Connecting structure of composite pipe-concrete-steel pipe double-wall hollow pier and pile foundation and construction method of connecting structure

Abstract

The invention discloses a connecting structure of a composite pipe-concrete-steel pipe double-wall hollow pier and a pile foundation and a construction method of the connecting structure. The method is achieved by prefabricating a double-wall hollow pier body and a cast-in-place concrete connecting section. The pier body comprises a composite pipe, a concrete interlayer and a steel pipe from outside to inside. The cross section of the connecting section can be circular or square; before connection is implemented, concrete can be poured in a certain range in the steel pipe to locally form steel pipe concrete, the steel plate at the lower end of the bridge pier and the embedded annular steel plate are fixed in a welding or bolt connection mode, and then a connection section formwork is erected and the connection section is poured at a time to serve as a main section connection measure. The prefabricated double-wall pier is rapidly and reliably connected with the pile foundation on the installation site, the construction period and the measure cost are saved, carbon emission in the construction process is obviously reduced, and the prefabricated double-wall pier is particularly suitable for construction in mountainous areas where the pier is difficult to cast on site.

Description

Technical Field

[0001] This invention relates to the field of novel low-carbon and corrosion-resistant civil engineering structures, specifically to a novel bridge pier-pile foundation connection structure based on corrosion-resistant high-performance fiber-reinforced composite material (FRP) pipes and its construction method. Background Technology

[0002] Existing bridge piers extensively utilize reinforced concrete (RC) structures, steel structures, or steel-concrete composite structures. In coastal environments, the corrosion of reinforcing steel and steel is a widespread problem, leading to severe infrastructure deterioration and resulting in GDP losses exceeding 3% both in my country and globally. Coastal areas are often among the more economically developed regions in these countries, and infrastructure deterioration due to steel corrosion poses a serious challenge to sustainable economic development. Using expensive heavy-duty anti-corrosion coatings and maintaining and reinforcing existing structures can alleviate the sustainability issues caused by these problems to some extent, but these measures will increase maintenance costs.

[0003] Fiber-reinforced composite materials (FRP) are the preferred material for solving metal corrosion problems due to their lightweight, high strength, corrosion resistance, and fatigue resistance. The composite tube-concrete-steel pipe double-wall hollow bridge pier (hereinafter referred to as the double-wall hollow bridge pier) is a new type of composite component that combines the advantages of these three materials. It consists of a composite tube, a concrete interlayer, and a steel pipe from the outside in, offering not only excellent load-bearing performance; but also the ability to use the composite tube and steel pipe as formwork for concrete pouring during construction, enabling formwork-free construction; and the corrosion-resistant composite tube as a protective shell during service. Therefore, the aforementioned double-wall hollow bridge pier is an integrated formwork-structure-function structure, particularly suitable for constructing bridge piers in areas requiring earthquake resistance and corrosion resistance. However, when connecting this new type of bridge pier to RC structure pile foundations or ground foundations, the following challenges need to be addressed: the outer composite tube wall is an orthotropic material, exhibiting high circumferential stiffness and strength but low axial stiffness and strength. Directly embedding it into the RC structure foundation does not provide a primary load-bearing function; it also significantly interrupts the main reinforcing steel bars inside the foundation. On the other hand, if the measure of inserting the composite pipe into the foundation a short distance and then cutting it off is taken, during rainfall, water may seep into the concrete foundation along the outer wall of the composite pipe, causing steel corrosion (Teng Jinguang, New Material Composite Structure, Journal of Civil Engineering, 2018, 51(12): 1-11). Summary of the Invention

[0004] To solve the technical challenges of double-walled hollow bridge piers made of composite material pipe, concrete, and steel pipe and pile foundations, this invention provides a connection structure and construction method for double-walled hollow bridge piers made of composite material pipe, concrete, and steel pipe and pile foundations.

[0005] The objective of this invention is achieved by at least one of the following technical solutions.

[0006] A construction method for a double-walled hollow bridge pier and pile foundation consisting of a composite material pipe-concrete-steel pipe, comprising the following steps: Step S1: Prefabricate the double-walled hollow bridge pier body, which consists of a composite material tube, a concrete interlayer, and a steel pipe from the outside to the inside; the composite material tube is a fiber-reinforced composite spiral wound tube (FRP tube). Step S2: Prepare the pile foundation, wherein the top of the pile foundation is equipped with pre-embedded anchor bolts and pre-embedded annular steel plates; Step S3: Connect the pier body and the pile foundation with a cast-in-place concrete connecting section. The connecting section has a circular or square cross-section and a height of h2. Step S3 includes: S31: As a main connection measure, concrete is poured into the area of ​​the bottom height of the steel pipe within h1+l1 to form a local steel pipe concrete, and the steel pipe section filled with concrete extends into the cast-in-place concrete connection section by a distance l1, and is connected to the end steel plate by welding at the lower end. S32: The composite pipe is buried only within a depth d1 of the top of the cast-in-place concrete connection section and supported on an upper annular steel plate. S33: The top of the pile foundation extends to a depth d2 above the bottom of the cast-in-place connection section; S34: Before pouring the concrete for the connecting section, fix the steel plate at the lower end of the pier to the pre-embedded ring steel plate by welding or bolting. S35: Erect the formwork for the connecting section and pour concrete for the connecting section in one go.

[0007] Further optimization, step S3 also includes segment reinforcement measures: Some longitudinal reinforcing bars extend from the concrete interlayer of the pier body and are embedded within the upper depth l1 range of the concrete connection section; some longitudinal reinforcing bars extend from the pile foundation and are embedded within the lower depth l2 range of the concrete connection section. Not less than 50mm and not greater than .

[0008] As a further optimization, step S3 also includes reinforcement measures for the connecting section: the outer ring plate of the steel pipe is made into discontinuous ring plate pieces to form gaps between the pieces, so that the concrete can pass through the gaps and remain continuous from top to bottom.

[0009] As a further optimization, step S3 also includes waterproofing measures: At the joint between the cast-in-place concrete connection section and the composite material pipe, a waterproof block with a triangular or rectangular cross-section is poured, and the joints between the waterproof block and the composite material pipe, and between the waterproof block and the cast-in-place concrete connection section, are sealed with waterproof adhesive; the width of the waterproof block... With height All are no less than 25mm and no more than 80mm.

[0010] Further optimization, step S3 also includes supplementary measures: When there is localized conflict between the steel pipe extending into the connecting section and the main reinforcing bars of the connecting section, a few circular holes are made in the steel pipe to allow some of the reinforcing bars to pass through. The ends of the remaining reinforcing bars are bent and welded to the surface of the steel pipe. The sum of the diameters of the circular holes is... , The diameter of the i-th opening is indicated; the length of the bent section at the end of the reinforcing bar is indicated. .

[0011] Further optimized, within the range of concrete pouring height at the bottom of the steel pipe (h1 + l1), both h1 and l1 are not less than the larger of 1.5 times the outer diameter of the steel pipe (D1) and 1.0 times the inner diameter of the composite pipe (D2); the inner diameter of the composite pipe (D2) is not less than the outer diameter of the steel pipe (D1) plus 40 mm; the diameter of the connecting section (D4) is not less than the pile foundation diameter (D3) plus 50 mm; all dimensions are in millimeters. and All are no less than 30mm and no more than 80mm.

[0012] In a further optimized version, the pier body of the double-walled hollow pier is prefabricated in the factory, including pouring concrete inside the steel pipe and concrete sandwiched between the two pipes. At this time, the ring plate supporting the composite pipe is a continuous ring plate. Concrete within the lower depth l2 range of the connecting section is poured simultaneously or in advance. After the concrete strength reaches more than 75%, it is transported to the site, and the lower steel plate is used for connection and pouring concrete within the upper height range of the connecting section. Alternatively, the pier body of the double-walled hollow pier may be cast on-site, including pre-assembling the composite pipe and steel pipe into a temporary whole. At this time, the ring plate supporting the composite pipe is a discontinuous ring plate. First, the concrete in the lower part of the connecting section within the high depth l2 range is poured. After the strength reaches more than 75%, the lower steel plate is used for connection and the remaining part of the connecting section concrete is poured in one go. Then, the pier body and part of the concrete inside the steel pipe are poured.

[0013] This invention also provides a connection structure between a composite pipe-concrete-steel pipe double-walled hollow bridge pier and a pile foundation, comprising: The double-walled hollow bridge pier body consists of composite material pipes, concrete interlayers, and steel pipes from the outside to the inside. The pile foundation has a ring-shaped embedded steel plate and embedded anchor bolts above the top. A cast-in-place concrete connection section connects the pier body and the pile foundation, and has a circular or square cross-section. The bottom of the steel pipe is filled with concrete to form a local steel pipe concrete. The steel pipe section filled with concrete extends outward by a set distance and is connected to the end steel plate by welding. The composite pipe is embedded to a set depth inside the top of the cast-in-place concrete connection section and is supported by a steel pipe outer ring plate. The top of the pile foundation extends to a predetermined depth above the bottom of the cast-in-place connection section.

[0014] In a further optimized version, the steel pipe is filled with concrete containing large aggregate blocks or recycled concrete blocks.

[0015] Further optimized, the composite tube is a fiber-reinforced composite material tube formed by a winding process, including one of carbon fiber winding tube, glass fiber winding tube, aramid fiber winding tube, and basalt fiber winding tube. The fiber can also be a composite fiber that combines at least two of the above-mentioned carbon fiber, glass fiber, aramid fiber, and basalt fiber. The inner side of the steel tube can retain the primer, and the outer side of the steel tube needs to be polished until the metallic luster is visible.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The proposed technology and construction process for connecting composite pipe-concrete-steel pipe double-wall hollow bridge piers with pile foundations solves the key technical problem of connecting composite pipe-concrete-steel pipe double-wall hollow bridge piers with foundations. Due to the inherent corrosion resistance of the pier structure and the waterproof and anti-corrosion measures provided by this patent, it is possible to build corrosion-resistant bridge pier structures, solving the corrosion resistance and service life management and maintenance problems commonly faced by RC structure, steel structure or steel pipe concrete composite structure bridges.

[0017] (2) The proposed technology and construction process for connecting composite pipe-concrete-steel pipe double-wall hollow bridge piers with pile foundations solves the node structure problem and construction process of connecting composite pipe-concrete-steel pipe double-wall hollow bridge piers with foundations. Its connection effectiveness and construction convenience have been verified by test and demonstration projects.

[0018] (3) The connection technology and its construction process are applicable to both the prefabrication and assembly construction of bridge piers and the on-site construction of bridge piers. Both can realize the integrated construction of formwork and structure, eliminating the formwork support and dismantling links, reducing the cost of measures (more than 50%) and labor costs (more than 50%). At the same time, it can realize the rapid construction of new bridge piers, greatly shorten the construction period, and significantly reduce carbon emissions during the construction process. For example, a certain demonstration project can be completed in about 7-8 days from the pouring of concrete for the pier body in the factory to the installation and pouring of concrete on site.

[0019] (4) Since composite materials are low-carbon and green materials, the application of composite pipe-concrete-steel pipe double-wall hollow bridge piers can reduce carbon emissions at the level of building materials and structural components. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure before the connection between the composite pipe-concrete-steel pipe double-walled hollow bridge pier and the pile foundation in the embodiment.

[0021] Figure 2 for Figure 1 A schematic diagram of the longitudinal section of the connection structure shown.

[0022] Figure 3a This is a schematic diagram of section AA of the connecting structure.

[0023] Figure 3b This is a schematic diagram of the BB section of the connecting structure.

[0024] Figure 3c This is a schematic diagram of the CC section of the connecting structure.

[0025] Figure 3d This is a schematic diagram of the cross section DD of the connecting structure.

[0026] Figure 4a This is a schematic diagram of a ring-shaped steel plate used to support FRP pipes.

[0027] Figure 4b This is a schematic diagram of an eight-part discontinuous annular steel plate used to support FRP pipes.

[0028] Figure 4c Schematic diagram of a discontinuous annular steel plate divided into twelve equal parts to support FRP pipes.

[0029] Figure 5 This is a schematic diagram of the annular steel plate structure inside the steel pipe.

[0030] The diagram includes: fiber-reinforced composite spiral pipe 11, concrete interlayer 21, concrete filling inside steel pipe 22, foundation 23, waterproof block 24, pile 25, steel pipe 31, local stiffening plate inside steel pipe 321, bottom stiffening rib of outer ring plate 322, upper stiffening rib of bottom plate of steel pipe 323, annular steel plate inside steel pipe 33, upper annular steel plate for supporting FRP pipe 34, through hole of reinforcing bar inside upper annular steel plate 341, central cavity of upper annular steel plate 342, lower steel plate 35, embedded annular steel plate 36, concrete pouring inlet of embedded annular steel plate 361, bolt hole inside embedded annular steel plate 362, gears distributed outside embedded annular steel plate 363, extended longitudinal reinforcement of double-walled hollow column 371, extended longitudinal reinforcement of pile foundation 372, embedded anchor bolt 38, concrete pouring inlet of annular steel plate inside steel pipe 331, and vent of annular steel plate inside steel pipe 332. Detailed Implementation

[0031] To better demonstrate the implementation steps of the composite pipe-concrete-steel pipe double-wall hollow bridge pier and foundation connection structure and its construction process, and to reveal its application value and beneficial effects, the implementation of the present invention will be further described below in conjunction with embodiments.

[0032] In the following embodiments, the pier body of the composite pipe-concrete-steel pipe double-walled hollow bridge pier consists of a fiber-reinforced composite material wound pipe (hereinafter referred to as composite pipe), a concrete interlayer, and a steel pipe from the outside to the inside. The following describes two technical routes for the pier body: factory prefabrication and on-site casting.

[0033] like Figures 1-5 The fiber-reinforced composite spiral pipe 11 (composite pipe), as the outermost layer of the pier body, is made of fiber-reinforced composite materials (such as carbon fiber, glass fiber, etc.) through a winding process. It possesses corrosion resistance and high strength, primarily serving a protective function and bearing circumferential stress. The bottom of the fiber-reinforced composite spiral pipe 11 is only embedded to a depth d1 within the top of the cast-in-place concrete connection section and is supported by the upper annular steel plate 34. A concrete interlayer 21 is located between the fiber-reinforced composite spiral pipe 11 and the steel pipe 31, filling the annular space between the two pipes. The concrete interlayer 21 provides structural integrity and compressive strength, and, in conjunction with the longitudinal reinforcement 371, enhances seismic performance. The steel pipe 31, as the inner layer of the pier body, is located inside the concrete interlayer 21. Concrete is poured into the steel pipe 31 within a height of h1+l1 at the bottom to form a localized steel-concrete composite pipe (i.e., concrete 22 filled inside the steel pipe). The bottom end of the steel pipe 31 is welded to the lower steel plate 35 and extends outward into the cast-in-place concrete connection section by a distance l1.

[0034] Concrete filling 22 inside the steel pipe: Concrete is poured within a height of h1+l1 at the bottom of the steel pipe 31, forming a local steel-concrete structure to enhance the compressive strength and overall stability of the steel pipe 31. This concrete 22 can be poured through the annular steel plate concrete pouring inlet 331 inside the steel pipe and air can be discharged through the vent 332. Annular steel plate 33 inside the steel pipe: Located inside the steel pipe 31, it is used to enhance the local stability of the steel pipe 31. The steel plate 33 is equipped with an annular steel plate concrete pouring inlet 331 and an annular steel plate vent 332 inside the steel pipe to facilitate concrete pouring and venting.

[0035] Pile 25 forms the foundation of the bridge pier and is typically a reinforced concrete pile embedded underground. The top of pile 25 extends to a depth d2 above the bottom of the cast-in-place concrete connecting section and is connected to the connecting section via longitudinal reinforcing bars 372 extending from the pile foundation. The pile cap 23 is located at the top of pile 25, serving as a transition between the pile foundation and the connecting section. The pile cap 23 contains a pre-embedded annular steel plate 36 and pre-embedded anchor bolts 38 for connection to the bridge pier. The pre-embedded annular steel plate 36 is fixed to the top of the pile cap 23 and anchored by the pre-embedded anchor bolts 38. The pre-embedded annular steel plate 36 has a concrete pouring inlet 361 and bolt holes 362 for concrete pouring and bolt connection. During connection, the pre-embedded annular steel plate 36 is temporarily fixed to the lower steel plate 35 by welding or bolting. The pre-embedded anchor bolts 38 (using anchor bolts) are embedded in the pile cap 23 to fix the pre-embedded annular steel plate 36 and ensure the stability of the connecting section. The longitudinal reinforcement 372 extending from the pile foundation is embedded within a depth l2 of the lower part of the cast-in-place concrete connection section, working together with the longitudinal reinforcement 371 extending from the double-walled hollow column to ensure the continuity of the connection section.

[0036] The waterproof block 24 is located at the joint between the cast-in-place concrete connection section and the fiber-reinforced composite spiral pipe 11. It has a triangular or rectangular cross-section and is made of epoxy mortar. The width a and height b of the waterproof block 24 are both not less than 25 mm and not more than 80 mm. The joint between the waterproof block 24 and the pipe 11 and the connection section is sealed with waterproof adhesive to prevent water penetration.

[0037] Upper annular steel plate 34: An annular steel plate used to support the fiber-reinforced composite spiral pipe 11, fixed to the outside of the steel pipe 31. This upper annular steel plate 34 can be designed as a continuous annular plate or a discontinuous annular plate (such as being divided into eight or twelve equal sections). Discontinuous annular plates have gaps between sections, allowing for continuous vertical flow of concrete. The upper annular steel plate 34 has a central cavity 342 and a through hole 341 for reinforcing bars inside the upper annular plate, used for concrete pouring and for the passage of reinforcing bars.

[0038] The lower steel plate 35 is located at the bottom of the steel pipe 31 and is connected to the steel pipe 31 by welding. During installation, the lower steel plate 35 is temporarily fixed to the pre-embedded annular steel plate 36 by welding or bolting to ensure the alignment of the pier body and the pile foundation. A local stiffening plate 321 is installed inside the steel pipe 31 to enhance the local stiffness and bending resistance of the steel pipe 31. The bottom stiffening rib 322 of the outer ring plate is located at the bottom of the upper annular steel plate 34 or the lower steel plate 35 to distribute the load and prevent deformation of the steel plate. The upper stiffening rib 323 of the steel pipe bottom plate is located above the lower steel plate 35 to strengthen the connection area between the steel pipe 31 and the lower steel plate 35. The concrete pouring inlet 331 of the annular steel plate inside the steel pipe is used to pour concrete into the steel pipe 31, ensuring the compactness of the concrete 22 filling the steel pipe. The vent 332 of the annular steel plate inside the steel pipe expels air during concrete pouring to prevent voids. The pre-embedded annular steel plate concrete pouring inlet 361 is located on the pre-embedded annular steel plate 36 and is used to ensure uniform concrete flow when pouring concrete in the connecting section. The bolt holes 362 inside the pre-embedded annular steel plate are used for the passage and fixation of the pre-embedded anchor bolts 38, realizing the connection between the pre-embedded annular steel plate 36 and the lower end steel plate 35. Its outer gear 363 is used to support and fix the annular stirrups of the longitudinal reinforcement 372. On the one hand, it allows the extended longitudinal reinforcement 372 of the pile foundation to pass through, and on the other hand, it can be better positioned (aligned with the position of the outer gear of the lower end steel plate 35).

[0039] Example 1 (Factory-cast bridge piers): In this embodiment, the foundation is a pile foundation; the connection technology is achieved through a cast-in-place concrete connection section. The cross-section of the connection section can be circular with a diameter of D4 and a height of h2. It is divided into upper and lower parts with heights of l1 and l2, respectively.

[0040] Before connection, the steel pipe section filled with concrete extends outward by a distance l1 (the distance within the cast-in-place concrete connection section) and is connected to the end steel plate by welding at the lower end. In this embodiment, concrete is first poured into the bottom height range (h1+l1) of the steel pipe (h1 refers to the top height of the connection section, h1 is not less than 1.5D1, D1 = outer diameter of the steel pipe) in the factory to form a solid steel pipe concrete. An annular steel plate 33 is provided at the upper end of the steel pipe. Then, concrete is poured into the interlayer between the steel pipe and the composite pipe to form a concrete interlayer. At this time, the annular plate supporting the composite pipe is a continuous annular plate. First, when constructing the concrete within the lower height l2 range of the cast-in-place concrete connection section, the anchoring steel bars (longitudinal steel bars extending from the pile foundation) extending from the pile foundation are embedded in it (the position of the pre-embedded annular steel plate 36 needs to be set before pouring, the pre-embedded bolts need to be fixed, and temporary supports need to be arranged). At the same time, the above-mentioned interlayer and the concrete inside the steel pipe within the pier body are poured in the factory. After the precast pier components are transported to the site and installed, concrete is poured within the upper height l1 range of the connecting section. Once the concrete strength reaches at least 75% of the expected strength (or after at least one week of curing), the precast pier body and the extended steel pipe are transported to the site as a whole. The steel pipe is lifted to connect the lower end steel plate (which can be a lower ring steel plate) to the pre-embedded ring steel plate 36. Simultaneously, the anchoring steel bars (extension longitudinal bars of the double-walled hollow column) extending from the pier body concrete interlayer are extended into the upper height l1 range of the cast-in-place section. Finally, concrete is poured within the height l1 range of the connecting section. At least 48 hours later, at the joint between the connecting section and the composite material pipe, a waterproof block with a triangular cross-section (width a, height b) is poured using epoxy mortar. The joints between the waterproof block and the composite material pipe, and between the waterproof block and the cast-in-place connecting section, are sealed with waterproof adhesive.

[0041] In this embodiment, the outer diameter of the inner steel pipe is D1=900mm and the thickness is t1=18mm; the inner diameter of the composite pipe is D2=1200mm and the thickness is t2=16mm; the pile foundation diameter is D3=1400mm; the diameter of the cast-in-place connection section is D4=2000mm, the height is l1=1400mm, the height is l2=300mm, the height of the concrete filling inside the steel pipe above the top of the cast-in-place section is h1=1400mm, the height of the cast-in-place connection section is h2=1700mm, a=30mm, b=50mm, d1=50mm, and d2=60mm.

[0042] This embodiment targets medium-sized bridge piers that are relatively easy to hoist, achieving integrated formwork-structure construction. The pier body is constructed directly in the factory, eliminating the need for formwork erection and dismantling, reducing construction costs by over 70% and labor costs by over 75%. Since factory casting of the pier body and on-site foundation construction proceed simultaneously, rapid construction of this new type of pier is possible, significantly shortening the construction period and noticeably reducing carbon emissions. For example, in a demonstration project, the entire process from factory casting of the pier body concrete to on-site installation and subsequent concrete pouring can be completed in approximately 7-8 days. Furthermore, due to the corrosion resistance and low-carbon characteristics of the double-walled hollow pier, both the pier and its construction achieve green construction, resulting not only in a shorter construction period but also minimal or no maintenance. Only simple UV-free coating of the composite pipes is required, reducing subsequent maintenance costs by over 80%.

[0043] Example 2 (cast-in-situ bridge piers): In this embodiment, the foundation is a pile foundation; the connection technology is achieved through a cast-in-place concrete connection section. The connection section has a square cross-section with a side length of D4 and a height of h2, and is divided into upper and lower parts with heights of l1 and l2, respectively.

[0044] Before connection, the bottom height range (h1+l1) of the steel pipe (the height h1 above the top of the connection section is not less than 1.5D1, where D1 = outer diameter of the steel pipe) can be locally filled with concrete to form a solid steel pipe concrete. The steel pipe section filled with concrete extends outward by a distance l1 and is connected to the bottom end plate by welding at the lower end. Before on-site pouring, the assembly including the composite pipe and the inner steel pipe is transported to the site as a whole. At this time, the ring plate supporting the composite pipe is a discontinuous ring plate. The pre-embedded annular steel plate is set at position 36, the pre-embedded bolts are fixed, temporary supports are arranged, and the steel pipe bottom end plate is lifted to connect with the pre-embedded plate. The anchoring steel bars extending from the concrete interlayer of the pier body penetrate into the upper height l1 range of the cast-in-place section, and the anchoring steel bars extending from the pile penetrate into the lower height l2 range of the cast-in-place section. Concrete within the height range l2 and l1 of the connecting section is poured in one go (at this time, a small amount of concrete can flow into the interlayer between the composite pipe and the steel pipe through the gap of the discontinuous ring plate). At least 48 hours later, the interlayer concrete between the composite pipe and the steel pipe of the pier body is poured. At the same time, at the joint between the cast-in-place connecting section and the composite pipe, a waterproof block with a rectangular cross section (width a and height b) is poured with epoxy mortar, and the joint between the waterproof block and the composite pipe, and between the waterproof block and the cast-in-place connecting section is sealed with waterproof glue.

[0045] In this embodiment, the outer diameter of the inner steel pipe is D1=1000mm and the thickness is t1=18mm; the inner diameter of the composite pipe is D2=1400mm and the thickness is t2=16mm; the pile diameter is D3=1600mm; the side length of the cast-in-place connection section is D4=2100mm, the height is l1=1500mm, the height is l2=300mm, the height of the concrete filling inside the steel pipe above the top of the cast-in-place section is h1=1500mm, the height of the cast-in-place section is h2=1800mm, a=40mm, b=60mm, d1=55mm, and d2=60mm.

[0046] This embodiment addresses the challenges of transporting large-sized bridge piers during overall hoisting. By pouring concrete on-site, it still achieves integrated formwork and structure construction, reducing formwork erection and dismantling steps and cutting costs by over 50% in both construction and labor. Furthermore, due to the corrosion resistance and low-carbon characteristics of the composite-concrete-steel pipe double-wall hollow pier, both the pier and its construction achieve green construction, requiring little or no maintenance. Only simple UV-free coating is needed on the composite pipes, reducing subsequent maintenance costs by over 80%.

[0047] As a further optimization, the interlayer concrete of the pier body can be ordinary strength concrete, recycled aggregate concrete, high-strength concrete, UHPC and ECC, or one or more of these (different concrete types for different height ranges). The concrete filling inside the steel pipe can be the same as or different from the interlayer concrete; for example, the steel pipe can be filled with concrete containing large aggregate blocks or recycled concrete blocks. The composite pipe refers to a fiber-reinforced composite material pipe formed by a winding process. Depending on the fiber, it can be divided into carbon fiber wound pipe, glass fiber wound pipe, aramid fiber wound pipe, and basalt fiber wound pipe. The fiber can also be a composite fiber that combines at least two of the above-mentioned carbon fiber, glass fiber, aramid fiber, and basalt fiber. The steel pipe can be high-strength steel, ordinary steel, stainless steel, or other metal pipes. Except for stainless steel pipes, before the foundation connection, the moisture and water vapor inside the pipe need to be drained, and an appropriate amount of absorbent material needs to be placed inside the pipe. The inner side of the steel pipe can retain the primer, while the outer side of the steel pipe needs to be polished until the metallic luster is visible.

Claims

1. A construction method for a double-walled hollow bridge pier and pile foundation consisting of a composite material pipe-concrete-steel pipe, characterized in that, Includes the following steps: Step S1: Prefabricate the double-walled hollow bridge pier body, which consists of a composite material tube, a concrete interlayer, and a steel pipe from the outside to the inside; the composite material tube is a fiber-reinforced composite spiral wound tube; Step S2: Prepare the pile foundation, wherein the top of the pile foundation is equipped with pre-embedded anchor bolts and pre-embedded annular steel plates; Step S3: Connect the pier body and the pile foundation with a cast-in-place concrete connecting section. The connecting section has a circular or square cross-section and a height of h2. Step S3 includes: S31: As a main connection measure, concrete is poured into the area of ​​the bottom height of the steel pipe within h1+l1 to form a local steel pipe concrete, and the steel pipe section filled with concrete extends into the cast-in-place concrete connection section by a distance l1, and is connected to the end steel plate by welding at the lower end. S32: The composite pipe is buried only within a depth d1 of the top of the cast-in-place concrete connection section and supported on an upper annular steel plate. S33: The top of the pile foundation extends to a depth d2 above the bottom of the cast-in-place connection section; S34: Before pouring the concrete for the connecting section, fix the steel plate at the lower end of the pier to the pre-embedded ring steel plate by welding or bolting. S35: Erect the formwork for the connecting section and pour concrete for the connecting section in one go.

2. The construction method according to claim 1, characterized in that, Step S3 also includes joint reinforcement measures: Some longitudinal reinforcing bars extend from the concrete interlayer of the pier body and are embedded within the upper depth l1 range of the concrete connection section; some longitudinal reinforcing bars extend from the pile foundation and are embedded within the lower depth l2 range of the concrete connection section. Not less than 50mm and not greater than .

3. The construction method according to claim 1, characterized in that, Step S3 also includes reinforcement measures for the connecting section: the outer ring plate of the steel pipe is made into discontinuous ring plate pieces to form gaps between the pieces, so that the concrete can pass through the gaps and maintain continuity from top to bottom.

4. The construction method according to claim 1, characterized in that, Step S3 also includes waterproofing measures: At the joint between the cast-in-place concrete connection section and the composite material pipe, a waterproof block with a triangular or rectangular cross-section is poured, and the joints between the waterproof block and the composite material pipe, and between the waterproof block and the cast-in-place concrete connection section, are sealed with waterproof adhesive; the width of the waterproof block... With height All are no less than 25mm and no more than 80mm.

5. The construction method according to claim 1, characterized in that, Step S3 also includes supplementary measures: When there is localized conflict between the steel pipe extending into the connecting section and the main reinforcing bars of the connecting section, a few circular holes are made in the steel pipe to allow some of the reinforcing bars to pass through. The ends of the remaining reinforcing bars are bent and welded to the surface of the steel pipe. The sum of the diameters of the circular holes is... , The diameter of the i-th opening is indicated; the length of the bent section at the end of the reinforcing bar is indicated. .

6. The construction method according to claim 1, characterized in that, Within the range of h1 + l1 for the height of the concrete poured at the bottom of the steel pipe, both h1 and l1 shall not be less than the larger of 1.5 times the outer diameter D1 of the steel pipe and 1.0 times the inner diameter D2 of the composite pipe; the inner diameter D2 of the composite pipe shall not be less than the outer diameter D1 of the steel pipe plus 40 mm; the diameter D4 of the connecting section shall not be less than the diameter D3 of the pile foundation plus 50 mm; all dimensions are in millimeters. and All are no less than 30mm and no more than 80mm.

7. The construction method according to claim 1, characterized in that, The pier body of the double-walled hollow bridge pier is prefabricated in the factory, including pouring concrete inside the steel pipe and concrete sandwiched between the two pipes. At this time, the ring plate supporting the composite pipe is a continuous ring plate. Concrete in the lower part of the connecting section within a depth l2 is poured simultaneously or in advance. After the concrete strength reaches more than 75%, it is transported to the site and connected using the lower steel plate and concrete in the upper part of the connecting section within a certain height range is poured. Alternatively, the pier body of the double-walled hollow pier may be cast on-site, including pre-assembling the composite pipe and steel pipe into a temporary whole. At this time, the ring plate supporting the composite pipe is a discontinuous ring plate. First, the concrete within the lower depth l2 range of the connecting section is poured. After the strength reaches more than 75%, the lower steel plate is used for connection and the remaining part of the connecting section concrete is poured in one go. Then, the pier body and part of the concrete inside the steel pipe are poured.

8. A connection structure between a composite pipe-concrete-steel pipe double-walled hollow bridge pier and a pile foundation obtained by the construction method according to any one of claims 1 to 7, characterized in that, include: The double-walled hollow bridge pier body consists of composite material pipes, concrete interlayers, and steel pipes from the outside to the inside. The pile foundation has a pre-embedded annular steel plate and pre-embedded anchor bolts above the top. A cast-in-place concrete connection section connects the pier body and the pile foundation, and has a circular or square cross-section. The bottom of the steel pipe is filled with concrete to form a local steel pipe concrete. The steel pipe section filled with concrete extends outward by a set distance and is connected to the end steel plate by welding. The composite pipe is embedded to a set depth inside the top of the cast-in-place concrete connection section and is supported by a steel pipe outer ring plate. The top of the pile foundation extends to a predetermined depth above the bottom of the cast-in-place connection section.

9. The connection structure between a composite pipe-concrete-steel pipe double-walled hollow bridge pier and a pile foundation as described in claim 8, characterized in that, The steel pipe is filled with concrete containing large aggregate blocks or recycled concrete blocks.

10. The connection structure between a composite pipe-concrete-steel pipe double-walled hollow bridge pier and a pile foundation as described in claim 8, characterized in that, The composite tube is a fiber-reinforced composite material tube formed by a winding process, including one of carbon fiber winding tube, glass fiber winding tube, aramid fiber winding tube, and basalt fiber winding tube. The fiber can also be a composite fiber that combines at least two of the above-mentioned carbon fiber, glass fiber, aramid fiber, and basalt fiber. The inner side of the steel tube can retain the primer, while the outer side of the steel tube needs to be polished until a metallic luster is visible.

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