A three-row pile structure and its construction method

Abstract

This invention relates to a three-row pile structure and its construction method, solving the problem that existing three-row pile foundation pit support structures suffer from pile settlement during foundation pit excavation, which easily leads to weakened support rigidity or even destruction. The structure includes a first row of retaining piles, a second row of retaining piles, and a third row of retaining piles arranged sequentially outward from the foundation pit direction. The pile bodies are set inside pile holes, and a reinforcing cage is installed inside the pile body. The reinforcing cage includes reinforcing bars arranged along the entire length of the pile body and hoop bars for the annular retaining bars. At least two layers of limiting structures are arranged vertically along the reinforcing cage. Each layer of limiting structures has at least three limiting plates evenly arranged around its circumference. The limiting plates are crescent-shaped, with the center of the limiting plate rotatably clamping onto one of the reinforcing bars. The outer half of the limiting plate is a limiting arm, and the inner half is a swing arm. Corresponding to the limiting structures are compression columns. The outer diameter of the compression column is smaller than the inner diameter of the reinforcing cage. The outer wall of the compression column compresses the swing arm of the limiting plate, driving the limiting arm of the limiting plate to engage with the outer wall of the pile hole. This invention increases the bonding force between the pile and the soil layer, enhances the anti-settlement performance of the pile, and solves the problem of weakened rigidity between three or more rows of piles due to pile displacement.

Description

Technical Field

[0001] This invention belongs to the field of engineering construction and relates to a construction support structure, particularly a three-row pile structure and its construction method. Background Technology

[0002] With the rapid development of underground space development, the surrounding environment of foundation pits is becoming increasingly complex, and the excavation area and depth of foundation pits are constantly increasing, leading to the emergence of various support methods. Under the condition of adjacent complex and sensitive environments, controlling the deformation of the retaining structure of deep foundation pits and its impact on nearby buildings / structures is a technical problem that urgently needs to be solved and is of great significance.

[0003] In environments adjacent to sensitive locations, existing foundation pit support structures typically employ diaphragm walls with multiple supports, single-row piles, or double-row piles with multiple supports. These support methods offer strong support and retaining capacity and are widely used in foundation pit support, especially in soft soil conditions. However, these horizontal support structures are temporary, generating significant construction waste during dismantling. Furthermore, the environmental impact of support replacement must be considered. When adjacent to sensitive buildings, static cutting of the support structure is often required, greatly increasing costs. Horizontal support structures often conflict with earthwork excavation, generally requiring excavation to the bottom of the support before further excavation can proceed, reducing construction efficiency and prolonging the foundation pit's exposure time.

[0004] To address the aforementioned issues, researchers designed a support structure for ultra-deep foundation pits using multi-row piles. The piles are arranged in multiple rows, with tie beams connecting adjacent rows to form a rigid, integrated structure. However, this pile-based support structure may face pile settlement during excavation, potentially weakening or even destroying the support's rigidity. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that existing three-row pile foundation pit support structures suffer from pile settlement during foundation pit excavation, which easily leads to weakened support rigidity or even damage. The invention provides a three-row pile structure and its construction method, which can effectively solve the problem of pile settlement and the problem of weakened rigidity between three or more rows of piles due to pile displacement.

[0006] The technical solution adopted by this invention to solve its technical problem is: a three-row pile structure, comprising a first row of retaining piles, a second row of retaining piles, and a third row of retaining piles arranged sequentially from the direction of the foundation pit. Each of the first, second, and third rows of retaining piles comprises several pile bodies. A capping beam is provided between pile bodies in the same row, and a tie beam is provided between pile bodies in adjacent rows that are aligned with each other. The pile bodies are set inside pile holes, and a reinforcing cage is installed inside the pile body. The reinforcing cage includes reinforcing bars arranged along the entire length of the pile body and an annular retaining ring. The reinforcing cage has at least two layers of limiting structures along its upper and lower edges. Each layer of limiting structures has at least three limiting plates evenly arranged around its circumference. The limiting plates are crescent-shaped, and the middle part of the limiting plate can rotatably clamp onto one of the reinforcing bars. The outer half of the limiting plate is a limiting arm, and the inner half is a swing arm. Corresponding to the limiting structures, there are compression columns. The outer diameter of the compression columns is smaller than the inner diameter of the reinforcing cage. The outer wall of the compression columns compresses the swing arm of the limiting plates, driving the limiting arm of the limiting plates to engage with the outer wall of the pile hole.

[0007] Traditional cast-in-place concrete piles typically rely on the friction between the pile and the soil to resist settlement. In this device, a limiting plate is installed at the reinforcement cage of the pile. The limiting plate is crescent-shaped and can rotate around the clamping point. After the reinforcement cage is placed into the pile hole, a compression column presses against the swing arm inside the limiting plate, causing the limiting plate to rotate outward and unfold, allowing the limiting arm to engage with the hole wall, increasing the pile's resistance to settlement. During the placement of the reinforcement cage, the limiting plates are installed at equal intervals on the reinforcing bars, and the limiting arm elastically hooks onto the outer surface of the reinforcement cage, preventing accidental unfolding and obstruction during placement. The compression force of the compression column is sufficient to overcome the hooking force of the limiting arm, allowing it to unfold. This structure does not alter the original structure of the reinforcement cage and does not affect the original structure of the pile. Instead, by adding limiting plates to the original structure, it increases the bonding force between the pile and the soil, enhancing the pile's resistance to settlement.

[0008] Preferably, the limiting piece is attached to the upper or lower part of one of the stirrups.

[0009] Preferably, the limiting arm of the limiting piece is provided with a hook that can elastically hook onto the reinforcing bar or stirrup.

[0010] Preferably, the limiting arm and the swing arm of the limiting plate are separate structures, which are fixed by bolts and clamp the stress rib at a fixed position.

[0011] Preferably, the lower end of the extrusion column is a tapered guide portion.

[0012] Preferably, the top of the reinforcing cage is detachably fitted with a guide sleeve for guiding the extrusion column.

[0013] Preferably, the extrusion column is provided with a rigid outer wall and the interior of the extrusion column is filled with a material, such as concrete, gravel, sand or water.

[0014] As a preferred option, the spacing between the first row of retaining piles, the second row of retaining piles, and the third row of retaining piles increases sequentially, with the pile spacing of the first row of retaining piles, the second row of retaining piles, and the third row of retaining piles being 1:2:4.

[0015] A construction method for three-row piles, applicable to the above-mentioned three-row pile structure, includes the following steps:

[0016] S1. Drill pile holes, insert the steel cage of the pile body into the pile holes, and arrange tie beam steel bars between adjacent pile bodies; when the steel cage is inserted, install several sets of limiting structures at equal intervals on the side wall of the steel cage. Each set of limiting structures includes several limiting plates evenly installed around the circumference. Specifically, the swing arm of the limiting plate is inside and the limiting arm is outside. They are combined into one piece by bolts and clamped and fixed to the reinforcing bar of the steel cage at the joint of the swing arm and the limiting plate. The limiting arm is elastically hooked to the outer wall of the steel cage to prevent the limiting arm from accidentally unfolding when the steel cage is inserted.

[0017] S2. After the steel cage is laid out, the extrusion column is lifted and aligned with the steel cage. Then the extrusion column is placed inside the steel cage. The extrusion column presses the swing arm of the limiting plate, causing the limiting plate to swing outward. At this time, the limiting arm unfolds outward and gets stuck into the hole wall of the pile hole, embedding itself in the soil layer to form a limit.

[0018] S3, the extrusion column is lifted again and removed, and concrete is poured into the pile hole to form a concrete cast-in-place pile.

[0019] As a preferred embodiment, in S2, a guide sleeve is placed on top of the reinforcing cage to guide the extrusion column.

[0020] This invention does not alter the original structure of the pile. Instead, it adds a limiting plate to the original structure, which increases the bonding force between the pile and the soil layer, enhances the pile's anti-settlement performance, and solves the problem of weakened rigidity between three or more rows of piles due to pile displacement. Attached Figure Description

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of a three-row pile structure according to the present invention.

[0023] Figure 2 This is a top view schematic diagram of a three-row pile structure according to the present invention.

[0024] Figure 3 This is a schematic diagram of a pile reinforcement and tie beam reinforcement structure according to the present invention.

[0025] Figure 4 This is a construction schematic diagram of a pile reinforcement cage limiting plate according to the present invention.

[0026] Figure 5 This is a top view schematic diagram of a guide sleeve structure according to the present invention.

[0027] Figure 6 This is one of the inventions Figure 4 A schematic diagram of the limiting piece at point AA not unfolded.

[0028] Figure 7 This is one of the inventions Figure 4 A schematic diagram of the unfolded state of the limiting piece at point AA.

[0029] Figure 8 This is a schematic diagram of a limiting piece structure according to the present invention.

[0030] In the diagram: 1. Soil foundation, 2. Reinforcing cage, 21. Reinforcing bar, 22. Stirrup, 3. Third row of retaining piles, 4. Second row of retaining piles, 5. First row of retaining piles, 6. Tie beam, 7. Limiting plate, 71. Clamp, 72. Bolt, 73. Limiting arm, 74. Swing arm, 75. Hook, 8. Guide sleeve, 9. Extrusion column, 10. Filler, 11. Hanging rope, 12. Lifting ring, 13. Pile hole, 14. Foundation pit, 15. Tie beam reinforcement, 16. Crown beam. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0032] Example: A three-row pile structure, such as Figure 1 , 2 As shown in Figure 3, this structure is constructed on foundation 1 and includes a first row of retaining piles 5, a second row of retaining piles 4, and a third row of retaining piles 3 arranged sequentially outward from the direction of foundation pit 14. Each row of retaining piles comprises several pile bodies, and the spacing between the pile bodies increases sequentially from the first row of retaining piles 5, the second row of retaining piles 4, to the third row of retaining piles 3, with a pile spacing ratio of 1:2:4. A capping beam 16 is installed between pile bodies in the same row, and a tie beam 6 is installed between adjacent rows of retaining piles that are aligned with each other. The arrangement of the tie beam reinforcement 15 and the pile reinforcement cage 2 is as follows... Figure 3 As shown. The pile body is set inside the pile hole 13, and a steel cage 2 is set inside the pile body. The steel cage includes reinforcing bars 21 arranged along the entire length of the pile body and forming a cylindrical shape, and stirrups 22 forming annular clamping reinforcing bars.

[0033] like Figure 4 As shown in this example, for a single pile, the reinforcing cage 2 has three layers of limiting structures arranged vertically. Each layer of limiting structures has four limiting plates 7 evenly arranged around its circumference. The limiting plates 7 are attached to the upper or lower part of one of the stirrups 22. The limiting plate structure is as follows: Figure 8As shown, the limiting piece 7 has a crescent-shaped structure. The middle part of the limiting piece is not clamped (71), but the clamp 71 can rotatably clamp onto one of the load-bearing ribs 21. The outer half of the limiting piece is a limiting arm 73, and the inner half is a swing arm 74. The limiting arm of the limiting piece is equipped with hooks 75 that can elastically hook onto the stirrups 22. The limiting arm 73 and the swing arm 74 are separate at the clamp 71, and are connected and fixed by bolts 72, forming the clamp 71 clamping the load-bearing rib 21 at the fixed position.

[0034] A compression column 9 is provided corresponding to the limiting structure. The outer diameter of the compression column is smaller than the inner diameter of the reinforcing cage 2. The lower end of the compression column 9 is a tapered guide section. The compression column 9 has a rigid outer wall and is filled with filler 10. In this example, the filler is crushed stone to increase weight. The top of the compression column 9 is connected to a lifting ring 12 via a pull rope 11 for easy lifting. The outer wall of the compression column compresses the swing arm 74 of the limiting plate, driving the limiting arm 73 of the limiting plate to engage with the outer wall of the pile hole 13. A guide sleeve 8 is detachably fastened to the top of the reinforcing cage 2 to guide the compression column 9. The structure of the guide sleeve is as follows: Figure 5 As shown.

[0035] In this example, the pile construction includes the following steps:

[0036] S1. Drill pile holes, insert the reinforcing cage of the pile body into the pile holes, and arrange the tie beam reinforcement between adjacent pile bodies; when inserting the reinforcing cage, install several sets of limiting structures at equal intervals on the side wall of the reinforcing cage. Each set of limiting structures includes several limiting plates evenly installed around the circumference. Specifically, the swing arm of the limiting plate is inside, and the limiting arm is outside. They are assembled into one piece by bolts, and are clamped and fixed to the main reinforcing bar of the reinforcing cage at the joint of the swing arm and the limiting plate. The limiting arm is elastically hooked to the outer wall of the reinforcing cage to prevent the limiting arm from accidentally unfolding when the reinforcing cage is inserted; at this time, the state of the limiting plate is as follows. Figure 6 As shown;

[0037] S2, After the reinforcement cage is installed, place a guide sleeve on top of the reinforcement cage, lift the extrusion column and align it with the reinforcement cage, then place the extrusion column inside the reinforcement cage. The extrusion column presses against the swing arm of the limiting plate, causing the limiting plate to swing outward. At this time, the limiting arm unfolds outward and engages with the hole wall of the pile hole, embedding itself in the soil layer to form a limit; the state of the limiting plate at this time is as follows. Figure 7 As shown;

[0038] S3, the extrusion column is lifted again and removed, and concrete is poured into the pile hole to form a concrete cast-in-place pile.

Claims

1. A three-row pile structure, comprising a first row of retaining piles, a second row of retaining piles, and a third row of retaining piles arranged sequentially outward from the direction of the foundation pit, wherein each of the first, second, and third rows of retaining piles comprises a plurality of pile bodies, a capping beam is provided between the pile bodies in the same row, and a tie beam is provided between the aligned pile bodies of adjacent rows of retaining piles, characterized in that: The pile body is set inside the pile hole, and a reinforcing cage is set inside the pile body. The reinforcing cage includes reinforcing bars arranged along the entire length of the pile body and stirrups of the annular clamping reinforcing bars. The reinforcing cage is provided with at least two layers of limiting structures along its upper and lower sides. Each layer of limiting structure is evenly provided with no less than three limiting plates around its circumference. The limiting plates are crescent-shaped structures, and the middle part of the limiting plate can rotatably clamp onto one of the reinforcing bars. The outer half of the limiting plate is a limiting arm, and the inner half is a swing arm. Corresponding to the limiting structure, a compression column is provided. The outer diameter of the compression column is smaller than the inner diameter of the reinforcing cage. The outer wall of the compression column compresses the swing arm of the limiting plate, driving the limiting arm of the limiting plate to engage with the outer wall of the pile hole.

2. The three-row pile structure according to claim 1, characterized in that: The limiting piece is attached to the upper or lower part of one of the stirrups.

3. The three-row pile structure according to claim 1, characterized in that: The limiting arm of the limiting piece is provided with a hook that can elastically hook onto the reinforcing bar or stirrup.

4. A three-row pile structure according to claim 1, characterized in that: The limiting arm and swing arm of the limiting plate are separate structures, which are fixed by bolt connection and clamp the stress rib at a fixed position.

5. A three-row pile structure according to claim 1, characterized in that: The lower end of the extrusion column is a tapered guide section.

6. A three-row pile structure according to claim 1, characterized in that: The top of the steel cage is detachably fitted with a guide sleeve to guide the extrusion column.

7. A three-row pile structure according to claim 1, characterized in that: The extrusion column is provided with a rigid outer wall, and the interior of the extrusion column is filled with a material, such as concrete, gravel, sand, or water.

8. A three-row pile structure according to claim 1, characterized in that: The spacing between the first, second, and third rows of retaining piles increases sequentially, with a pile spacing ratio of 1:2:

4.

9. A construction method for three-row piles, applicable to the three-row pile structure described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Drill pile holes, insert the steel cage of the pile body into the pile holes, and arrange tie beam steel bars between adjacent pile bodies; when the steel cage is inserted, install several sets of limiting structures at equal intervals on the side wall of the steel cage. Each set of limiting structures includes several limiting plates evenly installed around the circumference. Specifically, the swing arm of the limiting plate is inside and the limiting arm is outside. They are bolted together as one piece and clamped and fixed to the reinforcing bar of the steel cage at the splicing point of the swing arm and the limiting arm. The limiting arm is elastically hooked to the outer wall of the steel cage to prevent the limiting arm from accidentally unfolding when the steel cage is inserted. S2. After the steel cage is laid out, the extrusion column is lifted and aligned with the steel cage. Then the extrusion column is placed inside the steel cage. The extrusion column presses the swing arm of the limiting plate, causing the limiting plate to swing outward. At this time, the limiting arm unfolds outward and gets stuck into the hole wall of the pile hole, embedding itself in the soil layer to form a limit. S3, the extrusion column is lifted again and removed, and concrete is poured into the pile hole to form a concrete cast-in-place pile.

10. A construction method for three rows of piles according to claim 9, characterized in that: In S2, a guide sleeve is placed on top of the steel cage to guide the extrusion column.

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