Displacement pier for releasing space under existing road under cross-line bridge and construction method thereof

Abstract

The present application relates to a kind of replacement piers releasing the space under the existing road under the underpass of cross-line bridge and its construction method.In the existing road widening engineering, the vertical deflection of existing replacement pier cap beam is large, and the construction safety risk is high.The replacement pier pier body of the present application is in inverted L shape as a whole, and a replacement pier cap beam cantilever is arranged on one side of the top, a vertical through replacement pier reserved hole is arranged on the replacement pier cap beam cantilever, and the replacement pier reserved hole serves as the accommodation space of the top of the existing pier column.The replacement pier constructed by the present application can cleverly realize the lateral deviation of the existing pier column position, effectively release the longitudinal space under the bridge of the existing road underpass, and the construction design of the filling behind the reserved hole can gradually eliminate the deflection under the replacement pier, so that the jacking amount of each level upper main beam is strictly controlled within the range of the maximum support forced displacement allowed by the upper statically indeterminate structure, the load conversion is safe and smooth, the construction safety hazard is greatly reduced, the original bridge structure is maximized, and the engineering cost is saved.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, specifically to a replacement bridge pier for releasing the underpass space of an existing road under a cross-bridge and its construction method. Background Technology

[0002] The continuous growth in traffic volume on highways and urban roads has led to saturation of traffic on many existing highways and municipal roads, severely impacting normal vehicle operation. The contradiction between the demand for high-quality travel and limited capacity is prominent, and a significant proportion of existing roads urgently need expansion and renovation. Considering factors such as economy and driving safety, widening both sides of the road remains the optimal cross-section for road reconstruction and expansion. Cases of conflicts between widening space at existing underpasses and existing bridge piers are frequent. Furthermore, most underpasses were built in the 1990s and have been in operation for a long time. In such cases, replacing existing bridge piers becomes the most economical, safe, and effective technical means to free up road space beneath the bridges.

[0003] As highway and municipal road reconstruction and expansion projects gradually shift towards densely populated urban areas and ultra-wide spans, the expansion methods and cross-sections have undergone significant changes, placing increasingly higher demands on the replacement of existing bridge substructures and construction techniques. Currently, most existing bridge pier replacement technologies both domestically and internationally employ large portal pier replacements to increase column spacing. The main processes include foundation and pier construction, erecting temporary supports to support the superstructure, wrapping the pier top cap beam or column-beam system to form a large outer cap beam, cutting the old pier along the bottom of the outer cap beam, and transferring the superstructure load. This pier replacement process generally requires the erection of temporary supports to support the superstructure, sufficient space under the bridge, and temporary traffic control. It also presents a series of problems, such as large vertical deflection of the replacement pier cap beam and high construction safety risks. Furthermore, it is difficult to accommodate the permissible forced displacement of supports in bridge structures that have been in operation for a long time. Summary of the Invention

[0004] The purpose of this invention is to provide a replacement pier and its construction method for releasing the underpass space of the existing road under the overpass, so as to solve the problems of large vertical deflection of the existing replacement pier cap beam and high construction safety risks.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The replacement piers are used to release the space under the existing road under the overpass. The replacement piers, from bottom to top, include replacement pier pile foundations, replacement pier caps and replacement pier bodies.

[0007] The replacement pier body is generally inverted L-shaped. A replacement pier cap beam cantilever is provided on one side of the top of the replacement pier body. A vertically penetrating replacement pier reserved hole is provided on the replacement pier cap beam cantilever, which serves as the accommodating space for the top of the existing pier column.

[0008] Furthermore, the cross-sectional area of ​​the pre-reserved hole in the replacement pier is larger than the cross-sectional area of ​​the existing pier column;

[0009] The top of the existing bridge pier column is higher than the top of the replacement bridge pier body.

[0010] Furthermore, the inner wall of the reserved hole of the replacement pier is provided with a permanent embedded steel plate for the reserved hole wall, and shear nails are provided on both sides of the permanent embedded steel plate for the reserved hole wall.

[0011] The inner side of the pre-embedded steel plate in the wall of the pre-reserved hole is provided with a pre-reserved hole permanent steel diaphragm, and shear nails are provided on both sides of the pre-reserved hole permanent steel diaphragm.

[0012] Furthermore, temporary jacks for the top of the cantilever of the replacement pier cap beam and the outer periphery of the reserved holes of the replacement pier are provided.

[0013] Furthermore, the bottom surface of the cantilever of the replacement pier cap beam is an inclined surface.

[0014] Furthermore, the longitudinal width of the cantilever of the replacement pier cap beam is greater than the longitudinal width of the replacement pier body.

[0015] On the other hand, a method for constructing replacement bridge piers to release the underpass space of existing roads under overpasses is provided, the method comprising:

[0016] A temporary tie beam is constructed on the upper part of the existing pier column, which is located below the top tie beam of the existing pier column. The top tie beam of the existing pier column is cut. At the same time, replacement pier pile foundation and replacement pier cap are constructed on the outside of the existing pier.

[0017] Erect a support frame for the replacement pier body, construct the replacement pier body above the replacement pier cap, and reserve a vertical through-hole for the replacement pier on the cantilever of the replacement pier cap beam of the replacement pier body. The top of the existing pier column is located inside the reserved hole for the replacement pier.

[0018] Remove the ground support of the replacement pier body, set up temporary jacks on the top of the cantilever of the replacement pier cap beam and on the outer periphery of the reserved hole of the replacement pier, and lift the cast-in-place box girder of the existing bridge span superstructure step by step.

[0019] The existing bridge piers and columns were cut and removed, and the pre-reserved holes in the bridge piers were filled and replaced with micro-expansion steel fiber concrete.

[0020] Permanent intelligent force-measuring and height-adjusting bearings were installed at the original bearing locations to complete the replacement, and the existing road underpass space under the overpass was widened laterally.

[0021] Furthermore, before constructing the replacement pier pile foundation and replacement pier cap on the outside of the existing pier, a steel sheet pile retaining structure is continuously driven between the existing pier and the replacement pier.

[0022] Furthermore, after reserving the reserved holes for the replacement pier, a permanent embedded steel plate is installed on the inner wall of the reserved hole, and shear nails are installed on both sides of the permanent embedded steel plate.

[0023] A permanent steel diaphragm is installed on the inner side of the permanent embedded steel plate in the reserved hole wall, and shear studs are installed on both sides of the permanent steel diaphragm.

[0024] Furthermore, temporary jacks are installed at the top of the cantilever of the replacement pier cap beam and around the pre-reserved opening of the replacement pier to gradually lift the cast-in-place box girder of the existing bridge span superstructure, including:

[0025] The temporary jacks for replacing the pier tops are placed below the crossbeams and webs of the cast-in-place box girder of the existing bridge span superstructure.

[0026] By using temporary jacks on the top of the replacement pier to lift the structure above in stages, the load above is transferred to the replacement pier through the gradual lifting, thereby eliminating the deflection of the replacement pier.

[0027] After each stage of jacking is completed, temporary pads are promptly added to the bottom of the beam, and the temporary jacks on the top of the pier are unloaded and replaced. The temporary pads share the load with the existing piers.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The replacement pier constructed in this invention is an inverted L-shaped structure, which cleverly achieves lateral displacement of the existing pier position, effectively releasing the longitudinal underpass space of the intersecting road. The pre-reserved holes filled laterally can gradually eliminate the deflection of the replacement pier, ensuring that the lifting amount of each stage of the superstructure is strictly controlled within the maximum allowable forced displacement range of the superstructure's statically indeterminate support. After the single-stage lifting amount is completely eliminated, the old pier begins to participate in supporting the main beam, adding an extra layer of safety to the entire pier replacement construction process. Simultaneously, by arranging temporary jacks around the pre-reserved hole walls to support the main beam and complete the load transfer, it is ensured that the existing overpass traffic is not interrupted throughout the construction process, and no temporary piers are erected to support the main beam, greatly reducing construction safety hazards, maximizing the use of the original bridge structure, and saving project costs.

[0030] The inverted L-shaped replacement bridge pier construction method of the present invention can be widely applied to highway and municipal road reconstruction and expansion projects. It is particularly applicable in highly urbanized areas, densely populated urban areas and other scenarios where land resources are scarce, and has broad application prospects for similar road reconstruction projects. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0032] Figure 1 This is the front view of the replaced bridge pier.

[0033] Figure 2 This is a side view of the replaced bridge pier.

[0034] Figure 3 It is a 3D diagram of the replacement bridge pier.

[0035] Figure 4 This is a schematic diagram of the combination of replacement bridge piers and existing bridge piers.

[0036] Figure 5 This is a top view of the detailed construction of the steel-concrete composite structure used to fill the pre-reserved holes in the bridge pier.

[0037] Figure 6 This is a schematic diagram showing the changes in vertical deflection of the bridge pier under dead and live loads before and after the replacement.

[0038] Figure 7 This is a schematic diagram showing the changes in the cross-section of the existing road before and after the replacement.

[0039] Figure 8 This is a schematic diagram of the bridge span elevation layout and the elevation of the highway beneath the bridge.

[0040] Figure 9 This is a schematic diagram of step 1 of the construction method of the present invention.

[0041] Figure 10 This is a schematic diagram of step 2 of the construction method of the present invention.

[0042] Figure 11 This is a schematic diagram of step 3 of the construction method of the present invention.

[0043] Figure 12 This is a schematic diagram of step 4 of the construction method of the present invention.

[0044] Figure 13 This is a schematic diagram of step 5 of the construction method of the present invention.

[0045] The diagram is labeled as follows:

[0046] 1- Replace pier body, 2- Replace pier cap, 3- Replace pier pile foundation, 4- Existing pier column top tie beam, 5- Existing pier column, 6- Existing pier pile foundation, 7- Existing bridge span superstructure cast-in-place box girder, 8- Existing pier pile top tie beam, 9- Existing pier column temporary tie beam, 10- Replace pier top temporary jack, 11- Replace pier reserved hole, 12- Permanent intelligent force measuring and height adjustment support, 13- Permanent embedded steel plate in reserved hole wall, 14- Shear nail, 15- Micro-expansion steel fiber concrete, 16- Permanent steel diaphragm in reserved hole. Detailed Implementation

[0047] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0048] In the description of this patent, it should be understood that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "longitudinal", "lateral", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent.

[0049] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0050] In a specific embodiment, the direction of the line is defined as longitudinal, and the direction perpendicular to the line is defined as transverse.

[0051] To address the issue that the spacing between existing piers of current overpass bridges does not fully consider the needs of road expansion, this invention provides an inverted L-shaped replacement pier with pre-reserved holes that are then filled. This frees up space for existing roads to pass under the overpass, has a reasonable structural form, and is convenient and quick to construct. It can gradually eliminate the vertical deflection of the replacement pier before load conversion, reduce construction risks, and ensure uninterrupted traffic throughout the entire construction process of the overpass bridge.

[0052] like Figure 8The existing bridge piers are located on the left side of the existing left lane and the right side of the existing right lane of the expressway, specifically as a double-column pier structure, comprising existing pier pile foundations 6 and existing pier columns 5 from bottom to top. A longitudinal tie beam 8 is provided between the tops of the existing pier pile foundations 6, and a longitudinal tie beam 4 is provided between the tops of the existing pier columns 5. The width of the underpass space of the existing road under the overpass is limited by the lateral distance between the two existing piers. The inverted L-shaped replacement pier constructed in this invention can widen this width laterally.

[0053] like Figure 1-4 The replacement pier comprises, from bottom to top, a replacement pier pile foundation 3, a replacement pier cap 2, and a replacement pier body 1. In some embodiments, each replacement pier may include four replacement pier pile foundations 3, which together support the replacement pier cap 2. The replacement pier body 1 is a reinforced concrete structure, generally inverted L-shaped. A replacement pier cap beam cantilever is provided on one side of the top of the replacement pier body 1. The bottom surface of the replacement pier cap beam cantilever is a slope, sloping downwards from the inside out. The replacement pier cap beam cantilever and the replacement pier body 1 are an integral structure. In some embodiments, the longitudinal width of the replacement pier cap beam cantilever may be greater than the longitudinal width of the replacement pier body 1 to increase the bearing area of ​​the replacement pier cap beam cantilever.

[0054] A vertically penetrating pre-reserved hole 11 is provided on the cantilever of the replacement pier cap beam, serving as a space to accommodate the top of the existing pier column 5. The cross-sectional area of ​​the pre-reserved hole 11 is larger than that of the existing pier column 5, ensuring a minimum clear distance of 30cm between the hole wall and the surface of the existing pier column 5. The top of the existing pier column 5 is higher than the top of the replacement pier body 1. In some embodiments, the cross-section of the pre-reserved hole 11 can be square, the cross-section of the existing pier column 5 can be circular, and the top of the existing pier column 5 is located at the centroid of the pre-reserved hole 11. Figure 5The inner wall of the reserved hole 11 of the replacement pier is provided with a permanent embedded steel plate 13, and shear nails 14 are provided on both sides of the permanent embedded steel plate 13. When the cross-section of the reserved hole 11 of the replacement pier is square, the permanent embedded steel plate 13 forms a square tube structure. The inner side of the permanent embedded steel plate 13 is provided with a permanent steel diaphragm 16, which is arranged in a crisscross pattern. Shear nails 14 are also provided on both sides of the permanent steel diaphragm 16. During construction, shear nails 14 need to be pre-embedded in the reserved hole 11 of the replacement pier. The shear nails 14 are exposed inside the reserved hole 11 of the replacement pier. The permanent embedded steel plate 13 of the reserved hole has pre-set through holes for shear nails. The shear nails 14 are inserted and pre-embedded in the inner wall of the reserved hole 11 of the replacement pier. Subsequently, the permanent steel diaphragm 16 with the reserved hole is welded to the permanent embedded steel plate 13 on the wall of the reserved hole. The permanent steel diaphragm 16 with the reserved hole also has pre-set through holes for shear nails and is equipped with shear nails 14. After the upper load is transferred, the reserved hole 11 of the pier is filled and replaced with micro-expansion steel fiber concrete 15 to form a post-cast steel-concrete composite structure.

[0055] like Figure 7 The replacement piers are constructed on the outside of the existing piers. After replacement, the underpass space of the existing road under the overpass is freed up and the underpass space is widened laterally. Before construction, the lateral offset distance of the existing piers is determined according to the cross-sectional requirements of the road to be crossed under the bridge. One replacement pier is constructed on the outside of each existing pier column 5, for a total of 4 replacement piers on the left and right sides.

[0056] The specific construction method is as follows:

[0057] Step 1: As Figure 9 To ensure the lateral stability of the existing pier before and after pier replacement, a temporary tie beam 9 needs to be constructed 5-6 meters below the top of the existing pier before the replacement pier construction. This temporary tie beam 9 is located below the existing pier top tie beam 4 and below the cantilevered slope of the replacement pier cap beam. The existing pier top tie beam 4 is then cut and removed. Simultaneously, the replacement pier pile foundation 3 and replacement pier cap 2 are constructed at appropriate locations on the outside of the existing pier. The construction of the temporary tie beam 9 temporarily ensures the rectangular stability of the existing pier.

[0058] Before constructing the replacement pier pile foundation 3 and replacement pier cap 2 on the outside of the existing pier, a steel sheet pile retaining structure is continuously driven between the existing pier and the replacement pier to reduce the impact and disturbance of the replacement pier construction team on the existing pier.

[0059] Step 2: As Figure 10Erect a support frame for the replacement pier body, construct the replacement pier body 1 above the replacement pier cap 2, and reserve a vertical through-hole 11 for the replacement pier on the cantilever of the replacement pier cap beam of the replacement pier body 1. The top of the existing pier column 5 is located inside the reserved hole 11 of the replacement pier.

[0060] To avoid the complex construction process and tilting of the cantilever top surface of the replacement pier cap beam caused by the placement of prestressed tendons inside the replacement pier, both the pier body 1 and the cantilever of the replacement pier cap beam are reinforced concrete structures. In addition, to further reduce the vertical deflection of the replacement pier during operation, a rectangular hole is pre-reserved around the existing pier column 5 when pouring the concrete for the cantilever of the replacement pier cap beam, namely the pre-reserved hole 11 of the replacement pier. The hole runs through the top and bottom of the cantilever of the replacement pier cap beam to ensure that the replacement pier can move freely between the replacement pier and the existing pier.

[0061] After reserving the pre-reserved hole 11 for the replacement pier, a permanent embedded steel plate 13 is installed on the inner wall of the pre-reserved hole 11, and shear studs 14 are installed on both sides of the permanent embedded steel plate 13. A permanent steel diaphragm 16 is installed inside the permanent embedded steel plate 13, and shear studs 14 are installed on both sides of the permanent steel diaphragm 16. The shear studs 14 can be arranged at intervals of large and small sizes, with dimensions of Φ22×100mm and Φ22×200mm.

[0062] Step 3: As Figure 11 After the concrete strength of the pier body meets the design strength, the pier support for the replacement pier is removed. Temporary jacks 10 are installed at the top of the cantilever of the replacement pier cap beam and around the pre-reserved holes 11 of the replacement pier. The existing bridge span's superstructure cast-in-place box girder 7 is then lifted step by step. Lifting the existing bridge span's superstructure cast-in-place box girder 7 step by step according to the allowable forced displacement of the superstructure supports can gradually eliminate the dead and live loads of the replacement pier and reduce creep deflection. Specifically, this includes:

[0063] Step 3.1: Place the temporary jack 10 on the top of the replacement pier below the crossbeam and web of the cast-in-place box girder 7 of the existing bridge span superstructure;

[0064] Step 3.2: Use temporary jacks on the top of the replacement pier to lift the structure above in 10 stages. By lifting the structure in stages, the load above will be transferred to the replacement pier, and the deflection of the replacement pier will be gradually eliminated.

[0065] Step 3.3: After each stage of jacking is completed, temporary pads are promptly added to the bottom of the beam, and the temporary jacks 10 on the top of the pier are unloaded and replaced. The temporary pads share the load with the existing piers.

[0066] After the final stage of jacking is eliminated to zero, the old pier begins to bear the load and support the main beam. This process is repeated multiple times until the dead and live load deflection of the upper part of the replacement pier plus the shrinkage and creep deflection of the replacement pier itself are completely eliminated.

[0067] This method can cover the replacement of existing piers in small-span continuous structural systems for general highways and municipal projects. Under the action of dead and live loads on the superstructure, the maximum vertical deflection of the replaced pier is H mm, and the shrinkage and creep deflection of the replaced pier itself is h mm (e.g., Figure 6 The figure shows the total deflection of the replacement piers under dead and live loads on a 25m prestressed concrete continuous box girder bridge in the project. To broaden the versatility of the technical solution, the pier replacement locations were chosen at both the continuous pier and the transition pier at the connecting end. Finite element simulation calculations yielded the maximum permissible forced displacement Δmm at the supports of the statically indeterminate superstructure (generally less than ±5mm, ±2mm in the project). Figure 11 As shown, the pier support is removed, and jacks are arranged around the pre-reserved holes at the top of the cantilever of the replacement pier cap beam. To ensure the safety of the upper main beam during the jacking process, the jacks should be placed under the crossbeams and webs. The upper main beam is jacked in N stages (N = H / Δ) with the maximum single jacking amount less than Δmm and the jacking rate less than 1mm / 3min. By jacking the main beam stage by stage, the load is transferred to the replacement pier, and the deflection of the replacement pier is gradually eliminated. After each stage of jacking is completed, temporary pads are added to the bottom of the beam in time, and the jacks are unloaded to ensure that the pads and the old pier share the load.

[0068] Repeat step 3N times. After 4 to 5 months, once the shrinkage and creep deformation of the replaced bridge pier has stabilized, repeat step 3n (n = h / Δ) times. The purpose of this step is to further eliminate the shrinkage and creep deflection of the replaced bridge pier itself.

[0069] Step 4: As Figure 12 When the observed displacement at the bottom of the beam is less than 1 mm and remains stable, the existing bridge pier column 5 is promptly cut into sections and dismantled, and the pre-reserved holes 11 of the bridge pier are filled and replaced with micro-expansion steel fiber concrete 15.

[0070] An electric hoist was used to temporarily lift the top 5-10cm of the existing bridge pier column 1 and fix it temporarily. Then, the lower segments were cut sequentially and moved laterally out of the construction area. Finally, the first segment was moved down and then laterally moved out of the construction area. At this time, the replacement pier and the temporary jacks 10 on the top of the replacement pier jointly supported the cast-in-place box girder 7 of the superstructure of the existing bridge span. Due to the narrow space of the reserved holes 11 of the replacement pier, it was difficult to align the inner formwork (permanently embedded steel plate 13 in the reserved hole wall) and the reinforcing bars (shear nails 14) with the holes. Therefore, the inner formwork of the holes was pre-embedded, and micro-expansion steel fiber reinforced concrete was poured afterward to form a steel-concrete composite structure. The hoop effect of the steel plate further increased the local bearing strength of the post-cast section below the support. In the following 1-2 years, the elevation of the top surface of the support and the changes in the support reaction force can be continuously monitored through intelligent force measuring supports.

[0071] Step 5: Install permanent intelligent force-measuring and height-adjusting bearings 12 at the original bearing locations to complete the replacement. The existing road underpass space under the overpass is widened laterally. The elevation of the bearing top surface and changes in bearing reaction force can be continuously monitored through the permanent intelligent force-measuring and height-adjusting bearings 12 over the next 1-2 years.

[0072] This invention solves the problem of insufficient space reserved for the reconstruction and expansion of existing overpasses in highway and urban road reconstruction and expansion projects. The inverted L-shaped replacement piers, which are filled after the reserved holes are filled, have the advantages of not interrupting traffic on the existing overpasses during the entire construction process and not needing to erect temporary supports for the replacement pier cap beams or upper main beams. It can maximize the release of expansion space between the existing piers under the bridge, while making the most of the original bridge structure, saving project costs, and reducing construction risks.

[0073] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. Replacement piers for releasing the underpass space of existing roads under overpasses, characterized in that: The replacement pier, from bottom to top, includes the replacement pier pile foundation (3), the replacement pier cap (2), and the replacement pier body (1). The replacement pier body (1) is in the shape of an inverted L. A replacement pier cap beam cantilever is provided on one side of the top of the replacement pier body (1). A vertically penetrating replacement pier reserved hole (11) is provided on the replacement pier cap beam cantilever. The replacement pier reserved hole (11) serves as the accommodating space at the top of the existing pier column (5). The cross-sectional area of ​​the pre-reserved hole (11) of the replacement pier is greater than the cross-sectional area of ​​the existing pier column (5); The top of the existing bridge pier column (5) is higher than the top of the replacement bridge pier body (1); The cross-section of the reserved hole (11) of the replacement pier is square, and the inner wall is provided with a permanent embedded steel plate (13) to form a square tube structure. Shear nails (14) are provided on both sides of the permanent embedded steel plate (13). The inner side of the pre-embedded steel plate (13) of the pre-reserved hole wall is provided with a pre-reserved hole permanent steel diaphragm (16), the pre-reserved hole permanent steel diaphragm (16) is arranged in a crisscross pattern, and shear nails (14) are provided on both sides of the pre-reserved hole permanent steel diaphragm (16).

2. The replacement bridge pier for releasing the underpass space of the existing road under the overpass as described in claim 1, characterized in that: Temporary jacks (10) are provided on the top of the cantilever of the replacement pier cap beam and on the outer periphery of the reserved hole (11) of the replacement pier.

3. The replacement bridge pier for releasing the underpass space of the existing road under the overpass as described in claim 2, characterized in that: The bottom surface of the cantilever of the replacement pier cap beam is an inclined plane.

4. The replacement bridge pier for releasing the underpass space of the existing road under the overpass as described in claim 3, characterized in that: The longitudinal width of the cantilever of the replacement pier cap beam is greater than the longitudinal width of the replacement pier body (1).

5. A method for constructing replacement bridge piers to free up space under existing roads beneath overpasses, characterized by: The method is used to perform the replacement bridge pier as described in claim 4, comprising: A temporary tie beam (9) is constructed on the upper part of the existing pier column (5). The temporary tie beam (9) is located below the top tie beam (4) of the existing pier column. The top tie beam (4) of the existing pier column is cut. At the same time, replacement pier pile foundation (3) and replacement pier cap (2) are constructed on the outside of the existing pier. Erect a support frame for the replacement pier body, construct the replacement pier body (1) above the replacement pier cap (2), and reserve a vertical through-hole (11) for the replacement pier on the cantilever of the replacement pier cap beam of the replacement pier body (1). The top of the existing pier column (5) is located inside the reserved hole (11) of the replacement pier. Remove the support frame of the replacement pier body, set up temporary jacks (10) on the top of the cantilever of the replacement pier cap beam and on the outer periphery of the reserved hole (11) of the replacement pier, and lift the cast-in-place box girder (7) of the existing bridge span superstructure step by step. Cut and remove the existing bridge pier column (5), and fill and replace the reserved hole (11) of the bridge pier with micro-expansion steel fiber concrete (15). A permanent intelligent force-measuring and height-adjusting bearing (12) was installed at the original bearing location to complete the replacement, and the existing road underpass space under the overpass was widened laterally.

6. The method for constructing replacement bridge piers to release the underpass space of the existing road under the overpass according to claim 5, characterized in that: Before constructing the replacement pier pile foundation (3) and replacement pier cap (2) on the outside of the existing pier, a steel sheet pile retaining structure is continuously driven between the existing pier and the replacement pier.

7. The method for constructing replacement bridge piers to release the underpass space of an existing road under a cross-pass as described in claim 6, characterized in that: After reserving the reserved holes (11) for the replacement pier, a permanent embedded steel plate (13) is installed on the inner wall of the reserved hole (11) of the replacement pier, and shear nails (14) are installed on both sides of the permanent embedded steel plate (13). A permanent steel diaphragm (16) for the reserved hole is installed on the inner side of the permanent embedded steel plate (13) for the reserved hole, and shear nails (14) are installed on both sides of the permanent steel diaphragm (16).

8. The method for constructing replacement bridge piers to release the underpass space of the existing road under the overpass according to claim 7, characterized in that: Temporary jacks (10) are installed at the top of the cantilever of the replacement pier cap beam and around the pre-reserved hole (11) of the replacement pier to gradually lift the cast-in-place box girder (7) of the existing bridge span superstructure, including: The temporary jacks (10) on the top of the replacement pier are placed below the crossbeams and webs of the cast-in-place box girder (7) of the existing bridge span superstructure. Using temporary jacks (10) on the top of the replacement pier, the structure above is lifted in stages. The load above is transferred to the replacement pier through the gradual lifting, thereby eliminating the deflection of the replacement pier. After each stage of jacking is completed, temporary pads are promptly added to the bottom of the beam, and the temporary jacks on the top of the pier are unloaded and replaced (10). The temporary pads and the existing piers share the load.

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