Pier replacement construction method for increasing underpass space of existing bridge

Abstract

The invention belongs to the technical field of bridge construction, and particularly relates to a pier replacement construction method for increasing the underpass space of an existing bridge. The method comprises the steps that steel pipe supports are installed on the two longitudinal sides of an original pier of an existing bridge respectively, and jacking systems are installed at the top ends of the steel pipe supports; jacking the end parts of a front bridge span and a rear bridge span above the original bridge pier by using a jacking system until the support on the original bridge pier is disengaged, and taking away the support; block cutting and dismantling are conducted on an original bridge pier straining beam, a bent cap and a pier column in sequence; large-span portal piers are further built on the transverse outer sides of the original piers, and supports are installed; the two jacked bridge spans fall to the top faces of the portal pier supports through a jacking system; and the jacking system and the steel pipe support are dismantled from top to bottom, and pier replacement construction of the existing bridge is achieved. According to the pier replacement construction method, the underpass space of the existing bridge is increased, and the newly-built bridge can smoothly pass through the existing bridge through the large-span portal pier.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a pier replacement construction method for increasing the underpass space of an existing bridge. Background Art

[0002] With the construction and development of highway bridges, it is often the case that the extension direction of new bridges intersects with existing bridges. Figure 1 , Figure 2 As shown, existing bridges generally include an upper structure, a lower structure and a support 3; the upper structure is also called a span 1, and many spans 1 are composed of multiple T-beams 11; the lower structure includes piers 2 and foundations, wherein many piers 2 are double-column frame piers, including two oppositely arranged piers 21, a cap beam 22 connected to the top ends of the two piers 21, and at least one tie beam 23 connected between the two piers 21, and a plurality of support pads 24 are provided on the top surface of the cap beam 22; a plurality of supports 3 are installed one by one on the support pads 24, and the supports 3 are force transmission devices at the support points of the span 1 and the piers 2.

[0003] When a newly built bridge passes under an existing bridge, it is very likely to conflict with the position of the pier 21 of the original pier 2 of the existing bridge, that is, the space under the existing bridge cannot meet the needs of the newly built bridge passing under. Therefore, how to increase the space under the existing bridge so that the newly built bridge can pass smoothly under the existing bridge has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the deficiencies existing in the related art, the present invention provides a pier replacement construction method for increasing the underpass space of an existing bridge.

[0005] The pier replacement construction method for increasing the underpass space of an existing bridge of the present invention comprises the following steps:

[0006] Construction of temporary support system: a set of steel pipe supports are installed on both sides of the original piers of the existing bridge in the longitudinal direction, and a jacking system located under the span of the existing bridge is installed on the top of each set of steel pipe supports;

[0007] Lifting of the bridge span: Use the lifting system on the two sets of steel pipe supports to lift the ends of the front and rear spans above the original bridge piers. Stop lifting after the spans are completely separated from the supports on the original bridge piers; remove the supports;

[0008] Removal of the original bridge piers: The tie beam, cap beam and two pier columns of the original bridge piers were removed in sequence by cutting in blocks;

[0009] Construction of large-span portal piers: construct two pier columns of the portal pier on both sides of the original pier, then construct the portal pier cap beam and multiple bearing pads on the top of the two pier columns, then install the bearings one by one on the bearing pads of the portal pier, and adjust the top surface elevation of the bearings to be consistent with the preset elevation;

[0010] Lowering of the bridge span: Using the lifting system on two sets of steel pipe supports, the two bridge spans to be lifted are lowered to the top surface of the support of the portal pier;

[0011] Dismantling of temporary support system: dismantle the jacking system and steel pipe support from top to bottom to realize the pier replacement construction of the existing bridge.

[0012] In some of the embodiments, when executing the construction steps of the temporary support system, it also includes constructing a temporary support foundation on the ground on both sides of the original bridge pier in the longitudinal direction, and two sets of steel pipe supports are installed on the temporary support foundation; the construction of the temporary support foundation includes measuring and placing the plane positions of multiple pile foundations on the construction ground and carrying out pile foundation construction, and then excavating the foundation pit, supporting the pedestal formwork, pouring the foundation pedestal, and pre-burying multiple support seats in the top surface of the foundation pedestal; each support seat is evenly provided with a plurality of bolts, and the top ends of the bolts protrude from the top surface of the foundation pedestal; and the multiple support seats are used to connect with the steel pipe supports.

[0013] In some of the embodiments, each set of steel pipe supports includes a front row of steel pipe racks close to the original bridge piers and a rear row of steel pipe racks away from the original bridge piers; each row of steel pipe racks includes a plurality of steel pipe columns arranged at intervals in the transverse direction, and each steel pipe column includes a plurality of steel pipe segments connected vertically; parallel joints and diagonal braces are connected between the steel pipe segments adjacent to each other in the transverse direction and in the longitudinal direction of the front and rear rows of steel pipe racks;

[0014] The jacking system is installed on the top of the front row of steel pipe racks; the jacking system includes a first crossbeam, a first cushion beam and multiple jacks; the first crossbeam is connected to the top surfaces of all steel pipe columns of the front row of steel pipe racks; multiple jacks are transversely arranged on the top surface of the first crossbeam, wherein a jack is correspondingly provided under the web of each T-beam of the bridge span, and another jack is provided in addition to the two outermost jacks; the first cushion beam is crimped on the top surfaces of all jacks; multiple first cushion blocks are transversely arranged on the top surface of the first cushion beam, and the first cushion blocks are used to be crimped with the bottom surface of the T-beam.

[0015] In some of the embodiments, an emergency support system is provided on the top of each rear-row steel pipe rack; the emergency support system includes a second crossbeam, a second cushion beam and a plurality of support blocks, the second crossbeam is connected to the top surfaces of all steel pipe columns of the rear-row steel pipe rack, a plurality of support blocks are transversely arranged on the top surface of the second crossbeam, the second cushion beam is crimped on the top surfaces of all support blocks, a plurality of second cushion blocks are transversely arranged on the top surface of the second cushion beam, and a safety gap is reserved between the second cushion blocks and the bottom surface of the T-beam.

[0016] In some embodiments, the installation of the steel pipe support and the jacking system and emergency jacking system thereon comprises the following steps:

[0017] A crane is set up near the original pier under the bridge, and the steel pipe column is installed in sections by the crane. After the steel pipe sections at the same height are installed, the parallel joints and diagonal braces between two adjacent steel pipe sections in the horizontal and vertical directions are installed immediately until the installation of the steel pipe bracket within the crane's lifting height range is completed;

[0018] A hoisting system is arranged on the bridge span, and the hoisting system includes a traveling frame and a hoisting frame; the traveling frame spans across the existing bridge deck and can move back and forth in the longitudinal direction, and two hoisting winches are arranged laterally on the traveling frame; the hoisting frame is arranged laterally below the bridge span, and its two lateral ends are respectively connected to the two hoisting winches by lifting ropes, and an electric gantry vehicle that can move back and forth laterally along the hoisting frame is connected below the hoisting frame; the remaining steel pipe segments are installed by cooperating with the crane under the bridge and the hoisting system on the bridge, thereby completing the installation of the steel pipe bracket that exceeds the hoisting height range of the crane, and then the first crossbeam, the first cushion beam, the second crossbeam and the second cushion beam on the steel pipe bracket are installed.

[0019] In some of the embodiments, before executing the jacking step of the bridge span, two longitudinal and transverse limiting devices are arranged along the expansion joint between the front and rear spans above the original bridge piers, and the longitudinal and transverse limiting devices include a fixed part and a movable part respectively connected to the bridge decks of the front and rear spans, and the fixed part is provided with a plurality of circular holes, and a plurality of chemical anchor bolts pass through the circular holes one by one to fix the fixed part to the span, and the movable part is provided with a plurality of longitudinal flat holes, and a plurality of chemical anchor bolts pass through the longitudinal flat holes one by one to longitudinally slide the movable part to the span; a limit block is protruded from the top surface of each transverse end of each first pad beam, and the two limit blocks are respectively abutted against the horseshoe outer side surfaces of the T-beams at the transverse ends of the span.

[0020] In some of the embodiments, after the jacking step of the bridge span is completed, all the jacks are first locked, and then a plurality of steel pads are arranged between the first cross beam and the first pad beam to replace the support of the jacks, and then all the jacks are unloaded.

[0021] In some of the embodiments, after the construction of the large-span gantry pier is completed and reaches the design strength, the step of lowering the bridge span is executed; first, all the jacks between the first cross beam and the first pad beam are started to replace the support of the steel pads, then all the steel pads are removed, and then all the jacks are slowly lowered to allow the two lifted bridge spans to fall to the top surface of the support of the gantry pier.

[0022] In some embodiments, the steps of removing the original bridge piers include:

[0023] Design of cutting sequence and cutting blocks: the tie beam is used as the first cutting level, the cap beam part not corresponding to the pier is used as the second cutting level, the cap beam part corresponding to the pier is used as the third cutting level, and the pier is used as the fourth cutting level; the tie beam is divided into blocks horizontally, and its first cutting block is set in the middle of its length direction, and the second cutting block, the third cutting block, ..., the nth cutting block are set on both sides in turn; the cap beam part not corresponding to the pier is divided into blocks horizontally, and its first cutting block is set in the middle of its length direction, and the second cutting block, the third cutting block, ..., the mth cutting block are set on both sides in turn; the cap beam part corresponding to the pier is divided into blocks obliquely, and its first cutting block and the second cutting block are respectively set on the side away from the two piers, and its third cutting block and the fourth cutting block are respectively set on the side close to the two piers; the pier is divided into blocks vertically, and its first cutting block and the second cutting block are respectively set at the top of the height direction of the two piers, and the third cutting block, the fourth cutting block, ..., the kth cutting block are set downward in turn;

[0024] Measurement and layout: according to the block form of the cutting block, all cutting lines are drawn on the original bridge pier with ink lines;

[0025] Demolition equipment layout: a rope cutting construction platform is set up on the steel pipe support, on the erected steel pipe scaffolding or on the ground to place the diamond wire saw cutting equipment; a longitudinally extending transport track is laid on the ground between the two piers of the original bridge pier, and a transfer flat car is installed on the transport track; a hoisting frame is set up on the front and rear spans above the original bridge pier, and two sets of pulleys are arranged on the hoisting frame, and the driving end of each set of pulleys is connected to a hoisting winch; a traction winch is set on the ground on the lateral outside of a steel pipe support;

[0026] Bridge pier removal work: A number of lifting holes corresponding to a number of cutting blocks are respectively opened on the front and rear spans above the original bridge piers, and the lifting holes are all located at the wet joints of the T-beams; according to the cutting sequence, the lifting ends of the two sets of pulley groups are respectively passed through the lifting holes on the front and rear spans to be connected to a cutting block, and the traction winch is also connected to the cutting block; the cutting block is cut using a diamond wire saw cutting device, and after the cutting is completed, the cutting block is lowered using a lifting winch and its lowering direction is adjusted using a traction winch, so as to lower it onto a transfer flat car and transport it out; in this way, the tie beam, cap beam, and two pier columns of the original bridge pier are cut, lowered, and transported in blocks, thereby completing the removal of the original bridge pier.

[0027] In some of the embodiments, before the bridge pier removal operation is performed, a plurality of cross-shaped frames are vertically arranged outside each pier column of the original bridge pier, the cross-shaped frames are clamped to the pier columns, and the longitudinal ends of the cross-shaped frames are respectively connected to the flat joints of the two front-row steel pipe racks; a plurality of longitudinally extending support beams are arranged between the uppermost flat joints of the two front-row steel pipe racks; when the cap beam is cut, a plurality of pads are set between the two support beams corresponding to the cap beam cutting block, and the top surface of the pads is made to abut against the bottom surface of the cutting block, and when the cutting of the cap beam cutting block is completed, the pads and the support beams that hinder the lowering of the cap beam cutting block are removed.

[0028] Based on the above technical scheme, the pier replacement construction method for increasing the underpass space of an existing bridge in the embodiment of the present invention can safely and quickly realize the pier replacement construction of an existing bridge and increase its underpass space, solving the problem that the space under the existing bridge cannot meet the underpass needs of the new bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 This is the cross-sectional elevation of the existing bridge;

[0031] Figure 2 This is the longitudinal elevation of the existing bridge;

[0032] Figure 3 It is a flow chart of the pier replacement construction method for increasing the underpass space of an existing bridge according to the present invention;

[0033] Figure 4 A plan view of a temporary support foundation in the present invention;

[0034] Figure 5 It is a horizontal elevation view of the temporary support foundation in the present invention;

[0035] Figure 6 It is a horizontal and vertical relationship diagram of the temporary support system in the present invention and the existing bridge;

[0036] Figure 7 It is a longitudinal elevation relationship diagram of the temporary support system in the present invention and the existing bridge;

[0037] Figure 8 It is a planar relationship diagram of the temporary support system and the original bridge pier in the present invention;

[0038] Fig. 9 It is a horizontal and vertical relationship diagram of the jacking system in the present invention and the existing bridge;

[0039] Fig.10A longitudinal elevation diagram showing the relationship between the jacking system of the present invention and the existing bridge;

[0040] Fig.11 A plan view showing the relationship between the jacking system of the present invention and the existing bridge;

[0041] Fig.12 It is a horizontal and vertical relationship diagram of the hoisting system of the present invention and the existing bridge;

[0042] Fig.13 A longitudinal elevation diagram showing the relationship between the hoisting system of the present invention and the existing bridge;

[0043] Fig.14 It is a planar layout diagram of the longitudinal and transverse limiting devices of the present invention on the deck of an existing bridge;

[0044] Fig.15 It is a schematic diagram of the structure of the longitudinal and transverse limiting device in the present invention;

[0045] Fig.16 The design diagram of the original pier cutting sequence and cutting blocks in the present invention;

[0046] Fig.17 It is a horizontal elevation layout diagram of a partially dismantled device in the present invention;

[0047] Fig.18 It is a longitudinal elevation layout diagram of a partially dismantled device in the present invention;

[0048] Fig.19 It is a schematic diagram of the longitudinal elevation of the diamond wire saw cutting device in the present invention when cutting the cap beam;

[0049] Fig. 20 It is a cross-sectional view of the cutting block during transportation in the present invention;

[0050] Fig.21 It is a plan view of the cutting block during transportation in the present invention;

[0051] Fig. 22 It is a planar relationship diagram of the temporary support system and the large-span portal pier in the present invention;

[0052] Fig.23 It is a horizontal and vertical relationship diagram of the temporary support system and the large-span portal pier in the present invention;

[0053] Fig.24 It is a longitudinal elevation relationship diagram of the temporary support system and the large-span portal pier in the present invention.

[0054] In the figure:

[0055] 1. Bridge span; 11. T-beam; 12. Expansion joint; 13. Wet joint; 14. Lifting hole; 2. Bridge pier; 21. Pier column; 22. Cap beam; 23. Tie beam; 24. Support pad stone; 3. Support; 4. Temporary support system; 41. Temporary support foundation; 411. Pile foundation; 412. Foundation pedestal; 413. Support seat; 414. Bolt; 42. Steel pipe bracket; 421. Front steel pipe rack; 422. Rear steel pipe rack; 423. Steel pipe column; 4231. Steel pipe segment; 424. Flat joint; 425. Diagonal brace; 43. Lifting system; 431. First beam; 432. First pad beam; 433. Jack; 434. First pad block; 435. Limit block; 44. Emergency jacking system; 441. Second beam; 44 2. Second cushion beam; 443. Second cushion block; 444. Support block; 45. Cross frame; 46. Support beam; 47. Pads; 5. Door frame pier; 51. Pier column; 52. Cap beam; 53. Support cushion stone; 6. Hoisting system; 61. Traveling frame; 62. Hoisting frame; 63. Hoisting winch; 64. Electric gantry; 65. Lifting rope; 66. Traveling track; 67. Traveling trolley; 7. Longitudinal and transverse limit devices; 71. Fixed part; 711. Round hole; 72. Movable part; 721. Longitudinal flat hole; 81. Steel pipe scaffolding; 82. Springboard; 83. Diamond wire saw cutting equipment; 84. Hoisting frame; 85. Pulley block; 86. Hoisting winch; 87. Traction winch; 88. Transfer flat car; 89. Transport track; 90. Cutting block. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0057] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "top", "bottom", "inside", "outside", "left", "right", "front", "back", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0058] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0059] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] refer to Figure 1-Figure 24 As shown, the present invention provides a pier replacement construction method for increasing the underpass space of an existing bridge, including the steps of preparing a construction site, constructing a temporary support system 4, lifting the span 1, dismantling the original pier 2, constructing a large-span portal pier 5, lowering the span 1, dismantling the temporary support system 4, and the like.

[0061] The preparation steps for the construction site include building a temporary access road according to the site layout diagram, pouring plain concrete in the construction area near the original pier 2 of the existing bridge to harden and level it, providing conditions for the next step of construction machinery and materials to enter the site; clarifying the site elevation of the area where the temporary support system 4 is located, and taking good drainage measures for the site.

[0062] The construction steps of the temporary support system 4 include installing a set of steel pipe supports 42 on both sides of the original pier 2 of the existing bridge in the longitudinal direction; a jacking system 43 is installed on the top of each set of steel pipe supports 42, and the jacking system 43 is located below the span 1 of the existing bridge, that is, the jacking system 43 is provided below the front and rear spans 1 above the original pier 2; it can be understood that the original pier 2 refers to the pier 2 in the existing bridge that conflicts with the position of the new bridge when passing under the existing bridge.

[0063] The jacking step of the span 1 includes: using the jacking systems 43 on the two sets of steel pipe supports 42 to simultaneously jack up the ends (i.e., the ends close to each other) of the front and rear spans 1 located above the original pier 2; after the span 1 is completely separated from the supports 3 on the original pier 2, that is, after the supports 3 are empty, the jacking is stopped and all the supports 3 are removed; at this time, the ends of the front and rear spans 1 located above the original pier 2 are completely supported by the two sets of steel pipe supports 42 and the jacking systems 43 thereon, and the connection between the original pier 2 and the span 1 is released.

[0064] The steps of dismantling the original bridge pier 2 include cutting and dismantling the tie beam 23, the cap beam 22 and the two pier columns 21 of the original bridge pier 2 in sequence by block cutting, and transporting the cut blocks 90 to a preset storage area.

[0065] The construction steps of the large-span portal pier 5 include: first, constructing two piers 51 of the portal pier 5 on both sides of the original pier 2, that is, constructing on the lateral outside of the two piers 21 of the original pier 2, so that the distance between the two piers 51 of the portal pier 5 is greater than the distance between the two piers 21 of the original pier 2, so that the span of the newly built portal pier 5 is greater than the span of the original pier 2; then, constructing the cap beam 52 of the portal pier 5 and the multiple support shims 53 thereon on the top of the two piers 51 of the portal pier 5, and the mark of the support shims 53 needs to be accurately checked and controlled. High; then install multiple bearings 3 one by one on the bearing pad stone 53 of the portal pier 5. The bearing 3 can be a new part, or the bearing 3 removed from the original pier 2 can be directly used; when installing the bearing 3, the longitudinal and transverse center cross lines should be marked on the bearing pad stone 53 and the bearing 3 respectively so that the two can be accurately aligned. The installed bearing 3 shall not have any undesirable conditions such as deflection, uneven stress and voiding. The center positions of the multiple bearings 3 should be located directly below the center lines of the webs of the multiple T-beams 11 of the existing bridge span 1 in the direction of the bridge, and the top surface elevation of the bearing 3 should be adjusted to be consistent with the preset elevation.

[0066] It can be understood that the construction of the portal pier 5 also includes the construction of pile foundation 411, pedestal, etc.; the pedestal, pier column 51 and cap beam 52 of the portal pier 5 are all constructed using standardized steel formwork, and the construction process includes tying the steel bars of the pier column 51, tying the cap beam 52, the support pad stone 53 and the block steel bars on the cap beam 52, installing the formwork, pouring concrete, etc. The construction process of the portal pier 5 is well known to those skilled in the art and will not be expanded or elaborated here.

[0067] The step of lowering the span 1 includes using the jacking system 43 on the two sets of steel pipe supports 42 to slowly lower the front and rear spans 1 that have been jacked, until they fall into place on the top surface of the support 3 of the portal pier 5, thereby realizing the placement of the beam; after being in place, the bridge is inspected, and only after it is detected that there is no structural displacement of the bridge, the support condition of the support 3 and the elevation of the span 1 meet the requirements, can the subsequent step of dismantling the temporary support system 4 be carried out.

[0068] The dismantling steps of the temporary support system 4 include dismantling the jacking system 43 and the steel pipe support 42 in order from top to bottom, that is, the dismantling and installation process of the temporary support system 4 is carried out in reverse order, that is, install first and then dismantle, or install later and then dismantle; evacuate construction machinery and equipment, restore the existing bridge deck, and then realize the pier replacement construction of the existing bridge.

[0069] The above-mentioned schematic embodiment realizes the lifting, temporary support and lowering of the bridge span 1 above the original bridge pier 2 by setting up a temporary support system 4 near the original bridge pier 2; and increases the underpass space of the existing bridge by dismantling the original bridge pier 2 and rebuilding the large-span portal pier 5, so that the new bridge can smoothly pass under the existing bridge via the large-span portal pier 5, thus solving the problem that the space under the existing bridge cannot meet the need of the new bridge to pass under.

[0070] refer to Figure 4-Figure 8 As shown, in some embodiments, when executing the construction steps of the temporary support system 4, it also includes constructing temporary support foundations 41 on the ground on both sides of the original bridge pier 2 in the longitudinal direction, and the temporary support foundations 41 on both sides are connected as one, and two sets of steel pipe brackets 42 on both sides of the original bridge pier 2 in the longitudinal direction are installed on the temporary support foundation 41. The construction of the temporary support foundation 41 includes establishing a measurement control network on the construction ground according to the existing bridge centerline and the plane layout of the temporary support foundation 41, measuring and placing the plane positions of multiple pile foundations 411 of the temporary support foundation 41 on the construction ground according to the control network, and constructing the pile foundation 411 in a staggered manner. After the construction of the pile foundation 411 is completed, the foundation pit is excavated, the head of the pile foundation 411 is chiseled off, the foundation template is supported, the foundation steel bars are tied, and the foundation foundation 412 is poured in layers, and multiple support seats 413 are pre-buried in the top surface of the foundation foundation 412; the construction process of the pile foundation 411 and the foundation foundation 412 is well known to those skilled in the art, and will not be expanded or repeated here. Furthermore, a plurality of bolts 414 are evenly distributed on each support seat 413 , the top end of the bolt 414 protrudes from the top surface of the base support 412 , and the bottom end of the bolt 414 is buried in the base support 412 ; the plurality of support seats 413 are connected to the steel pipe bracket 42 via the bolts 414 .

[0071] The above-mentioned schematic embodiment improves the bearing capacity of the construction ground by setting up the temporary support foundation 41, and can provide a solid and stable installation foundation for the steel pipe bracket 42, so that the temporary support system 4 can provide stable and safe temporary support for the bridge span 1; by setting up the support seat 413 pre-buried in the temporary support foundation 41, a stable connection between the steel pipe bracket 42 and the temporary support foundation 41 is achieved, thereby improving the installation stability of the steel pipe bracket 42.

[0072] refer to Figure 6-Figure 11As shown, in some embodiments, each set of steel pipe supports 42 includes a front row of steel pipe supports 421 close to the original bridge pier 2 and a rear row of steel pipe supports 422 away from the original bridge pier 2, that is, the front and rear rows of steel pipe supports are arranged longitudinally; each row of steel pipe supports includes a plurality of steel pipe columns 423 arranged transversely and spaced apart; the steel pipe columns 423 are connected one by one with the support seats 413 embedded in the temporary support foundation 41. The steel pipe columns 423 are processed in sections according to the preset height, that is, each steel pipe column 423 includes a plurality of vertically connected steel pipe segments 4231, and flanges for connection are provided at both ends of the steel pipe segments 4231. The steel pipe segments 4231 adjacent to each other in the transverse direction and in the longitudinal direction of the front and rear rows of steel pipe supports are connected with parallel joints 424 and diagonal braces 425, and the connection forms include but are not limited to welding or bolt connection, thereby connecting the front and rear rows of steel pipe supports into a whole, realizing the integrity of the steel pipe supports 42, and thus ensuring the structural strength and stability of the steel pipe supports 42. Furthermore, an operating platform is set up at the position where the steel pipe support 42 needs to be operated by personnel, and a ladder or stairs are set up to facilitate the passage of personnel up and down.

[0073] refer to Figure 6-Figure 11 As shown, in some embodiments, the jacking system 43 on the top of each set of steel pipe supports 42 is installed on the top of the front row of steel pipe frames 421 of the steel pipe supports 42. The jacking system 43 includes a first cross beam 431, a first cushion beam 432 and a plurality of jacks 433. The first crossbeam 431 is connected to the top surface of all the steel pipe columns 423 of the front row of steel pipe frames 421; multiple jacks 433 are arranged horizontally on the top surface of the first crossbeam 431, wherein a jack 433 is correspondingly provided under the web of each T-beam 11 of the span 1. Since the span 1 also has a relatively high anti-collision wall structure on both sides of the span 1, a jack 433 is further provided at a preset horizontal distance in addition to the two jacks 433 corresponding to the webs of the two outermost T-beams 11 of the span 1; the first cushion beam 432 is crimped onto the top surfaces of all the jacks 433, and multiple first cushion blocks 434 are arranged horizontally on the top surface of the first cushion beam 432, and the first cushion blocks 434 are used to be crimped to the bottom surface of the T-beam 11 of the span 1 above it. When performing the lifting step of the bridge span 1, the jack 433 is started to lift it upward, which can push the first cushion beam 432 and the first cushion block 434 thereon to move upward, thereby lifting the bridge span 1; when performing the lowering step of the bridge span 1, the jack 433 is started to lower it, and the first cushion beam 432 and the first cushion block 434 thereon are lowered accordingly, thereby lowering the lifted bridge span 1. This exemplary embodiment refines the arrangement of the lifting system 43 to ensure that the lifting system 43 can smoothly lift and lower the bridge span 1.

[0074] refer to Figure 6-Figure 11As shown, in some embodiments, an emergency support system 44 is provided on the top of each rear steel pipe frame 422. The emergency support system 44 includes a second crossbeam 441, a second cushion beam 442 and a plurality of support blocks 444; the second crossbeam 441 is connected to the top surface of all steel pipe columns 423 of the rear steel pipe frame 422, a plurality of support blocks 444 are transversely arranged on the top surface of the second crossbeam 441, the second cushion beam 442 is crimped on the top surfaces of all support blocks 444, a plurality of second cushion blocks 443 are transversely arranged on the top surface of the second cushion beam 442, and a safety gap L is reserved between the second cushion block 443 and the bottom surface of the T beam 11 of the bridge span 1 above it, and the height of the safety gap L is usually 15mm-20mm. Further explanation, when the existing bridge pier replacement construction is in normal progress, the second pad 443 is in a virtual connection state without contact with the bridge span 1. If the jacking system 43 on the front steel pipe frame 421 fails unexpectedly and the temporary support fails and the bridge span 1 drops, the emergency jacking system on the rear steel pipe frame 422 can quickly participate in the support to avoid the risk of possible collapse of the bridge. In this exemplary embodiment, by setting the emergency jacking system 44 on the rear steel pipe frame 422 on both sides of the original bridge pier 2, an emergency support reserve for the bridge span 1 is realized to ensure the construction safety when replacing the existing bridge pier.

[0075] refer to Figure 6-Figure 13 As shown, in some embodiments, the installation of each set of steel pipe supports 42 and the jacking system 43 and emergency jacking system 44 thereon includes the following steps:

[0076] A crane is set up near the original pier 2 under the bridge, and the steel pipe column 423 is installed in sections by the crane. After the installation of the steel pipe segments 4231 at the same height is completed, the parallel joints 424 and the diagonal braces 425 between the adjacent steel pipe segments 4231 in the horizontal and vertical directions are immediately installed until the installation of the steel pipe bracket 42 within the crane hoisting height range is completed; further, the steel pipe segments 4231 are bolted with flange high-strength bolts, and the verticality and overall plane position of the steel pipe column 423 are checked every time a steel pipe segment 4231 is installed;

[0077] A hoisting system 6 is arranged on the bridge span 1, and the hoisting system 6 includes a traveling frame 61 and a hoisting frame 62 in a truss structure; the traveling frame 61 spans across the existing bridge deck and can move back and forth in the longitudinal direction. Specifically, a traveling track 66 extending longitudinally is arranged on both sides of the existing bridge deck in the transverse direction, and a traveling trolley 67 is installed on the traveling track 66. The traveling frame 61 is carried on the traveling trolley 67, and the traveling trolley 67 moves along the traveling track 66 to drive the traveling frame 61 to move back and forth in the longitudinal direction; two hoisting winches 63 are arranged in the transverse direction on the traveling frame 61; the hoisting frame 62 is arranged in the transverse direction below the bridge span 1, and its transverse ends are respectively connected to the two hoisting winches 63 by hanging ropes 65, and an electric truss car 64 that can move back and forth in the transverse direction along the hoisting frame 62 is connected below the hoisting frame 62, and the electric truss car 64 is used to hoist the parts to be installed; it can be seen that the longitudinal position of the parts to be installed can be achieved by moving the traveling frame 61 Adjustment, the lifting height of the parts to be installed can be adjusted by the lifting winch 63, and the lateral position of the parts to be installed can be adjusted by the movement of the electric gantry 64; further, the remaining steel pipe segments 4231 are installed by the cooperation of the crane under the bridge and the lifting system 6 on the bridge, that is, the steel pipe segments 4231 are first lifted to a certain height by the crane and then transferred to the electric gantry 64, and then the lifting system 6 completes the installation of the steel pipe bracket 42 that exceeds the lifting height range of the crane; after the installation of the steel pipe bracket 42 is completed, the first crossbeam 431, the first cushion beam 432, the second crossbeam 441 and the second cushion beam 442 thereon are installed; it should be noted that due to the large sizes of the first crossbeam 431, the first cushion beam 432, the second crossbeam 441 and the second cushion beam 442, they are first assembled into a whole under the bridge, and then the crane under the bridge and the lifting system 6 on the bridge cooperate with each other to lift them into place one by one.

[0078] It can be understood that after the first pad beam 432 and the second pad beam 442 are installed, the exact height difference between the first pad beam 432 and the second pad beam 442 and the bottom surface of the T beam 11 is measured immediately, and the first pad block 434 is made according to the line shape of the T beam 11 and supported between the first pad beam 432 and the bottom surface of the T beam 11, and the second pad block 443 is made and installed on the second pad beam 442; when the line shape of the T beam 11 is a diagonal line, the first pad block 434 and the second pad block 443 are wedge-shaped pads.

[0079] It is further explained that stress and strain observation points need to be set at the stress characteristic parts of the steel pipe support 42, and the strain gauges need to be connected to the computer terminal; the stress and deformation of the temporary support system 4 are monitored throughout the construction process to ensure construction safety.

[0080] The above-mentioned schematic embodiment realizes the convenient installation of the steel pipe support 42 and the upper jacking system 43 and the emergency jacking system 44 through the setting and coordination of the crane under the bridge and the hoisting system 6 on the bridge, without being restricted by the high height under the existing bridge and the narrow construction site, thus ensuring the construction safety.

[0081] refer to Fig.14 , Fig.15 As shown, in some embodiments, before performing the jacking step of the bridge span 1, two longitudinal and transverse limiting devices 7 are arranged along the expansion joint 12 between the front and rear spans 1 above the original bridge pier 2. The longitudinal and transverse limiting devices 7 include a fixed portion 71 and a movable portion 72 respectively connected to the bridge deck of the front and rear spans 1; a plurality of circular holes 711 are provided on the fixed portion 71, and a plurality of chemical anchor bolts pass through the circular holes 711 one by one to fix the fixed portion 71 with one span 1; a plurality of longitudinal flat holes 721 are provided on the movable portion 72, and a plurality of chemical anchor bolts pass through the longitudinal flat holes 721 one by one to longitudinally slide the movable portion 72 with another span 1. Specifically, the longitudinal and transverse limiting devices 7 are made of a steel plate with a thickness of 30 mm and are installed between two T-beams 11 close to the crash barrier, but the web position of the T-beam 11 must be avoided.

[0082] In the above-mentioned illustrative embodiment, by setting the longitudinal and transverse limiting devices 7, the ends of the two front and rear spans 1 above the original piers 2 only undergo longitudinal relative movement during jacking and no lateral relative movement occurs, thereby realizing the longitudinal free expansion and contraction and lateral limitation of the existing bridge, and ensuring the lateral relative stability of the two front and rear spans 1 for a relatively long time (the time period from the jacking of the span 1 to the fall back) when supported by the temporary support system 4, thereby ensuring that the existing bridge as a whole does not suffer secondary damage due to the jacking; it should be noted that after the step of falling back of the span 1 is completed, the longitudinal and transverse limiting devices 7 should be removed in time.

[0083] refer to Fig. 9 As shown, in some embodiments, a stopper 435 is protruded on the top surface of each transverse end of each first cushion beam 432, and the two stopper blocks 435 are respectively abutted against the horseshoe outer side surfaces of the T beams 11 at the transverse ends of the bridge span 1. In this exemplary embodiment, by setting the stopper blocks 435 on the first cushion beams 432 of the two sets of steel pipe brackets 42, it is ensured that the ends of the two front and rear bridge spans 1 above the original bridge pier 2 will not move laterally relative to the first cushion beam 432 during the entire period from being jacked up to falling back, and it is ensured that the two front and rear bridge spans 1 will not have non-actively corrected transverse displacement during the entire pier replacement construction, and further ensure that the existing bridge as a whole will not suffer secondary damage due to jacking.

[0084] refer to Fig. 9 , Fig.10As shown, in some embodiments, after the jacking step of the span 1 is completed, the deadweight of the span 1 is transferred to the temporary support system 4, and after the support 3 is emptied and stabilized, a mechanical self-locking device is first used to lock each jack 433; because the original piers 2 must be dismantled and the large-span portal piers 5 must be rebuilt after the span 1 is jacked up, the construction time is relatively long. In order to ensure that the temporary support continues to be effective, a plurality of steel pads are then arranged between the first cross beam 431 and the first pad beam 432 to replace the support of the jack 433, thereby completing the conversion of the force system of the span 1; and then all the jacks 433 are unloaded.

[0085] refer to Fig.23 , Fig.24 As shown, in some embodiments, after the construction of the large-span portal pier 5 is completed and reaches the design strength, the step of lowering the span 1 is performed; first, all the jacks 433 between the first crossbeam 431 and the first cushion beam 432 are started, and the front and rear spans 1 are lifted until the first cushion beam 432 is no longer in contact with the steel pad, and all the jacks 433 are locked, that is, the support of the steel pad is replaced by the jacks 433, and all the steel pads are removed after confirming that the jacks 433 are in good working condition, and then all the jacks 433 are slowly lowered so that the ends of the front and rear spans 1 that are lifted fall to the top surface of the support 3 of the portal pier 5, so that the beam is put into place. Furthermore, when the span 1 is lowered, a level observation point is set to control the elevation of the end of the span 1, and the lateral deviation of the span 1 is observed with a total station. This exemplary embodiment refines the step of lowering the span 1 to ensure the smooth lowering of the span 1.

[0086] refer to Figure 16-Figure 21 As shown, in some embodiments, the steps of dismantling the original pier 2 include the design of the cutting sequence and the cutting block 90, measurement and layout, arrangement of dismantling equipment, and dismantling operations of the pier 2.

[0087] The design steps of the cutting sequence include taking the tie beam 23 as the first cutting level, the portion of the cap beam 22 not corresponding to the pier 21 as the second cutting level, the portion of the cap beam 22 corresponding to the pier 21 as the third cutting level, and the pier 21 as the fourth cutting level; further explaining that cutting the tie beam 23 first, on the one hand, will not have a significant impact on the main structure of the original pier 2, and will not cause the original pier 2 to become unstable or overturned, etc., and on the other hand, it can provide space for the lowering of the cutting block of the cap beam 22.

[0088] The design steps of the cutting block 90 include: the tie beam 23 is divided into blocks in a transverse manner, wherein the first cutting block J1 is arranged in the middle of the length direction thereof, and the second cutting block J2, the third cutting block J3, ..., the nth cutting block Jn are arranged on both sides in turn, and the cutting of the tie beam 23 will be carried out in the order of J1, J2, J3, ..., Jn; the portion of the cap beam 22 that does not correspond to the pier 21 is divided into blocks in a transverse manner, wherein the first cutting block G1 is arranged in the middle of the length direction thereof, and the second cutting block G2, the third cutting block G3, ..., the mth cutting block Gm are arranged on both sides in turn; the portion of the cap beam 22 corresponding to the pier 21 is divided into blocks in an oblique manner, wherein the first cutting block C1 and the second cutting block C2 are respectively arranged on the side away from the two piers 21, and the The third cutting block C3 and the fourth cutting block C4 are respectively arranged on one side close to the two piers 21; the cap beam 22 will be cut in the order of G1, G2, G3, ..., Gm, C1, C2, C3, C4; the pier 21 adopts a vertical block method, and its first cutting block Z1 and the second cutting block Z2 are respectively arranged at the top of the height direction of the two piers 21, and the third cutting block Z3, the fourth cutting block Z4, ..., the kth cutting block Zk are arranged downward in turn, and the two piers 21 will be cut in the order of Z1, Z2, Z3, Z4, ..., Zk; thus, the block form of the cutting blocks on the tie beam 23, the cap beam 22 and the two piers 21 of the original bridge pier 2 is clarified, which can reduce the unbalanced load when the original bridge pier 2 is cut later. The weight of each cutting block 90 is usually controlled within 10t, but it is not limited to this, and it will be controlled by referring to the equipment parameters of the hoisting winch 86.

[0089] The measurement and layout step includes drawing all cutting lines on the original bridge pier 2 with ink lines according to the block form of the cutting block 90, so as to facilitate the subsequent block cutting of the original bridge pier 2.

[0090] The dismantling equipment arrangement steps include: referring to the position of the cutting block 90, laying a springboard 82 on the steel pipe support 42, on the erected steel pipe scaffolding 81 or on the ground to form a rope cutting construction platform for placing the diamond rope saw cutting equipment 83; laying a longitudinally extending transport track 89 on the ground between the two piers 21 of the original bridge pier 2, the transport track 89 extending outward through the gap of the steel pipe support 42, and installing a transfer flat car 88 that can move along the transport track 89 on the transport track 89, and installing a plurality of wheels on the bottom of the transfer flat car 88; on the original bridge pier 2, laying a longitudinally extending transport track 89 on the ground between the two piers 21 of the original bridge pier 2, and the transport track 89 extending outward through the gap of the steel pipe support 42. A hoisting frame 84 is set on the front and rear spans 1 above the pier 2. The two legs of the hoisting frame 84 are respectively supported on the bridge deck of the front and rear spans 1. Two sets of pulley groups 85 are arranged on the hoisting frame 84. The two sets of pulley groups 85 correspond to the front and rear spans 1 respectively, and the hoisting ends of each set of pulley groups 85 are located at the wet joints 13 of the T-beam 11. The driving ends of each set of pulley groups 85 are connected to a hoisting winch 86, which can be used interchangeably with the hoisting winch 63. A traction winch 87 is set on the ground laterally outside a steel pipe bracket 42.

[0091] The steps of dismantling the bridge pier 2 include: opening a plurality of lifting holes 14 corresponding to a plurality of cutting blocks 90 on the front and rear spans 1 above the original bridge pier 2, and the lifting holes 14 are all located at the wet joints 13 of the T-beam 11, thereby preventing the lifting holes 14 from causing damage to the main stress-bearing parts of the bridge span 1, such as the web of the T-beam 11; according to the cutting sequence, the lifting ends of the two sets of pulley groups 85 are respectively passed through the lifting holes 14 on the front and rear spans 1 to connect to a cutting block 90, and the traction winch 87 is also connected to the cutting block 90 for pulling; the cutting block 90 is cut by the diamond wire saw cutting device 83, and the vibration and noise of the diamond wire saw cutting device 83 are very small, so that the cutting block 90 can be separated with almost no disturbance; the cutting block 90 After the cutting is completed, the lifting winch 86 is used to drive the lifting end of the pulley group 85 to move to slowly lower the cutting block 90, and the traction winch 87 is used to pull the cutting block 90 laterally to adjust the lowering direction of the cutting block 90 and avoid interference with the steel pipe support 42, etc., and then the cutting block 90 is lowered to the transfer flat car 88 through the gap, and the connection between the lifting winch 86 and the traction winch 87 and the cutting block 90 is released. The transfer flat car 88 carries the cutting block 90 out of the construction area along the transportation track 89 and transports it out until the cutting block 90 is transferred to the preset storage area; in this way, the tie beam 23, the cap beam 22, and the two piers 21 of the original bridge pier 2 are cut, lowered and transferred in block, thereby completing the demolition construction of the original bridge pier 2.

[0092] The above-mentioned exemplary embodiment refines the steps of dismantling the original bridge pier 2, which can reduce the difficulty of dismantling the original bridge pier 2 and reduce the damage and impact on the existing bridge foundation and the surrounding environment during the dismantling construction.

[0093] refer to Figure 6-Figure 8 , Figure 17-Figure 20 As shown, in some embodiments, before the pier 2 is dismantled, a plurality of cross-shaped frames 45 are vertically arranged outside each pier column 21 of the original pier 2, the cross-shaped frames 45 are clamped with the pier column 21, and the longitudinal ends of the cross-shaped frames 45 are respectively connected to the flat joints 424 of the two front steel pipe frames 421, thereby connecting the cross-shaped frames 45 to the temporary support system 4; since the pier column 21 will have an unbalanced load when the cap beam 22 is cut and dismantled, the setting of the cross-shaped frames 45 can prevent the pier column 21 from being eccentrically unstable or even overturning when the cap beam 22 is cut.

[0094] Furthermore, a plurality of longitudinally extending support beams 46 are arranged between the uppermost flat joints 424 of the two front-row steel pipe racks 421; when executing the dismantling step of the original bridge pier 2, when the cap beam 22 is cut, a plurality of pads 47 are set between the two support beams 46 corresponding to the cutting block 90 of the cap beam 22, and the top surface of the pads 47 is made to abut against the bottom surface of the cutting block 90; the cutting block 90 of the cap beam 22 is supported by the support beams 46 and the pads 47, so as to cooperate with the hoisting winch 86 to tighten the cutting block 90 of the cap beam 22, and ensure that the impact force generated at the moment when the cutting block 90 of the cap beam 22 is cut off will not have an adverse effect on the bridge deck; after the cutting of the cutting block 90 of the cap beam 22 is completed, the cutting block 90 can be slightly lifted by the hoisting winch 86, so as to remove the pads 47 and the support beams 46 that hinder the lowering of the cutting block 90 of the cap beam 22, thereby facilitating the lowering and transportation of the cutting block 90. In addition, when the first cutting block G1 in the middle of the length direction of the cap beam 22 is cut, the cap beam 22 is in the maximum cantilever state. In order to ensure the stability of the cap beam 22 and the pier 21 at this time, a hoisting rope is also hung on the bridge deck to lift the cantilever end of the cap beam 22 using the hoisting rope.

[0095] The above exemplary embodiment ensures the safety of the removal construction of the original bridge pier 2 by disposing the cross frame 45, the support beam 46 and the pad 47.

[0096] In some embodiments, after the step of lowering the span 1 is completed and inspected as qualified and before the step of dismantling the temporary support system 4 is executed, the two longitudinal and transverse limit devices 7 between the front and rear spans 1 above the original pier 2 are removed, and all the hanging holes 14 opened at the wet joints 13 are restored, and the steel bars at the opening positions are restored by embedding reinforcement, and micro-expansion early-strength concrete is poured to repair the bridge deck to meet the requirements of the original bridge deck, and then the highway bridge can be controlled for access.

[0097] When executing the dismantling steps of the temporary support system 4, the jacking system 43 and the steel pipe support 42 are dismantled in order from top to bottom; first dismantle the first cushion block 434 and the second cushion block 443, then dismantle the first cushion beam 432 and the second cushion beam 442, then dismantle the jack 433 and the support block 444, then dismantle the first crossbeam 431, the second crossbeam 441, the support beam 46, and then dismantle the steel pipe support 42. The dismantling order of the steel pipe support 42 is the reverse order of its installation, and should be carried out according to the principles of multi-point, symmetry, slowness and uniformity; it should be noted that when the temporary support system 4 is dismantled, the jacking system 43 and the upper structure of the steel pipe support 42 are first dismantled by cooperating with the crane under the bridge. When the hoisting system 6 on the bridge cannot cooperate with the crane under the bridge to dismantle the steel pipe support 42, the hoisting system 6 on the bridge is immediately dismantled, other construction machinery and equipment are evacuated, and the traffic of vehicles on the highway bridge is restored. The remaining steel pipe supports 42 are continued to be dismantled using the crane under the bridge.

[0098] In summary, the pier replacement construction method for increasing the underpass space of an existing bridge of the present invention can safely and quickly realize the pier replacement construction of the existing bridge and increase its underpass space by setting up a temporary support system 4, dismantling the original pier 2 and rebuilding the large-span portal pier 5, so that the new bridge can smoothly pass under the existing bridge through the large-span portal pier 5, thereby solving the problem that the space under the existing bridge cannot meet the need of the new bridge to pass under.

[0099] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0100] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A pier replacement construction method for increasing the underpass space of an existing bridge, characterized in that: The following steps are involved: Construction of temporary support system: a set of steel pipe brackets are respectively installed on both sides of the original piers of the existing bridge in the longitudinal direction, and a jacking system located under the span of the existing bridge is installed on the top of each set of the steel pipe brackets; Lifting of the bridge span: using the lifting systems on the two sets of the steel pipe supports to lift the ends of the front and rear bridge spans located above the original bridge piers, and stopping the lifting after the bridge spans are completely separated from the supports on the original bridge piers; removing the supports; Removal of the original bridge piers: The tie beam, cap beam and two pier columns of the original bridge piers were removed in sequence by cutting in blocks; Construction of large-span portal piers: construct two pier columns of the portal pier on both sides of the original bridge pier, then construct the portal pier cap beam and multiple support pads on the top of the two pier columns of the portal pier, and then install the supports one by one on the support pads of the portal pier, and adjust the top surface elevation of the supports to be consistent with the preset elevation; Lowering of the bridge span: using the jacking systems on the two sets of steel pipe supports, the two jacked bridge spans are lowered to the top surface of the support of the portal pier; Dismantling of the temporary support system: dismantle the jacking system and steel pipe support in order from top to bottom to realize the pier replacement construction of the existing bridge.

2. The pier replacement construction method according to claim 1, characterized in that: When executing the construction steps of the temporary support system, it also includes constructing a temporary support foundation on the ground on both sides of the original bridge pier in the longitudinal direction, and the two sets of the steel pipe brackets are installed on the temporary support foundation; the construction of the temporary support foundation includes measuring and placing the plane positions of multiple pile foundations on the construction ground and carrying out pile foundation construction, and then excavating the foundation pit, erecting the pedestal formwork, pouring the foundation pedestal, and pre-burying multiple support seats in the top surface of the foundation pedestal; each of the support seats is evenly provided with multiple bolts, and the top ends of the bolts protrude from the top surface of the foundation pedestal; multiple support seats are used to connect with the steel pipe brackets.

3. The pier replacement construction method according to claim 1, characterized in that: Each set of the steel pipe supports includes a front row of steel pipe racks close to the original bridge piers and a rear row of steel pipe racks away from the original bridge piers; each row of the steel pipe racks includes a plurality of steel pipe columns arranged at intervals in the transverse direction, and each of the steel pipe columns includes a plurality of steel pipe segments connected vertically; parallel joints and diagonal braces are connected between the steel pipe segments adjacent to each other in the transverse direction and in the longitudinal direction of the front and rear rows of steel pipe racks; The jacking system is installed on the top of the front row of steel pipe racks; the jacking system includes a first crossbeam, a first cushion beam and a plurality of jacks; the first crossbeam is connected to the top surfaces of all steel pipe columns of the front row of steel pipe racks; a plurality of jacks are transversely arranged on the top surface of the first crossbeam, wherein a jack is correspondingly provided under each T-beam web of the bridge span, and a jack is provided respectively in addition to the two outermost jacks; the first cushion beam is crimped on the top surfaces of all jacks; a plurality of first cushion blocks are transversely arranged on the top surface of the first cushion beam, and the first cushion blocks are used to be crimped with the bottom surface of the T-beam.

4. The pier replacement construction method according to claim 3 is characterized in that: An emergency support system is provided on the top of each of the rear-row steel pipe racks; the emergency support system includes a second crossbeam, a second cushion beam and a plurality of support blocks, the second crossbeam is connected to the top surfaces of all the steel pipe columns of the rear-row steel pipe racks, a plurality of support blocks are transversely arranged on the top surface of the second crossbeam, the second cushion beam is crimped on the top surfaces of all the support blocks, a plurality of second cushion blocks are transversely arranged on the top surface of the second cushion beam, and a safety gap is reserved between the second cushion block and the bottom surface of the T-beam.

5. The pier replacement construction method according to claim 4, characterized in that: The installation of the steel pipe support and the jacking system and emergency jacking system thereon comprises the following steps: A crane is set up near the original bridge pier under the bridge, and the steel pipe column is installed in sections by using the crane. After the installation of the steel pipe sections at the same height is completed, the parallel joints and diagonal braces between two adjacent steel pipe sections in the horizontal direction and the vertical direction are installed immediately until the installation of the steel pipe bracket within the lifting height range of the crane is completed; A hoisting system is arranged on the bridge span, and the hoisting system includes a traveling frame and a hoisting frame; the traveling frame spans across the existing bridge deck and can move back and forth in the longitudinal direction, and two hoisting winches are arranged transversely on the traveling frame; the hoisting frame is arranged transversely below the bridge span, and its two transverse ends are respectively connected to the two hoisting winches by lifting ropes, and an electric gantry vehicle that can move back and forth transversely along the hoisting frame is connected below the hoisting frame; the remaining steel pipe segments are installed by cooperating with the crane under the bridge and the hoisting system on the bridge, thereby completing the installation of the steel pipe bracket that exceeds the crane hoisting height range, and then the first crossbeam, the first cushion beam, the second crossbeam and the second cushion beam on the steel pipe bracket are installed.

6. The pier replacement construction method according to claim 1, characterized in that: Before executing the jacking step of the bridge span, two longitudinal and transverse limiting devices are arranged along the expansion joint between the front and rear spans above the original piers, the longitudinal and transverse limiting devices include a fixed part and a movable part respectively connected to the bridge decks of the front and rear spans, the fixed part is provided with a plurality of circular holes, and a plurality of chemical anchor bolts pass through the circular holes one by one to fix the fixed part to the span, the movable part is provided with a plurality of longitudinal flat holes, and a plurality of chemical anchor bolts pass through the longitudinal flat holes one by one to longitudinally slide the movable part to the span; a limiting block is respectively convexly provided on the top surface at the transverse ends of each of the first cushion beams, and the two limiting blocks are respectively abutted against the horseshoe outer side surfaces of the T-beams at the transverse ends of the span.

7. The pier replacement construction method according to claim 3, characterized in that: After the jacking step of the bridge span is completed, all the jacks are first locked, and then a plurality of steel pads are arranged between the first cross beam and the first cushion beam to replace the support of the jacks, and then all the jacks are unloaded.

8. The pier replacement construction method according to claim 7, characterized in that: When the construction of the large-span gantry pier is completed and reaches the designed strength, the step of lowering the bridge span is executed; first, all the jacks between the first cross beam and the first pad beam are started to replace the support of the steel pads, and then all the steel pads are removed, and then all the jacks are slowly lowered to allow the two lifted bridge spans to fall to the top surface of the support of the gantry pier.

9. The pier replacement construction method according to claim 1, characterized in that: The steps of removing the original bridge piers include: Design of cutting sequence and cutting blocks: the tie beam is used as the first cutting level, the cap beam part not corresponding to the pier is used as the second cutting level, the cap beam part corresponding to the pier is used as the third cutting level, and the pier is used as the fourth cutting level; the tie beam is divided into blocks horizontally, and its first cutting block is set in the middle of its length direction, and the second cutting block, the third cutting block, ..., the nth cutting block are set on both sides in turn; the cap beam part not corresponding to the pier is divided into blocks horizontally, and its first cutting block is set in the middle of its length direction, and the second cutting block, the third cutting block, ..., the mth cutting block are set on both sides in turn; the cap beam part corresponding to the pier is divided into blocks obliquely, and its first cutting block and the second cutting block are respectively set on the side away from the two piers, and its third cutting block and the fourth cutting block are respectively set on the side close to the two piers; the pier is divided into blocks vertically, and its first cutting block and the second cutting block are respectively set at the top of the height direction of the two piers, and the third cutting block, the fourth cutting block, ..., the kth cutting block are set downward in turn; Measurement and setting out: according to the block form of the cutting block, all cutting lines are drawn on the original bridge pier with ink lines; Demolition equipment layout: a rope cutting construction platform is set up on the steel pipe support, on the erected steel pipe scaffolding or on the ground to place the diamond wire saw cutting equipment; a longitudinally extending transport track is laid on the ground between the two piers of the original bridge pier, and a transfer flat car is installed on the transport track; a hoisting frame is set up on the front and rear bridge spans above the original bridge pier, and two sets of pulley groups are arranged on the hoisting frame, and the driving end of each set of the pulley group is connected to a hoisting winch; a traction winch is set on the ground on the lateral outer side of one of the steel pipe supports; Bridge pier removal operation: a plurality of lifting holes corresponding to the plurality of cutting blocks are respectively opened on the front and rear spans above the original bridge pier, and the lifting holes are all located at the wet joints of the T-beam; according to the cutting sequence, the lifting ends of the two sets of the pulley groups are respectively passed through the lifting holes on the front and rear spans to be connected to a cutting block, and the traction winch is also connected to the cutting block; the cutting block is cut by the diamond wire saw cutting equipment, and after the cutting is completed, the cutting block is lowered by the lifting winch and the lowering direction is adjusted by the traction winch so as to lower it onto the transfer flat car and transport it out; the tie beam, cap beam and two piers of the original bridge pier are cut, lowered and transported in blocks in turn, thereby completing the removal of the original bridge pier.

10. The pier replacement construction method according to claim 3, characterized in that: Before carrying out the bridge pier removal operation, a plurality of cross frames are vertically arranged outside each pier column of the original bridge pier, the cross frames are clamped to the pier columns, and the longitudinal ends of the cross frames are respectively connected to the flat joints of the two front-row steel pipe racks; a plurality of longitudinally extending support beams are arranged between the uppermost flat joints of the two front-row steel pipe racks; when cutting the cap beam, a plurality of pads are set between the two support beams corresponding to the cap beam cutting block, and the top surface of the pads is made to abut against the bottom surface of the cutting block, and when the cutting of the cap beam cutting block is completed, the pads and the support beams that hinder the lowering of the cap beam cutting block are removed.

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