Connecting structure and connecting method for PHC pipe pile and reinforced concrete prefabricated bearing platform

Abstract

The invention belongs to the technical field of overhead transmission line engineering, and provides a connecting structure and a connecting method of a PHC pipe pile and a reinforced concrete prefabricated bearing platform, the structure comprises the prefabricated bearing platform, a soil-squeezing PHC pipe pile, a connecting cavity, a mechanical connecting piece and a grouting connecting piece; a plurality of connecting cavities are formed in the prefabricated bearing platform, a soil-squeezing type PHC pipe pile is correspondingly arranged in each connecting cavity, and the soil-squeezing type PHC pipe piles form a first-stage connecting structure through mechanical connecting pieces; a reserved space is formed between the inner side wall of the connecting cavity and the soil-squeezing type PHC pipe pile, and a grouting connecting piece is arranged in the reserved space to form a secondary connecting structure. Through the combined action of a first-stage connecting structure formed by the mechanical connecting pieces and a second-stage connecting structure formed by the grouting connecting pieces, the connecting strength and stability between the PHC pipe pile and the reinforced concrete prefabricated bearing platform are remarkably improved. The composite connection mode can more effectively resist various external forces and vibrations, and ensures the safety and durability of the structure.

Description

Technical Field

[0001] The invention relates to the technical field of overhead power transmission line engineering, and in particular to a connection structure and a connection method between a PHC pipe pile and a reinforced concrete prefabricated cap. Background Art

[0002] Transmission lines are distributed in point and line forms. The terrain and traffic conditions at the tower locations along the lines vary greatly. The industry characteristics of single-point and multi-regional distribution of on-site construction are very obvious. It is difficult and expensive for large-scale machinery and equipment to enter and exit the site, which requires that construction machinery and equipment must be lightweight and detachable. The miniaturization and miniaturization of the foundation structure are prerequisites for lightweight construction machinery and equipment. At present, State Grid Corporation requires that the design source be grasped, and the application of micro pile foundations be promoted according to local conditions to promote the comprehensive promotion of mechanized construction in the construction of power transmission and transformation projects.

[0003] Micro pile foundation is a foundation composed of small diameter piles and a cap connected to the top of the pile. The pile body diameter is generally 150mm~400mm according to the pile forming method. The pile body can be a cast-in-place pile, a steel pipe pile, or a PHC pipe pile. The cap is generally cast on site. The current practical constraint is that the construction period of concrete pouring and wet curing is long, and construction cannot be carried out when the temperature is low in winter, which cannot meet the requirements of rapid construction engineering.

[0004] In the clay foundation of plains and hilly areas where overhead transmission lines of voltage levels of 500kV and below pass, the use of soil-squeezing PHC pipe piles and reinforced concrete prefabricated caps can well meet the construction needs of on-site mechanized construction and less wet concrete pouring operations. If PHC pipe piles and reinforced concrete prefabricated caps are connected mechanically, the construction accuracy of PHC pipe piles is very high. However, the soil-squeezing PHC pipe piles of transmission lines are generally constructed with hydraulic vibrating hammers or diesel hammers. Due to the unevenness of underground rock and soil and the uneven technical level of the construction team, it is inevitable that there will be construction accuracy errors such as pile position deviation, inclination, and uncontrolled pile top elevation. How to ensure the installation accuracy of soil-squeezing PHC pipe piles and reinforced concrete prefabricated caps and take into account construction errors is a dilemma, so the design of the connection method between PHC pipe piles and reinforced concrete prefabricated caps is particularly important. Summary of the invention

[0005] The object of the present invention is to provide a connection structure and a connection method for a PHC pipe pile and a reinforced concrete prefabricated cap, so as to solve the problems of pile position deviation, inclination and uncontrolled pile top elevation in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a connection structure between a PHC pipe pile and a prefabricated reinforced concrete cap, comprising a prefabricated cap, a soil-extruding PHC pipe pile, a connection cavity, a mechanical connector and a grouting connector; a plurality of connection cavities are arranged in the prefabricated cap, and a soil-extruding PHC pipe pile is correspondingly arranged inside each connection cavity, and the soil-extruding PHC pipe pile forms a primary connection structure through a mechanical connector; a reserved space is provided between the inner side wall of the connection cavity and the soil-extruding PHC pipe pile, and a grouting connector is arranged in the reserved space to form a secondary connection structure.

[0007] Furthermore, the mechanical connector includes an anchor, a fixing plate, a connecting bolt and a connecting plate; a plurality of anchors are embedded in a prefabricated cap around the connecting cavity; the fixing plate is fixedly installed on the top of the soil-squeezing PHC pile, and one end of the connecting bolt is fixedly installed on the fixing plate; the connecting plate is covered on the prefabricated cap at the connecting cavity and fixed by the anchor, and the other end of the connecting bolt is fixedly connected to the connecting plate.

[0008] Furthermore, the anchoring piece is a fastening bolt.

[0009] Furthermore, an end plate is fixedly provided on the top of the soil-squeezing PHC pile, and the end plate is fixedly connected to the fixing plate by bolts.

[0010] Furthermore, holes are provided at the geometric centers of the end plate and the fixing plate, connecting bolts are provided in the holes, and the connecting bolts are fixed to the fixing plate by upper and lower nuts.

[0011] Furthermore, a center hole is opened at the geometric center of the connecting plate, a connecting bolt is arranged in the center hole, and the connecting bolt is fixed to the connecting plate by a nut.

[0012] Furthermore, the size of the center hole is larger than the diameter of the connecting bolt.

[0013] Furthermore, the grouting connector includes a pre-buried steel pipe and grouting material; the pre-buried steel pipe is fitted in the connection cavity, and the grouting material is filled in the space between the pre-buried steel pipe and the soil-squeezing PHC pile.

[0014] Furthermore, positioning rings for fixing the embedded parts are symmetrically arranged on the upper and lower outer surfaces of the embedded steel pipes; and the grouting material is an early-strength cement-based micro-expansion grouting material.

[0015] In a second aspect, the present invention provides a method for connecting a PHC pipe pile with a reinforced concrete prefabricated cap, comprising the following steps: First, fasten the connecting bolts to the fixing plate with the upper and lower nuts, and ensure that the top of the connecting bolts extends to the outside of the prefabricated cap. Connect and fasten the fixing plate to the end plate of the soil-squeezing PHC pile with high-strength bolts. Then, the connecting bolts extending to the outside of the precast cap are fastened to the embedded parts of the reinforced concrete precast cap through the connecting plate, ensuring that the central opening size of the connecting plate is larger than the diameter of the connecting bolts, thus completing the primary connection; Finally, early-strength cement-based micro-expansion grouting material is poured between the cavity of the soil-squeezing PHC pile and the embedded steel pipe to complete the secondary connection.

[0016] Compared with the prior art, the present invention has the following technical effects: The present invention significantly improves the connection strength and stability between the PHC pile and the reinforced concrete prefabricated cap by the primary connection structure formed by the mechanical connector and the secondary connection structure formed by the grouting connector. This composite connection method can more effectively resist various external forces and vibrations, ensuring the safety and durability of the structure.

[0017] The use of high-strength bolts and anchors, as well as fixing plates and connecting plates, further enhances the reliability and stability of the connection. These high-strength materials can withstand large tensile and shear forces, ensuring the safety of the connection nodes under complex stress conditions.

[0018] The central opening size of the connection plate of the present invention is larger than the diameter of the connection bolt on the end plate of the PHC pile. This design solves the construction accuracy error problem of the displacement and tilt of the soil-squeezing PHC pile. Even if the PHC pile has a certain position deviation or tilt during construction, it can be reliably connected to the prefabricated cap through the adjustment and adaptation of the connection plate.

[0019] The early-strength cement-based micro-expansion grouting material is poured between the PHC pile and the cavity of the reinforced concrete prefabricated foundation. This measure solves the problem of construction accuracy error in the uncontrolled construction elevation of the squeezed soil PHC pile. The grouting material can automatically fill the gap in the cavity to form a uniform and dense connection layer, thereby eliminating the connection gap caused by construction errors.

[0020] This technical solution uses prefabricated caps and PHC piles. These prefabricated components can be standardized in the factory and then transported to the construction site for assembly and connection. This method greatly improves construction efficiency and convenience, shortens construction period and reduces construction costs.

[0021] The combination of mechanical connection and grouting connection simplifies the construction process and reduces the workload and difficulty of on-site work. At the same time, this connection method also makes it easier to achieve mechanized construction and automated control, further improving construction efficiency and quality.

[0022] Early-strength cement-based micro-expansion grouting material: The early-strength cement-based micro-expansion grouting material used has excellent mechanical properties and durability, and can withstand various external forces and environmental factors for a long time without damage or deterioration. At the same time, the grouting material also has good corrosion resistance, and can resist the erosion of corrosive media such as groundwater and sewage, thus extending the service life of the structure.

[0023] In summary, this technical solution solves the problem of construction accuracy error by providing a reliable, stable, efficient and durable connection structure and method between PHC pipe piles and precast reinforced concrete caps, improves construction efficiency and convenience, enhances the durability and corrosion resistance of the structure, and has significant technical effects and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the mechanical connection of the PHC pipe pile with bolts and the reinforced concrete prefabricated cap and the composite connection of grouting and bonding.

[0025] Figure 2 It is a schematic diagram of the connection of the end plate of the PHC pipe pile of the present invention.

[0026] Figure 3 It is a schematic diagram of the connecting plate structure of the present invention.

[0027] Figure 4 It is a schematic diagram of the positioning ring structure of the present invention.

[0028] in: 1. PHC piles; 2. Prefabricated caps; 3. Connecting bolts; 4. Fixing plates; 5. Connecting plates; 6. Grouting materials; 7. Embedded parts; 8. Embedded steel pipes; 9. Positioning rings; 10. End plates. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Glossary: Soil squeezing PHC pipe pile: Soil squeezing PHC pipe pile is a pile foundation treatment method that produces soil squeezing effect on the surrounding soil during the pile sinking process. The soil squeezing effect is a significant feature of soil squeezing PHC pipe pile. It refers to the phenomenon that during the pile sinking process, the pile body is squeezed into the soil, causing the soil around the pile to be compressed and displaced. This effect may have an impact on the surrounding environment and structures.

[0033] PHC pipe piles are made of prestressed concrete and have the characteristics of high strength, high rigidity and high durability. The tensioning process of prestressed steel bars generates compressive stress inside the pile body, which improves the overall strength and rigidity of the pile body.

[0034] Soil squeezing effect: During the pile sinking process, the pile body squeezes into the soil, causing the soil around the pile to be compressed and displaced. This soil squeezing effect will cause a remodeling zone to form in the soil around the pile, and the properties of the soil within the remodeling zone may change, such as increased density and increased pore water pressure.

[0035] Soil squeezing PHC piles are widely used in various engineering fields, such as high-rise buildings, bridges, tunnels, ports, etc. Its advantages include high single pile bearing capacity, strong penetration, fast construction speed, etc. However, due to the existence of soil squeezing effect, special treatment is required during the design and construction process to ensure the quality and safety of the project.

[0036] Early strength cement-based micro-expansion grouting material: It is a high-performance building material, mainly used for grouting connection and reinforcement in various engineering structures. It is a building material formulated with a variety of admixtures and high molecular polymers. It has the characteristics of early strength, high strength, micro-expansion, no shrinkage, etc. It can reach a high strength in a short time and has good bonding performance and durability.

[0037] Early strength and high strength: Grouting materials can reach high strength in a short time. Usually, the compressive strength can exceed 20MPa in one day and 40MPa or even higher in three days. This feature effectively shortens the project cycle and improves project efficiency.

[0038] Micro-expansion: The grouting material will expand slightly during use, and can automatically adapt to and fill the gaps between the original building structures, ensuring close contact between the equipment and the foundation, and improving the reinforcement effect.

[0039] No shrinkage: It has micro-expansion compensation function, which eliminates the shrinkage phenomenon of cement hardening and ensures the stability and durability of the grouting layer.

[0040] High bonding strength: It has high bonding strength with steel bars, concrete and other materials, which can improve the integrity and seismic resistance of the structure.

[0041] Durability: After multiple fatigue tests and freeze-thaw cycle tests, it has been proved that the strength of the grouting material has no obvious change and has excellent durability.

[0042] Corrosion resistance: Early-strength cement-based micro-expansion grouting material also has good resistance to sulfate and sewage erosion, and can be used in projects such as seaports and sewage treatment plants.

[0043] Example 1, please refer to Figure 1 The present invention provides a connection structure between a PHC pipe pile and a reinforced concrete prefabricated cap, comprising a prefabricated cap 2, a soil-squeezing PHC pipe pile 1, a connection cavity, a mechanical connector and a grouting connector; a plurality of connection cavities are arranged in the prefabricated cap 2, and a soil-squeezing PHC pipe pile 1 is correspondingly arranged inside each connection cavity, and the soil-squeezing PHC pipe pile 1 forms a primary connection structure through a mechanical connector; a reserved space is provided between the inner side wall of the connection cavity and the soil-squeezing PHC pipe pile 1, and a grouting connector is arranged in the reserved space to form a secondary connection structure.

[0044] The structure adopts a dual connection mechanism combining mechanical connectors and grouting connectors. The mechanical connectors tightly connect the PHC piles and prefabricated caps through high-strength bolts and anchors to form a stable primary connection structure. The grouting connectors fill the reserved space to form a dense secondary connection structure, further enhancing the strength and stability of the connection.

[0045] This connection method forms a composite force system between the PHC piles and the prefabricated cap, which can more effectively transfer and disperse the load and improve the bearing capacity of the overall structure.

[0046] The reserved space between the inner wall of the connection cavity and the PHC pile provides sufficient operating space for grouting connection, while also allowing a certain construction error, thereby improving the flexibility and adaptability of the construction.

[0047] Since both the mechanical connectors and the grouting connectors have a certain degree of adjustment capability, this structure can better adapt to the problems of displacement and tilt that may occur in the PHC piles during construction, ensuring the accuracy and reliability of the connection.

[0048] The early-strength cement-based micro-expansion grouting material used has excellent mechanical properties, durability and corrosion resistance. It can withstand various external forces and environmental factors for a long time without damage or deterioration, thus extending the service life of the structure.

[0049] The dense filling layer formed by the grouting connector can provide good protection for the connection between the PHC pile and the prefabricated cap, preventing erosion and damage from the external environment.

[0050] The structure uses prefabricated components such as prefabricated caps and PHC piles, which can be standardized in the factory and then transported to the construction site for assembly and connection. This method greatly improves construction efficiency and convenience, shortens construction period and reduces construction costs.

[0051] The combination of mechanical connection and grouting connection simplifies the construction process and reduces the workload and difficulty of on-site work. At the same time, this connection method also makes it easier to achieve mechanized construction and automated control, further improving construction efficiency and quality.

[0052] In summary, the connection structure of PHC pipe piles and reinforced concrete precast caps adopts a dual connection mechanism combining mechanical connectors and grouting connectors to enhance the strength and stability of the connection; the construction accuracy and adaptability are improved by improving the reserved space design and adjustment ability; the long-term use of the structure and the maximization of economic benefits are achieved through excellent durability and corrosion resistance as well as construction efficiency and cost control; at the same time, its broad application prospects also provide more possibilities and opportunities for this connection structure in future engineering practice.

[0053] Embodiment 2, the present invention provides a connection structure between a PHC pipe pile and a reinforced concrete prefabricated cap, specifically comprising: A composite connection that is a combination of a bolted mechanical connection between a PHC pipe pile and a precast reinforced concrete cap and a grouting connection between a PHC pipe pile and a precast reinforced concrete cap.

[0054] The PHC pile is mechanically connected to the reinforced concrete prefabricated cap by bolts. An M24 bolt made of 45# steel is embedded in the reinforced concrete prefabricated cap 2 to form an anchor 7, and a pre-embedded steel pipe 8 forms a vertically penetrating cavity. The inner diameter of the cavity is 100mm to 200mm larger than the diameter of the PHC pile. Two upper and lower positioning rings 9 are welded to the outside of the embedded steel pipe 8 for fixing the above-mentioned M24 bolts 7. The diameter of the PHC pile 1 is generally 300mm and 400mm, the height of the prefabricated cap 2 is at least 400mm, and the exposed height of the PHC pile 1 is lower than the height of the reinforced concrete prefabricated cap.

[0055] First, fasten the M56 connecting bolts made of 45# carbon structural steel and 250mm in length to the fixing plate 4 through two upper and lower M56 nuts, and ensure that the exposed length of the connecting bolts 3 is at least 150mm. The thickness of the fixing plate 4 is consistent with the thickness of the end plate 11 of the PHC pile 1. The material is Q355B, and a bolt hole with an opening diameter of 60mm is processed in the center, and M30 bolt holes with the same number and distribution circle diameter as the prestressed steel bar tensioning holes of the top end plate of the PHC pile are processed on the periphery. Secondly, connect and fasten the fixing plate 4 to the end plate 11 of the PHC pile 1 through M27 or M30 (M30 is used only when the prestressed steel bar diameter of the PHC pile is 14mm) 6.8 or 8.8 grade high-strength bolts.

[0056] The connecting bolts 3 fixed on the end plate 11 of the PHC pile 1 pass through the cavity of the reinforced concrete prefabricated cap and are fastened and connected with the embedded bolts of the reinforced concrete prefabricated cap 2 through the connecting plate 5 .

[0057] The diameter of the opening in the middle of the connecting plate 5 is Φ80mm, and the diameter of the outer opening is Φ30mm. The number of openings is consistent with the number of M24 embedded bolts of the reinforced concrete prefabricated foundation. The plate thickness is 20-40mm, and the material is Q355B. The central opening size of the connecting plate 5 is larger than the diameter of the connecting bolt 3 on the end plate of the PHC pile, which solves the construction accuracy error problem of the displacement and inclination of the soil-squeezing PHC pile.

[0058] The grouting connection between the PHC pipe pile and the reinforced concrete prefabricated cap is made by pouring an early-strength cement-based slightly expansive grouting material 6 between the cavities of the PHC pipe pile and the reinforced concrete prefabricated cap, with a strength grade of not less than C80. The grouting can be poured from the hole mouth during construction. Before pouring, the debris on the exposed part of the PHC pipe pile needs to be cleaned up. The addition ratio of the cement-based slightly expansive grouting material to the mixing water is about 13%. The grouting connection solves the problem of uncontrolled construction accuracy error of the soil-squeezing PHC pipe pile construction elevation.

[0059] In this embodiment, a strong mechanical connection is formed by combining M56 connecting bolts and M24 embedded bolts. This connection method can effectively transmit and disperse the load, and improve the connection strength and stability between the PHC pile and the prefabricated cap.

[0060] Early-strength cement-based micro-expansion grouting material is poured between the cavity of the PHC pile and the prefabricated cap to form a dense grouting connection layer, which not only enhances the integrity of the connection, but also improves the durability and corrosion resistance of the structure.

[0061] The central opening size of the connecting plate 5 of this embodiment is larger than the diameter of the connecting bolt 3 on the end plate of the PHC pile. This design allows a certain construction error and can solve the construction accuracy error problem of the displacement and inclination of the soil-squeezing PHC pile.

[0062] The grouting material is able to fill the gaps between the PHC piles and the precast caps, and even if these gaps vary in size due to construction errors, the grouting material can adapt and fill them well, thereby improving the adaptability of the connection.

[0063] This embodiment uses high-strength, corrosion-resistant materials such as 45# steel and Q355B, as well as early-strength cement-based micro-expansion grouting materials. These materials have excellent mechanical properties and durability, and can withstand various external forces and environmental factors for a long time without being damaged or deteriorated.

[0064] Protective effect of grouting material: The dense filling layer formed by the grouting material can provide good protection for the connection between the PHC piles and the prefabricated cap, preventing erosion and damage from the external environment, thereby extending the service life of the structure.

[0065] The PHC piles and prefabricated caps in this embodiment are prefabricated components, which can be standardized and produced in a factory and then transported to the construction site for assembly and connection. This method improves construction efficiency and reduces construction costs.

[0066] The combined use of bolt mechanical connection and grouting connection simplifies the construction process and reduces the amount and difficulty of on-site work. At the same time, this connection method is also easier to achieve mechanized construction and automated control, further improving construction efficiency and quality.

[0067] The composite connection scheme of this embodiment is applicable to various engineering fields that require the connection between PHC piles and reinforced concrete prefabricated caps, such as high-rise buildings, bridges, tunnels, ports, etc. Its excellent performance and adaptability make this scheme have broad application prospects in these fields.

[0068] In summary, the composite connection scheme of the combination of bolted mechanical connection and grouting connection between the PHC pipe pile and the reinforced concrete precast cap achieves the long-term use of the structure and maximizes the economic benefits through many technical effects such as enhanced connection strength and stability, improved construction accuracy and adaptability, excellent durability and corrosion resistance, construction efficiency and cost control, and broad application prospects.

[0069] Embodiment 3, a method for connecting a PHC pile with a prefabricated reinforced concrete cap, It includes three key steps: tightening the connecting bolts, connecting the connecting plate with the embedded parts, and pouring the grouting material. Through these steps, a firm connection between the PHC pile and the prefabricated cap is achieved.

[0070] Tightening of connecting bolts: Use the upper and lower nuts to tighten the connecting bolts to the fixing plate.

[0071] Make sure the top of the connecting bolts extends to the outside of the precast cap and is exposed long enough to connect with the connecting plate.

[0072] Use high-strength bolts to connect and tighten the fixing plate to the end plate of the soil-squeezing PHC pile to ensure that the connection between the fixing plate and the PHC pile is firm and reliable.

[0073] Connection between connecting plate and embedded parts: Place the connecting plate on top of the precast pedestal, making sure the center opening of the connecting plate is larger than the diameter of the connecting bolt so that the connecting bolt can pass through smoothly.

[0074] Use appropriate fasteners (such as nuts, washers, etc.) to fasten the connecting plate to the embedded parts to ensure a firm and stable connection.

[0075] Through this step, the primary connection between the PHC piles and the precast cap is completed.

[0076] Grouting Early-strength cement-based micro-expansion grouting material is poured between the cavity of the soil-squeezing PHC pile and the embedded steel pipe to form a secondary connection, further enhancing the integrity and stability of the connection.

[0077] Clean the cavity between the PHC piles and the embedded steel pipes to ensure that there is no debris or water accumulation.

[0078] Prepare the early-strength cement-based slightly expansive grouting material and mix it in the prescribed proportion.

[0079] Pour the grouting material from the hole to ensure that the grouting material can fully fill the cavity and reach the required strength.

[0080] Wait for the grouting material to solidify and form a solid grouting layer to complete the secondary connection.

[0081] Composite connection: The integrity and stability of the connection are improved through the combined use of mechanical connection and grouting connection.

[0082] Strong adaptability: It can adapt to different construction environments and geological conditions, especially the possible deviation and inclination of soil-squeezing PHC piles.

[0083] Easy construction: The connection process is relatively simple and does not require complicated construction equipment and processes.

[0084] Good durability: The materials and grouting materials used have good durability and can withstand various external forces and environmental factors for a long time without damage or deterioration.

[0085] In summary, the connection method between the PHC pipe pile and the reinforced concrete prefabricated cap provided by the present invention realizes a firm connection between the PHC pipe pile and the prefabricated cap through the combined use of mechanical connection and grouting connection, and has the advantages of advanced technology, simple construction, strong adaptability, good durability, etc.

[0086] Its working principle is divided into: 1. Working principle of bolt mechanical connection Prefabricated foundation preparation: M24 bolts made of 45# steel are embedded in the precast reinforced concrete cap to form anchors.

[0087] The embedded steel pipe forms a cavity that runs through from top to bottom. The inner diameter of the cavity is 100mm to 200mm larger than the diameter of the PHC pile to accommodate the PHC pile and allow a certain construction error.

[0088] Two upper and lower positioning rings are welded on the outside of the embedded steel pipe to fix the M24 bolts and ensure the accuracy of the bolt position.

[0089] PHC pile preparation: The diameter of PHC pipe piles is generally 300mm or 400mm, which is selected according to design requirements.

[0090] The height of the prefabricated cap shall be at least 400mm to ensure the stability and strength of the connection structure.

[0091] The exposed height of PHC piles should be lower than the height of the reinforced concrete precast cap to facilitate subsequent connection and grouting operations.

[0092] Bolting process: The M56 connecting bolts made of 45# carbon structural steel and 250mm in length are fastened to the fixing plate through two upper and lower M56 nuts. The thickness of the fixing plate is consistent with the end plate thickness of the PHC pile, and the material is Q355B.

[0093] A bolt hole with a diameter of 60mm is processed in the center of the fixing plate, and M30 bolt holes consistent with the prestressed steel bar tensioning holes in the end plate at the top of the PHC pile are processed on the periphery.

[0094] Use M27 or M30 (M30 is used when the diameter of the prestressed steel bar of the PHC pile is 14mm) 6.8 or 8.8 grade high-strength bolts to connect and tighten the fixing plate to the end plate of the PHC pile.

[0095] The connecting bolts fixed on the end plate of the PHC pile pass through the cavity of the prefabricated cap and are fastened to the embedded bolts of the prefabricated cap through the connecting plate. The opening size in the center of the connecting plate is larger than the diameter of the connecting bolts on the end plate of the PHC pile to accommodate the possible deviation and tilt of the soil-squeezing PHC pile.

[0096] 2. Working principle of grouting connection Preparation before grouting: Before grouting connection, it is necessary to remove debris from the exposed part of the PHC pile to ensure the quality of the grouting layer.

[0097] Prepare early-strength cement-based slightly expansive grouting material with a strength grade not less than C80 to ensure the strength and durability of the grouting layer.

[0098] Grouting process: Early-strength cement-based micro-expansion grouting material is poured from the hole to fill the gap between the PHC pile and the precast cap.

[0099] The mixing water addition ratio of the grouting material is about 13%. The specific ratio can be adjusted according to the performance of the grouting material and construction requirements.

[0100] During the grouting process, the grouting material will penetrate into the tiny gaps between the PHC piles and the prefabricated cap to form a dense grouting layer.

[0101] Effect after grouting: The grouting layer not only enhances the connection strength between the PHC piles and the precast cap, but also improves the integrity and durability of the structure.

[0102] The micro-expansion properties of the grouting material can effectively compensate for cracks caused by concrete shrinkage and further improve the stability of the connection structure.

[0103] 3. Overall effect of composite connection structure Through the combined use of bolt mechanical connection and grouting connection, the composite connection structure realizes a firm connection between the PHC pile and the reinforced concrete prefabricated cap. The bolt mechanical connection provides the initial connection strength and stability, while the grouting connection further enhances the integrity and durability of the connection. This composite connection structure is not only suitable for various complex geological conditions and construction environments, but also can improve construction efficiency and reduce construction costs while ensuring the connection quality.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A connection structure between a PHC pipe pile and a reinforced concrete prefabricated cap, characterized in that: The invention comprises a prefabricated foundation (2), a soil-squeezing PHC pipe pile (1), a connection cavity, a mechanical connector and a grouting connector; a plurality of connection cavities are arranged in the prefabricated foundation (2), a soil-squeezing PHC pipe pile (1) is arranged in each connection cavity, and the soil-squeezing PHC pipe pile (1) forms a primary connection structure through the mechanical connector; a reserved space is provided between the inner side wall of the connection cavity and the soil-squeezing PHC pipe pile (1), and a grouting connector is arranged in the reserved space to form a secondary connection structure.

2. The connection structure of a PHC pipe pile and a reinforced concrete prefabricated cap according to claim 1 is characterized in that: The mechanical connecting parts include anchors (7), fixing plates (4), connecting bolts (3) and connecting plates (5); a plurality of anchors (7) are pre-buried in a prefabricated cap (2) around a connecting cavity; the fixing plate (4) is fixedly mounted on the top of a soil-squeezing PHC pipe pile (1), and one end of the connecting bolt (3) is fixedly mounted on the fixing plate (4); the connecting plate (5) covers the prefabricated cap (2) at the connecting cavity and is fixed by the anchors (7), and the other end of the connecting bolt (3) is fixedly connected to the connecting plate (5).

3. The connection structure of a PHC pipe pile and a reinforced concrete prefabricated cap according to claim 2 is characterized in that: The anchor (7) is a fastening bolt.

4. The connection structure of a PHC pipe pile and a reinforced concrete prefabricated cap according to claim 2 is characterized in that: An end plate (10) is fixedly provided on the top of the soil-squeezing PHC pipe pile (1), and the end plate (10) is fixedly connected to the fixing plate (4) by bolts.

5. The connection structure of a PHC pipe pile and a reinforced concrete prefabricated cap according to claim 4 is characterized in that: A hole is provided at the geometric center of the end plate (10) and the fixing plate (4), the connecting bolt (3) is arranged in the hole, and the connecting bolt (3) is fixed to the fixing plate (4) by means of two upper and lower nuts.

6. The connection structure of a PHC pipe pile and a prefabricated reinforced concrete cap according to claim 2, characterized in that: A center hole is opened at the geometric center of the connection plate (5), and the connection bolt (3) is arranged in the center hole, and the connection bolt (3) is fixed to the connection plate (5) by a nut.

7. The connection structure of a PHC pipe pile and a prefabricated reinforced concrete cap according to claim 6, characterized in that: The size of the center hole is larger than the diameter of the connecting bolt (3).

8. The connection structure of a PHC pipe pile and a reinforced concrete prefabricated cap according to claim 2 is characterized in that: The grouting connection piece comprises a pre-buried steel pipe (8) and a grouting material (6); the pre-buried steel pipe (8) is arranged in a close fit in the connection cavity, and the grouting material (6) is filled in the space between the pre-buried steel pipe (8) and the soil-squeezing PHC pile (1).

9. The connection structure of a PHC pipe pile and a prefabricated reinforced concrete cap according to claim 8, characterized in that: Positioning rings (9) for fixing the embedded parts (7) are symmetrically arranged on the outer surface of the embedded steel pipe (8) in the upper and lower parts; the grouting material (6) is an early-strength cement-based micro-expansion grouting material.

10. A method for connecting a PHC pile with a reinforced concrete prefabricated cap, characterized in that: The connection structure between the PHC pipe pile and the reinforced concrete prefabricated cap according to any one of claims 1 to 9 comprises the following steps: First, the connection bolts are fastened to the fixing plate (4) by means of two upper and lower nuts, and the tops of the connection bolts (3) are ensured to extend to the outside of the prefabricated cap (2), and the fixing plate (4) is fastened to the end plate (10) of the soil-squeezing PHC pile (1) by means of high-strength bolts; Then, the connecting bolts (3) extending to the outside of the prefabricated cap (2) are fastened and connected to the embedded parts (7) of the reinforced concrete prefabricated cap (2) through the connecting plate (5), ensuring that the size of the central opening of the connecting plate (5) is larger than the diameter of the connecting bolts (3), thereby completing the first-level connection; Finally, early-strength cement-based micro-expansion grouting material (6) is poured between the cavity of the soil-squeezing PHC pile (1) and the pre-buried steel pipe (8) to complete the secondary connection.

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