A bridge pier segment rapid replacement construction method based on a steel pipe concrete connection

Abstract

This invention discloses a rapid replacement construction method for bridge pier segments based on steel-concrete composite pipe connections, comprising the following steps: 1. Precasting steel-concrete composite pipe replacement segments; 2. Chiseling and jacking the damaged segments of the existing bridge pier; 3. Installing the lower splicing steel pipe and injecting micro-expansion grout; 4. Installing the upper splicing steel pipe; 5. Hoisting the precast steel-concrete composite pipe replacement segments; 6. Injecting micro-expansion grout at the upper splicing steel pipe; 7. Reinforcing the outer surface of the steel-concrete composite pipe replacement segments. This invention features simple steps, a reasonable design, and convenient construction. Connecting the steel-concrete composite pipe replacement segments to the upper and lower segments of the existing bridge pier provides good load-bearing capacity and excellent disaster resistance, making it suitable for replacing segments of damaged reinforced concrete bridge piers.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, and in particular relates to a construction method for rapid replacement of bridge pier segments based on steel-concrete composite connections. Background Technology

[0002] my country has a vast territory and diverse terrain, and bridges are vital transportation hubs connecting the entire country. Bridge piers, as the main load-bearing structures, are susceptible to localized damage and destruction. Demolishing and rebuilding piers damaged by earthquakes, impacts, mudslides, etc., incurs significant costs and is difficult to restore traffic in a short time, potentially causing severe traffic disruptions and resulting in substantial social waste. Therefore, the reinforcement and repair of damaged bridge piers is crucial for bridge engineering.

[0003] Currently, the main methods for strengthening and repairing reinforced concrete bridges in my country include cross-section enlargement, external prestressing, and steel sleeve reinforcement. However, these methods are complex in structure, involve a large workload, and are difficult to implement. Furthermore, they are not suitable for repairing and strengthening severely damaged piers, or the stress and disaster resistance performance of the piers after repair and reinforcement may not be restored to a high level.

[0004] Therefore, there is currently a lack of a construction method for rapid replacement of bridge pier segments based on steel-concrete composite connections that is convenient to construct, has a short construction period, strong versatility, good economy, good load-bearing capacity and excellent disaster resistance, and is suitable for the replacement of segments of damaged reinforced concrete bridge piers. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a construction method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections, which addresses the shortcomings of the prior art. The method is simple in steps, reasonable in design, convenient in construction, short in construction period, highly versatile and economical. It connects the steel-concrete composite pipe replacement segments with the existing upper and lower segments of the bridge pier, and has good bearing capacity and excellent disaster resistance, making it suitable for segment replacement of damaged reinforced concrete bridge piers.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a construction method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections, characterized in that the method includes the following steps:

[0007] Step 1: Replacement of precast steel pipe concrete segments:

[0008] Step 101: Weld a steel pipe to the inner side of the upper end of the replaced steel pipe section for patching, and weld a lower steel pipe to the inner side of the lower end of the replaced steel pipe section for patching.

[0009] Step 102: Pour concrete into the replacement segment steel pipe to form the replacement segment concrete, thus forming the steel pipe concrete replacement segment; wherein, the replacement segment concrete includes the intermediate segment concrete precast in the replacement segment steel pipe, the lower segment concrete integrally formed with the intermediate segment concrete, and the upper segment concrete.

[0010] Step 2: Removal of damaged sections of existing bridge piers and installation of jack supports:

[0011] Step 201: Install a support frame on the existing bridge pier abutment and install a jack device between the support frame and the cap beam;

[0012] Step 202: Remove the concrete of the damaged segment of the existing pier, and use a cutting instrument to cut off the longitudinal reinforcement of the damaged segment of the existing pier, and remove the stirrups of the damaged segment of the existing pier to form the upper segment and the lower segment of the existing pier; wherein, the jack device supports the upper segment of the existing pier to create a gap between the upper segment and the lower segment of the existing pier.

[0013] Step 3: Installation of the lower splicing steel pipes and injection of micro-expansion grout:

[0014] Step 301: Remove the surface of the concrete at the top of the lower segment of the existing pier to expose the outer wall of the lower longitudinal reinforcement. The top of the lower segment of the existing pier after removal is the convex part of the lower segment. The cross section of the convex part of the lower segment gradually decreases from bottom to top.

[0015] Step 302: Install a lower splicing steel pipe on the outer sleeve of the lower longitudinal reinforcement; wherein, the inner side of the lower splicing steel pipe is welded to the outer wall of the lower longitudinal reinforcement;

[0016] Step 303: Inject micro-expansion grout into the lower splicing steel pipe;

[0017] Step 4: Installation of the upper splicing steel pipes:

[0018] Step 401: Remove the lower outer circumferential concrete of the upper segment of the existing bridge pier to expose the outer wall of the upper longitudinal reinforcement, and the bottom of the upper segment of the existing bridge pier after removal is the convex part of the upper segment.

[0019] Step 402: Install splicing steel pipes on the outer sleeve of the upper longitudinal reinforcement; wherein, the inner side of the upper splicing steel pipes is welded to the outer side wall of the upper longitudinal reinforcement.

[0020] Step 5: Hoisting of the precast steel pipe concrete replacement segment:

[0021] Step 501: Hoist and place the precast steel-concrete replacement segment between the upper segment and the lower segment of the existing pier.

[0022] Step 502: Lower the steel pipe concrete replacement segment. Insert the lower end of the lower steel pipe into the upper end of the lower splicing steel pipe, and the bottom of the lower segment concrete extends into the lower splicing steel pipe. At the same time, insert the upper end of the upper steel pipe into the lower end of the upper splicing steel pipe, and the top of the upper segment concrete extends into the upper splicing steel pipe.

[0023] Step 503: Adjust the verticality of the steel pipe concrete replacement segment. The bottom of the convex part of the upper segment should fit with the top of the upper segment concrete, and the top of the convex part of the lower segment should fit with the bottom of the lower segment concrete. At the same time, squeeze out the excess micro-expansion grout from the lower splicing steel pipe.

[0024] Step 504: Use an electric welding machine to weld and fix the upper end of the lower splicing steel pipe and the lower end of the lower steel pipe patch, and weld and fix the inner lower end of the upper splicing steel pipe and the outer upper end of the upper steel pipe patch.

[0025] Step 6: Inject micro-expansion grout at the joint of the steel pipe;

[0026] Step 7: Reinforce the outer surface of the steel-concrete composite replacement segment:

[0027] Step 701: Construct a steel mesh around the steel-concrete composite replacement segment, the upper splicing steel pipe, and the lower splicing steel pipe; wherein, a gap is provided between the inner side of the steel mesh and the outer side of the steel-concrete composite replacement segment, the upper splicing steel pipe, and the lower splicing steel pipe.

[0028] Step 702: Concrete is poured around the steel pipe concrete replacement section, the upper splicing steel pipe and the lower splicing steel pipe to form a concrete layer; wherein, the steel mesh is embedded in the concrete layer.

[0029] The above-mentioned method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connection is characterized in that: in step 101, both the upper and lower steel pipe reinforcements extend beyond the steel pipe of the replacement segment, and the outer surfaces of the upper and lower steel pipe reinforcements are attached to the inner surface of the steel pipe of the replacement segment.

[0030] In step 102, the lower and upper concrete segments are symmetrically arranged and their cross-sections gradually decrease away from the middle concrete segment. The lower concrete segment extends out of the lower steel pipe to fill the gap, and the upper concrete segment extends out of the upper steel pipe to fill the gap.

[0031] The above-mentioned method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections is characterized by: injecting micro-expansion grout at the upper splicing steel pipe in step six, the specific process of which is as follows:

[0032] Step 601: On both sides of the upper segment of the existing bridge pier, and in the area adjacent to the upper splicing steel pipe, drill grouting holes and grout outlet holes with a diameter of 16mm; wherein, the grouting holes and grout outlet holes are connected to the gap between the inner side of the upper splicing steel pipe and the protrusion of the upper segment and the outer side of the upper segment concrete.

[0033] Step 602: Inject micro-expansion grout into the gap between the upper segment of the existing pier and the steel-concrete composite replacement segment through the grouting hole until micro-expansion grout flows out of the grout outlet on the upper segment of the existing pier. Wait 3 to 5 minutes and then stop grouting to ensure that the micro-expansion grout fills the gap between the upper segment of the existing pier and the steel-concrete composite replacement segment.

[0034] Step 603: Treat the surface of the steel-concrete composite replacement segment to remove residual micro-expansion grout and concrete particles from the surface of the steel-concrete composite replacement segment.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The method of the present invention has simple steps, reasonable design and convenient construction, and ensures reliable connection between the steel pipe concrete replacement segment and the lower segment and upper segment of the existing bridge pier.

[0037] 2. This invention achieves the segment replacement of damaged reinforced concrete piers by hoisting steel pipe concrete between the lower segment and the upper segment of the existing pier, which is convenient for construction.

[0038] 3. The present invention includes a steel pipe concrete replacement segment, an upper splicing steel pipe and a lower splicing steel pipe, and an outer construction steel mesh and concrete layer. Through the concrete layer and steel mesh, the steel pipe concrete replacement segment and the connection between the steel pipe concrete replacement segment and the existing lower segment and upper segment of the existing bridge pier are reinforced, thereby improving the load-bearing capacity and disaster resistance.

[0039] 4. The present invention injects micro-expansion grout into the lower splicing steel pipe and injects micro-expansion grout into the upper splicing steel pipe. By injecting micro-expansion grout, the connection between the steel pipe concrete replacement segment and the upper segment of the existing bridge pier, as well as the connection between the steel pipe concrete replacement segment and the lower segment of the existing bridge pier, are effectively combined, so that the steel pipe concrete replacement segment is well stressed.

[0040] 5. The present invention first involves the replacement of precast steel-concrete composite sections, followed by the removal of damaged sections of existing bridge piers and the installation of jack supports. Then, the installation of the lower splicing steel pipe and the injection of micro-expansion grouting material are carried out in sequence, followed by the installation of the upper splicing steel pipe, the hoisting of the precast steel-concrete composite section, the injection of micro-expansion grouting material at the upper splicing steel pipe, and the reinforcement of the outer surface of the steel-concrete composite section to ensure that the steel-concrete composite section is installed in place.

[0041] In summary, the method of the present invention is simple in steps, reasonable in design, convenient in construction, short in construction period, highly versatile and economical. It connects the steel-concrete composite replacement segment with the upper segment and the lower segment of the existing bridge pier, and the reinforced bridge pier has high bearing capacity and strong disaster resistance, making it suitable for segment replacement of damaged reinforced concrete bridge piers.

[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the present invention.

[0044] Figure 2 This is a schematic diagram of the steel-concrete composite replacement segment of the present invention.

[0045] Figure 3 This is a flowchart of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] Detailed Implementation

[0048] like Figures 1 to 3 The method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections, as shown, includes the following steps:

[0049] The method includes the following steps:

[0050] Step 1: Replacement of precast steel pipe concrete segments:

[0051] Step 101: Weld steel pipe patch 5-2 to the inner side of the upper end of the replacement section steel pipe 4, and weld lower steel pipe patch 5-1 to the inner side of the lower end of the replacement section steel pipe 4.

[0052] Step 102: Pour concrete into the replacement segment steel pipe 4 to form replacement segment concrete 6, forming steel pipe concrete replacement segment 2; wherein, the replacement segment concrete 6 includes intermediate segment concrete 6-1 precast in the replacement segment steel pipe 4, lower segment concrete 6-2 integrally formed with the intermediate segment concrete 6-1, and upper segment concrete 6-3.

[0053] Step 2: Removal of damaged sections of existing bridge piers and installation of jack supports:

[0054] Step 201: Install a support frame on the existing pier cap 7, and install a jack device between the support frame and the cap beam 8.

[0055] Step 202: Remove the concrete of the damaged segment of the existing pier, and use a cutting instrument to cut off the longitudinal reinforcement of the damaged segment of the existing pier, and remove the stirrups of the damaged segment of the existing pier to form the upper segment 13 and the lower segment 17 of the existing pier; wherein, the jack device supports the upper segment 13 of the existing pier so that there is a gap between the upper segment 13 and the lower segment 17 of the existing pier.

[0056] Step 3: Installation of the lower splicing steel pipes and injection of micro-expansion grout:

[0057] Step 301: Remove the surface of the concrete at the top of the lower segment 17 of the existing pier to expose the outer wall of the lower longitudinal reinforcement 18. The top of the lower segment 17 of the existing pier after removal is the lower segment protrusion 17-1. The lower segment protrusion 17-1 gradually decreases in cross section from bottom to top.

[0058] Step 302: Install a lower splicing steel pipe 16 on the outer sleeve of the lower longitudinal reinforcement 18; wherein, the inner side of the lower splicing steel pipe 16 is welded to the outer side wall of the lower longitudinal reinforcement 18.

[0059] Step 303: Inject micro-expansion grout into the lower splicing steel pipe 16;

[0060] Step 4: Installation of the upper splicing steel pipes:

[0061] Step 401: Remove the lower outer circumferential concrete of the upper segment 13 of the existing pier to expose the outer wall of the upper longitudinal reinforcement 10, and the bottom of the upper segment 13 of the existing pier after removal is the upper segment protrusion 13-1.

[0062] Step 402: Install splicing steel pipe 12 on the upper longitudinal reinforcement 10; wherein, the inner side of the upper splicing steel pipe 12 is welded to the outer side wall of the upper longitudinal reinforcement 10.

[0063] Step 5: Hoisting of the precast steel pipe concrete replacement segment:

[0064] Step 501: Hoist the precast steel-concrete replacement segment 2 and place it between the upper segment 13 and the lower segment 17 of the existing pier.

[0065] Step 502: Lower the steel pipe concrete replacement segment 2. Insert the lower end of the lower steel pipe reinforcement 5-1 into the upper end of the lower splicing steel pipe 16, and extend the bottom of the lower segment concrete 6-2 into the lower splicing steel pipe 16. At the same time, insert the upper end of the upper steel pipe reinforcement 5-2 into the lower end of the upper splicing steel pipe 12, and extend the top of the upper segment concrete 6-3 into the upper splicing steel pipe 12.

[0066] Step 503: Adjust the verticality of the steel pipe concrete replacement segment 2. The bottom of the upper segment protrusion 13-1 is attached to the top of the upper segment concrete 6-3, and the top of the lower segment protrusion 17-1 is attached to the bottom of the lower segment concrete 6-2. At the same time, squeeze out the excess micro-expansion grouting material in the lower splicing steel pipe 16.

[0067] Step 504: Use an electric welding machine to weld and fix the upper end of the lower splicing steel pipe 16 and the lower end of the lower steel pipe patch 5-1, and weld and fix the inner lower end of the upper splicing steel pipe 12 and the outer upper end of the upper steel pipe patch 5-2.

[0068] Step 6: Inject micro-expansion grout at the joint of the steel pipe;

[0069] Step 7: Reinforce the outer surface of the steel-concrete composite replacement segment:

[0070] Step 701: Construct a steel mesh 21 around the upper splicing steel pipe 12 and the lower splicing steel pipe 16 of the steel-concrete composite replacement segment 2; wherein, a gap is provided between the inner side of the steel mesh 21 and the outer side of the upper splicing steel pipe 12 and the lower splicing steel pipe 16 of the steel-concrete composite replacement segment 2.

[0071] Step 702: Concrete is poured around the upper splicing steel pipe 12 and the lower splicing steel pipe 16 of the steel-concrete replacement segment 2 to form a concrete layer 22; wherein, the steel mesh 21 is embedded in the concrete layer 22.

[0072] In this embodiment, in step 101, both the upper steel pipe patch 5-2 and the lower steel pipe patch 5-1 extend out of the replacement section steel pipe 4, and the outer surfaces of the upper steel pipe patch 5-2 and the lower steel pipe patch 5-1 are attached to the inner surface of the replacement section steel pipe 4.

[0073] In step 102, the lower segment concrete 6-2 and the upper segment concrete 6-3 are symmetrically arranged and their cross sections gradually decrease away from the middle segment concrete 6-1. The lower segment concrete 6-2 extends out of the lower steel pipe to fill 5-1, and the upper segment concrete 6-3 extends out of the upper steel pipe to fill 5-2.

[0074] In this embodiment, the injection of micro-expansion grout at the upper splicing steel pipe in step six is ​​as follows:

[0075] Step 601: On both sides of the upper segment 13 of the existing bridge pier, and in close proximity to the upper splicing steel pipe 12, drill grouting holes 14 and grout outlet holes 15 using a drill bit with a diameter of 16mm; wherein, the grouting holes 14 and grout outlet holes 15 are connected to the gap between the inner side of the upper splicing steel pipe 12 and the outer side of the upper segment protrusion 13-1 and the upper segment concrete 6-3;

[0076] Step 602: Inject micro-expansion grout 20 into the gap between the existing pier upper segment 13 and the steel-concrete replacement segment 2 through the grouting hole 14 until micro-expansion grout flows out of the grout outlet hole 15 on the existing pier upper segment 13. Wait 3 to 5 minutes and then stop grouting to ensure that the micro-expansion grout 20 fills the gap between the existing pier upper segment 13 and the steel-concrete replacement segment 2.

[0077] Step 603: Treat the surface of the steel-concrete composite replacement segment 2 to remove residual micro-expansion grout and concrete particles from the surface of the steel-concrete composite replacement segment 2.

[0078] In this embodiment, the cross-sectional shape of the steel-concrete composite replacement segment 2 is square, rectangular, or circular, depending on the cross-sectional shape of the existing pier 8. The length of the steel-concrete composite replacement segment 2 is adjustable, depending on the length of the damaged segment of the existing pier. The strength grade of the steel-concrete composite replacement segment 2 is not less than the concrete strength grade in the upper segment 13 of the existing pier, i.e., not less than C50.

[0079] In this embodiment, in actual use, the lower steel pipe reinforcement 5-1 and the upper steel pipe reinforcement 5-2 are hollow structures.

[0080] In this embodiment, in actual use, the upper splicing steel pipe 12, the lower splicing steel pipe 16, and the replacement segment steel pipe 4 have the same cross-sectional shape.

[0081] In this embodiment, during actual use, the dimensions of the damaged segments of the existing bridge piers are measured and marked;

[0082] The cross-section of the steel-concrete composite replacement segment 2 is square. The length of the replacement segment steel pipe 4 in the steel-concrete composite replacement segment 2 is determined based on the measured dimensions of the damaged segment of the existing pier. The wall thickness of the replacement segment steel pipe 4 is equal to the diameter of the existing pier longitudinal reinforcement 3, which is 14mm. Lower steel pipe reinforcement 5-1 and upper steel pipe reinforcement 5-2 are welded to the inner sides of both ends of the replacement segment steel pipe 4. The welding length of the lower steel pipe reinforcement 5-1 and upper steel pipe reinforcement 5-2 is equal to the diameter of the existing pier longitudinal reinforcement 3, which is 14mm. The length of the lower steel pipe reinforcement 5-1 and upper steel pipe reinforcement 5-2 is greater than three times the diameter of the existing pier longitudinal reinforcement 3, which is 45mm. The strength grade of the steel-concrete composite replacement segment 2 is not less than the concrete strength grade in the upper segment 13 of the existing pier, which is not less than C50. The lower segment concrete 6-2 and the upper segment concrete 6-3 extend 180mm beyond the replacement segment steel pipe 4.

[0083] In this embodiment, in actual use, the upper end of the lower concrete segment 6-2 is flush with the upper end of the lower steel pipe reinforcement 5-1, and the lower end of the upper concrete segment 6-3 is flush with the upper end of the upper steel pipe reinforcement 5-2.

[0084] In this embodiment, in actual use, the height of both the upper segment protrusion 13-1 and the lower segment protrusion 17-1 is 320mm.

[0085] In this embodiment, the concrete layer 22 is UHPC concrete or ECC concrete.

[0086] In this embodiment, the micro-expansion grouting material refers to the material that expands in volume by 0.1% to 0.5% during the hardening process, which can fill small cracks and gaps.

[0087] In this embodiment, the micro-expansion grout, with its good self-flowability, rapid hardening, early strength, no shrinkage, and micro-expansion characteristics, can be used to quickly and effectively bond together and improve load-bearing capacity.

[0088] In this embodiment, the reinforcing mesh 21 can be a welded reinforcing mesh or a woven reinforcing mesh. The reinforcing bars can be cold-rolled ribbed steel bars or hot-rolled steel bars of grade I or II. The diameter of the reinforcing bars should be 0.5mm to 1.5mm. The perimeter of the reinforcing mesh is approximately the perimeter of the outer section of the steel pipe and is laid around the outside of the steel pipe.

[0089] In this embodiment, during actual use, the welding length of the outer side of the lower steel pipe patch 5-1 to the inner side of the upper end of the lower spliced ​​steel pipe 16 is 14mm, and the top of the lower steel pipe patch 5-1 extends upward beyond the top of the lower spliced ​​steel pipe 16 by 31mm; the welding length of the outer side of the upper steel pipe patch 5-2 to the inner side of the lower end of the upper spliced ​​steel pipe 12 is 14mm, and the bottom of the upper steel pipe patch 5-2 extends downward beyond the bottom of the upper spliced ​​steel pipe 12 by 31mm.

[0090] In this embodiment, in actual use, the two ends of the steel pipe concrete replacement segment 2, the lower end of the upper splicing steel pipe 12, and the upper end of the lower splicing steel pipe 16 are chamfered, and the cross-section of the ends gradually decreases away from each other.

[0091] Weld the two ends of the steel-concrete replacement segment 2 to the lower end of the upper splicing steel pipe 12 and the upper end of the lower splicing steel pipe 16, as well as the exposed parts of the lower steel pipe patch 5-1 and the upper steel pipe patch 5-2.

[0092] In this embodiment, during actual use, a jack device is used to raise and lower the upper segment 13 of the existing bridge pier.

[0093] In this embodiment, during actual use, the support frame and jack device are removed after the replacement is completed.

[0094] In this embodiment, during actual use, the welding anchorage lengths of the upper longitudinal reinforcement and the upper splicing steel pipe 12, and the lower longitudinal reinforcement and the lower splicing steel pipe 16, meet the seismic resistance level. Furthermore, in this embodiment, the welding anchorage length for seismic resistance levels I and II is 320mm.

[0095] In summary, the method of the present invention is simple in steps, reasonable in design, convenient in construction, short in construction period, highly versatile and economical. It connects the steel-concrete composite replacement segment with the upper segment and the lower segment of the existing bridge pier, and the reinforced bridge pier has high bearing capacity and strong disaster resistance, making it suitable for segment replacement of damaged reinforced concrete bridge piers.

[0096] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A construction method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections, characterized in that, The method includes the following steps: Step 1: Replacement of precast steel pipe concrete segments: Step 101: Weld a steel pipe patch (5-2) to the inner side of the upper end of the replacement section steel pipe (4), and weld a lower steel pipe patch (5-1) to the inner side of the lower end of the replacement section steel pipe (4). Step 102: Pour concrete into the replacement segment steel pipe (4) to form replacement segment concrete (6), forming steel pipe concrete replacement segment (2); wherein, the replacement segment concrete (6) includes intermediate segment concrete (6-1) precast in the replacement segment steel pipe (4), lower segment concrete (6-2) integrally formed with the intermediate segment concrete (6-1) and upper segment concrete (6-3). Step 2: Removal of damaged sections of existing bridge piers and installation of jack supports: Step 201: Install a support frame on the existing pier cap (7) and install a jack device between the support frame and the cap beam (8); Step 202: Remove the concrete of the damaged section of the existing pier, and use a cutting instrument to cut off the longitudinal reinforcement of the damaged section of the existing pier, and remove the stirrups of the damaged section of the existing pier to form the upper section (13) and the lower section (17) of the existing pier; wherein, the jack device supports the upper section (13) of the existing pier so that there is a gap between the upper section (13) and the lower section (17) of the existing pier. Step 3: Installation of the lower splicing steel pipes and injection of micro-expansion grout: Step 301: Remove the surface of the concrete at the top of the lower segment (17) of the existing pier to expose the outer wall of the lower longitudinal reinforcement (18), and the top of the lower segment (17) of the existing pier after removal is the lower segment protrusion (17-1); wherein, the cross section of the lower segment protrusion (17-1) gradually decreases from bottom to top. Step 302: Install a lower splicing steel pipe (16) over the lower longitudinal reinforcement (18); wherein the inner side of the lower splicing steel pipe (16) is welded to the outer side wall of the lower longitudinal reinforcement (18); Step 303: Inject micro-expansion grout into the lower splicing steel pipe (16); Step 4: Installation of the upper splicing steel pipes: Step 401: Remove the outer periphery of the lower part of the upper segment (13) of the existing pier to expose the outer wall of the upper longitudinal reinforcement (10), and the bottom of the upper segment (13) of the existing pier after removal is the upper segment protrusion (13-1). Step 402: Install a splicing steel pipe (12) over the upper longitudinal reinforcement (10); wherein the inner side of the upper splicing steel pipe (12) is welded to the outer side wall of the upper longitudinal reinforcement (10); Step 5: Hoisting of the precast steel pipe concrete replacement segment: Step 501: Hoist the precast steel-concrete replacement segment (2) and place it between the upper segment (13) of the existing pier and the lower segment (17) of the existing pier. Step 502: Lower the steel pipe concrete replacement segment (2), insert the lower end of the lower steel pipe reinforcement (5-1) into the upper end of the lower splicing steel pipe (16), and extend the bottom of the lower segment concrete (6-2) into the lower splicing steel pipe (16); at the same time, insert the upper end of the upper steel pipe reinforcement (5-2) into the lower end of the upper splicing steel pipe (12), and extend the top of the upper segment concrete (6-3) into the upper splicing steel pipe (12); Step 503: Adjust the verticality of the steel pipe concrete replacement segment (2). The bottom of the upper segment protrusion (13-1) is attached to the top of the upper segment concrete (6-3), and the top of the lower segment protrusion (17-1) is attached to the bottom of the lower segment concrete (6-2). At the same time, the excess micro-expansion grouting material in the lower splicing steel pipe (16) is squeezed out. Step 504: Use an electric welding machine to weld and fix the upper end of the lower splicing steel pipe (16) and the lower end of the lower steel pipe patch (5-1), and weld and fix the inner lower end of the upper splicing steel pipe (12) and the outer upper end of the upper steel pipe patch (5-2); Step 6: Inject micro-expansion grout at the joint of the steel pipe; Step 7: Reinforce the outer surface of the steel-concrete composite replacement segment: Step 701: Construct a steel mesh (21) around the steel pipe concrete replacement section (2), the upper splicing steel pipe (12), and the lower splicing steel pipe (16); wherein, a gap is provided between the inner side of the steel mesh (21) and the outer side of the steel pipe concrete replacement section (2), the upper splicing steel pipe (12), and the lower splicing steel pipe (16); Step 702: Concrete is constructed around the steel pipe concrete replacement section (2), the upper splicing steel pipe (12) and the lower splicing steel pipe (16) to form a concrete layer (22); wherein, the steel mesh (21) is embedded in the concrete layer (22).

2. The construction method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections according to claim 1, characterized in that: In step 101, both the upper steel pipe patch (5-2) and the lower steel pipe patch (5-1) extend out of the replacement section steel pipe (4), and the outer surfaces of the upper steel pipe patch (5-2) and the lower steel pipe patch (5-1) are attached to the inner surface of the replacement section steel pipe (4); In step 102, the lower segment concrete (6-2) and the upper segment concrete (6-3) are symmetrically arranged and their cross sections gradually decrease away from the middle segment concrete (6-1). The lower segment concrete (6-2) extends out of the lower steel pipe to fill in (5-1), and the upper segment concrete (6-3) extends out of the upper steel pipe to fill in (5-2).

3. The construction method for rapid replacement of bridge pier segments based on steel-concrete composite pipe connections according to claim 1, characterized in that: In step six, micro-expansion grout is injected at the joint of the steel pipe. The specific process is as follows: Step 601: On both sides of the upper segment (13) of the existing bridge pier and adjacent to the upper splicing steel pipe (12), drill grouting holes (14) and grout outlet holes (15) with a diameter of 16mm; wherein, the grouting holes (14) and grout outlet holes (15) are connected to the gap between the inner side of the upper splicing steel pipe (12) and the upper segment protrusion (13-1) and the outer side of the upper segment concrete (6-3); Step 602: Inject micro-expansion grout (20) into the gap between the existing pier upper segment (13) and the steel-concrete replacement segment (2) through the grouting hole (14) until micro-expansion grout flows out of the grout outlet (15) on the existing pier upper segment (13). Wait 3 to 5 minutes and then stop grouting to ensure that the micro-expansion grout (20) fills the gap between the existing pier upper segment (13) and the steel-concrete replacement segment (2). Step 603: Treat the surface of the steel-concrete replacement segment (2) to remove residual micro-expansion grout and concrete particles from the surface of the steel-concrete replacement segment (2).

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