Steel pipe pile structure capable of improving bearing capacity and construction method

Abstract

The invention relates to the technical field of building construction, discloses a steel pipe pile structure capable of improving bearing capacity and a construction method, and aims to solve the problems that a traditional steel pipe pile is unstable in soil plug effect, insufficient in pile end resistance and high in cost. The steel pipe pile structure comprises a steel pipe pile with the inner wall provided with protrusions and a prefabricated concrete pile plug arranged in the steel pipe pile at the designed depth. The pile plug is of a gradient structure, a permeable hole is formed in the middle, a pressure sensor is installed at the bottom, and a groove is formed by the top slope and the inner wall of the steel pipe pile and embedded with the protrusion to form an interlocking structure. During construction, the holes are firstly guided, the pile plugs are placed, then the steel pipe piles are driven to form interlocking, and graded grouting reinforcement is achieved through the water permeable holes. The pile foundation bearing capacity and reliability are remarkably improved, the design is optimized, steel is saved, the construction difficulty and cost are reduced, and the method is suitable for municipal engineering, bridge engineering and other projects.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a steel pipe pile structure and construction method for improving load-bearing capacity. Background Technology

[0002] Steel pipe piles are widely used in municipal engineering, bridges, highways, and railways due to their high strength and ability to withstand large loads. In traditional applications as friction piles or end-bearing friction piles, the load-bearing capacity of steel pipe piles primarily relies on the pile's side friction and end resistance. During driving, while the soil plug effect can form a soil core to some extent, its density, uniformity, and bearing capacity are difficult to control and unstable, resulting in insufficient utilization of the pile end resistance. To achieve the design bearing capacity, it is often necessary to increase the pile length (increasing steel consumption) or the pile diameter (increasing steel consumption and construction difficulty), leading to high costs. Furthermore, due to the uncertainty of the soil plug effect—its formation height and density are greatly affected by geological conditions and construction techniques—its contribution is difficult to accurately consider in the design and is often treated as a safety margin or ignored, leading to conservative design.

[0003] In view of this, the present invention proposes an effective method that can actively and reliably form a high-bearing-capacity pile end core at the design depth and ensure that it works in coordination with the steel pipe pile. Summary of the Invention

[0004] To address the shortcomings of the aforementioned background technology, the present invention aims to provide a steel pipe pile structure and construction method that improves bearing capacity.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a steel pipe pile structure for improving bearing capacity, comprising: Steel pipe piles, with protrusions on their inner walls; A precast concrete pile plug is installed at the designed depth position inside the steel pipe pile; The protrusion presses downward against the precast concrete pile plug and forms an interlocking structure therewith, which is used to restrict the upward displacement of the precast concrete pile plug.

[0006] As a preferred embodiment of the present invention, the protrusion is an annular rib or a plurality of protrusions distributed circumferentially along the inner wall of the steel pipe pile.

[0007] As a preferred embodiment of the present invention, the steel pipe pile is provided with a reinforcing steel plate at the protrusion.

[0008] As a preferred embodiment of the present invention, the precast concrete pile plug is composed of a gradient structure of different materials, which includes a high-strength concrete layer, a steel fiber concrete layer and a permeable concrete layer from top to bottom.

[0009] As a preferred embodiment of the present invention, the precast concrete pile plug has a water-permeable hole in the middle.

[0010] As a preferred embodiment of the present invention, a pressure sensor is provided at the bottom of the precast concrete pile plug.

[0011] As a preferred embodiment of the present invention, the top of the precast concrete pile plug is provided with inclined surfaces around its perimeter, and a groove for embedding the protrusion is formed between the inclined surfaces and the inner wall of the steel pipe pile.

[0012] As a preferred embodiment of the present invention, the diameter of the precast concrete plug is smaller than the inner diameter of the steel pipe pile and larger than the minimum inner diameter of the throat formed by the protrusion; the height of the precast concrete plug is greater than the height of the protrusion.

[0013] Secondly, the present invention provides a construction method for improving the bearing capacity of steel pipe piles, using the aforementioned steel pipe pile structure, comprising the following steps: Drill pilot holes at the designed pile locations in the foundation soil to the designed depth; Place the precast concrete pile plug at the bottom of the pilot hole; The steel pipe pile with protrusions on the inner wall is aligned with the pilot hole and driven into the foundation soil until the protrusions are fitted into the precast concrete pile plug to form an interlocking structure. Grouting is performed in stages through the permeable holes of the precast concrete pile plug. First, quick-setting grout is injected to fix the precast concrete pile plug, and then expansive grout is injected to strengthen the contact surface.

[0014] As a preferred technical solution of the present invention, in the step of placing the precast concrete pile plug, the contact pressure is fed back in real time by the pressure sensor at the bottom of the precast concrete pile plug to determine whether the precast concrete pile plug is in place.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved and stable transmission of pile end bearing capacity. The precast concrete pile plug adopts a gradient structure of high-strength concrete layer + steel fiber concrete layer + permeable concrete layer. The high-strength concrete at the top can resist local crushing when the protrusion is embedded, the middle transition layer smooths the stress distribution, and the permeable concrete at the bottom accelerates the dissipation of pore water pressure, forming a highly efficient bearing body that is rigid at the top and permeable at the bottom. At the same time, the interlocking structure formed by the protrusion on the inner wall of the steel pipe pile and the inclined surface at the top of the pile plug can firmly restrict the upward displacement of the pile plug, ensuring that the axial load is transmitted through a clear path of steel pipe pile-protrusion-pile plug-pile end soil, allowing the pile end resistance to be fully utilized. Compared with the unstable support of traditional soil plugs, the bearing capacity is significantly improved and the transmission is more reliable.

[0016] 2. Actively transforming the soil plug effect, making the core load-bearing body controllable. The soil plug effect of traditional steel pipe piles is greatly affected by geology and construction, and its density and height are difficult to control, often being ignored or only used as a safety reserve. This invention uses precast, controllable concrete pile plugs to replace natural soil plugs, and with the pressure sensor at the bottom of the pile plug providing real-time feedback on contact pressure (≥10kPa is considered accurate), it can accurately ensure that the pile plug forms a stable core load-bearing body at the design depth, transforming the originally uncontrollable soil plug effect into an active and reliable load-bearing contribution, completely solving the design problems caused by the uncertainty of traditional soil plugs.

[0017] 3. A dual-strength mechanism is formed for overall bearing capacity. On the one hand, the contact between the steel pipe pile and the foundation soil provides the pile side friction resistance; on the other hand, the precast concrete pile plug, as a rigid bearing body, efficiently transfers the load to the soil layer at the pile tip, forming a dual bearing structure of pile side friction resistance + pile tip resistance (pile plug transmission); at the same time, staged grouting is implemented through the permeable hole in the middle of the pile plug. First, quick-setting grout is injected to fix the pile plug, and then expansive grout is injected to strengthen the contact surface between the pile plug and the steel pipe pile and the soil at the pile tip, further improving the overall bearing efficiency.

[0018] 4. Optimized pile foundation design significantly reduces building material costs. Due to the increased bearing capacity of the pile tip and the more efficient bearing mechanism, it is not necessary to compensate by increasing the pile length or enlarging the pile diameter (the main source of cost in traditional solutions) when meeting the same design bearing capacity requirements. Combined with structural optimizations such as reinforcing the shear resistance of the protrusion with steel plates and precise design of the pile plug size (diameter Db=Dp−2δ, height Hb≥0.3Dp), the amount of steel used in steel pipe piles can be significantly reduced, avoiding over-design and making the pile foundation design more economical and reasonable.

[0019] 5. Simplified construction process, reducing difficulty and overall cost. The construction process employs a pre-drilling method combined with BIM model simulation of the hoisting path, along with guiding devices to ensure accurate installation of pile plugs and steel pipe piles; pressure sensors provide real-time feedback on the pile plug's position, eliminating the need for repeated verification; simultaneously, improved load-bearing efficiency reduces the driving depth of steel pipe piles, shortening the construction period; the staged grouting process is simple and controllable, requiring no complex equipment, thus reducing overall construction difficulty and significantly decreasing the comprehensive costs of construction period, labor, and equipment.

[0020] 6. Improved reliability and controllability of bearing capacity. The material ratio and dimensional parameters of the precast concrete pile plugs are all controlled in the factory, ensuring stable quality; the interlocking structure ensures a clear load transfer path, avoiding the randomness of traditional soil plug bearing capacity; pressure sensors, staged grouting and other processes further enhance the controllability of the construction process, making the prediction of pile foundation bearing capacity more accurate, eliminating the need for excessive safety redundancy in the design, solving the design conservatism problem caused by the uncertainty of the soil plug effect in traditional steel pipe piles, and significantly improving the reliability of project quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the internal structure of the steel pipe pile structure of the present invention (using annular ribs).

[0022] Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the steel pipe pile structure of the present invention (using annular ribs).

[0023] Figure 3 This is a schematic diagram of the transverse cross-sectional structure of the steel pipe pile structure of the present invention (using distributed bumps).

[0024] Figure 4 This is a schematic diagram of the cross-sectional structure of the steel pipe pile structure constructed in the foundation soil according to the present invention.

[0025] Figure reference numerals: 1-Foundation soil; 2-Steel pipe pile; 3-Protrusion; 301-Annular rib; 302-Protrusion; 4-Precast concrete pile plug; 401-Inclined surface; 402-Water-permeable hole; 5-Reinforcing steel plate. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present invention. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. For those skilled in the art, the omission of certain well-known structures and their descriptions in the drawings is understandable. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present invention.

[0027] like Figures 1-4 As shown, an embodiment of the present invention provides a steel pipe pile structure for improving bearing capacity, including a steel pipe pile 2, a protrusion 3, and a precast concrete pile plug 4.

[0028] In one specific embodiment of the present invention, the protrusion 3 is fixed to the inner wall of the steel pipe pile 2, and the precast concrete pile plug 4 is disposed at a designed depth position inside the steel pipe pile 2. The protrusion 3 presses downward against the precast concrete pile plug 4 and forms an interlocking structure therewith, thereby restricting the upward displacement of the precast concrete pile plug 4.

[0029] In the above scheme, a stable connection is formed through mechanical interlocking, directly locking the pile plug displacement and preventing the pile plug from detaching or loosening during load transfer. This ensures that the axial load can be efficiently transferred to the pile plug through the interlocking structure, completely solving the problems of easy displacement and unstable bearing capacity of traditional soil plugs, allowing the pile end resistance to be fully utilized, and improving the bearing reliability of the pile foundation.

[0030] Optional, such as Figure 1 and Figure 2 As shown, protrusion 3 is an annular rib 301.

[0031] Optional, such as Figure 3 As shown, the protrusion 3 consists of multiple protrusions 302 that are evenly distributed or distributed at a specific angle along the inner circumference of the steel pipe pile 2.

[0032] The protrusion 3 structure must have sufficient strength, rigidity, and height / depth to ensure effective clamping of the precast block and load transfer. A reinforcing steel plate 5 can be installed at the protrusion 3 of the steel pipe pile 2 to improve its shear resistance, prevent deformation and breakage of the protrusion 3 during load transfer or engagement, and extend the service life of the steel pipe pile 2.

[0033] In the above scheme, the different structural forms of protrusion 3 can flexibly adapt to different geological conditions, construction techniques, and load requirements. The annular rib 301 bears more evenly, and the distributed protrusions 302 are easier to process and install. This expands the scope of application of the technology, allowing for flexible selection according to different engineering scenarios such as municipal works, bridges, and highways, reducing design and construction limitations, and improving the practicality of the technology.

[0034] In one specific embodiment of the present invention, in order to make the connection between the protrusion 3 and the precast concrete pile plug 4 tighter, an inclined surface 401 is provided around the top of the precast concrete pile plug 4, and a groove for embedding the protrusion 3 is formed between the inclined surface 401 and the inner wall surface of the steel pipe pile 2. After the protrusion 3 and the precast concrete pile plug 4 are fitted together, their top surfaces are flush.

[0035] In the above scheme, the inclined surface 401 and groove design at the top of the pile plug improve the tightness of the fit between the protrusion 3 and the pile plug, increase the contact area, avoid local stress concentration, and ensure that the force is evenly distributed between the two. This can reduce wear at the fitting parts, extend the service life of the structure, and make the load transfer smoother, avoid local damage caused by stress concentration, and further enhance the interlocking load-bearing effect.

[0036] Furthermore, the diameter of the precast concrete plug 4 is smaller than the inner diameter of the steel pipe pile 2 and larger than the minimum inner diameter of the throat formed by the protrusion 3; the height of the precast concrete plug 4 is greater than the height of the protrusion 3.

[0037] In the above scheme, the pile plug is precisely sized to fit the groove, balancing ease of installation with secure engagement. This design avoids jamming during installation while ensuring that protrusion 3 is fully embedded in the groove, forming a reliable lock. This improves construction efficiency, reduces installation difficulty, and prevents the pile plug from falling off or shifting during load-bearing, ensuring structural stability and providing a foundation for subsequent load transfer.

[0038] In one specific embodiment of the present invention, a permeable hole 402 is provided in the middle of the precast concrete pile plug 4 to provide a drainage channel during the driving of the steel pipe pile 2, thereby improving driving efficiency and soil bearing capacity. After the interlocking structure is engaged, staged grouting can also be carried out through the permeable hole 402. It has dual functions: it can quickly drain water around the pile during the driving stage, and after interlocking, it can serve as a grouting channel, realizing integrated drainage and grouting.

[0039] In one specific embodiment of the present invention, a pressure sensor is provided at the bottom of the precast concrete pile plug 4, which can provide real-time feedback on the contact pressure to determine whether the precast concrete pile plug 4 is in place.

[0040] In the above scheme, the design of the pressure sensor at the bottom of the pile plug provides real-time feedback on the contact pressure between the pile plug and the soil at the pile tip, accurately determining whether the pile plug has reached the design depth and avoiding errors from manual verification.

[0041] In one specific embodiment of the present invention, the precast concrete pile plug 4 is composed of a gradient structure of different materials, including, from top to bottom, a high-strength concrete layer, a steel fiber reinforced concrete layer, and a permeable concrete layer. The top of the precast concrete pile plug 4 is made of high-strength concrete to prevent local crushing when the protrusion 3 is embedded; the lower part is made of permeable concrete to accelerate the dissipation of excess pore water pressure around the pile and improve initial bearing capacity; the lower permeable concrete allows for the prefabrication of a large-void structure, reducing the overall weight of the precast concrete pile plug 4 by 10% to 15%; a 50mm thick steel fiber reinforced concrete transition layer is provided in the middle. This design achieves a synergistic effect of a rigid upper structure and a permeable lower structure through the gradient distribution of materials: the upper rigid body ensures reliable load transfer, the lower permeable body maintains smooth drainage of the foundation, and the transition layer smooths stress distribution.

[0042] Based on the above structural design, the axial load is transferred to the surrounding soil through the wall of the steel pipe pile 2 (side skin friction), and the load is transferred to the precast concrete plug 4, which is held in place, through the inner wall of the steel pipe pile 2 (especially the protrusion 3 structure). The precast concrete plug 4, as a rigid load-bearing body, transfers the load to the soil layer at the pile tip (end resistance). This forms an efficient force transmission path of steel pipe pile 2 - protrusion 3 - precast concrete plug 4 - soil at the pile tip.

[0043] Design formulas for key parameters of precast concrete pile plugs: Precast concrete pile plug diameter Dp: Inner diameter of steel pipe pile; δ: Installation gap (10~20mm); The height of the precast concrete pile plug Hb ≥ 0.3Dp; Precast concrete pile plug throat diameter Δd is the width of the protrusion, ≥15cm; Interlock strength F: Design load, τu: Shear strength of steel, h: Effective height of the protrusion; Steel pipe pile bearing capacity ; Qs: Pile side friction resistance Up: pile perimeter, fi: frictional resistance of the i-th soil layer, Li: soil layer thickness; Qb: Resistance at the end of the precast concrete pile plug ; Ab: Area of ​​the bottom of the precast concrete pile plug ( ); qb: ultimate bearing capacity of soil at pile tip (corrected value), α, β: synergistic effect coefficients (determined by test), α=1.0~1.2 (lateral resistance enhancement); β=1.3~1.8 (end resistance enhancement).

[0044] Correction calculation for pile end resistance: kc, ks: precast concrete pile plug effect coefficients, determined by finite element analysis and model tests, and can be taken as 1~1.8; Nq, Nc: bearing capacity coefficients, σv′: effective overburden stress at the pile end, cu: soil cohesion.

[0045] The aforementioned key parameters are quantitatively designed with precision, allowing for targeted calculations based on actual project loads and geological conditions, thus avoiding biases from experience-based designs. This approach eliminates steel waste caused by over-design and prevents load-bearing hazards resulting from under-design, enhancing the scientific nature of the design, ensuring that the pile foundation bearing capacity fully meets project requirements, and simultaneously reducing building material costs.

[0046] Based on the above structural design, such as Figure 4 As shown in the figure, this invention provides a construction method for improving the bearing capacity of steel pipe piles, including the following steps: (1) Pre-hole construction: According to the design requirements, drilling equipment is used to carry out pre-hole operation in the foundation soil 1, and the pre-hole depth reaches the design depth.

[0047] (2) Placement of precast concrete pile plug 4: The precast concrete pile plug 4 is a precast concrete structure. The precast concrete pile plug 4 is placed into the pilot hole by hoisting equipment and accurately reaches the design depth position. A guide device can be used to ensure accurate positioning. The hoisting path is pre-simulated using a BIM model. The pressure sensor installed at the bottom of the precast concrete pile plug 4 provides real-time feedback. When the contact pressure is ≥10kPa, the position is determined to be in place.

[0048] (3) Installation of steel pipe pile 2: Lift the steel pipe pile 2 with protrusion 3 on the inner wall, align it with the pilot hole and slowly insert it. During the insertion process, use pile driving equipment to drive the steel pipe pile 2 into the foundation soil 1.

[0049] (4) Combination of steel pipe pile 2 and precast concrete pile plug 4: When the steel pipe pile 2 is driven to the design depth, the protrusion 3 structure on the inner wall of the steel pipe pile 2 is embedded in the groove at the top of the precast concrete pile plug 4, so that the steel pipe pile 2 and the precast concrete pile plug 4 are tightly locked together to form a whole, forming a steel pipe pile 2 with active enhancement based on the soil plug effect. After the interlocking structure is locked, staged grouting is carried out through the permeable hole 402: ① First, quick-setting grout is injected to fix the precast concrete pile plug 4, ② 24 hours later, expansive grout is injected to strengthen the contact surface. In addition, grouting of the stratum can be carried out through the permeable hole 402 to further improve the bearing capacity of the steel pipe pile 2.

[0050] Based on the description and accompanying drawings of this invention, those skilled in the art can easily manufacture or use the steel pipe pile structure and construction method for improving bearing capacity according to this invention, and can achieve the positive effects described in this invention.

[0051] Unless otherwise specified, in this invention, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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 terms used to describe orientation or positional relationships in this invention are for illustrative purposes only and should not be construed as limiting this invention. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0052] Unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A steel pipe pile structure for improving bearing capacity, characterized in that, include: Steel pipe pile (2), with protrusions (3) on its inner wall; A precast concrete plug (4) is installed at the designed depth inside the steel pipe pile (2); The protrusion (3) presses the precast concrete plug (4) downward and forms an interlocking structure with it to restrict the upward displacement of the precast concrete plug (4).

2. The steel pipe pile structure according to claim 1, characterized in that, The protrusion (3) is an annular rib (301) or a plurality of protrusions (302) distributed along the circumference of the inner wall of the steel pipe pile (2).

3. The steel pipe pile structure according to claim 1 or 2, characterized in that, The steel pipe pile (2) is provided with a reinforcing steel plate (5) at the protrusion (3).

4. The steel pipe pile structure according to claim 1, characterized in that, The precast concrete plug (4) is composed of a gradient structure of different materials, including a high-strength concrete layer, a steel fiber concrete layer and a permeable concrete layer from top to bottom.

5. The steel pipe pile structure according to claim 1, characterized in that, The precast concrete pile plug (4) has a water-permeable hole (402) in the middle.

6. The steel pipe pile structure according to claim 1, characterized in that, A pressure sensor is provided at the bottom of the precast concrete plug (4).

7. The steel pipe pile structure according to claim 1, characterized in that, The precast concrete plug (4) has a ramp (401) around its top, and the ramp (401) forms a groove between the inner wall of the steel pipe pile (2) for embedding the protrusion (3).

8. The steel pipe pile structure according to claim 1, characterized in that, The diameter of the precast concrete plug (4) is smaller than the inner diameter of the steel pipe pile (2) and larger than the minimum inner diameter of the throat formed by the protrusion (3); the height of the precast concrete plug (4) is greater than the height of the protrusion (3).

9. A construction method for improving the bearing capacity of steel pipe piles, characterized in that, Using the steel pipe pile structure as described in any one of claims 1-7 includes the following steps: Drill pilot holes at the designed pile locations in the foundation soil (1) to the designed depth; Place the precast concrete plug (4) at the bottom of the pilot hole; The steel pipe pile (2) with protrusions (3) on the inner wall is aligned with the pilot hole and driven into the foundation soil (1) until the protrusions (3) are fitted into the precast concrete pile plug (4) to form an interlocking structure. Graded grouting is carried out through the permeable holes (402) of the precast concrete pile plug (4). First, quick-setting grout is injected to fix the precast concrete pile plug (4), and then expansive grout is injected to strengthen the contact surface.

10. The construction method according to claim 9, characterized in that, In the step of placing the precast concrete plug (4), the contact pressure is fed back in real time by the pressure sensor at the bottom of the precast concrete plug (4) to determine whether the precast concrete plug (4) is in place.

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