Steel pipe pile and pile cap anchoring system construction method

Abstract

The application discloses a construction method of a steel pipe pile and a bearing platform anchoring system, which comprises the following steps: preliminary preparation; anchoring system design calculation: design of an anchoring structure body structure to make it connect the steel pipe pile and the bearing platform to form the anchoring system and calculation. Anchoring system construction: a group of anchoring structure bodies are constructed on the outer circle of each steel pipe pile, and the top end of the anchoring structure body protrudes an anchoring rib for extending into the upper bearing platform. Foundation pit bottom sealing and bearing platform construction: a second layer of bottom sealing concrete layer with isolation joints between each anchoring structure body is constructed on the first layer of bottom sealing concrete layer outside the anchoring structure body, and the bearing platform is constructed on the top surface of the second layer of bottom sealing concrete layer, the top surface of the isolation joint, the top surface of the anchoring structure body and the top surface of the steel pipe pile. The anchoring system constructed by the construction method has the advantages that the anchoring system can realize the adhesion and compactness between the steel pipe pile and the concrete, the anchoring quality between the steel pipe pile and the bearing platform is reliable, the overall structure is stable, and the bearing capacity is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge pile cap construction, in particular to a steel pipe pile and pile cap anchoring system construction method. BACKGROUND

[0002] In recent years, in the bridge construction, the cast-in-place pile is a common pile foundation. In a certain A-shaped single-tower cable-stayed bridge in the Guangdong Delta plain, which is located in a strong seismic intensity area with an earthquake fortification intensity of 8 degrees (0.20g), in order to resist strong earthquake force, the pile foundation of the main bridge 7# of the bridge is provided with a permanent steel casing with a length of 25m and an outer diameter of 2.5m, which is tightly bonded with the pile foundation concrete to form a large-diameter steel pipe pile (i.e. the steel pipe pile is composed of a steel casing and cast-in-place pile concrete), which jointly bears and participates in earthquake resistance, so that the pile foundation has sufficient bearing capacity and good bending resistance.

[0003] During the construction of the 7# pier cap of the main bridge, the upper end of the large-diameter steel pipe pile is extended into the cap. The anchoring between the steel casing and the cap is required to be reliable so that the steel casing can effectively bear the load and work together with the pile foundation concrete. The bridge cap serves as the force transmission body between the large-diameter steel pipe pile and the bridge superstructure. Common connection methods between it and the steel casing are: (1) cutting the part of the steel casing extending into the cap into a strip to form a steel strip, welding reinforcing steel bars on the steel strip, and the cap load-bearing steel bars pass through the cut steel casing; (2) welding anchor steel bars on the end plate of the top surface of the steel casing; (3) placing dowel bars in the steel casing and pouring core-filling concrete; (4) as disclosed in patent application number CN201711023517.2, a steel pipe composite pile and cap The anchoring structure of the platform and its construction method are as follows: a horizontal annular pressure plate is placed on the outer wall of the steel casing, and a stiffening rib is welded on the upper plate surface of the annular pressure plate. One end of the prestressed steel bar is anchored on the annular pressure plate, and the other end passes through the corrugated casing upward and extends to the interface between the second pouring layer and the third pouring layer of the platform, and is anchored after prestressing; (5) A new type of winged pile disclosed in patent application number CN201620844479.1 is a pile with an annular plate welded on the steel pipe pile, and the upper surface of the annular plate is connected to the steel pipe pile through triangular ribs. The annular plate is connected, and a plurality of wings staggered with the ribs are welded below the annular plate; (6) As disclosed in patent application number CN202010065869.X, a new anchoring device for steel pipe piles and a later added pedestal in foundation renovation and its anchoring method, pile rings are evenly arranged in the axial direction at the bottom of the steel pipe pile, L-arm components and reinforcement plates are evenly arranged in the axial and radial directions of the lower part of the steel pipe pile, and the steel pipe piles, pile rings, L-arm components and reinforcement plates are cast on the pedestal and anchored together with the pedestal; (7 ... No. CN201320733682.8 discloses a connection structure between a concrete pipe pile and a foundation cap, wherein the upper end of the pipe pile is connected to the foundation cap, the upper and lower ends of the anchor steel bar are respectively connected to the foundation cap and the pipe pile, the embedded steel bar is located inside the pipe pile body, a pile end plate is provided on the end face of the pipe pile, a plurality of bolt holes are evenly distributed along the circumference on the end face of the pile end plate, a plurality of embedded sleeves corresponding to the bolt holes are evenly distributed along the circumference on the bottom of the pile end plate inside the pipe pile body, the bottom end of the anchor steel bar passes through the pile end plate and is located inside the pipe pile and connected to the embedded sleeve.

[0004] The above anchor connection method has the following defects:

[0005] (1) The first connection method: a large number of steel strips are cut off, making it difficult for the steel casing to fully play its role. The anchor connection construction volume is large and the construction efficiency is low, resulting in an extension of the bridge pedestal construction period.

[0006] (2) The second connection method: The on-site welding workload is large, the quality reliability is poor, and the force is discontinuous. The welds of the ordinary steel bars anchored in the pedestal are perpendicular to the force direction of the steel bars, which easily leads to weld tearing and failure.

[0007] (3) The third connecting mode has strict technical requirements, is difficult to be completely realized on a construction site, needs to pour core concrete, and needs to spend a lot of manpower and mechanical cooperation, and has very high requirements on the quality of construction personnel.

[0008] (4) The fourth to seventh connecting modes are all provided with annular bearing plates, annular plates, pile rings, L-arm components, reinforcing plates and pile end plates in a horizontal direction of the steel pipe pile, and when the bottom concrete and the pile cap concrete are poured, there are gaps formed by the bubbles in the concrete that cannot be discharged outward or the plastic shrinkage of the concrete on the bottom surfaces of the annular bearing plates, the annular plates, the pile rings, the L-arm components, the reinforcing plates and the pile end plates, which causes the annular bearing plates, the annular plates, the pile rings, the L-arm components, the reinforcing plates and the pile end plates to be separated from the bottom concrete and the pile cap concrete and not to be tightly bonded, and hidden dangers are left for the engineering quality. SUMMARY

[0009] The steel pipe pile and pile cap anchoring system construction method is provided, so as to solve the technical problems of the poor bonding between the steel pipe pile and the concrete, the poor anchoring connection quality, the poor reliability and the poor bearing capacity of the steel pipe pile and the pile cap.

[0010] The technical scheme adopted by the present application is as follows:

[0011] The steel pipe pile and pile cap anchoring system construction method comprises the following steps: preliminary preparation: cutting and breaking the steel pipe pile of the over-poured part on the top of the steel pipe pile in the deep foundation pit to expose the reserved main reinforcement, and constructing a first layer of bottom sealing concrete layer on the bottom of the foundation pit; anchoring system design calculation: designing the anchoring structure to form an anchoring system after connecting the steel pipe pile and the pile cap, and calculating the bearing capacity of the important components in the anchoring structure; anchoring system construction: constructing a group of anchoring structures for connecting the steel pipe pile and the first layer of bottom sealing concrete layer on the outer circle of each steel pipe pile, and the top end of the anchoring structure protrudes an anchoring bar for extending into the upper pile cap; foundation bottom sealing and pile cap construction: constructing a second layer of bottom sealing concrete layer with isolation joints between each anchoring structure on the first layer of bottom sealing concrete layer outside the anchoring structure, and constructing a pile cap on the top surface of the second layer of bottom sealing concrete layer, the top surface of the isolation joint, the top surface of the anchoring structure and the top surface of the steel pipe pile.

[0012] Further, the step of "preliminary preparation" specifically comprises the following steps: preliminary construction preparation: according to the construction design drawing, constructing the steel pipe pile, the pile cap foundation pit cofferdam, the foundation pit support, the foundation pit earthwork excavation to the bottom of the foundation pit; cutting and breaking: cutting the steel casing of the over-poured part on the top of the steel pipe pile to expose the cast-in-place pile, and breaking the exposed cast-in-place pile to expose the reserved main reinforcement; first layer pouring: pouring the first layer of bottom sealing concrete layer on the bottom surface of the foundation pit.

[0013] Further, the step of "anchorage system design calculation" specifically comprises the following steps: anchorage system design: design the anchorage structure to connect the steel pipe pile and the pile cap to form a radial ring anchorage system and a vertical ring anchorage system; force transmission path analysis: analyze the force transmission path of the radial ring anchorage system and the vertical ring anchorage system; component force calculation: calculate the force of important components in the anchorage structure.

[0014] Further, each group of anchorage structures comprises a group of anti-slide steel rings for fixing on the outer circle of the corresponding steel pipe pile, a hollow cage-shaped ring-shaped steel reinforcement cage for fitting on the outer circle of the steel pipe pile, a hollow ring-shaped anchoring steel reinforcement ring with a lower end inserted into the ring-shaped steel reinforcement cage and an upper end inserted into the pile cap, and an anchoring concrete layer formed by pouring the group of anti-slide steel rings, the ring-shaped steel reinforcement cage and the anchoring steel reinforcement ring and connecting the steel pipe pile and the first layer of bottom sealing concrete layer.

[0015] Further, the step of "anchorage system construction" specifically comprises the following steps: anti-slide steel ring group installation; ring-shaped steel reinforcement cage installation; anchoring steel reinforcement ring installation; anchoring concrete layer construction.

[0016] Further, the step of "anti-slide steel ring group installation" specifically comprises the following steps: structure construction: constructing the constituent components of the anti-slide steel ring group, i.e. multiple anti-slide steel rings; coating removal: removing the protective coating on the outer wall of the steel casing of the steel pipe pile; installation: installing multiple anti-slide steel rings on the outer circle of the steel casing to form an anti-slide steel ring group.

[0017] Further, the step of "ring-shaped steel reinforcement cage installation" specifically comprises the following steps: structure construction: constructing a ring-shaped steel reinforcement cage using multiple ring-shaped steel reinforcements and stirrups; installation: fitting the ring-shaped steel reinforcement cage onto the outer circle of the steel casing and radially spacing it from the anti-slide steel ring group.

[0018] Further, the step of "anchoring steel reinforcement ring installation" specifically comprises the following steps: structure construction: constructing the constituent components of the anchoring steel reinforcement ring, i.e. multiple anchoring steel reinforcements; installation: arranging multiple anchoring steel reinforcements in sequence along the outer side of the steel casing in a ring shape, and vertically inserting each anchoring steel reinforcement into the concrete of the first layer of anchoring concrete layer formed by the first pouring in the ring-shaped steel reinforcement cage.

[0019] Further, the step of "anchoring concrete layer construction" specifically comprises the following steps: formwork installation: installing a ring-shaped formwork around the ring-shaped steel reinforcement cage on the first layer of bottom sealing concrete layer outside the ring-shaped steel reinforcement cage; concrete pouring: pouring in the ring-shaped formwork to form the anchoring concrete layer.

[0020] Further, the step of "foundation pit bottom sealing and construction of the bearing platform" specifically comprises the following steps: second layer pouring: setting a partition plate outside the anchoring structure, and pouring a second layer of bottom sealing concrete layer on the first layer of bottom sealing concrete layer outside the partition plate; bearing platform construction: pouring a bearing platform on the top surface of the second layer of bottom sealing concrete layer, the top surface of the partition joint, the top surface of the anchoring structure and the top surface of the steel pipe pile.

[0021] The present application has the following advantages:

[0022] The construction method of the present application has the following advantages: (1) a radial and vertical ring-shaped anchoring system can be constructed: a group of anchoring structures are constructed on the outer circles of the steel pipe piles, and the anchoring structures are fixed with the corresponding steel pipe piles and the first layer of bottom sealing concrete layer below, thereby being connected with the steel pipe piles in a radial ring-shaped anchoring manner to form a "flat head rivet" type steel pipe pile and bearing platform radial ring-shaped anchoring system, so that the anchoring structures and the steel pipe piles are tightly bonded to generate radial friction force, and resist vertical sliding between the steel pipe piles and the anchoring structures; when the concrete layer in the anchoring structure expands in volume, radial counterforce can be formed under the constraint of the steel bars in the anchoring structure, which uniformly acts on the steel pipe pile in a radial prestressing manner, so that the anchoring structures and the steel pipe piles are tightly bonded to generate radial friction force, and resist vertical sliding between the steel pipe piles and the anchoring structures; at the same time, the reserved main steel bars in the steel pipe piles and the anchoring steel bars protruding out of the top ends of the anchoring structures are anchored into the bearing platform, and are connected with the bearing platform in a vertical ring-shaped anchoring manner to form a "series connection" type steel pipe pile and bearing platform vertical ring-shaped anchoring system, so that the steel pipe piles and the bearing platform are tightly bonded to generate vertical friction force, and resist vertical sliding between the steel pipe piles and the bearing platform; (2) good force transmission of the anchoring structure is achieved: when the force transmitted by the bridge superstructure to the bearing platform is partially transmitted through the bearing platform → the reserved main steel bars → the bearing concrete and the top part of the steel casing → the steel pipe pile, and partially transmitted through the bearing platform → the anchoring structure → the steel casing, so that the anchoring system constructed by the construction method of the present application can tightly bond the steel pipe pile and the concrete, has good anchoring quality between the steel pipe pile and the bearing platform, has stable overall structure, and has good bearing capacity.

[0023] In addition to the objects, features, and advantages described above, the present application has other objects, features, and advantages. The present application will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the application. In the drawings:

[0025] Figure 1 is a flow chart of the steel pipe pile and bearing platform anchoring system construction method of the preferred embodiment of the present application;

[0026] Figure 2 is a front view of a steel pipe pile and cap anchoring connection structure of a preferred embodiment of the present application;

[0027] Figure 3 is Figure 2 is a middle Ι-Ι sectional view.

[0028] Legend:

[0029] 1, cast-in-place pile; 2, reserved main reinforcement; 3, steel casing;

[0030] 4, anti-slide reinforcement ring;

[0031] 501, first layer of bottom sealing concrete; 502, second layer of bottom sealing concrete;

[0032] 6, ring reinforcement; 7, anchoring reinforcement; 8, anchoring concrete layer; 9, isolation joint;

[0033] 10, cap. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following.

[0035] With reference to Figures 1-3 , the preferred embodiment of the present application provides a construction method of a steel pipe pile and cap anchoring system, comprising the following steps:

[0036] Preparation: cutting and breaking the steel pipe pile at the top of the steel pipe pile in the deep foundation pit to expose the reserved main reinforcement 2, and constructing the first layer of bottom sealing concrete 501 on the bottom of the foundation pit.

[0037] Design and calculation of anchoring system: designing the anchoring structure to form the anchoring system after connecting the steel pipe pile and the cap 10, and calculating the bearing force of important components in the anchoring structure.

[0038] Construction of anchoring system: constructing a group of anchoring structures connecting the steel pipe pile and the first layer of bottom sealing concrete 501 on the outer circle of each steel pipe pile, and the top end of the anchoring structure protrudes an anchoring reinforcement for extending into the cap 10 above.

[0039] Foundation bottom sealing and cap 10 construction: constructing the second layer of bottom sealing concrete 502 with isolation joints 9 between each anchoring structure on the first layer of bottom sealing concrete 501 outside the anchoring structure, and constructing the cap 10 on the top surface of the second layer of bottom sealing concrete 502, the top surface of the isolation joint 9, the top surface of the anchoring structure, and the top surface of the steel pipe pile.

[0040] The construction method of the present application can construct radial and vertical annular anchoring systems: a group of anchoring structures is constructed on the outer circle of each steel pipe pile, and the anchoring structures are fixed with the corresponding steel pipe pile and the first layer of bottom sealing concrete layer 501 below, thereby being connected with the steel pipe pile in radial annular anchoring, forming a "flat rivet" type steel pipe pile and cap 10 radial annular anchoring system, realizing the bonding and compaction between the anchoring structures and the steel pipe pile to generate radial friction force, resisting vertical slip between the steel pipe pile and the anchoring structure, and when the concrete layer in the anchoring structure expands in volume, a radial counterforce can be formed under the constraint of the steel bars in the anchoring structure, which will generate radial prestress on the steel pipe pile and uniformly act on the steel pipe pile, so that the bonding and compaction between the anchoring structure and the steel pipe pile generate radial friction force, resisting vertical slip between the steel pipe pile and the anchoring structure; at the same time, the reserved main steel bars 2 in the steel pipe pile and the anchoring bars protruding out of the top of the anchoring structure are anchored into the cap 10 and connected with the cap 10 in vertical annular anchoring, forming a "series" type steel pipe pile and cap 10 vertical annular anchoring system, realizing the bonding and compaction between the steel pipe pile and the cap 10 to generate vertical friction force, resisting vertical slip between the steel pipe pile and the cap 10; (2) realizing good force transmission of the anchoring structure: when the force transmitted by the bridge superstructure to the cap 10, in addition to a part of the force being transmitted through the cap 10→reserved main steel bars 2→cap 10 concrete and steel casing 3 top pressure bearing→steel pipe pile, another part of the force is also transmitted through the cap 10→anchoring structure→steel casing 3, so that the anchoring system constructed by the construction method of the present application can realize the bonding and compaction between the steel pipe pile and the concrete, the anchoring quality between the steel pipe pile and the cap 10 is reliable, the overall structure is stable, and the bearing capacity is good.

[0041] Optionally, the step "S1: preliminary preparation" specifically includes the following steps:

[0042] 1. Preliminary construction preparation: according to the construction design drawing, the steel pipe pile, cap 10 foundation pit cofferdam, foundation pit support, and foundation pit earthwork excavation to the foundation pit bottom are constructed. Specifically, the steel pipe pile includes cast-in-place pile 1 and external steel casing 3; after the foundation pit is excavated to the design elevation of the foundation pit bottom, the quality of the foundation pit bottom needs to be inspected and accepted.

[0043] 2. Cutting and breaking: the steel casing 3 above the top of the steel pipe pile is cut to expose the cast-in-place pile 1, and the exposed cast-in-place pile 1 is broken to expose the reserved main steel bars 2. Specifically, the steel casing 3 above the top of the steel pipe pile is cut, the concrete of the part of the cast-in-place pile 1 is broken, and the concrete debris on the top of the cast-in-place pile 1 and the dust on the reserved main steel bars 2 are removed.

[0044] 3. First layer pouring: Pouring the first layer of bottom sealing concrete layer 501 on the bottom surface of the foundation pit. Specifically, leveling the bottom surface of the foundation pit, pouring the first layer of bottom sealing concrete with a thickness of 200 mm and a compressive strength grade of C30 on the surface thereof; exposing the height of the pile head of the cast-in-place pile 1 by 800 mm, the height of the steel casing 3 by 800 mm, and the height of the reserved main reinforcement 2 by 2300 mm (the anchoring length of the reserved main reinforcement 2 is required to be ≥ 35d, d is the diameter of the reserved main reinforcement 2, and the diameter of the reserved main reinforcement 2 is 32 mm), so as to ensure the firmness of the anchoring connection between the steel pipe pile and the pile cap 10.

[0045] Optionally, the step "S2: anchoring system design calculation" specifically comprises the following steps:

[0046] 1. Anchoring system design: designing the anchoring structure to form a radial annular anchoring system and a vertical annular anchoring system after connecting the steel pipe pile and the pile cap 10.

[0047] 2. Force transmission path analysis: analyzing the force transmission path of the radial annular anchoring system and the vertical annular anchoring system.

[0048] 3. Component force calculation: calculating the force of important components in the anchoring structure.

[0049] In this optional solution, each group of anchoring structures includes a group of anti-slide reinforcement rings for fixing on the outer circle of the corresponding steel pipe pile, a hollow cage-shaped ring-shaped reinforcement cage for fitting on the outer circle of the steel pipe pile, a hollow annular lower end for inserting into the ring-shaped reinforcement cage and an upper end for inserting into the pile cap 10, an anchoring reinforcement ring, and a group of anchoring concrete layers 8 formed by pouring the anti-slide reinforcement ring group, the ring-shaped reinforcement cage, and the anchoring reinforcement ring and connecting the steel pipe pile and the first layer of bottom sealing concrete layer 501.

[0050] Specifically, the step "1. Anchoring system design" specifically comprises:

[0051] (1) Radial annular anchoring system: by setting a group of radial anti-slide reinforcement rings, anchoring reinforcement rings, ring-shaped reinforcement cages, and anchoring concrete layers 8 on the outer side of the steel pipe pile, the radial annular anchoring connection with the steel pipe pile is formed, which constitutes a "flat head rivet" shaped radial annular anchoring system of the steel pipe pile and the pile cap 10, thereby improving the anchoring quality reliability of the steel pipe pile and the pile cap 10. When vertical slip occurs between the steel pipe pile and the anchoring concrete layer 8, the anchoring concrete layer 8 will expand in volume, generating radial stress outside the anchoring concrete layer 8, forming radial counterforce under the constraint of the ring-shaped reinforcement cage, and generating radial prestress inside the anchoring concrete layer 8 (towards the steel pipe pile), which uniformly acts on the steel pipe pile, making the anchoring concrete layer 8 and the steel casing 3 adhere tightly to generate radial friction force, resisting the vertical slip between the steel pipe pile and the anchoring concrete layer 8.

[0052] (2) Vertical annular anchoring system: by anchoring the reserved main steel bars 2 on the top of the cast-in-place pile 1 and the upper end of the anchoring steel ring into the pile cap 10, and connecting with the pile cap 10 in a vertical annular anchoring mode, a "series" type steel pipe pile and pile cap 10 vertical annular anchoring system is formed, which ensures the effective connection between the steel pipe pile and the pile cap 10, and enhances the overall stability and safety of the pile cap 10 structure through the vertical annular anchoring system, thereby improving the anchoring quality reliability of the steel pipe pile and the pile cap 10. When vertical slip occurs between the steel pipe pile and the pile cap 10, the reserved main steel bars 2 and the anchoring steel ring will generate vertical anti-sliding force on the steel pipe pile, so that the vertical friction force is generated between the steel pipe pile and the pile cap 10, resisting the vertical slip between the steel pipe pile and the pile cap 10.

[0053] Specifically, step "2. Analysis of force transmission path" is as follows: when the force of the bridge superstructure is transmitted to the pile cap, part of the force is transmitted through the pile cap 10→ the reserved main steel bars 2→ the bearing pressure between the pile cap concrete and the top of the steel casing 3→ the steel pipe pile, and the other part is transmitted through the pile cap 10→ the anchoring steel ring→ the anchoring concrete layer 8→ the contact surface between the anchoring concrete layer 8 and the steel casing 3 and the anti-sliding steel ring group on the contact surface→ the steel casing 3.

[0054] Specifically, step "3. Component force calculation" is as follows:

[0055] The axial pull-out force calculation of the anchoring steel ring generally only considers the adhesion between the surface of the anchoring steel ring embedded in the concrete foundation and the concrete, and does not consider the anchoring effect of the bent hooks at the end of the anchoring steel ring in the concrete foundation.

[0056] The anchoring steel ring in this embodiment includes 40 anchoring steel bars 7, each anchoring steel bar 7 has an anchoring depth h = 0.70 m (i.e. 35d, d is the diameter of the anchoring steel bar 7, the diameter of the anchoring steel bar 7 is 20 mm), and the concrete adhesion strength E b = 2.5 N mm2 mm. According to the anchoring strength calculation method of the anchor bolt, the axial pull-out force of the anchoring steel bar 7 is calculated as follows:

[0057] F = nπdh E b = 4396 kN

[0058] In the formula: F - axial pull-out force of the anchoring steel bar 7 (N);

[0059] n - anchoring number of the anchoring steel bar 7;

[0060] π - 3.14;

[0061] d - diameter of the anchoring steel bar 7 (mm);

[0062] h - anchoring depth of the anchoring steel bar 7 in the concrete foundation (mm);

[0063] E b - concrete bond strength (N / mm 2 ).

[0064] Optionally, the step of "anchoring system construction" specifically includes the following steps:

[0065] S3: anti-slide reinforcement ring group installation;

[0066] S4: ring reinforcement cage installation;

[0067] S5: anchoring reinforcement ring installation;

[0068] S6: anchoring concrete layer 8 construction.

[0069] In this optional solution, the step of "S3: anti-slide reinforcement ring group installation" specifically includes the following steps:

[0070] 1. Structure construction: Construct the constituent components of the anti-slide reinforcement ring group - multiple anti-slide reinforcement rings 4. Specifically, the anti-slide reinforcement ring 4 uses Φ8mm, HRB400 hot-rolled ribbed steel with a length of 7850mm (i.e. the outer circumference of the steel casing 3); the anti-slide reinforcement ring 4 is arranged horizontally in the axial and radial directions of the outer wall of the steel casing 3.

[0071] 2. Coating removal: Remove the protective coating on the outer wall of the steel casing 3 on the outer layer of the steel pipe pile. Specifically, use high-temperature baking and electric steel wire brushes to remove the protective coating on the outer wall of the steel casing 3 that exposes the top surface of the first layer of bottom sealing concrete layer 501, until the steel base surface of the steel casing 3 is exposed.

[0072] 3. Installation: Install multiple anti-slide reinforcement rings 4 on the outer circle of the steel casing 3 to form an anti-slide reinforcement ring group. Specifically, on the steel base surface of the outer wall of the steel casing 3 within the 750mm effective area of shear failure of the anchoring concrete layer 8 at the top of the steel casing 3, at positions 250mm and 500mm from the top surface of the steel casing 3, respectively horizontally weld 1 Φ8mm anti-slide reinforcement ring 4; the anti-slide reinforcement ring 4 and the steel casing 3 are connected by manual electric arc welding, making the anti-slide reinforcement ring 4 and the steel casing 3 firmly welded; after welding, clean the welding slag; after installation, the center of the anti-slide reinforcement ring 4 and the center of the steel pipe pile overlap consistently, all welds must be full, flat, smooth, without slag inclusion, bubbles or cracks.

[0073] The function of the anti-slide reinforcement ring 4 is to increase the roughness of the outer wall surface of the steel casing 3 within the 750mm effective area of shear failure of the anchoring concrete layer 8 at the top of the steel casing 3, and to increase the radial friction between the steel casing 3 and the anchoring concrete layer 8, thereby resisting vertical slip between the steel pipe pile and the anchoring concrete layer 8.

[0074] In this optional solution, the step "S4: installation of the ring-shaped reinforcement cage" specifically includes the following steps:

[0075] 1. Structure construction: a ring-shaped reinforcement cage is constructed using a plurality of ring-shaped reinforcements 6 and stirrups. Specifically, the main reinforcement of the ring-shaped reinforcement 6 is Φ8mm, HRB400 hot-rolled ribbed steel with a length of 8040mm (inner main reinforcement), 8830mm (middle main reinforcement), and 9610mm (outer main reinforcement); the ring-shaped reinforcement 6 is radially and horizontally arranged outside the top of the steel casing 3.

[0076] 2. Installation: the ring-shaped reinforcement cage is fitted onto the outer circle of the steel casing 3 and radially spaced from the anti-slide reinforcement ring group. Specifically, the dust on the top surface of the first layer of bottom sealing concrete layer 501 within a range of 320mm from the outer wall of the steel casing 3 is removed; a ring-shaped reinforcement cage with a width of 250mm and a height of 700mm (i.e., 35d, d is the diameter of the anchoring reinforcement 7) is installed radially and horizontally along the outer side of the steel casing 3 on the top surface of the first layer of bottom sealing concrete layer 501; during installation, the main reinforcements at both ends of the ring-shaped reinforcement cage are one-to-one corresponding to each other and are firmly connected by manual electric arc welding; 2 ring-shaped reinforcements 6 are evenly arranged at the height side middle position of the ring-shaped reinforcement cage, with a spacing of 217mm between adjacent ring-shaped reinforcements 6; 1 ring-shaped reinforcement 6 is evenly arranged at the width side middle position of the ring-shaped reinforcement cage, with a spacing of 105mm between adjacent ring-shaped reinforcements 6; the stirrups of the ring-shaped reinforcement cage are Φ6mm, HRB400 hot-rolled ribbed steel, and are evenly arranged in 40 rows radially along the steel casing 3; the spacing between adjacent stirrups on the outer side of the ring-shaped reinforcement cage is 234mm, and the spacing between adjacent stirrups on the inner side is 195mm; the thickness of the outer side reinforcement protection layer of the ring-shaped reinforcement cage is 50mm, and the thickness of the inner side reinforcement protection layer is 20mm; after installation, the centers of the ring-shaped reinforcement cage, the anti-slide reinforcement ring group, and the steel pipe pile are overlapped and consistent, which is beneficial to the uniform action of the radial prestress generated by the anchoring concrete layer 8 on the steel pipe pile.

[0077] The role of the ring-shaped reinforcement cage: when vertical slip occurs between the steel pipe pile and the anchoring concrete layer 8, the anchoring concrete layer 8 will expand in volume, generating radial stress outside the anchoring concrete layer 8, which forms a radial reaction force under the constraint of the ring-shaped reinforcement cage, and uniformly acts on the steel pipe pile in the radial direction (towards the steel pipe pile), making the anchoring concrete layer 8 and the steel casing 3 adhere tightly and generate radial friction, resisting the vertical slip between the steel pipe pile and the anchoring concrete layer 8.

[0078] In this optional solution, the step "S5: installation of the anchoring reinforcement ring" specifically includes the following steps:

[0079] 1. Structure construction: the constituent members of the anchoring steel bar ring are constructed, i.e. a plurality of anchoring steel bars 7. Specifically, the anchoring steel bars 7 adopt Φ20mm, HRB400 hot-rolled ribbed steel bars with a length of 2400mm; a 100mm-long, 90°-angle-bent short side is processed at one end of the anchoring steel bar 7 to form a lower bent section, and a 1400mm-long, 30°-angle-bent oblique side is processed at the other end of the anchoring steel bar 7 to form an upper bent section; after processing, the upper bent section at the top of the anchoring steel bar 7 and the lower bent section at the bottom of the anchoring steel bar 7 are both bent towards the same side direction, and the upper bent section, the vertical section and the lower bent section are all in the same plane; the anchoring steel bar 7 is arranged vertically along the radial direction outside the steel casing 3 in the ring-shaped steel reinforcement cage.

[0080] 2. Installation: the plurality of anchoring steel bars 7 are arranged in sequence along the circumference outside the steel casing 3, and each anchoring steel bar 7 is vertically inserted into the concrete of the first layer of anchoring concrete layer 8 formed by the first pouring in the ring-shaped steel reinforcement cage. Specifically, in the ring-shaped steel reinforcement cage, a row of 40 anchoring steel bars 7 is vertically and uniformly installed along the radial direction outside the steel casing 3, and the spacing between adjacent anchoring steel bars 7 is 184mm; when installing, the lower bent section end of the anchoring steel bar 7 is inserted into the concrete of the first layer of anchoring concrete layer 8 from the top to the bottom at a position 20mm away from the top surface of the first layer of bottom-sealing concrete layer 501; the upper bent section end of the anchoring steel bar 7 is installed away from the top surface of the first layer of bottom-sealing concrete layer 501 upwards, and the upper bent section, the vertical section and the lower bent section of the anchoring steel bar 7 are all installed away from the steel casing 3; after installation, the distance between the anchoring steel bar 7 and the outer wall of the steel casing 3 is 50mm (i.e. 2 times the maximum particle size 25mm of the coarse aggregate used in the anchoring concrete layer 8); the length of the anchoring steel bar 7 anchored in the anchoring concrete layer 8 is 700mm, and the length of the anchoring steel bar 7 anchored in the pile cap 10 is 1550mm (the anchoring length of the anchoring steel bar 7 is required to be ≥35d, d is the diameter of the anchoring steel bar 7, and the diameter of the anchoring steel bar 7 is 20mm), so as to ensure the firmness of the anchoring connection between the steel pipe pile and the pile cap 10; the centers of the anchoring steel bar ring, the ring-shaped steel reinforcement cage, the ring-shaped anti-slide steel reinforcement ring and the steel pipe pile are overlapped and consistent; when the anchoring steel bar ring is subjected to uplift detection, the anchoring steel bar 7 is allowed to be broken without damaging the ring-shaped anchoring concrete layer 8.

[0081] The role of the anchoring steel ring arrangement is: (1) reducing the welding workload between the anchoring steel 7 and the steel casing 3 on the construction site, avoiding poor welding quality of the anchoring steel 7; (2) the anchoring steel 7 installation has high safety and reliability, is easy and fast to operate, greatly improves the construction efficiency, shortens the construction period, and saves the construction cost; (3) the anchoring steel 7 and the reserved main steel 2 are anchored into the pile cap 10, and are vertically and annularly anchored with the pile cap 10, forming a “series” type steel pipe pile and pile cap 10 vertical annular anchoring system, ensuring the effective connection between the steel pipe pile and the pile cap 10, and enhancing the overall stability and safety of the pile cap 10 structure through the vertical annular anchoring system, thereby improving the anchoring quality reliability of the steel pipe pile and the pile cap 10; when vertical slip occurs between the steel pipe pile and the pile cap 10, the anchoring steel 7 and the reserved main steel 2 will generate vertical anti-sliding force on the steel pipe pile, so that the steel pipe pile and the pile cap 10 generate vertical friction force, resisting the vertical slip between the steel pipe pile and the pile cap 10; (4) when the force transmitted by the bridge superstructure to the pile cap is transmitted to the pile cap, part of the force is transmitted through the pile cap 10→ the reserved main steel 2→ the pile cap concrete and the bearing pressure between the top of the steel casing 3→ the steel pipe pile, and the other part of the force is transmitted through the pile cap 10→ the anchoring steel ring→ the anchoring concrete layer 8→ the contact surface between the anchoring concrete layer 8 and the steel casing 3 and the convex anti-sliding steel ring group on the contact surface→ the steel casing 3.

[0082] In this optional solution, the step “S6: Anchoring concrete layer 8 construction” specifically includes the following steps:

[0083] 1. Formwork installation: install the annular formwork around the annular steel reinforcement cage on the first layer of bottom sealing concrete layer 501 outside the annular steel reinforcement cage. Specifically, install the annular formwork on the top surface of the first layer of bottom sealing concrete layer 501 outside the annular steel reinforcement cage; when the formwork is installed, the steel reinforcement protective layer thickness of the outer side and the top surface of the anchoring concrete layer 8 must be 50 mm.

[0084] 2. Concrete pouring: pouring in the annular formwork to form the anchoring concrete layer 8. Specifically, after the installation quality inspection and acceptance of the anchoring steel ring, the annular steel cage, and the anti-slide steel ring group are qualified, the anchoring concrete layer 8 with a width of 320 mm and a height of 800 mm is poured on the top surface of the first layer of bottom sealing concrete layer 501, and the anchoring concrete layer 8 uses C40 micro-expanding concrete. When pouring, the anchoring concrete layer 8 is poured in three layers, each layer has a pouring thickness of 250-300 mm, so that the anchoring concrete layer 8 is poured to be flush with the top surface of the steel casing 3. Before the anchoring concrete layer 8 is initially cured, the anchoring concrete layer 8 must be secondarily vibrated to prevent the anchoring concrete layer 8 from sinking when it is in plastic shrinkage, separating the anchoring steel ring, the annular steel cage, and the anti-slide steel ring group from the steel casing 3 to produce gaps, and reducing the gripping force between the anchoring concrete layer 8 and the anchoring steel ring, the annular steel cage, and the anti-slide steel ring group or the bonding force between the anchoring concrete layer 8 and the steel casing 3. After the pouring of the anchoring concrete layer 8, the center of the annular anchoring concrete layer 8, the center of the anchoring steel ring, the center of the annular steel cage, the center of the anti-slide steel ring group, and the center of the steel pipe pile are overlapped and consistent, which ensures that after the anchoring concrete layer 8 expands in volume, the radial counterforce is formed under the constraint of the annular steel cage, which produces a uniform radial prestress on the inside of the anchoring concrete layer 8 (towards the steel pipe pile direction) and acts on the steel pipe pile, so that the anchoring concrete layer 8 and the steel casing 3 are bonded and compacted to produce radial friction force, resisting the vertical slip between the steel pipe pile and the anchoring concrete layer 8. After the anchoring concrete layer 8 is finally cured, the geotextile is used for covering and water is sprayed for maintenance, and the maintenance age is not less than 14 d.

[0085] The annular anchoring concrete layer 8 is arranged to have the following effects: when the anchoring concrete layer 8 expands in volume, a radial reaction force is formed under the constraint of the annular reinforcement cage, which generates a radial prestress on the inner side of the anchoring concrete layer 8 (towards the steel pipe pile) and uniformly acts on the steel pipe pile, so that the anchoring concrete layer 8 and the steel casing 3 are bonded and compacted to generate a radial friction force, which resists the vertical slip between the steel pipe pile and the anchoring concrete layer 8. The anchoring concrete layer 8 resists shear failure: when the vertical slip occurs between the steel pipe pile and the anchoring concrete layer 8, the anchoring steel reinforcement ring in the anchoring concrete layer 8 generates an upward anti-sliding force on the anchoring concrete layer 8, so that the anchoring concrete layer 8 resists shear failure, and a shear failure crack failure surface is formed, which intersects the outer wall surface of the steel casing 3 and the top surface of the first layer of bottom sealing concrete layer 501 at an angle of 45°. Among them: the part of the anchoring concrete layer 8 above the shear failure crack failure surface is the effective area of the anchoring concrete layer 8 against shear failure, which plays a role in resisting shear and resisting the vertical slip between the steel pipe pile and the anchoring concrete layer 8; the part of the anchoring concrete layer 8 below the shear failure crack failure surface is the failure area of the anchoring concrete layer 8 against shear failure, that is, the approximately triangular annular shear failure failure area of the anchoring concrete layer 8 with the first layer of bottom sealing concrete layer 501 top surface and the steel casing 3 outer wall intersection as the center and 2 times the maximum particle size of the coarse aggregate used in the anchoring concrete layer 8 as the width and height, which loses the role of resisting shear and cannot resist the vertical slip between the steel pipe pile and the anchoring concrete layer 8.

[0086] Optionally, the step "S7: foundation pit bottom sealing and pile cap 10 construction" specifically comprises the following steps: 1. Second layer pouring: set a partition plate on the outer periphery of the anchoring structure, and pour the second layer of bottom sealing concrete layer 502 on the first layer of bottom sealing concrete layer 501 outside the partition plate. Specifically, after the annular formwork is removed, a layer of 0.2mm thick oil paper is arranged on the outer side of the anchoring concrete layer 8 to fill and separate the anchoring concrete layer 8 and the second layer of bottom sealing concrete layer 502 to form a separation joint 9, which prevents the second layer of bottom sealing concrete layer 502 from damaging the anchoring concrete layer 8 when it shrinks, and is more conducive to the expansion of the anchoring concrete layer 8; the second layer of C30 bottom sealing concrete is poured on the top surface of the first layer of bottom sealing concrete layer 501 outside the anchoring concrete layer 8 to the same level as the top surface of the anchoring concrete layer 8 and the top surface of the steel casing 3.

[0087] 2. Construction of the bearing platform 10: Pour the bearing platform 10 on the top surface of the second layer of bottom sealing concrete 502, the top surface of the isolation joint 9, the top surface of the anchoring structure and the top surface of the steel pipe pile. Specifically, on the top surface of the second layer of bottom sealing concrete 502, the top surface of the isolation joint 9, the top surface of the anchoring concrete layer 8, the top surface of the steel casing 3 and the top surface of the cast-in-place pile 1, the construction of anchoring the reserved main steel bars 2 and the anchoring steel bars 7 into the bearing platform 10, the lightning protection grounding construction, the installation of the steel bars of the bearing platform 10, the installation of the cooling pipes and the installation of the embedded components are completed in sequence. After the installation quality is accepted, the formwork of the bearing platform 10 and the pouring of the concrete of the bearing platform 10 can be installed. After the construction of the bearing platform 10, the reserved main steel bars 2 and the anchoring steel bars 7 are anchored into the bearing platform 10 and connected with the vertical annular anchoring of the bearing platform 10, so as to ensure the firmness of the anchoring connection between the steel pipe pile and the bearing platform 10, form the vertical annular anchoring system of the "series connection" type steel pipe pile and the bearing platform 10, ensure the effective connection between the steel pipe pile and the bearing platform 10, and enhance the overall stability and safety of the structure of the bearing platform 10 through the vertical annular anchoring system, thereby improving the anchoring quality reliability of the steel pipe pile and the bearing platform 10.

[0088] The construction method of the steel pipe pile and bearing platform anchoring system of the present application can be applied not only to the construction of the bridge bearing platform in the above-mentioned embodiment, but also to the construction of the pile foundation of highway bridges, the foundation of industrial and civil buildings, structures in strong earthquake intensity areas, structures under strong scouring and deep water structures.

[0089] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for constructing a steel pipe pile and cap anchoring system, characterized in that: The following steps are involved: Preliminary preparation: cutting and breaking the excess steel pipe piles in the deep foundation pit to expose the reserved main steel bars (2), and constructing the first bottom sealing concrete layer (501) on the bottom of the foundation pit; Anchorage system design and calculation: Design the anchorage structure to connect the steel pipe piles and the cap (10) to form an anchorage system, and calculate the bearing capacity of important components in the anchorage structure; Anchoring system construction: a set of anchoring structures connecting the steel pipe piles and the first bottom concrete layer (501) is constructed on the outer circle of each steel pipe pile, and the top of the anchoring structure protrudes with anchoring bars for extending into the upper pedestal (10); Construction of foundation pit bottom seal and foundation cap (10): constructing a second bottom seal concrete layer (502) on the first bottom seal concrete layer (501) outside the anchor structure, with isolation joints (9) between each anchor structure, and constructing foundation caps (10) on the top surface of the second bottom seal concrete layer (502), the top surface of the isolation joints (9), the top surface of the anchor structure, and the top surface of the steel pipe piles; Each anchoring structure comprises an anti-slip steel ring group for fixedly fitting on the outer circle of the corresponding steel pipe pile, a hollow cage-shaped annular steel cage for fitting on the outer circle of the steel pipe pile, an anchoring steel ring with a hollow ring-shaped lower end for inserting into the annular steel cage and an upper end for inserting into the pedestal (10), and an anchoring concrete layer (8) formed by pouring the anti-slip steel ring group, the annular steel cage and the anchoring steel ring and connecting the steel pipe pile and the first bottom sealing concrete layer (501).

2. The method for constructing a steel pipe pile and cap anchoring system according to claim 1, characterized in that: The step "Preliminary Preparation" specifically includes the following steps: Preliminary construction preparation: According to the construction design drawings, complete the construction of steel pipe piles, foundation pile cap (10), foundation pit cofferdam, foundation pit support, and excavation of foundation pit to the bottom of the foundation pit; Cutting and breaking: cutting the excess steel casing (3) on the top of the steel pipe pile to expose the cast-in-place pile (1), and breaking the exposed cast-in-place pile (1) to expose the reserved main steel bar (2); First layer pouring: pour the first bottom sealing concrete layer (501) on the bottom surface of the foundation pit.

3. The method for constructing a steel pipe pile and cap anchoring system according to claim 1, characterized in that: The steps of "Anchorage System Design Calculation" specifically include the following steps: Anchorage system design: Design the anchorage structure so that the anchorage structure connects the steel pipe piles and the cap (10) to form a radial annular anchorage system and a vertical annular anchorage system; Force transmission path analysis: Analyze the force transmission paths of radial annular anchor systems and vertical annular anchor systems; Component bearing calculation: Calculate the bearing capacity of important components in the anchoring structure.

4. The method for constructing a steel pipe pile and cap anchoring system according to claim 3, characterized in that: The step "anchor system construction" specifically includes the following steps: Installation of anti-slip steel ring group; Ring reinforcement cage installation; Anchor reinforcement ring installation; Construction of anchoring concrete layer (8).

5. The method for constructing a steel pipe pile and cap anchoring system according to claim 4, characterized in that: The steps of "installing the anti-slip steel ring assembly" specifically include the following steps: Structural construction: constructing components of the anti-slip steel ring group - multiple anti-slip steel rings (4); Coating removal: remove the protective coating on the outer wall of the steel casing (3) of the steel pipe pile; Installation: A plurality of anti-slip steel bar rings (4) are installed on the outer circle of the steel casing (3) to form an anti-slip steel bar ring group.

6. The method for constructing a steel pipe pile and cap anchoring system according to claim 4, characterized in that: The steps of "ring reinforcement cage installation" specifically include the following steps: Structural construction: a circular reinforcement cage is constructed using a plurality of circular reinforcement bars (6) and stirrups; Installation: Put the annular steel cage onto the outer circle of the steel casing (3) and space it radially from the anti-slip steel ring group.

7. The method for constructing a steel pipe pile and cap anchoring system according to claim 4, characterized in that: The step "Installation of anchor reinforcement rings" specifically includes the following steps: Structural construction: constructing the components of the anchor steel ring - multiple anchor steel bars (7); Installation: multiple anchoring steel bars (7) are sequentially arranged in a circumferential direction along the outer side of the steel casing (3), and each anchoring steel bar (7) is sequentially inserted vertically into the concrete of the first anchoring concrete layer (8) formed by the first pouring in the annular steel cage.

8. The method for constructing a steel pipe pile and cap anchoring system according to claim 4, characterized in that: The step "construction of anchoring concrete layer (8)" specifically includes the following steps: Formwork installation: installing a ring formwork surrounding the ring reinforcement cage on the first bottom sealing concrete layer (501) outside the ring reinforcement cage; Concrete pouring: Concrete is poured inside the ring formwork to form an anchoring concrete layer (8).

9. The method for constructing a steel pipe pile and cap anchoring system according to claim 1, characterized in that: The step "foundation pit bottom sealing and foundation bearing platform (10) construction" specifically includes the following steps: Second layer pouring: an isolation plate is provided on the periphery of the anchoring structure, and a second bottom seal concrete layer (502) is poured on the first bottom seal concrete layer (501) outside the isolation plate; Construction of the cap (10): The cap (10) is cast on the top surface of the second bottom concrete layer (502), the top surface of the isolation joint (9), the top surface of the anchoring structure and the top surface of the steel pipe pile.

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