A crown beam for a foundation pit enclosure

Abstract

The application discloses a crown beam for a foundation pit support structure, which comprises supporting piles, lattice columns and a bottom plate arranged below the crown beam, the supporting piles are connected to the bottom of the crown beam, one end of the bottom plate is connected to the supporting piles and is parallel to the crown beam, one end of the lattice column is connected perpendicularly to the inclined surface of the crown beam, the other end of the lattice column is at least partially anchored in the bottom plate and extends towards the direction of the foundation pit, and the cross-sectional shape of the crown beam is pentagonal. The crown beam and the lattice column are connected perpendicularly to the inclined surface, which can effectively transfer the oblique support force, improve the stress stability of the crown beam and the lattice column and the quality of the joint between the crown beam and the lattice column, ensure the reliability and effectiveness of the connection between the lattice column and the crown beam, reduce local stress concentration, facilitate construction, greatly save time cost, effectively reduce the engineering quantity of the crown beam, improve construction efficiency, and further save the cost.

Description

Technical Field

[0001] This application relates to the field of building engineering technology, specifically to a capping beam for foundation pit retaining structure. Background Technology

[0002] Existing foundation pit retaining structures primarily employ external anchoring, internal bracing, and inclined internal bracing systems. Due to the frequent proximity of urban underground space development to existing underground buildings or structures, the use of external anchoring is limited. While horizontal internal bracing is not constrained by external pit conditions, its horizontal inward support across the pit can hinder excavation. Therefore, in recent years, retaining structures combining pile-wall support with inclined internal bracing have become more popular. This approach not only requires less space around the pit but also reduces the support coverage area, improving excavation efficiency. Consequently, higher demands are placed on the capping beams connecting the retaining wall and the inclined internal bracing.

[0003] The foundation pit capping beam is a reinforced concrete beam set on top of the pile-wall support. Its main function is to connect the separately arranged pile structure or the continuously arranged wall structure into a whole, prevent the top edge of the foundation pit from collapsing, increase the overall stability of the pile-wall support structure, balance the force between the support and the pile-wall support structure, transfer the soil pressure to the support structure, and control the deformation of the support structure.

[0004] In traditional internal bracing systems, the capping beam primarily transfers the horizontal force of the concrete support, mainly bearing horizontal compressive or tensile forces. However, in inclined internal bracing systems, the capping beam must withstand not only the horizontal compressive force from the inclined piles but also the vertical shear force, placing much stricter stress requirements on it. Therefore, if an inclined internal bracing system is used, its capping beam structure is one of the key factors ensuring the safety and reliability of the overall support system.

[0005] Commonly used inclined internal bracing components include structural steel, steel pipes, and lattice columns. Traditional inclined internal bracing systems using steel pipes as internal supports often connect to the capping beam via pre-embedded steel plates. While this allows for rapid construction and reliable pile quality through servo system testing of pile bearing capacity, the steel pipes below the base slab are non-recyclable, resulting in high enclosure costs. In contrast, inclined internal bracing systems using lattice columns or combinations of lattice columns and precast piles significantly reduce steel waste, thus saving on enclosure costs to some extent.

[0006] Currently, the commonly used obliquely inwardly supported capping beams mainly include two types: traditional capping beam + shear pier combination type and integrated capping beam type. Traditional capping beam + shear pier combination: As the name suggests, this combination consists of two parts: a traditional capping beam and a shear pier. The traditional capping beam mainly bears the horizontal component of the inclined pile force, while the shear pier not only transmits the horizontal component but also bears the vertical component, meeting shear resistance requirements. Each part of this type of capping beam has a clearly defined function and exhibits good stress distribution. The ends of the internal support components are cast integrally during capping beam pouring, ensuring reliable connection. However, some drawbacks exist. The construction quality at the connection point between the capping beam and the shear pier directly affects the stress distribution of the inclined internal support system. Furthermore, the independent installation of the traditional capping beam and shear pier significantly increases the amount of capping beam work, increasing costs and impacting construction speed.

[0007] Integrated capping beam: This type of capping beam combines shear-resistant piers with traditional capping beams. The reinforcement of the capping beam comprehensively considers the horizontal compressive force and vertical shear force of the inclined inner support. The capping beam inside the foundation pit is designed with a pentagonal cross-section perpendicular to the inclined inner support, saving concrete usage. Steel plates are pre-embedded at the connection between the capping beam and the inclined inner support, facilitating the connection of the preloading device of the inclined inner support with the capping beam to form a unified load-bearing structure. In this type, the capping beam and the inclined inner support are independent entities, connected by a loading device. This type of capping beam is suitable for inclined inner supports with steel pipe components, and the quality of the joint connection is crucial to the effective load-bearing capacity of the inclined inner support. However, due to the difficulty in controlling the accuracy of on-site casting, the quality of this joint often has certain defects. Utility Model Content

[0008] In view of this, and addressing the technical problems of unstable stress when the capping beam is connected to the inclined inner support system in the prior art, poor quality of the joint between the two, difficult construction, and high cost, this application provides a capping beam for foundation pit retaining structure, which can improve the stress stability of the capping beam and the lattice column and the quality of the joint between the two, facilitate construction, ensure the reliability and effectiveness of the connection between the lattice column and the capping beam, and save on project costs.

[0009] To achieve the above objectives, this application provides the following technical solution: a capping beam for a foundation pit retaining structure, comprising: The support piles, lattice columns, and base plate are installed below the capping beam. The support piles are connected to the bottom of the capping beam, and one end of the base plate is connected to the support piles and is parallel to the capping beam. One end of the lattice column is perpendicularly connected to the inclined surface of the capping beam, and the other end is at least partially anchored in the bottom plate and extends toward the foundation pit. The cross-sectional shape of the crown beam is pentagonal.

[0010] Compared to existing technologies, setting the cross-sectional shape of the capping beam to pentagonal optimizes the reinforcement arrangement and concrete stress state. The pentagonal cross-section allows the capping beam to better adapt to the connection angle of the lattice column. Specifically, one end of the lattice column is perpendicularly connected to the inclined surface of the capping beam at a 90° angle. This perpendicular connection effectively transfers the diagonal support force, improves the stress stability of both the capping beam and the lattice column, and enhances the quality of their joint. It also ensures the reliability and effectiveness of the connection between the lattice column and the capping beam, reduces local stress concentration, facilitates construction, significantly saves time and costs, effectively reduces the amount of capping beam work, improves construction efficiency, and ultimately saves on costs.

[0011] Preferably, the lattice column and the cap beam are cast integrally.

[0012] In this embodiment, the integral casting ensures the reliability and effectiveness of the connection between the lattice column and the capping beam. The integral structure comprehensively considers the compressive, shear, and bending stress stability of the capping beam, simplifies the structure of the capping beam, and also improves the utilization rate of traditional capping beams.

[0013] Preferably, the support piles are bored cast-in-place piles or precast concrete piles, and the distance between the outer edge of the support pile and the outer edge of the capping beam is L1; Among them, L1 is greater than the thickness of the concrete cover for the steel reinforcement.

[0014] In this embodiment, the support piles are bored cast-in-place piles or precast concrete piles. The distance between the sidewall of the support pile and the outer side of the cap beam only needs to be greater than the thickness of the protective layer of the reinforcing steel, thus saving space and materials.

[0015] Preferably, the support piles are PC method combined piles, which include multiple Larssen steel sheet piles and multiple steel pipe piles, with the multiple steel pipe piles connected to the Larssen steel sheet piles; The distance between the outer edge of the steel pipe pile and the outer edge of the capping beam is L2, where L2 > 300 mm.

[0016] In this embodiment, in order to ensure that there is a sufficient gap (at least 300mm) between the sidewall of the steel pipe pile and the outer side of the cap beam, so as to meet the safety distance of the structural design, prevent the components from interfering with each other, and facilitate construction operations and subsequent maintenance.

[0017] Preferably, the steel pipe pile extends into the top surface of the capping beam and connects to the capping beam, and is flush with the top surface of the capping beam; The Larsen sheet pile extends into the cap beam by a length of L3, where L3 ≥ 50 mm.

[0018] In this embodiment, by reasonably setting the length of the Larssen sheet piles extending into the capping beam, it can be ensured that the concrete of the capping beam tightly wraps around the PC method composite piles to achieve a tight connection, thereby ensuring the force transmission performance and water-stopping effect between the capping beam and the PC method composite piles, and improving the stability of the overall structure.

[0019] Preferably, the steel pipe pile has multiple reinforcing bars on both sides, and the reinforcing bars are welded to the steel pipe pile; The reinforcing steel bars have a U-shaped structure.

[0020] In this embodiment, the reinforcing steel bars are anchored to the capping beam as a whole to avoid the bending moment generated by the lattice column causing the capping beam concrete to detach from the interface encasing the steel pipe pile, resulting in the capping beam turning outward, thus ensuring a firm connection between the reinforcing steel bars and the steel pipe pile.

[0021] Preferably, the support piles are SMW method piles, which include multiple H-beams and multiple cement mixing piles, with the multiple H-beams arranged at intervals between the cement mixing piles; The distance between the outer edge of the H-beam and the outer edge of the cap beam is L4, where L4 is greater than 300mm.

[0022] In this embodiment, in order to ensure that there is a sufficient gap (at least 300mm) between the outer side of the H-beam and the outer side of the cap beam, so as to meet the safety distance of the structural design, prevent the components from interfering with each other, and facilitate construction operations and subsequent maintenance.

[0023] Preferably, the top of the cement mixing pile is connected to the bottom of the capping beam; The H-beam extends into the top surface of the crown beam and connects to the crown beam, and extends beyond the top surface of the crown beam by a distance of L5, where L5 ≥ 500 mm.

[0024] In this embodiment, by reserving sufficient elongation length, it is convenient to pull out the H-beams during the later steel recycling process, which facilitates dismantling and recycling operations, reduces construction and dismantling costs, and improves the efficiency of resource recycling.

[0025] Preferably, the H-beam is provided with reinforcing angle steel on both sides, the reinforcing angle steel is welded to both sides of the H-beam respectively, and the bottom of the reinforcing angle steel is closely attached to the top surface of the cap beam.

[0026] In this embodiment, the reinforcing angle steel can enhance the stability of the connection between the H-beam and the cap beam to meet the stress requirements, avoid the separation of the cap beam concrete from the H-beam wrapping interface caused by the bending moment generated by the lattice column, and thus prevent the cap beam from overturning.

[0027] Preferably, multiple additional stirrups are provided within the area where the lattice column intersects with the capping beam. The additional stirrups are arranged along the extension direction of the foundation pit, and the arrangement width of the additional stirrups is L6, where L6 > 600mm.

[0028] In this embodiment, the additional stirrups are arranged along the extension direction of the foundation pit and the width should be greater than 600mm to ensure sufficient stress area and number of steel bars. At the same time, the additional stirrups can also enhance the shear resistance of the cap beam in the node area (intersection range) and prevent shear failure. Attached Figure Description

[0029] Figure 1 This is a structural schematic diagram of a capping beam for a foundation pit retaining structure provided in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of a crown beam provided in one embodiment of this application; Figure 3 This is a schematic diagram of the reinforcement of a cap beam provided in one embodiment of this application; Figure 4 A schematic diagram of a drilled cast-in-place pile structure provided in an embodiment of this application; Figure 5 This is a schematic diagram of a structure using precast concrete piles as the support piles provided in an embodiment of this application; Figure 6 A schematic diagram of the reinforcement of the support piles, which are made of bored cast-in-place piles and precast concrete piles, provided for an embodiment of this application; Figure 7 This is a schematic diagram of the structure of a lattice column provided in an embodiment of this application; Figure 8 A schematic diagram of a PC method composite pile structure provided in an embodiment of this application; Figure 9 A schematic diagram of the reinforcement of the cap beam for the support piles using PC method composite piles provided in an embodiment of this application; Figure 10 A schematic diagram of the reinforcement of the cap beam when the support piles are PC method composite piles without steel pipe piles, as provided in an embodiment of this application; Figure 11 A schematic diagram of the reinforcement of the capping beam when the support piles are made using PC method composite piles with steel pipe piles, as provided in an embodiment of this application; Figure 12 A schematic diagram of the structure of the support pile using the SMW method provided in an embodiment of this application; Figure 13 A schematic diagram of the reinforcement of the capping beam in the position of the H-beam without the inserted H-section in a support pile using the SMW method provided in an embodiment of this application; Figure 14 A schematic diagram of the reinforcement of the capping beam at the position between the inserted H-beams in a support pile provided in an embodiment of this application; Figure 15 This is a schematic diagram of the reinforcement of the capping beam for the support piles using PC method combined piles and SMW method piles, provided as an embodiment of this application.

[0030] In the diagram: 1. Crown beam; 2. Support piles; 3. Lattice column; 4. Base slab; 5. Subbase. 11. Additional stirrups; 12. Outer longitudinal reinforcement; 13. Inner longitudinal reinforcement; 14. Top longitudinal reinforcement; 15. Bottom longitudinal reinforcement; 16. Stirrup reinforcement; 17. Stirrups; 18. First bending reinforcement; 19. Second bending reinforcement; 21. Drilled cast-in-place piles; 22. Precast concrete piles; 23. PC method combined piles; 24. SMW method piles; 31. Water-stop steel plates; 32. Welded plates; 33. Angle steel; 211. Continuous reinforcing bars; 221. Anchoring reinforcing bars; 231. Larssen sheet piles; 232. Steel pipe piles; 233. Reinforcing bars; 241. H-beams; 242. Cement mixing piles; 243. Reinforcing angle steel. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this disclosure, the following detailed, clear, and complete description of this disclosure is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit it.

[0032] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0033] Those skilled in the art should understand that in the disclosure of this application, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0034] The present application will now be described in further detail with reference to the accompanying drawings, see below. Figures 1 to 15 illustrate.

[0035] Example 1 This embodiment provides a capping beam 1 for a foundation pit retaining structure, which is applied in the field of building engineering technology. Specifically, as shown in... Figures 1 to 7As shown, the structure includes retaining piles 2, lattice columns 3, a base slab 4, and concrete piles, all positioned below the capping beam 1. The lattice columns 3 are located between the capping beam 1 and the concrete piles. The retaining piles 2 are connected to the bottom of the capping beam 1. The capping beam 1 provides overall support and load transfer, while the retaining piles 2 serve as a robust support system to ensure the stability of the foundation pit slope. A concrete cushion layer 5 is provided at the bottom of the base slab 4. One end of the base slab 4 is connected to the retaining piles 2 and is parallel to the capping beam 1, which improves the bearing capacity of the bottom of the foundation pit. The capping beam 1 is suitable for various types of retaining pile connections. The retaining piles 2 can be various types, such as bored piles 21, precast concrete piles 22, PC method combined piles 23, and SMW method piles 24. They are widely used and not limited to a single type, resulting in high market utilization.

[0036] One end of the lattice column 3 is perpendicularly connected to the inclined surface of the capping beam 1 at a 90° angle. The other end of the lattice column 3 is at least partially anchored within the base slab 4 and extends towards the foundation pit. This perpendicular connection method effectively transmits the oblique support force, improves the stress stability of the capping beam 1 and the lattice column 3, and enhances the quality of their joint. It also ensures the reliability and effectiveness of the connection between the lattice column 3 and the capping beam 1, reduces local stress concentration, facilitates construction, ensures uniform and reliable stress distribution on the capping beam 1, saves on reinforced concrete usage, significantly reduces time costs, improves construction efficiency, and ultimately saves on construction costs. The capping beam 1 has a pentagonal cross-section. That is, the cross-section of the capping beam 1 is uniformly set to a pentagonal shape in both the intersecting and non-intersecting areas of the lattice column 3 and the capping beam 1. The pentagonal cross-section optimizes the reinforcement arrangement and concrete stress state, allowing the capping beam 1 to better adapt to the connection angle of the lattice column 3.

[0037] Furthermore, such as Figure 4 , Figure 5 As shown, the length of the lattice column 3 extending into the capping beam 1 should be greater than 300mm. The lattice column 3 and the capping beam 1 are integrally cast to ensure the reliability and effectiveness of the connection between the lattice column 3 and the capping beam 1. Moreover, the integrated structure comprehensively considers the compressive, shear, and bending stress stability of the capping beam 1, simplifies the structure of the capping beam 1, and also improves the utilization rate of the traditional capping beam 1.

[0038] Among them, the lattice column 3 is a precast steel lattice column. The top of the precast steel lattice column is directly and integrally cast with the concrete of the capping beam 1, so that the lattice column 3 is completely wrapped by the concrete structure to form a whole, ensuring smooth force transmission and overall performance and load-bearing capacity. Moreover, when recycling the lattice column 3, only a small number of lattice columns 3 above the four sides of the base plate need to be cut off, and the concrete of the capping beam 1 needs to be chiseled away, which improves the utilization rate of the lattice column 3 and reduces steel waste.

[0039] Among them, such as Figure 7As shown, the prefabricated lattice column 3 has a horizontally positioned water-stop steel plate 31 pre-welded into the base plate 4 along its height. It is easy to understand that each leg of the lattice column 3 is an angle steel 33, such as four angle steels 33. A water-stop steel plate 31 is welded to both the concave and convex parts of the angle steel 33. Multiple connecting plates 32, or transverse connecting plates, are also welded to the four angle steels 33 of the lattice column 3. The angle steels 33 are used for load-bearing and force transmission, while the connecting plates 32 ensure the integrity of the lattice column 3. When the lattice column 3 is embedded in the capping beam 1, the first ring of connecting plates 32 at the top of the lattice column 3 must be completely embedded in the capping beam 1, with a distance of 50mm between the top of the first ring of connecting plates 32 and the top of the angle steel 33, ensuring that the lattice column 3 is embedded in the capping beam 1 to a depth greater than 300mm.

[0040] Furthermore, such as Figures 4 to 6 As shown, the support piles 2 are either bored cast-in-place piles 21 or precast concrete piles 22. The distance between the outer edge of the support pile 2 and the outer edge of the capping beam 1 is L1. L1 is greater than the thickness of the concrete cover for the reinforcing steel, ensuring sufficient cover thickness and avoiding problems such as exposed reinforcing steel or insufficient cover thickness. In other words, in this embodiment, the support piles 2 are either bored cast-in-place piles 21 or precast concrete piles 22. The distance between the sidewall of the bored cast-in-place pile 21 or the sidewall of the precast concrete pile 22 and the outer side of the capping beam 1 only needs to be greater than the thickness of the concrete cover for the reinforcing steel, saving space and materials. The continuous reinforcing steel bar 211 of the bored cast-in-place pile 21 extends into the top surface of the capping beam 1 and connects to it. The anchoring reinforcing steel bar 221 of the precast concrete pile 22 extends into the top surface of the capping beam 1 and connects to it, and is flush with the top surface of the capping beam 1.

[0041] Furthermore, such as Figure 3 , Figure 11 As shown, the capping beam 1 includes multiple outer longitudinal steel bars 12, inner longitudinal steel bars 13, top longitudinal steel bars 14, bottom longitudinal steel bars 15, stirrups 16, and stirrups 17. The stirrups 16 are at least partially tied to the top longitudinal steel bars 14 and at least partially tied to the bottom longitudinal steel bars 15. The inner longitudinal steel bars 13 are located on the side of the capping beam 1 closest to the lattice column 3. The outer longitudinal steel bars 12 are evenly arranged according to the conventional capping beam 1 steel bars. The inner longitudinal steel bars 13 are non-uniformly arranged along the inclined surface of the capping beam 1, and are arranged according to the stress requirements of the inclined surface. This arrangement satisfies the stress requirements, facilitates the binding of the capping beam 1 steel bars, and avoids the lattice column 3, thereby improving construction efficiency. Within the area where the lattice column 3 intersects with the capping beam 1, a first bending reinforcement 18 and a second bending reinforcement 19 are provided along the cross-sectional direction of the capping beam 1. The first bending reinforcement 18 and the second bending reinforcement 19 are both located inside the inner longitudinal reinforcement 13, the top longitudinal reinforcement 14, and the bottom longitudinal reinforcement 15. The first bending reinforcement 18 bears the compressive force, and the second bending reinforcement 19 bears the tensile force. The stress between each reinforcement is clear, and the overall structure meets the bending resistance requirements of the capping beam 1 at the diagonal bracing position. This not only reduces costs but also lowers the construction difficulty of setting additional stirrups 17 and speeds up the construction progress.

[0042] Furthermore, such as Figures 3 to 6 As shown, multiple additional stirrups 11 are provided within the intersection area of ​​the lattice column 3 and the capping beam 1. The additional stirrups 11 are shear-resistant reinforcements set within the intersection area of ​​the lattice column 3 and the capping beam 1. Together with the concrete, they bear the shear force of the lattice column 3 in the vertical direction, thus meeting the shear resistance requirements of the capping beam 1. The additional stirrups 11 are arranged along the extension direction of the foundation pit, and the arrangement width of the additional stirrups 11 is L6, where L6 > 600mm. That is to say, the additional stirrups 11, along with the first bending reinforcement 18 and the second bending reinforcement 19 of the capping beam 1, are set along the extension direction of the foundation pit, and the arrangement width should be greater than 600mm, ensuring sufficient bearing area and reinforcement quantity. At the same time, the additional stirrups 11 can also enhance the shear resistance of the capping beam 1 in the node area (intersection area) and prevent shear failure. If the support pile 2 (using PC construction method combined pile 23) conflicts with the additional stirrups 11, the first bending reinforcement 18, and the second bending reinforcement 19 of the capping beam 1, the first bending reinforcement 18 and the second bending reinforcement 19 should be properly avoided to ensure the binding and installation of the reinforcement.

[0043] The construction steps are as follows: Step S1: According to the needs of the foundation pit project, complete the prefabrication of lattice column 3 and concrete pile; Step S2: Construct the support piles 2 for this project, and sink the concrete piles and lattice columns 3 to the design elevation; Step S3: Tie the reinforcing bars of the cap beam 1; Step S4: Fix the capping beam 1 to the lattice column 3, and pour the capping beam concrete and the lattice column concrete together. Step S5: After excavating the foundation pit to the bottom elevation of the cushion layer 5, tie the reinforcing bars of the bottom slab 4 and pour the reinforced concrete of the bottom slab 4. At the same time, pour the waterstop steel plate 31 pre-welded to the lattice column 3 together with the concrete of the bottom slab 4. Step S6: Once the base plate 4 reaches the design strength, remove the crown beam 1 and cut off the portion of the lattice column 3 located above the top surface of the base plate 4 one by one.

[0044] Example 2 The difference between this embodiment and Embodiment 1 is that, in this embodiment, as... Figures 8 to 11As shown, the support pile 2 adopts PC method combined pile 23 (a new type of support pile 2 technology, combining Larssen piles and steel pipes, widely used in foundation pit engineering, with advantages such as green environmental protection and good economy). PC method combined pile 23 includes multiple Larssen steel sheet piles 231 (also called U-shaped steel sheet piles) and multiple steel pipe piles 232. The multiple steel pipe piles 232 are connected to the Larssen steel sheet piles 231. The Larssen steel sheet piles 231 and steel pipe piles 232 are vertically set in the foundation pit. The Larssen steel sheet piles 231 have good waterproof performance, which can greatly reduce the amount of soil excavation and concrete used, and have good durability and a long service life. The combined use of Larssen steel sheet piles 231 and steel pipe piles 232 can improve the utilization efficiency of the foundation pit and extend its service life. The distance between the outer edge of the steel pipe pile 232 and the outer edge of the capping beam 1 is L2, where L2 > 300mm. In other words, in order to ensure that there is a sufficient gap (at least 300mm) between the outer edge of the steel pipe pile 232 and the outer edge of the capping beam 1, so as to meet the safety distance of the structural design, prevent the components from interfering with each other, and facilitate construction operations and later maintenance.

[0045] Among them, the steel pipe pile 232 extends into the top surface of the capping beam 1 and connects with the capping beam 1, and is flush with the top surface of the capping beam 1. The Larssen steel sheet pile 231 extends into the capping beam 1 for a length of L3, where L3≥50mm. This ensures that the concrete of the capping beam 1 is tightly wrapped around the PC method composite pile 23 to achieve a tight connection, thereby ensuring the force transmission performance and water-stopping effect between the capping beam 1 and the PC method composite pile 23, and improving the stability of the overall structure.

[0046] The steel pipe pile 232 has multiple reinforcing bars 233 on both sides. Each of the steel pipe piles 232 on the two sides of the inclined inward support has 4 reinforcing bars 233. The reinforcing bars 233 have a U-shaped structure and are welded to the steel pipe piles 232. The contact surfaces between the reinforcing bars 233 and the steel pipe piles 232 are all connected by welding. The reinforcing bars 233 and the capping beam 1 are anchored together to form a whole. This avoids the bending moment generated by the lattice column 3 from causing the concrete of the capping beam 1 to separate from the interface of the steel pipe piles 232 and causing the capping beam 1 to turn outward. This ensures a firm connection between the reinforcing bars 233 and the steel pipe piles 232. After the reinforcing bars 233 are installed, they are poured together with the concrete of the capping beam 1, so that the reinforcing bars 233, the steel pipe piles 232 and the concrete of the capping beam 1 form an integral structure, which improves the bearing capacity and stability of the connection parts and enhances the stability of the overall structure. The number of reinforcing steel bars 233 is 8, and the length of reinforcing steel bars 233 is 600mm. Different numbers and lengths of reinforcing steel bars 233 can also be selected according to different construction sites.

[0047] Example 3 The difference between this embodiment and Embodiment 1 is that, in this embodiment, as... Figures 12 to 15As shown, the support pile 2 adopts the SMW method pile 24 (a diaphragm wall construction technology developed in Japan in 1976). The SMW method pile 24 includes multiple H-beams 241 and multiple cement mixing piles 242. The multiple H-beams 241 are arranged at intervals between the cement mixing piles 242. Through the cooperation between the H-beams 241 and the cement mixing piles 242, in terms of construction, it has the advantages of not disturbing the adjacent soil, avoiding the hazards such as adjacent ground settlement, building tilting, road cracking, and movement of underground facilities. In addition, the H-beams 241 can be partially recycled, which saves resources and realizes green building. The distance between the outer edge of the H-beam 241 and the outer edge of the capping beam 1 is L4, where L4 > 300mm. That is to say, in order to ensure that there is a sufficient gap (at least 300mm) between the outer edge of the H-beam 241 and the outer edge of the capping beam 1 to meet the safety distance of the structural design, prevent mutual interference of components, and facilitate construction operations and later maintenance.

[0048] Furthermore, the top of the cement mixing pile 242 is connected to the bottom of the capping beam 1, meaning the top elevation of the cement mixing pile 242 is flush with the top surface of the capping beam 1; the H-beam 241 extends into the top surface of the capping beam 1 and connects with it, with a distance of L5 extending beyond the top surface of the capping beam 1, where L5 ≥ 500 mm. This ensures a firm connection between the H-beam 241 and the capping beam 1. By reserving sufficient extension length, it is convenient to pull out the H-beam 241 during subsequent steel recycling, facilitating dismantling and recycling operations, reducing construction and dismantling costs, and improving the efficiency of resource recycling.

[0049] Among them, the H-beam 241 is provided with reinforcing angle steel 243 on both sides. The reinforcing angle steel 243 is welded to both sides of the H-beam 241 respectively, and the bottom of the reinforcing angle steel 243 is close to the top surface of the cap beam 1. That is to say, after the concrete is poured, the reinforcing angle steel 243 is welded to both sides of the H-beam 241. The reinforcing angle steel 243 can enhance the stability of the connection between the H-beam 241 and the cap beam 1 to meet the stress requirements, avoid the interface between the concrete of the cap beam 1 and the H-beam 241 due to the bending moment generated by the lattice column 3, and thus prevent the cap beam 1 from overturning.

[0050] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the embodiments above are only for the purpose of helping to understand the present application and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A corbel for a foundation enclosure, characterized by, include: The support piles (2), lattice columns (3) and base plate (4) are set below the capping beam (1). The support piles (2) are connected to the bottom of the capping beam (1), and one end of the base plate (4) is connected to the support piles (2) and is parallel to the capping beam (1). One end of the lattice column (3) is perpendicularly connected to the inclined surface of the cap beam (1), and the other end is at least partially anchored in the bottom plate (4) and extends toward the foundation pit. The cross-sectional shape of the crown beam (1) is pentagonal.

2. The capping beam for the foundation pit retaining structure according to claim 1, characterized in that, The lattice column (3) and the cap beam (1) are integrally cast.

3. The capping beam for the foundation pit retaining structure according to claim 1, characterized in that, The support pile (2) is a bored cast-in-place pile (21) or a precast concrete pile (22), and the distance between the outer edge of the support pile (2) and the outer edge of the cap beam (1) is L1; Among them, L1 is greater than the thickness of the concrete cover for the steel reinforcement.

4. The capping beam for the foundation pit retaining structure according to claim 1, characterized in that, The support pile (2) adopts PC method combined pile (23), which includes multiple Larssen steel sheet piles (231) and multiple steel pipe piles (232), and the multiple steel pipe piles (232) are connected to the Larssen steel sheet piles (231); The distance between the outer edge of the steel pipe pile (232) and the outer edge of the cap beam (1) is L2, where L2 > 300 mm.

5. The capping beam for the foundation pit retaining structure according to claim 4, characterized in that, The steel pipe pile (232) extends into the top surface of the capping beam (1) and connects with the capping beam (1), and is flush with the top surface of the capping beam (1); The Larsen sheet pile (231) extends into the cap beam (1) by a length of L3, where L3 ≥ 50 mm.

6. The capping beam for the foundation pit retaining structure according to claim 4, characterized in that, The steel pipe pile (232) is provided with multiple reinforcing bars (233) on both sides, and the reinforcing bars (233) are welded to the steel pipe pile (232); The reinforcing steel bar (233) has a U-shaped structure.

7. The capping beam for the foundation pit retaining structure according to claim 1, characterized in that, The support pile (2) adopts the SMW method pile (24), which includes multiple H-beams (241) and multiple cement mixing piles (242), with multiple H-beams (241) arranged at intervals between the cement mixing piles (242); The distance between the outer edge of the H-beam (241) and the outer edge of the crown beam (1) is L4, where L4 > 300 mm.

8. The capping beam for the foundation pit retaining structure according to claim 7, characterized in that, The top of the cement mixing pile (242) is connected to the bottom of the cap beam (1); The H-beam (241) extends into the top surface of the crown beam (1) and is connected to the crown beam (1), and extends out of the top surface of the crown beam (1) by a distance of L5, where L5 ≥ 500 mm.

9. The capping beam for the foundation pit retaining structure according to claim 7, characterized in that, The H-beam (241) is provided with reinforcing angle steel (243) on both sides. The reinforcing angle steel (243) is welded to both sides of the H-beam (241) respectively, and the bottom of the reinforcing angle steel (243) is closely attached to the top surface of the crown beam (1).

10. The capping beam for the foundation pit retaining structure according to claim 1, characterized in that, Multiple additional stirrups (11) are provided within the area where the lattice column (3) intersects with the cap beam (1). The additional stirrups (11) are arranged along the extension direction of the foundation pit, and the arrangement width of the additional stirrups (11) is L6, where L6 > 600 mm.

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