, 212-Middle segment, 213-Tail end segment, 22-Lifting gantry, 221-First lifting gantry, 222-Second lifting gantry, 223-Wind, 224-Embedded part, 225-Corner, 23-Sliding support, 24-Adjustment system, 241-Rail, 242-Sliding beam, 243-Adjustment reaction seat, 244-Traction rod, 245-Adjustment jack, 2 46-Slide plate, 247-Limiting plate, 25-Steel connecting beam, 26-Support, 30-Temporary support, 31-Distribution beam, 32-Support jack, 33-Padded seat, 34-Rubber pad, 40-Horizontal sliding bracket, 50-Sliding system, 51-Slide track, 52-Sliding trolley, 521-Arc-shaped limiting component, 53-Padded beam, 54-Spreader beam, 55-Connecting rod, 56-Correction plate, 60-Traction system, 61-Continuous jack, 62-Traction reaction seat, 63-Steel strand, 64-Anchor fixing device, 641-Reinforced column, 70-Suspension system, 71-Hanging rod, 80-Wire saw. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention; therefore, the invention is not limited to the specific embodiments disclosed below.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0022] Please see Figures 1 to 20One embodiment of the construction method for replacing the pier column of the bridge underpass of the operating line is as follows: a steel crossbeam 21 is set above the two portal pier columns 20 in the transverse direction of the bridge to connect them, the pier cap 11 of the old bridge pier 10 is removed, and then a steel connecting beam 25 is set between the two steel crossbeams 21. A support 26 is set on the steel connecting beam 25 to support the upper structure beam 1.

[0023] Please see Figure 1 Specifically, the construction method includes the following steps: Step S110: Set up portal pier columns 20 on both sides of the pier 10 to be demolished, and connect the two steel beams 21 to the two portal pier columns 20. The pier 10 to be demolished is located between the two steel beams 21.

[0024] Please refer to the following: Figure 2 and Figure 3 Specifically, two steel crossbeams 21 extend outwards along the transverse direction of the bridge, and the pier 10 to be demolished is located between the two steel crossbeams 21. There are a total of four portal pier columns 20, with two on each side of the bridge. The two portal pier columns 20 on the same side are connected as a single unit by a connecting beam. The two ends of a steel crossbeam 21 connect to a pair of portal pier columns 20 on each side of the bridge. It is understandable that only one portal pier column 20 may be installed on one side of the bridge. The portal pier column 20 has a relatively large width along the longitudinal direction of the bridge, and two steel crossbeams 21 are installed alternately on the top surface of the portal pier column 20.

[0025] During the construction of the steel crossbeam 21, a lifting gantry 22 is installed on top of the portal pier columns 20, and a sliding support 23 is erected between the two portal pier columns 20. An adjustment system 24 is installed on the sliding support 23. The steel crossbeam 21 segments are lifted by the lifting gantry 22 and slid to the designed position by the adjustment system 24. Finally, all the steel crossbeam 21 segments are connected and assembled into the steel crossbeam 21.

[0026] In one embodiment, the construction of the two steel beams 21 can be carried out simultaneously. That is, the lifting gantry 22 is used to lift the steel beam 21 segments simultaneously, and the adjustment system 24 is used to slide the steel beam 21 segments simultaneously.

[0027] Please refer to the following: Figure 4 In one embodiment, during the installation of the lifting gantry 22, embedded parts 224 are arranged on the side of the portal pier column 20, and brackets 225 are set at the bottom of the lifting gantry 22. The embedded parts 224 are connected to the brackets 225 by precision-rolled threaded steel bars, thereby enabling the lifting gantry 22 to be installed on the portal pier column 20. While ensuring the safety of the lower anchorage of the lifting gantry 22, sufficient clearance is provided for the lifting and sliding of the steel crossbeam 21 through the gantry.

[0028] In one embodiment, the two lifting gantry frames 22 are of two types: a first lifting gantry frame 221 and a second lifting gantry frame 222. The first lifting gantry frame 221 is a unidirectional yoke-type crane, used only for lifting the first segment 211 of the steel crossbeam 21. During lifting, the diagonal support on that side of the sliding bracket 23 is not installed; it is lifted between the portal pier column 20 and the operational railway pier. The diagonal support, distribution beam, and slider are installed before lifting the middle segment 212 of the steel crossbeam 21. The second lifting gantry frame 222 is a bidirectional yoke-type crane, used for lifting the middle segment 212 and the tail segment 213 of the steel crossbeam 21. During lifting, the segments are lifted from the outside of the portal pier column 20.

[0029] In one embodiment, the lifting height of the lifting gantry 22 should match the design height of the portal steel beam 21. The heights of the first lifting gantry 221 and the second lifting gantry 222 should be strictly controlled and should not exceed the elevation of the beam surface of the operating line beam 1. A limit switch is set at the upper end of the top beam of the gantry to prevent the winch 223 from slipping out, while reducing the impact on the safety of the operating line train and the safety of the operating line equipment.

[0030] In one embodiment, a sliding support 23 is erected around the outer perimeter of the pier 10 to be demolished. The height of the sliding support 23 should match the design height of the portal steel beam 21. The sliding support 23 adopts a four-steel pipe column plus connecting system, which is safe and stable. The upper two sides adopt diagonal bracing, which meets the strength, rigidity and stability of the support while reducing the material usage of the sliding support 23.

[0031] Please refer to the following: Figure 5 The adjustment system 24 includes a track 241, a sliding beam 242, an adjustment reaction seat 243, a traction rod 244, and an adjustment jack 245. The specific steps for setting up the adjustment system 24 on the sliding support 23 are as follows: A track 241 is set on the sliding support 23; a sliding beam 242 for supporting the steel crossbeam 21 segment is installed on the track 241; an adjustment reaction seat 243 is installed at the end of the sliding support 23; a traction rod 244 is installed on the adjustment reaction seat 243; and the traction rod 244 passes through the sliding beam 242 and connects to the adjustment jack 245.

[0032] In one embodiment, two sets of sliding beams 242 are provided, spaced apart on the track 241. The two sets of sliding beams 242 support the steel crossbeam 21 segment. A hole is provided in the middle of each sliding beam 242 for a traction rod 244 to pass through, and an adjustment jack 245 is installed on the latter of the two sliding beams 242. Four pads are provided on each sliding beam 242, located at both ends, supporting the steel crossbeam 21 segment. The four pads are symmetrically positioned on both sides of the center of gravity, below the vertical stiffening ribs on the sliding beam 242, with stiffening plates added on both sides of the stiffening ribs. The positions of the stiffening plates on the pads correspond to the positions of the stiffening plates on the sliding beam 242, ensuring accurate force transmission.

[0033] Please refer to the following: Figure 6 In one embodiment, a sliding plate 246 is installed at the bottom of the sliding beam 242 to reduce friction between the sliding beam 242 and the track 241, ensuring smooth sliding of the sliding beam 242 under load. Limiting plates 247 are installed on both sides of the sliding plate 246, forming limiting grooves with the sliding plate 246. The track 241 is accommodated within these grooves to prevent the sliding beam 242 from becoming detached from the track 241. Specifically, the traction rod 244 can be made of high-strength threaded steel, and the sliding plate 246 can be made of NGE plate.

[0034] Please see Figure 2 , Figure 3 and Figure 7 In one embodiment, the steel crossbeam 21 is formed by assembling multiple segments, including a first end segment 211, a middle segment 212, and a last end segment 213. The construction process of the steel crossbeam 21 is as follows: The first segment 211 of the steel crossbeam 21 is lifted by the lifting gantry 22 and connected to one of the portal pier columns 20. Then, the middle segment 212 of the steel crossbeam 21 is lifted by the lifting gantry 22 and slid to the designed position via the adjustment system 24. Finally, the last segment 213 of the steel crossbeam 21 is lifted by the lifting gantry 22 and connected to another portal pier column 20.

[0035] In this embodiment, the first segment 211 of the steel crossbeam 21 is lifted by the first lifting gantry 221, and then the first segment 211 is slid to the designed position by the movement of the winch 223 on the lifting gantry 221, and the steel-concrete joint section between the first segment 211 of the steel crossbeam 21 and the pier column is poured. The middle segment 212 of the steel crossbeam 21 is lifted by the second lifting gantry 222, and then the second lifting gantry 222 places the middle segment 212 of the steel crossbeam 21 on the adjustment system 24. Before the middle segment 212 of the steel crossbeam 21 lands on the adjustment system 24, the elevation of the steel crossbeam 21 is coarsely adjusted by using shims and shims. The lateral offset of the middle segment 212 of the steel crossbeam 21 is adjusted by the lateral sliding of the winch 223 on the lifting gantry 22 before it is placed on the adjustment system 24, therefore no lateral adjustment is required.

[0036] After the intermediate segment 212 of the steel crossbeam 21 is placed on the adjustment system 24, the sliding beam 242 and the intermediate segment 212 of the steel crossbeam 21 are moved by the continuous extension and retraction of the adjustment jack 245. The sliding is controlled by the same pump station jacks. The continuous extension and retraction of the jacks moves the sliding beam 242 and the intermediate segment 212 of the steel crossbeam 21 forward, and automatic and manual switching can be realized. Automatic uniform sliding is used in the initial and process sliding stages. When the sliding is close to the design position, it is switched to manual mode for inching adjustment. After the intermediate segment 212 of the steel crossbeam 21 is slid into place, the height difference at the four corners is finely adjusted by setting four jacks next to the pad of the sliding beam 242.

[0037] During the sliding process of the intermediate segment 212 of the steel crossbeam 21, scale lines are set on the sliding beam 242 for easy manual observation, and the synchronization of the sliding is monitored in conjunction with a laser sensor (displacement monitor). When the sliding is not synchronized, it can be seen from the scale lines on the limit plate 247 on the slide rail 51 and the monitoring data of the laser sensor, and adjustment can be achieved by sliding one side unilaterally.

[0038] Finally, the tail segment 213 of the steel crossbeam 21 is hoisted using the second lifting gantry 222, and then the tail segment 213 is slid to the designed position by the movement of the winch 223 on the lifting gantry 22. The steel crossbeam tail segment 213 and the steel-concrete joint section with the pier column are then poured. After the concrete pouring of the steel crossbeam 21 head segment 211 and the steel crossbeam 21 tail segment and the pier column meets the design requirements, the alignment of the steel crossbeam 21 middle segment 212 is adjusted according to the design alignment requirements. Finally, the steel crossbeam middle segment 212 is welded to the steel crossbeam 21 head and tail segments 213 to form a portal frame.

[0039] Step S120: A horizontal sliding support 40 is installed at the adjacent pier cap 11. The horizontal sliding support 40 and the steel crossbeam 21 constitute a sliding support system. A sliding system 50 is installed on the sliding support system.

[0040] Please refer to the following: Figure 8 Specifically, the horizontal sliding support 40 is used to increase the sliding length of the pier cap 11. The horizontal sliding support 40 extends beyond the operating line and the restricted lifting area along the transverse direction of the bridge, making it easier to slide the pier cap 11 to the outside of the operating line and the restricted lifting area. Using the portal pier that supports the old bridge as a component of the sliding support system can reduce the number of support beams and improve construction efficiency.

[0041] Please refer to the following: Figure 9 and Figure 10In one embodiment, the sliding system 50 includes a slide rail 51, a sliding trolley 52, a pad beam 53, and a spreader beam 54. The steps for installing the sliding system 50 on the sliding support system are as follows: The slide rail 51 is installed on the sliding support system; then, the sliding trolley 52 is installed on the slide rail 51; the pad beam 53 is installed on the sliding trolley 52; and finally, both ends of the spreader beam 54 are respectively positioned on the two sliding trolleys 52.

[0042] Because the sliding system 50 is located on the steel beam 21 of the portal pier, the space between the steel beam 21 of the portal pier and the existing operating line beam 1 is limited, thus restricting the design height of the sliding system 50. Therefore, it is necessary to conduct an on-site investigation and measurement of the limited height of the space below beam 1. Using skylights, dedicated personnel and surveyors will conduct on-site investigations and measurements to obtain specific data, facilitating subsequent steel structure design and construction procedures. The tallest component below beam 1 is the spreader beam 54. The height of the spreader beam 54 should be controlled to not exceed the lowest point of beam 1, ideally leaving a 2-3cm space to ensure smooth sliding.

[0043] In one embodiment, the spreader beam 54 is made of Q345 steel, with a thickness of 3cm. The thickness of the middle part of the spreader beam 54 is greater than that of the two ends. The structure of the spreader beam 54 is high in the middle (placed on top of the pier cap 11 and between the support pad stone 13) and low at both ends (sliding pad beams 53 are arranged below the two ends). It is mainly made of high-strength steel, which meets the structural stress requirements while providing the required height for the pad beams 53 and other steel components at both ends.

[0044] In one embodiment, the sliding trolley 52 is securely connected to the bottom of the pad beam 53 by bolts. The sliding trolley 52 needs to be set in conjunction with the arrangement of the spreader beams 54, and in principle, one sliding trolley 52 is set at the end of each spreader beam 54. Two pad beams 53 are set on each side of the slide rail 51. To ensure the overall stability of the pier cap 11 during sliding and to ensure that the sliding trajectories of the front and rear sliding trolleys 52 are basically consistent and straight during sliding, the front and rear pad beams 53 are firmly welded with steel sections, and the connection between the pad beams 53 and the spreader beams 54 is also firmly welded. To further enhance the rigidity of the sliding structure of the pier cap 11, the front and rear sliding trolleys 52 can be firmly welded with steel sections.

[0045] Please refer to the following: Figure 11In one embodiment, the sliding trolley 52 on the slide rail 51 is driven by a traction system 60. Specifically, the traction system 60 includes a continuous jack 61, a traction reaction seat 62, a steel strand 63, and an anchor fixing device 64. During installation, the traction system 60 is installed on the horizontal sliding support 40, the continuous jack 61 is installed on the traction reaction seat 62, one end of the steel strand 63 is connected to the continuous jack 61, and the other end of the steel strand 63 is connected to the pad beam 53 through the anchor fixing device 64. The continuous jack 61 serves as the power source for the traction system 60 and is installed at the end of the horizontal sliding support 40 together with the traction reaction seat 62, simultaneously meeting the length requirements for the overall sliding of the pier cap 11 out of the operating line and the restricted lifting range.

[0046] In one embodiment, the anchor fixing device 64 is provided with a reinforcing column 641, and the steel strand 63 is threaded through the reinforcing column 641, which can increase the strength of the anchor fixing device 64 and ensure the stability of the steel strand 63. The anchor fixing device 64 can be made of steel plate, with steel strand 63 channel holes opened in both layers of steel plate, and the tail steel plate is connected to fix the anchor. The number of steel strands 63 should be set according to the calculation result of the traction force required for the overall sliding of the pier cap 11, and an even number of steel strands 63 should be used to ensure uniform traction force. The bottom steel plate of the traction reaction seat 62 and the sliding beam 242 can be welded, and bolt holes can be provided for bolt connection and fixation to ensure reliability and reversibility.

[0047] Please refer to the following: Figure 12 In one embodiment, before installing the sliding system 50, the suspension connection holes 12 of the pier cap 11 are drilled first to facilitate the subsequent suspension of the pier cap 11 and prevent the sliding system 50 from affecting the drilling of the connection holes 12. The connection holes 12 are located between the two support pads 13 at the top and at the chamfered edge of the hollow pier cavity at the bottom, and the number is even. A total of four spreader beams 54 are provided, each requiring two holes. The spreader beams 54 are distributed in pairs, located between the two furthest support pads 13.

[0048] In one embodiment, after step S120, the method further includes: drawing a cutting line 14 on the pier wall, wherein the starting end of the cutting line 14 along the sliding direction of the pier cap 11 is higher than the ending end.

[0049] Please refer to the following: Figure 13 Specifically, cutting platforms are erected on the outer and inner sides of the pier wall. Cutting lines 14 are drawn on the pier wall using a laser level and an oil-based pen. The outer cutting line 14 is drawn first, followed by the inner line. A laser level and an oil-based pen can be used for marking. The two lines should be basically consistent.

[0050] Cutting line 14 is drawn using a laser level as a reference, and then marked with an oil-based pen and a steel ruler, with the tilt angle controlled at approximately 5‰. Due to the structural dimensions of the circular bridge piers, it is recommended to use four laser levels to facilitate drawing cutting line 14 in one go. Alternatively, one level can be used to draw the line segment by segment, paying attention to the continuity of the lines. Cutting line 14 should be verified using professional surveyors and instruments, checking its elevation, tilt angle, etc.

[0051] In one embodiment, the height of the cutting line 14 gradually decreases along the sliding direction of the pier cap 11, that is, the cutting line 14 exhibits a linear downward trend along the sliding direction, so that the starting end of the cutting line 14 along the sliding direction of the pier cap 11 is higher than the ending end. Alternatively, the cutting line 14 has multiple segments along the sliding direction of the pier cap 11, and the multiple segments of the cutting line 14 are spaced apart in the axial direction of the pier cap 11. In other words, the cutting line 14 on the pier wall can be set in a stepped shape, gradually descending along the sliding direction to facilitate sliding.

[0052] In one embodiment, the cutting line 14 is positioned below the solid section of the pier cap 11, at the beginning of the hollow pier cavity. This cutting position can shorten the height of the pier cap 11, reduce the overall weight of the pier cap 11 after cutting, and lower the requirements for stress calculations of the horizontal sliding support 40 and the sliding system 50. Simultaneously, selecting the position at the end of the solid section and the beginning of the hollow section, where the wall thickness of the hollow pier is minimum, reduces the cross-sectional area of ​​the pier cap 11 during cutting, thus reducing cutting time.

[0053] In one embodiment, after drawing the cutting line 14 on the pier wall, the method further includes installing limiting strips on both sides of the cutting line 14. The limiting strips can limit the cutting device during the cutting process of the pier cap 11, so that the cutting device moves along the cutting line 14 during the cutting process, ensuring that the final cut surface is flat.

[0054] Specifically, the limiting strips can be rubber strips, which are installed on both sides of the inner and outer cutting lines 14. The rubber strips are nailed into the concrete with cement nails at intervals of 8-10cm to ensure that the rubber strips are firmly installed. Wear-resistant rubber strips should be selected, and the width of the rubber strips should be 2-3cm. They are installed on both sides of the cutting line 14, and fixed after leaving the required dimensions for the cutting rope to work.

[0055] Step S130: Connect the sliding system 50 to the pier cap 11 of the pier to be demolished and the steel connecting beam 25.

[0056] Please refer to the following: Figure 14Specifically, the sliding system 50 and the pier cap 11 are connected by a suspension system 70, which includes a suspension rod 71. One end of the suspension rod 71 is connected to the spreader beam 54, and the other end is connected to the pier cap 11 through a connecting hole 12. A lifting jack lifts the pad beam 53, applying pre-tension to the suspension rod 71 to allow the pier cap 11 to bear load in advance. A connector is used during this process. After applying pre-tension to the suspension rod 71, a wrench is used to tighten the nut at the upper end of the suspension rod 71, the lifting jack is removed, and the connector is disconnected. The purpose of applying pre-tension to the suspension rod 71 is to eliminate the deflection of the spreader beam 54 after it fully bears the load of the pier cap 11, thereby reducing the lifting height and preventing the space between the beam 1 and the pier cap 11 from failing to meet the sliding requirements.

[0057] In one embodiment, the installation of the suspender 71 should utilize the gap between the upper structural beams 1 of the operating line and the gap between the pier top support pads 13, and the space required for the installation of the spreader beam 54 should be taken into account. The suspender 71 can be made of steel bar or precision-rolled threaded steel. In one embodiment, the suspender 71 is made of 40Cr alloy steel bar, with threaded ends, anchor plates, and double nuts. The top end of the pier cap 11 is set inside the spreader beam 54, and is equipped with vertical stiffeners and horizontal plates for limiting and anchoring. The total height does not extend beyond the top surface of the spreader beam 54 and does not affect the sliding.

[0058] In one embodiment, the suspension rod 71 can be used for both hollow and solid piers. When used for hollow piers, the suspension rod 71 is positioned on the top surface of the pier's inner cavity. If the lower part of the suspension rod 71 is located at the chamfered edge of the hollow pier's inner cavity, the chamfered concrete can be removed before anchoring, or wedge-shaped clamps can be used to fix the suspension rod 71 before anchoring. When used for solid piers, post-anchoring methods such as rebar installation or chemical anchors can be used.

[0059] In one embodiment, one end of the lifting jack supports the sliding support system, while the other end of the lifting jack lifts the end of the pad beam 53, thereby lifting the spreader beam 54. Pads and supports 33 are arranged below the pad beam 53, and lifting jacks are arranged at both ends. The pads and supports 33 are both made of steel plates or structural steel, and the supports 33 prevent excessive stress on the sliding support system.

[0060] In one embodiment, the thickness of the middle section of the pad beam 53 is greater than the thickness of both ends of the pad beam 53. The middle section of the pad beam 53 is located on the sliding trolley 52, and both ends of the pad beam 53 are connected to the lifting jacks. Since the pad beam 53 needs to be lifted by the jacks, in order to meet the working space of the jacks and to further increase the gap between the piers and the beam 1 of the operating line, the pad beam 53 can be designed with a structure that is higher in the middle and lower at both ends. This satisfies the stress requirements of the middle structure while reducing the height of the two sides to meet the height required for jack lifting.

[0061] In one embodiment, the connection process between the sliding system 50 and the steel connecting beam 25 is as follows: the steel connecting beam 25 is lifted to its initial position using the lifting gantry 22, and then the sliding system 50 and the steel connecting beam 25 are connected by a steel sling. One end of the steel sling is connected to the spreader beam 54, and the other end of the steel sling is connected to the steel connecting beam 25, so that the spreader beam 54 suspends the steel connecting beam 25.

[0062] At this point, the spreader beam 54 of the suspended pier cap 11 and the spreader beam 54 of the suspended steel connecting beam 25 are connected as a whole by the connecting rod 55, so that the pier cap 11 and the steel connecting beam 25 can slide synchronously. After the steel connecting beam 25 is suspended, the reinforcing steel of the support pad 13 is installed on the steel connecting beam 25, concrete is poured, and the new support 26 is installed in the anchor bolt hole of the support pad 13.

[0063] Step S140: Install temporary supports 30 on the steel crossbeam 21 to bear the load of the bridge beam 1.

[0064] Please refer to the following: Figure 15 Specifically, temporary supports 30 are set on both sides of the support 26, 3.65m from the beam end (the location needs to be determined by the design unit after calculation to avoid cracking at the top of the beam caused by changes in the support position below the beam 1). They are close to the sliding system 50 but do not affect the sliding space. One temporary support 30 consists of a distribution beam 31 (a large double-section I-beam with stiffening plates), 4 support jacks 32 (located at the bottom of the corresponding T-beam), pads (8 in total, located on both sides of the jacks), several shims, 4 pads 33 (below the jacks and pads, providing support and increasing the concrete pressure area to prevent cracking), and 4 rubber pads 34 (on top of the large distribution beam 31 and at the bottom of the T-beam to prevent concrete cracking).

[0065] During the lifting of beam 1 using jack 32, the lifting was controlled by a synchronous lifting system using an oil pump and PLC. A displacement device was installed to monitor the lifting height, supplemented by manual measurement with a steel ruler to ensure consistent lifting height. The total lifting height was 10mm, achieved through a staged lifting process, performed in three stages, each lifting 3-4mm. The lifting was monitored manually and by the displacement device.

[0066] It is understood that in other embodiments, the timing of the temporary support 30 supporting the upper beam 1 can be adjusted according to specific needs, as long as it is done before the pier cap 11 of the pier 10 to be demolished is cut. For example, the temporary support 30 can be installed before the sliding system 50 is installed.

[0067] Step S150: Cut off the pier cap 11 of the pier to be demolished 10, lift and suspend the pier cap 11 using the sliding system 50, slide the pier cap 11 out of the operating line and the restricted hoisting area using the sliding system 50, and slide the steel connecting beam 25 to the design position.

[0068] Please refer to the following: Figure 13 and Figure 16 Specifically, a drilling rig drills connecting holes 15 along the cutting line 14 on the pier wall. The sawing rope of the wire saw 80 is inserted through the connecting hole 15 into the inner cavity of the pier cap 11 and then exits through another adjacent connecting hole 15. Multiple sets of wire saws 80 are arranged circumferentially around the pier cap 11, and these sets of wire saws 80 are symmetrically distributed about the plane containing the axis of the pier cap 11. Multiple sets of wire saws 80 cut the pier cap 11 simultaneously to improve the cutting efficiency of the pier cap 11. During the cutting of the pier wall, short sections of round steel can be inserted into the pier wall in a timely manner as the cutting progresses. The diameter of these steel sections must not exceed the diameter of the sawing rope. They can be directly inserted into the pier wall to facilitate the subsequent sliding and removal of the pier cap 11.

[0069] In one embodiment, horizontal holes are drilled using a water-cooled drill, symmetrically arranged along cutting line 14. The number of holes and their spacing are approximately the same as the cross-sectional area of ​​the pier wall between adjacent holes. An even number of wire saw 80 cutting machines are symmetrically arranged, based on the efficiency of each machine and calculated according to the number of sections of the entire pier wall cross-sectional area. In this embodiment, six wire saw 80 cutting machines are used, controlled by multiple machines and operators. The operation time of each machine is kept consistent by dividing the cutting surface into equal-area sections, using the same type of cutting machine, and using the same cutting rope.

[0070] Please refer to the following: Figure 17 In one embodiment, after the pier cap 11 is cut off, the sliding system 50 lifts and suspends the pier cap 11 to ensure the separation of the pier cap 11 from the pier body, while maintaining a gap between the pier cap 11 and the concrete of the pier body to facilitate the sliding out of the pier cap 11.

[0071] Specifically, the lifting jacks lift the pad beam 53 upwards, thereby raising the spreader beam 54 and then lifting the suspended pier cap 11 via the hoisting rod 71. The lifting height of the pier cap 11 needs to be determined by considering the overall flatness of the cut of the pier cap 11 and the distance between the top of the spreader beam 54 and the bottom surface of the existing beam 1. The flatness of the cut of the pier cap 11 will affect the height of the pier cap 11 required for overall sliding, and the distance between the top of the spreader beam 54 and the bottom surface of the existing beam will limit the height that the pier cap 11 can be lifted.

[0072] In this embodiment, by drawing cutting lines 14, installing limiting strips, and arranging cutting lines 14 at an angle, the lifting height of 1cm during the pier cap 11 lifting construction is sufficient to meet the sliding requirements, thereby achieving the separation of the pier cap 11 from the pier body, reducing friction with the pier wall concrete, and facilitating smooth sliding.

[0073] After the pier cap 11 is lifted into position, a shim steel plate is added between the sliding trolley 52 and the pad beam 53 to maintain the height of the pad beam 53. Then, the sliding trolley 52 and the pad beam 53 are fixedly connected with bolts, and the hydraulic jack and its lower pad block and seat are removed. Finally, the continuous extension and retraction of the continuous jack 61 drives the sliding trolley 52 to slide along the slide rail 51, driving the spreader beam 54 to move, thereby realizing the sliding movement of the pier cap 11 until the pier cap 11 is slid out of the operating line and the restricted lifting area.

[0074] In one embodiment, to ensure smooth overall sliding of the pier cap 11 and to ensure that the local stiffness of the sliding support 23 meets the requirements, pads are installed under the slide rail 51, and stiffening plates are installed on the pads and the slide rail 51 at certain intervals. Reinforcing columns are also installed at the junction of the portal pier and the horizontal sliding support 40. To ensure straight overall sliding of the pier cap 11, and to slide it to the planned position according to the slide rail 51 line, slide rail 51 clamping plates and stiffening plates are added to both sides of the slide rail 51.

[0075] Please refer to the following: Figure 18 In one embodiment, to prevent the sliding trolley 52 from getting stuck during the sliding process, which could cause the pier cap 11 to collide with other structures, the sliding trolley 52 is provided with arc-shaped limiting members 521 on both sides. At the same time, a slender triangular correction plate 56 is prepared in advance. When the sliding trolley 52 is about to touch the limiting members on both sides of the slide rail 51, the triangular correction plate 56 is inserted between the arc-shaped limiting members 521 and the slide rail 51 to adjust the position of the sliding trolley 52 on the slide rail 51 and correct its deviation.

[0076] Please refer to the following: Figure 19 In one embodiment, after the steel connecting beam 25 slides into place, the connection between the pier cap 11 and the sliding system of the steel connecting beam 25 is dismantled, and the pier cap 11 continues to slide to the position to be dismantled. When the pier cap 11 slides as a whole near the design position, attention should be paid to setting a limiting device in advance to avoid excessive sliding. After the pier cap 11 slides to the design position, it can be lowered using jacks.

[0077] Step S160: Connect the steel connecting beam 25 to the two steel crossbeams 21, and install the support 26 on the steel connecting beam 25 to support the bridge beam 1.

[0078] Please refer to the following: Figure 20 Specifically, the connection between the steel connecting beam 25 and the steel crossbeam 21 is a bolted and welded connection. The external part is welded, and the internal part has 8 connecting plates connected by high-strength bolts. Before connection, the steel connecting beam 25 needs to be adjusted to the design position, the high-strength bolts are initially tightened, then the butt welding between the steel connecting beam 25 and the steel crossbeam 21 is performed, and finally the high-strength bolts are tightened and the final tightening torque is checked.

[0079] After the steel connecting beam 25 slides to the designed position, the new support 26 slides to the designed position as well, and the support 26 can be installed. First, the upper steel plate is fabricated and installed, and it is tightly attached to the bottom of the beam with bolts. After the steel connecting beam 25 is finely adjusted into position and bolted and welded to be fixed, the lower steel plate of the support is temporarily fixed and the T-beam elevation is adjusted to the designed position. Then, the anchor bolt holes of the support 26 are grouted. After the strength meets the design requirements, the installation of the new support 26 is completed.

[0080] Finally, the temporary support 30 was removed, and the load was transferred to the new support 26, completing the existing pier replacement project. Then, the horizontal sliding support 40, lifting gantry 22, spreader beam 54, pad beam 53, and slide rail 51 were dismantled. A 20t electric hoist gantry crane was installed on the sliding support 23 to cut, hoist, and dismantle the existing pier concrete in sections. The cutting platform was lowered using a winch 223 until the pier was completely dismantled, thus completing the demolition of the entire pier.

[0081] The aforementioned method for replacing the pier column of a bridge crossing an operational railway line, under limited maintenance windows and with confined space at the bottom of the existing railway beam 1, avoids the use of large hoisting equipment, minimizes construction site requirements, reduces the risks of hoisting operations, and further enhances railway traffic safety and the safety of operational line equipment. The steel crossbeam 21, steel connecting beam 25, and pier cap 11 are moved by sliding, allowing construction to be carried out within the confined space at the bottom of the existing operational railway beam 1. The entire process is based on a clear principle, ensuring construction efficiency and quality. By tilting and cutting the pier cap 11, using limiting strips to restrict the path of the cutting device, and lifting and suspending the pier cap 11, the pier cap 11 can be smoothly moved out. The sliding process of the pier cap 11 is labor-saving and avoids jamming, ensuring the pier can be dismantled within the limited maintenance window, resulting in low construction costs and high operational safety.

[0082] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for replacing pier columns of a bridge crossing an operational railway line, characterized in that, Includes the following steps: Portal pier columns are installed on both sides of the pier to be demolished, and two steel beams are connected to the two portal pier columns. The pier to be demolished is located between the two steel beams. A horizontal sliding support is installed near the pier cap. The horizontal sliding support and the steel crossbeam constitute a sliding support system. A sliding system is installed on the sliding support system. Connect the sliding system to the pier cap and steel connecting beam of the pier to be demolished; Temporary supports are installed on the steel crossbeams to bear the load of the bridge beams. The pier cap of the pier to be demolished is cut off, the sliding system lifts the pier cap to separate it from the pier body, the sliding system slides the pier cap out of the operating line and the restricted hoisting area, and slides the steel connecting beam to the design position; The steel connecting beam is connected to the two steel crossbeams, and supports are installed on the steel connecting beam to support the bridge beam.

2. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 1, characterized in that, The specific steps for connecting the steel beam to the two portal pier columns are as follows: A lifting gantry is installed on the top of the portal pier, a sliding support is erected between the two portal piers, and an adjustment system is installed on the sliding support. The steel beam segments are lifted using the lifting gantry and then slid to the designed position using the adjustment system. All steel beam segments are connected and assembled into the steel beam.

3. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 2, characterized in that, The specific steps for lifting the steel beam segment via the lifting gantry and sliding it to the designed position via the adjustment system are as follows: The first segment of the steel crossbeam is lifted by lifting the gantry frame and connected to one of the aforementioned portal pier columns; The middle section of the steel crossbeam is lifted by lifting the gantry and then slid to the designed position via the adjustment system. The tail section of the steel crossbeam is lifted by lifting the gantry frame and connected to another gantry pier column. The segments of the steel beam are assembled into one piece.

4. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 2, characterized in that, The specific steps for setting up the adjustment system on the sliding bracket are as follows: A track is provided on the sliding support, and a sliding beam for supporting the steel beam segment is installed on the track; A traction reaction seat is installed on the sliding bracket, and a traction rod is installed on the traction reaction seat; The traction rod is passed through the slide beam and then connected to the adjustment jack.

5. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 4, characterized in that, The specific steps for sliding the steel beam segment to the design position via the adjustment system are as follows: The continuous extension and retraction of the adjusting jack causes the sliding beam and steel crossbeam segments to slide. During the initial and intermediate sliding stages, the adjustment jacks automatically slide at a constant speed. When the sliding approaches the design position, the jacks switch to manual mode for inching adjustment.

6. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 1, characterized in that, The step of installing the sliding system on the sliding support system further includes: A cutting line is drawn on the pier wall, with the starting end of the cutting line along the sliding direction of the pier cap being higher than the ending end.

7. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 6, characterized in that, The step of drawing the cutting line on the pier wall also includes: Limiting strips are installed on both sides of the cutting line.

8. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 6, characterized in that, The specific steps for cutting off the pier cap of the bridge pier to be demolished are as follows: A drilling rig is used to drill a connecting hole on the pier wall along the cutting line. The wire saw is inserted through the connecting hole into the inner cavity of the pier cap and then out through another adjacent connecting hole. Multiple sets of wire saws are arranged around the circumference of the pier cap. The multiple sets of wire saws are symmetrically distributed about the plane containing the axis of the pier cap, and the multiple sets of wire saws cut the pier cap simultaneously.

9. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 1, characterized in that, The specific steps of the sliding system to slide the pier cap out of the operating line and the restricted hoisting area, and to slide the steel connecting beam to the design position are as follows: The traction system pulls the sliding trolley to slide on the slideway, which moves the pad beam and the spreader beam. The spreader beam suspends the pier cap and the steel connecting beam. The spreader beam moves the pier cap out of the operating line and the restricted hoisting area, and moves the steel connecting beam to the design position.

10. The method for replacing pier columns of a bridge underpass for an operational railway line according to claim 1, characterized in that, When the sliding trolley slides on the slide track, arc-shaped limiting components are provided on both sides of the sliding trolley. A triangular correction plate is inserted between the arc-shaped limiting components and the slide track to adjust the position of the sliding trolley on the slide track.

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