A prefabricated double-column pier system equivalent to cast-in-place and its construction method

Abstract

A prefabricated and assembled double-column pier system equivalent to cast-in-place and a construction method thereof, the system comprises a prefabricated cap and a cap beam with reserved corrugated pipe channels, and prefabricated pier body segments with reserved connecting steel bars at both ends; the construction method comprises hoisting the prefabricated cap and the cap beam into place, using ultra-tough fiber concrete (UTFC) grouting pipe connection to connect the prefabricated pier bottom and pier top segments with the prefabricated cap and the cap beam into an integrated node, and then using ultra-tough fiber concrete (UTFC) wet joint connection in sequence to complete the connection between adjacent prefabricated pier body segments, wherein the lower pier segment is spliced ​​upright at the cap node, and the upper pier segment is spliced ​​inverted at the cap beam node, and finally the upper pier segment is turned over and wet-jointed with the lower pier segment to assemble into a pier as a whole; the prefabricated and assembled double-column pier connection system equivalent to cast-in-place proposed by the present invention adopts factory production and assembly construction, and has the advantages of fast construction speed, small impact on construction site traffic and surrounding environment, and easy control of component quality.

Description

Technical Field

[0001] The present invention relates to the technical field of assembled bridge piers, and in particular to a cast-in-place prefabricated assembled double-column pier system and a construction method thereof. Background Art

[0002] Prefabricated assembled bridge piers are to divide the bridge piers into several pieces along the vertical direction according to a certain modulus, cast them on the prefabrication site around the bridge site, transport them to the construction site by means of transportation, and then assemble them on site. Its construction process mainly includes: prefabrication of components, transportation, installation and joint assembly. Its main advantages are: shortening the construction period, ensuring the construction quality, ensuring the safety of construction workers in dangerous areas during bridge construction, and ensuring that the environment and traffic near the construction are less disturbed. Its main design difficulty is: how to ensure that the stress performance at the splicing section of the bridge pier can meet the requirements it needs to achieve, and it can be easily realized during construction and has a simple structure.

[0003] At present, the research and development of prefabricated assembled pier systems can be divided into two types according to their different mechanical properties: one is the "non-equivalent cast-in-place" system and the other is the "equivalent cast-in-place" system. The connection between the pier components of the "non-equivalent cast-in-place" system is mainly formed by tensioning prestress, while the connection between the pier components of the "equivalent cast-in-place" system is more, such as grouting corrugated pipe connection, grouting pipe connection, socket connection, slot connection, etc. Through the study of the mechanical properties of piers under the two connection forms by domestic and foreign scholars, it can be seen that under static loads, the mechanical properties of the pier structures of the two connection methods are slightly different. Under dynamic loads (such as seismic loads), the pier structure connected by tensioning prestress has good ductility and self-reset ability, but its energy dissipation capacity is poor; the pier structure connected by grouting corrugated pipe connection, grouting pipe connection, socket connection, slot connection, etc. can achieve similar mechanical properties as the integral cast-in-place pier and has a strong energy dissipation capacity. Observing the construction convenience of the two pier connection methods, it can be seen that the construction method of the pier structure formed by tensioning prestress is relatively complex, with high requirements for construction machinery, construction personnel, construction sites, etc., and it is difficult to achieve, and it cannot meet the requirements of rapid construction required by prefabricated piers. For the pier structure formed by connection methods such as grouting corrugated pipe connection, grouting pipe connection, socket connection, and slot connection, its structure is simple and the assembly construction is simple, and it has gradually become the main pier construction form for prefabricated bridge construction.

[0004] In the current research on the connection method of bridge piers in the "equivalent cast-in-place" system, the research results are mostly concentrated on the connection between the bridge pier and the cap beam, and there is less research on the connection method between the bridge pier segments, which greatly limits the application of this connection method in high pier structures. In addition, in the research on the connection method of prefabricated assembled piers, most of the research is on single-column piers, and the research on the prefabricated assembly construction method of double-column piers widely used in urban bridges is relatively weak. Therefore, it is of great significance to the construction and development of current bridge piers to develop a prefabricated assembly connection system that is low-cost, conducive to the rapid and environmentally friendly construction of urban bridges, and suitable for double-column piers. Summary of the invention

[0005] In order to overcome the defects of the above-mentioned prior art and enrich and optimize the construction method of the prefabricated assembled pier system, the purpose of the present invention is to provide a prefabricated assembled double-column pier system equivalent to cast-in-place and a construction method thereof, and adopt ultra-tough fiber concrete (UTFC) grouting pipe connection and ultra-tough fiber concrete (UTFC) wet joint connection to respectively complete the connection between the prefabricated pier bottom segment and the prefabricated abutment, the connection between the prefabricated pier top segment and the prefabricated cap beam, and the connection between each adjacent prefabricated pier body segment; the good self-compactness of ultra-tough fiber concrete (UTFC) can improve the compressive strength of concrete, increase the grip of concrete on steel bars, and improve the bonding effect between the two. The added fibers can also effectively improve the toughness and tensile properties of UTFC materials and limit the development of cracks; through reasonable structural design, the prefabricated assembled double-column pier system can achieve the performance level equivalent to cast-in-place in terms of stress characteristics and seismic performance.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A prefabricated assembled double-column pier system equivalent to cast-in-place, comprising a prefabricated cap 1 arranged on a foundation soil layer, a bridge pier arranged above the prefabricated cap 1, the bridge pier consisting of a prefabricated pier body bottom segment 2 and a pier body top segment 5; a prefabricated cap beam 6 is arranged above the bridge pier;

[0008] The prefabricated foundation 1 is spliced ​​upwards to the bridge pier section by section from the top surface, and the prefabricated cap beam 6 is spliced ​​upwards to the bridge pier section by section from the bottom surface.

[0009] The precast cap 1, precast cap beam 6, pier body bottom segment 2 and pier body top segment 5 are all cast with ordinary reinforced concrete materials; the precast cap 1 and the precast cap beam 6 are provided with a steel cage 4; the pier body longitudinal reinforcement 11 and the pier body stirrups 9 are provided inside the pier; the precast cap 1 and the precast cap beam 2 are respectively embedded with the cap pre-embedded corrugated pipe 15 and the cap beam pre-embedded corrugated pipe 7; the top surface of the precast cap 1 and the bottom surface of the precast cap beam 6 are respectively provided with a cap reserved groove 13 and a cap beam reserved groove 8; the joint between the precast pier body top segment 5 and the precast pier body bottom segment 2 is provided with a longitudinal segment pier connecting steel bar 10 and a segment pier connecting transverse stirrup 19.

[0010] The prefabricated foundation 1 and the pier body bottom segment 2, and the prefabricated cap beam 6 and the prefabricated pier body top segment 5 are connected by ultra-tough fiber concrete UTFC grouting foundation embedded corrugated pipe 15 and cap beam embedded corrugated pipe 7, and the adjacent pier body bottom segment 2 and pier body top segment 5 are connected by ultra-tough fiber concrete UTFC wet joint 3.

[0011] The longitudinal segment pier connecting steel bars 10 in the UTFC wet joint 3 are connected by longitudinal connecting steel bar lap connection 23, longitudinal connecting steel bar welding 24 or longitudinal connecting steel bar mechanical sleeve connection 25.

[0012] The longitudinal reinforcement 14 inserted into the metal corrugated pipe used in the connection between the pre-embedded corrugated pipe 15 of the pedestal and the pre-embedded corrugated pipe 7 of the cap beam is provided with a longitudinal reinforcement stripping section 12 of at least 4d in length, where d represents the diameter of the longitudinal reinforcement 14 .

[0013] Based on the above-mentioned construction method of a prefabricated assembled double-column pier system equivalent to cast-in-place, the steps are as follows:

[0014] Step 1: hoist the prefabricated cap 1 into place, hoist and flip the prefabricated cap beam 6, so that the reserved corrugated pipe interface connecting the prefabricated cap beam 6 and the prefabricated pier body top segment 5 faces upward; pour UTFC grouting material 16 into the prefabricated cap embedded corrugated pipe 15 and the cap beam embedded corrugated pipe 7, the cap reserved groove 13 and the cap beam reserved groove 8; hoist the prefabricated pier body bottom segment 2 and the prefabricated pier body top segment 2 to the predetermined position to connect the pier segment with the prefabricated cap 1 and the prefabricated cap beam 6; adjust its verticality after splicing, and fix it with a bracket; after the UTFC pipe grouting material 16 reaches the required strength, the integrated node connection of the prefabricated cap 1, the prefabricated cap beam 6 and the prefabricated pier body bottom segment 2 and the prefabricated pier body top segment 5 is completed;

[0015] Step 2: After the UTFC pipe grouting material 16 in step 1 reaches the strength, the upper pier structure 17 formed by splicing the prefabricated cap beam 6 and the prefabricated pier body top segment 5 is turned over and hoisted to the corresponding position above the bottom pier structure 18; the pier height is adjusted and the joints at the segment pier connection steel bars 10 are made. The connection method can be overlapped, welded or mechanically connected. After the steel bar connection is completed, the UTFC wet joint outer formwork 20 is supported;

[0016] Step 3: A grouting port 21 and a grouting outlet 22 are provided on the outer formwork 20. UTFC is poured through the grouting port 21 until UTFC emerges from the grouting outlet 22. Vibration and curing are performed, and the pouring of the UTFC wet joint 3 is completed. Thus, the assembly of the double-column bridge pier is completed.

[0017] If the pier structure is a multi-segment pier, the cast-in-place wet joints are used symmetrically in sequence to add segment piers to the upper pier structure 17 and the bottom pier structure 18, and finally the upper and bottom pier structures are connected at the center of the pier, thereby completing the assembly construction of the prefabricated double-column pier.

[0018] Advantages of the present invention:

[0019] 1. Taking advantage of the fact that the strength and toughness of UTFC materials are much higher than those of ordinary concrete, the good self-compactness of ultra-tough fiber concrete (UTFC) and its excellent gripping effect on steel bars can effectively reduce the connection length required for UTFC grouting pipe connection and UTFC wet joint connection; it can also effectively improve the tensile properties of UTFC materials and limit the development of cracks.

[0020] 2. A groove of a certain depth is reserved at the connection between the cap beam and the bridge pier to form an integrated connection node during splicing, thereby improving the shear resistance of the connection and the same seismic performance as the integral cast-in-place connection. The inclined open groove is more conducive to positioning and grouting the splicing node. At the connection surface between the bottom (top) of the pier and the bottom of the reserved groove, in order to reduce the stress concentration of the longitudinal connecting steel bars, a longitudinal stripping section of 4d in length can be set above and below the longitudinal bars at the joint surface to prevent fatigue damage that is easy to occur under earthquake action.

[0021] 3. The above measures can ensure that the mechanical performance and seismic performance of the prefabricated double-column bridge pier system proposed in the present invention are close to those of the integral cast-in-place double-column pier. In addition, the prefabricated assembly method proposed in this article can realize an integrated node connection at the connection between the bridge pier and the cap beam foundation, which greatly ensures the reliability of the connection node and will not become a weak point in the connection of the bridge pier structure under earthquake action.

[0022] 4. The construction sequence of the prefabricated double-column pier is to gradually splice from both ends to the center, that is, first connect the pier and the cap beam of the abutment to ensure that there is no joint error at the connection and the connection is firm. After completing the connection at both ends of the pier, the pier segment is installed upright above the bottom pier and the pier segment is installed inverted below the top pier to gradually form the upper and lower pier structures. Finally, the connected upper pier structure (i.e., the integral pier structure formed by connecting the multi-segment pier and the cap beam) is lifted and turned over to be spliced ​​with the lower pier structure (i.e., the integral pier structure formed by connecting the multi-segment pier and the abutment) to form an integrally assembled pier structure. The construction method of splicing and connecting from both sides to the center of the pier greatly reduces the error accumulation effect caused by the splicing method from bottom to top by reducing the splicing height. Since the construction error is concentrated in the center of the pier, it effectively prevents the defect of weak force at the connection node between the cap beam and the pier in the splicing method from bottom to top. For a double-column pier structure, the center of the pier is the part subject to the least stress. Therefore, controlling the construction error at the center connection of the pier is most beneficial to the stress performance and seismic performance of the entire pier structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the prefabricated assembled double-column bridge pier structure of the present invention.

[0024] Figure 2 The present invention is a schematic diagram of the prefabricated cap beam and prefabricated foundation structure, wherein (a) is the prefabricated cap beam and (b) is the prefabricated foundation.

[0025] Figure 3 It is a schematic diagram of the structure of each prefabricated pier segment of the present invention.

[0026] Figure 4 It is a schematic diagram of the upper and lower pier structures during assembly of the present invention.

[0027] Figure 5 This is a schematic diagram of the structure of the UTFC wet joint connection of the present invention using overlapping longitudinal connecting steel bars.

[0028] Figure 6 This is a schematic diagram of the structure of the UTFC wet joint connection of the present invention using welding for longitudinal connecting steel bars.

[0029] Figure 7 This is a schematic diagram of the structure of the UTFC wet joint connection of the present invention using mechanical connection for longitudinal connecting steel bars.

[0030] Figure 8a It is the splicing of the prefabricated cap beam and the upper segment of the prefabricated pier.

[0031] Figure 8b It is the splicing of the prefabricated abutment and the lower section of the prefabricated pier.

[0032] Figure 8cUTFC wet joints are used to connect the upper and lower pier structures.

[0033] Figure 8d The splicing construction of the prefabricated double-column bridge piers is finally completed.

[0034] Among them: 1. Prefabricated cap; 2. Bottom segment of pier body; 3. UTFC wet joint; 4. Steel cage; 5. Top segment of pier body; 6. Prefabricated cap beam; 7. Pre-embedded corrugated pipe in cap beam; 8. Reserved groove in cap beam; 9. Pier body stirrups; 10. Segmental pier connection steel bars; 11. Pier body longitudinal reinforcement; 12. Longitudinal reinforcement stripping section; 13. Reserved groove in cap; 14. Longitudinal reinforcement inserted into metal corrugated pipe; 15. Pre-embedded corrugated pipe in cap; 16. UTFC pipeline grouting material; 17. Upper pier structure; 18. Bottom pier structure; 19. Transverse stirrups at the connection of segmental piers; 20. External formwork; 21. Grouting port; 22. Grouting outlet; 23. Longitudinal connection steel bar overlap; 24. Longitudinal connection steel bar welding; 25. Longitudinal connection steel bar mechanical sleeve connection. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0036] like Figure 1 As shown, a prefabricated assembled double-column pier system equivalent to cast-in-place includes a prefabricated cap 1 set on the foundation soil layer, a bridge pier is set above the prefabricated cap 1, and the bridge pier is composed of a prefabricated pier body bottom segment 2 and a pier body top segment 5; a prefabricated cap beam 6 is set above the bridge pier. For bridge piers with higher pier heights, segments can be added in the middle of the pier body, but the pier top segment and the pier bottom segment respectively form an integrated node with the cap beam cap, which is different from the connection of other segment bridge piers.

[0037] The prefabricated foundation 1 is spliced ​​upwards to the bridge pier section by section from the top surface, and the prefabricated cap beam 6 is spliced ​​upwards to the bridge pier section by section from the bottom surface.

[0038] like Figure 2 , Figure 3 , Figure 4 As shown, the precast cap 1, precast cap beam 6, pier body bottom segment 2 and pier body top segment 5 are all cast with ordinary reinforced concrete materials; the precast cap 1 and the precast cap beam 6 are provided with steel cage 4; the pier body longitudinal reinforcement 11 and pier body stirrups 9 are provided inside the pier; the precast cap 1 and the precast cap beam 2 are respectively embedded with cap pre-embedded corrugated pipes 15 and cap beam pre-embedded corrugated pipes 7; the top surface of the precast cap 1 and the bottom surface of the precast cap beam 6 are respectively provided with cap reserved grooves 13 and cap beam reserved grooves 8; the joint between the precast pier body top segment 5 and the precast pier body bottom segment 2 is provided with longitudinal segment pier connecting steel bars 10 and segment pier connecting transverse stirrups 19, and each precast pier body segment is a solid circular section.

[0039] The prefabricated foundation 1 and the pier body bottom segment 2, and the prefabricated cap beam 6 and the prefabricated pier body top segment 5 are connected by ultra-tough fiber concrete UTFC grouting foundation embedded corrugated pipe 15 and cap beam embedded corrugated pipe 7, and the adjacent pier body bottom segment 2 and pier body top segment 5 are connected by ultra-tough fiber concrete UTFC wet joint 3.

[0040] like Figure 5 , Figure 6 , Figure 7 As shown, the longitudinal segment pier connection steel bars 10 in the UTFC wet joint 3 are connected by longitudinal connection steel bar lap connection 23, longitudinal connection steel bar welding 24 or longitudinal connection steel bar mechanical sleeve connection 25. In addition to the lap connection 23, the connection height of the UTFC wet joint section 3 only needs to meet the steel bar connection requirements.

[0041] The longitudinal reinforcement 14 inserted into the metal corrugated pipe used in the connection between the pre-embedded corrugated pipe 15 of the cap and the pre-embedded corrugated pipe 7 of the cap beam is provided with a longitudinal reinforcement stripping section 12 of at least 4d in length, where d represents the diameter of the longitudinal reinforcement 14;

[0042] The longitudinal connecting steel bars between adjacent prefabricated pier segments in the UTFC wet joint connection can be overlapped, welded or mechanically connected. If the steel bar connection is welded, the UTFC wet joint connection length L only needs to meet the steel bar connection length requirements specified in the relevant specifications.

[0043] like Figure 8a , 8b 8c, 8d, a construction method of a prefabricated assembled double-column pier system equivalent to cast-in-place, comprising the following steps:

[0044] Step 1: hoist the prefabricated cap 1 into place, hoist and flip the prefabricated cap beam 6, and turn the side of the reserved groove upward, so that the reserved corrugated pipe interface connecting the prefabricated cap beam 6 and the prefabricated pier body top segment 5 faces upward; pour UTFC grouting material 16 into the prefabricated cap embedded corrugated pipe 15 and the cap beam embedded corrugated pipe 7, the cap reserved groove 13 and the cap beam reserved groove 8; hoist the prefabricated pier body bottom segment 2 and the prefabricated pier body top segment 2 to the predetermined position to connect the pier segment with the prefabricated cap 1 and the prefabricated cap beam 6; after the splicing is completed, adjust its verticality, fix it with a bracket, and let it stand for curing; after the UTFC pipe grouting material 16 reaches the required strength, the integrated node connection of the prefabricated cap 1, the prefabricated cap beam 6 and the prefabricated pier body bottom segment 2 and the prefabricated pier body top segment 5 is completed;

[0045] Step 2: After the UTFC pipe grouting material 16 in step 1 reaches the strength, the upper pier structure 17 formed by splicing the prefabricated cap beam 6 and the prefabricated pier body top segment 5 is turned over and hoisted to the corresponding position above the bottom pier structure 18; the pier height is adjusted and the joints at the segment pier connection steel bars 10 are made. The connection method can be overlapped, welded or mechanically connected. After the steel bar connection is completed, the UTFC wet joint outer formwork 20 is supported;

[0046] Step 3: A grouting port 21 and a grouting outlet 22 are provided on the outer formwork 20. UTFC is poured through the grouting port 21 until UTFC emerges from the grouting outlet 22. Vibration and static curing are performed. The UTFC wet joint 3 is cast, and the assembly of the double-column bridge pier is completed.

[0047] If the pier structure is a multi-segment pier, the cast-in-place wet joints are used symmetrically in sequence to add segment piers to the upper pier structure 17 and the bottom pier structure 18, and finally the upper and bottom pier structures are connected at the center of the pier, thereby completing the assembly construction of the prefabricated double-column pier.

[0048] Principle of the invention: The prefabricated and assembled double-column bridge pier system and its construction method equivalent to cast-in-place proposed by the invention utilize a new type of ultra-tough fiber concrete (UTFC) material. Compared with ordinary concrete materials, this material greatly improves the strength and toughness of the material, and due to its excellent self-compactness, it has better bonding performance with steel bars, greatly improves the steel bar connection length at the bridge pier connection, and has better connection performance. The construction of prefabricated and assembled bridge piers through the connection method of the invention has a simple structure and low construction difficulty, which can more effectively shorten the construction time of bridge piers.

[0049] Ultra-tough fiber concrete (UTFC) is a proprietary name in this field. In the present invention, it generally refers to cement-based concrete using millimeter-sized particles (aggregates) and added with steel fibers. It is another type of concrete material with better comprehensive mechanical properties than ordinary concrete and high-performance concrete, such as reactive powder concrete, ultra-high performance fiber reinforced concrete, grouting fiber concrete, dense reinforced composite materials, etc., but preferably ultra-high performance steel fiber reinforced concrete or grouting fiber concrete.

[0050] Compared with the traditional prefabricated pier construction technology, the present invention not only sets up an integrated node at the connection between the pier and the abutment cap beam, but also adds a cast-in-place wet joint connection between the pier segments. Therefore, this double-column pier construction method is more suitable for the construction of a large number of piers, especially for high-pier bridge structures, which has the advantages of fast and easy construction. The main advantages of the double-column pier connected by ultra-tough fiber concrete UTFC are:

[0051] First, the present invention uses ultra-tough fiber concrete as the casting material for the pier connection. Its excellent mechanical properties can provide reliable connection performance for the connection section, so that the mechanical performance and seismic performance of the pier structure can reach the same mechanical performance as that of cast-in-place piers. At the same time, its good compactness can improve the corrosion resistance and durability of the pier under harsh environmental conditions.

[0052] Secondly, when the double-column piers of the present invention are spliced, the first thing to be done is the connection between the pier and the pedestal cap beam. This construction method can ensure that there is no splicing error in the connection section between the pier and the pedestal cap beam. The connection of the node is an integrated node connection. Under the action of an earthquake, the stress performance of each plastic hinge area of ​​the pier structure is complete, and no weak connection points will be generated.

[0053] In the double-column bridge pier structure under this connection mode, different connection modes are adopted between the segment steel bars, and the height of the wet joint section is also different. If the steel bar connection mode of welding connection is adopted, the height of the cast-in-place section only needs to meet the relevant specifications of the steel bar welding length. In summary, the ultra-tough fiber concrete proposed in the present invention as a prefabricated assembled double-column bridge pier wet joint has high structural rigidity, good interlayer adhesion, good durability, and good fatigue resistance. In addition, the steel bar welding connection mode is adopted, and the height of the wet joint section is relatively small, which can greatly reduce the amount of on-site work and save ultra-tough fiber concrete materials. It has great practical value and good economic benefits.

Claims

1. A construction method for a prefabricated and assembled double-column pier system equivalent to cast-in-place, the prefabricated and assembled double-column pier system equivalent to cast-in-place comprising a prefabricated cap (1) arranged on a foundation soil layer, a bridge pier arranged above the prefabricated cap (1), the bridge pier consisting of a prefabricated pier body bottom segment (2) and a prefabricated pier body top segment (5); a prefabricated cap beam (6) arranged above the bridge pier; the prefabricated cap (1) is spliced ​​upwards to the bridge pier section by section from the top surface, and the prefabricated cap beam (6) is invertedly assembled upwards to the bridge pier section by section from the bottom surface; characterized in that: The construction method steps of the prefabricated double-column pier system equivalent to cast-in-place are as follows: Step 1: hoist the prefabricated cap (1) into place, hoist and flip the prefabricated cap beam (6) so that the reserved corrugated pipe interface for connecting the prefabricated cap beam (6) with the prefabricated pier body top segment (5) faces upward; pour UTFC grouting material (16) into the prefabricated cap pre-embedded corrugated pipe (15) and the cap beam pre-embedded corrugated pipe (7), the cap pre-embedded groove (13) and the cap beam pre-embedded groove (8); hoist the prefabricated pier body bottom segment (2) and the pier body top segment (5) to the predetermined position to connect the pier segment with the prefabricated cap (1) and the prefabricated cap beam (6); after the splicing is completed, adjust its verticality and fix it with a bracket; after the UTFC pipe grouting material (16) reaches the required strength, the integrated node connection of the prefabricated cap (1), the prefabricated cap beam (6) and the pier body bottom segment (2) and the prefabricated pier body top segment (5) is completed; Step 2: After the UTFC pipe grouting material (16) in step 1 reaches the required strength, the upper pier structure (17) formed by splicing the prefabricated cap beam (6) and the prefabricated pier body top segment (5) is turned over and hoisted to the corresponding position above the bottom pier structure (18); the pier height is adjusted and the joints at the segmental pier connection steel bars (10) are made. The connection method may be overlapped, welded or mechanically connected. After the steel bar connection is completed, the UTFC wet joint outer formwork (20) is supported; Step 3: A grouting port (21) and a grouting outlet (22) are provided on the outer formwork (20), and UTFC is poured through the grouting port (21) until UTFC emerges from the grouting outlet (22), and then vibrated and cured. The UTFC wet joint (3) is poured, and the assembly of the double-column bridge pier is completed.

2. The construction method of a prefabricated double-column pier system equivalent to cast-in-place according to claim 1, characterized in that: If the pier structure is a multi-segment pier, the cast-in-place wet joints are sequentially and symmetrically adopted to add segment piers to the upper pier structure (17) and the bottom pier structure (18), and finally the upper and bottom pier structures are joined at the center of the pier, thereby completing the assembly construction of the prefabricated double-column pier.

3. The construction method of a prefabricated double-column pier system equivalent to cast-in-place according to claim 1, characterized in that: The prefabricated cap (1), prefabricated cap beam (6), pier body bottom segment (2) and pier body top segment (5) are all cast with ordinary reinforced concrete materials; the prefabricated cap (1) and the prefabricated cap beam (6) are provided with a steel cage (4); the pier body longitudinal reinforcement (11) and the pier body stirrups (9) are provided inside the pier; the prefabricated cap (1) and the prefabricated cap beam (6) are respectively pre-embedded with a cap pre-embedded corrugated pipe (15) and a cap beam pre-embedded corrugated pipe (7); the top surface of the prefabricated cap (1) and the bottom surface of the prefabricated cap beam (6) are respectively provided with a cap pre-reserved groove (13) and a cap beam pre-reserved groove (8); the joint between the prefabricated pier body top segment (5) and the prefabricated pier body bottom segment (2) is provided with longitudinal segment bridge pier connection reinforcement (10) and segment bridge pier connection transverse stirrups (19).

4. The construction method of a prefabricated double-column pier system equivalent to cast-in-place according to claim 1, characterized in that: The prefabricated cap (1) and the pier body bottom segment (2), and the prefabricated cap beam (6) and the prefabricated pier body top segment (5) are connected by ultra-tough fiber concrete (UTFC) grouting cap pre-embedded corrugated pipe (15) and cap beam pre-embedded corrugated pipe (7), and the adjacent pier body bottom segments (2) and pier body top segments (5) are connected by ultra-tough fiber concrete (UTFC) wet joints (3).

5. The construction method of a prefabricated double-column pier system equivalent to cast-in-place according to claim 1, characterized in that: The longitudinal segment pier connecting steel bars (10) in the UTFC wet joint (3) are connected by longitudinal connecting steel bar lap connection (23), longitudinal connecting steel bar welding (24) or longitudinal connecting steel bar mechanical sleeve connection (25).

6. The construction method of a prefabricated double-column pier system equivalent to cast-in-place according to claim 1, characterized in that: The longitudinal steel bars (14) inserted into the metal corrugated pipe used in the connection between the pre-embedded corrugated pipe of the pedestal (15) and the pre-embedded corrugated pipe of the cap beam (7) are provided with a longitudinal steel bar stripping section (12) of at least 4d in length, where d represents the diameter of the longitudinal steel bar (14).

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