A steel-concrete combined hollow screw pile and a preparation method thereof

Abstract

The present application belongs to the technical field of screw pile, and discloses a steel-concrete combined hollow screw pile and a preparation method thereof; the present application aims at solving the problems of high manufacturing cost and low bearing capacity of the screw pile in the prior art; the screw pile specifically comprises a pile cap, a pile body, screw threads and a pile tip; the pile cap is a solid disc structure, the pile body is connected below the pile cap, the pile body is a conical column structure with a large diameter at the top and a small diameter at the bottom, and the conical column structure is hollow; the screw threads are spirally wound around the pile body; the pile tip is arranged below the pile body and is a conical structure; the hollow design of the pile body of the screw pile reduces the material for preparing the pile body and lowers the construction cost; the screw threads are arranged around the pile body, so that the screw pile is more stable in the soil, and the stability and the bearing capacity of the screw pile are increased; the preparation method of the screw pile directly pours the concrete inner layer in the outer layer of the steel structure, so that the prepared steel part and the concrete part of the screw pile are more closely attached, the connection is more firm, and the bearing capacity is stronger.

Description

Technical Field

[0001] This invention relates to the field of screw pile technology, and in particular to a steel-concrete composite hollow screw pile and its preparation method. Background Technology

[0002] With the continuous expansion of urbanization and infrastructure construction, pile foundation technology has developed rapidly and has been widely used in civil engineering projects such as high-speed railways, highways, urban rail transit, bridges, airports, and high-rise buildings. As a widely used foundation type, pile foundations can effectively improve the bearing capacity of the ground, reduce deformation, and ensure the stability of buildings. In existing pile foundation construction, large-diameter solid piles or deep foundation pits are common. Solid piles require more material and have a longer construction period, which increases the project cost.

[0003] Therefore, various new types of pile foundations have emerged in existing technologies, including PCC piles, cast-in-place X-shaped concrete piles, Y-shaped piles, threaded piles, and helical piles. While these pile types each have their unique engineering advantages, they often require complex procedures and have high manufacturing and construction costs. Considering economic costs, large-diameter hollow screw piles and prestressed screw piles are economical, reasonable, and offer excellent cost-effectiveness. Large-diameter hollow screw piles, due to their large diameter and complex structure, have complex construction processes and are difficult to maintain later. Prestressed screw piles have a more complex prefabrication process, including the tensioning of prestressed steel bars, requiring high-level technology and strict construction control. Furthermore, both require internal steel cages to improve their torsional resistance during the spinning process, which increases manufacturing costs to some extent.

[0004] Therefore, a new type of screw post is invented that has higher load-bearing capacity while saving costs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a steel-concrete composite hollow screw pile and its preparation method, thereby solving the problems of high manufacturing cost and low bearing capacity of screw piles in existing technologies.

[0006] Firstly, in order to achieve the aforementioned objectives, the technical solution adopted by this invention is as follows: A steel-concrete composite hollow screw pile includes a pile cap, a pile body, screw threads, and a pile tip. The pile cap is a solid disc structure, and the pile body is connected below the pile cap. The pile body is a conical column structure with a larger diameter at the top and a smaller diameter at the bottom, and the inside of the conical column structure is hollow. The screw threads are coiled and wrapped around the pile body. A pile tip is provided below the pile body, and the pile tip is a conical structure with the cone tip facing downwards.

[0007] In this design, the hollow design inside the pile body reduces the amount of material used in pile preparation and lowers the preparation cost. Furthermore, the pile cap and pile tip are set at the top and bottom of the pile body respectively, which increases the sealing of the screw pile. The screw threads are wrapped around the pile body, making the screw pile more stable in the soil and increasing its stability and bearing capacity.

[0008] Furthermore, the pile body includes a steel pile body and a concrete pile body, both of which are hollow structures; the top of the concrete pile body is connected to a pile cap, the steel pile body is fitted onto the outside of the concrete pile body, and the interior of the concrete pile body forms an inner cavity.

[0009] In this scheme, the steel pile body and the concrete pile body are combined to form a steel-concrete composite hollow screw pile, which combines the advantages of concrete and steel, greatly improving the bearing capacity of the screw pile; making it applicable to various projects and various geological environments, thus expanding the scope of application of screw piles.

[0010] Furthermore, the threaded parts include steel threaded parts and concrete threaded parts. The concrete threaded parts are evenly wrapped around the concrete pile body, while the steel threaded parts are wrapped around the concrete threaded parts. The steel threaded parts are connected to the steel pile body.

[0011] In this scheme, the steel-concrete composite solid structure formed by the steel screw thread wrapping the concrete screw thread increases the contact area between the steel pile body and the concrete pile body. Furthermore, the concrete screw thread is embedded inside the steel screw thread, making the connection between the steel pile body and the concrete pile body more secure and improving the overall stability of the screw pile.

[0012] Furthermore, the cross-section of the screw thread has a trapezoidal structure, and the trajectory of the screw thread winding around the pile body is an Archimedean spiral.

[0013] In this design, the threads are wound around the pile body according to the Archimedes spiral trajectory. The threads are evenly distributed, which can evenly bear the load in engineering applications and avoid stress concentration that could damage the pile body.

[0014] Furthermore, the pile tip includes a steel pile tip and a concrete pile tip. The top of the concrete pile tip is connected to the concrete pile body, and the steel pile tip is fitted outside the concrete pile tip. The top of the steel pile tip is connected to the steel pile body. The concrete pile body forms a pile tip cavity.

[0015] In this design, a pile tip is installed at the bottom, which increases the overall airtightness of the screw pile and facilitates the screw pile body to penetrate deeper into the soil.

[0016] Secondly, based on the steel-concrete composite hollow screw pile provided in the first aspect, the present invention provides a method for preparing a steel-concrete composite hollow screw pile, comprising the following steps: S1: Making steel structure molds; S2: Cast the outer layer of the steel structure using steel structure molds; S3: Making concrete molds; S4: Use concrete molds to pour an inner layer of concrete inside the outer layer of the steel structure to obtain screw piles.

[0017] In this scheme, the outer steel structure of the screw pile is cast using a steel mold, resulting in a one-time molding process with high strength. After casting, a concrete inner layer is directly poured inside the outer steel structure, making the inner concrete layer and the outer steel structure a single unit. This results in a screw pile with a strong connection between the steel and concrete parts, and a stronger load-bearing capacity.

[0018] Furthermore, S1 includes: S101: Fabrication of steel structure outer mold and steel structure inner mold; both the steel structure outer mold and the steel structure inner mold are hollow rotating structures; the bottom of the steel structure outer mold is equipped with a steel structure mold pivot. S102: Apply a release agent to the inner surface of the steel structure outer mold; and hoist and fix the steel structure outer mold inside the centrifuge tank so that the rotating shaft of the steel structure mold is connected to the lower end of the centrifuge tank; S103: Apply a release agent to the outer surface of the inner steel structure mold; and hoist and fix the inner steel structure mold inside the outer steel structure mold, forming an inner cavity of the steel structure mold between the outer steel structure mold and the inner steel structure mold.

[0019] In this scheme, steel outer mold and steel inner mold are made for the pouring of the outer layer of steel structure. The design of the steel structure mold rotation shaft facilitates vibration through the centrifugal tank, ensuring high density of the outer layer of steel structure. Applying a release agent facilitates subsequent demolding.

[0020] Furthermore, S2 includes: S201: Inject molten steel into the inner cavity of the steel structure mold; the thickness of the inner cavity of the steel structure mold is the thickness of the outer layer of the steel structure. S202: After the molten steel has solidified and formed, the inner mold and outer mold of the steel structure are removed in sequence to obtain the outer layer of the steel structure; S203: Perform maintenance and repair on the outer layer of the steel structure.

[0021] In this scheme, a steel structure mold cavity is formed between the outer steel structure mold and the inner steel structure mold. Molten steel is poured into the inner cavity of the steel structure mold to form an integrated steel structure outer layer. The resulting steel structure outer layer has high strength and strong load-bearing capacity.

[0022] Furthermore, S3 includes: S301: Prepare the pile cap model and the pile body cavity model; the pile cap model is a hollow rotating body structure, the internal dimensions of the hollow rotating body structure are the same as the pile cap size, the bottom of the pile cap model is open, and the top is provided with a semi-closed rolled edge; S302: A concrete mold rotating shaft is vertically installed inside the pile body cavity model, and the concrete mold rotating shaft is connected to the top of the pile cap model through a rod; thus completing the preparation of the concrete mold.

[0023] In this scheme, a pile cap model and a pile body cavity model are designed, and the pile cap and concrete pile body are poured in one go, eliminating the need for multiple pours of the pile cap and concrete pile body. This improves construction efficiency and reduces construction time. Furthermore, the poured pile cap and concrete pile body are an integral structure with high strength and strong bearing capacity.

[0024] Furthermore, S4 includes: S401: Hoist the outer layer of the steel structure into the interior of the outer formwork of the steel structure and fix it in place; S402: Hoist the concrete mold into the inner part of the outer layer of the steel structure; align the rotating shaft of the concrete mold with the upper end of the centrifuge tank; S403: Secure the pile cap model to the top of the steel structure outer formwork using bolts; S404: Inject concrete from the semi-closed opening of the rolled edge, allowing the concrete to flow into the gap between the concrete mold and the outer layer of the steel structure; intermittently start the centrifugal tank during the concrete pouring process. S405: Concrete pouring is complete. Restart the centrifuge tank to vibrate the concrete. S406: After the concrete has solidified and set, the concrete mold and the steel outer mold will be removed in sequence to obtain the complete screw pile; S407: Maintain and repair the bolt piles, and apply an anti-rust protective layer to the outer surface of the steel structure.

[0025] In this scheme, the concrete mold is set inside the outer layer of the steel structure, and concrete is poured between the outer layer of the steel structure and the concrete mold. The poured inner layer of concrete is directly connected to the outer layer of the steel structure. This pouring method can make the inner layer of concrete and the outer layer of steel structure fit more tightly, increase the connection strength between the two, and improve the overall integrity of the steel-concrete composite screw pile.

[0026] The beneficial effects of this invention are: The steel-concrete composite hollow screw pile provided by this invention adopts a novel steel-concrete composite hollow structure. This new structure can not only withstand greater loads, making the pile foundation support more reliable, but also reduces material usage and lowers the construction cost of the pile foundation. Furthermore, the screw threads around the pile allow for a tighter connection between the steel and concrete parts of the pile, and the surrounding threads also improve the torsional resistance of the pile body under rotational compression, increasing the load-bearing capacity of the pile body. Simultaneously, the hollow screw pile structure reduces the amount of concrete used, reducing resource consumption and carbon emissions. By saving manufacturing costs while protecting the environment, it aligns with the national strategic goal of green and sustainable development.

[0027] The method for preparing steel-concrete composite hollow screw piles provided by this invention uses a mold to cast an integral steel structure outer layer and directly casts a concrete inner layer inside the steel structure outer layer. This method results in a higher degree of adhesion between the steel structure outer layer and the concrete inner layer of the screw pile, making the overall connection of the screw pile stronger. The mold casting method makes the preparation and installation methods simpler and more efficient, which can effectively improve efficiency and reduce construction time, help reduce the overall cost of the project, and improve the competitiveness of the project. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a steel-concrete composite hollow screw pile structure according to the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the cross-sectional structure at position AA; Figure 3 This is a schematic diagram of the steel structure outer mold of the present invention; Figure 4 For the present invention Figure 3 Schematic diagram of the cross-sectional structure at the BB location; Figure 5 This is a schematic diagram of the concrete mold structure of the present invention; Figure 6 For the present invention Figure 5 Schematic diagram of the cross-sectional structure at the CC position.

[0029] Figure label: 1. Pile cap; 2. Pile body; 201. Steel pile body; 202. Concrete pile body; 203. Pile body inner cavity; 3. Thread; 301. Steel thread; 302. Concrete thread; 4. Pile tip; 401. Steel pile tip; 402. Concrete pile tip; 403. Pile tip inner cavity; 5. Steel mold; 501. Steel outer mold; 502. Steel inner mold; 503. Steel mold inner cavity; 504. Steel mold pivot; 6. Concrete mold; 601. Pile cap model; 602. Rolled edge; 603. Concrete mold pivot; 604. Pile body inner cavity model. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0031] like Figure 1-2As shown, this embodiment provides a steel-concrete composite hollow bolt pile. This bolt pile utilizes a combined hollow design of steel and concrete, combining the advantages of both materials to achieve strong load-bearing capacity and low manufacturing cost. Specifically, it includes: 1. Pile cap; 2. Pile body; 3. Threaded thread; 4. Pile tip; Among them, the pile cap 1 is a solid disc structure made of concrete. The pile body 2 is connected to the bottom of the pile cap 1. The pile body 2 is a conical column structure with a larger diameter at the top and a smaller diameter at the bottom. The inside of the conical column structure is hollow. The screw thread 3 is coiled and wrapped around the pile body 2. The pile tip 4 is provided below the pile body 2. The pile tip 4 is a conical structure with the tip of the conical structure facing downward.

[0032] like Figure 2 As shown, the pile body 2 includes a steel pile body 201 and a concrete pile body 202, both of which are hollow structures. The top of the concrete pile body 202 is connected to the pile cap 1, and the steel pile body 201 is fitted onto the outside of the concrete pile body 202. The interior of the concrete pile body 202 forms a pile body cavity 203. The combination of the steel pile body 201 and the concrete pile body 202 forms a steel-concrete composite hollow screw pile, which greatly improves the bearing capacity of the screw pile and enables it to be applied to various engineering projects and geological environments, thus expanding the application range of screw piles.

[0033] As a preferred embodiment, the pile cap 1 has a diameter of 850mm and a height of 200mm; the pile body 2 has a top diameter of 650mm and a bottom diameter of 450mm.

[0034] like Figure 2 As shown, the screw thread 3 includes a steel screw thread 301 and a concrete screw thread 302. The concrete screw thread 302 is evenly wound around the coiled concrete pile body 202, and the steel screw thread 301 is wrapped around the concrete screw thread 302. The steel screw thread 301 is connected to the steel pile body 201. The steel-concrete composite solid structure screw thread 3 formed by the steel screw thread 301 wrapping the concrete screw thread 302 increases the contact area between the steel pile body 201 and the concrete pile body 202. Moreover, the concrete screw thread 302 is embedded inside the steel screw thread 301, making the connection between the steel pile body 201 and the concrete pile body 202 more secure and improving the overall stability of the screw pile.

[0035] As a preferred embodiment, the thread 3 has a pitch of 400mm, an outer thickness of 50mm, an inner thickness of 100mm, and a height of 50mm.

[0036] like Figure 1 and Figure 2 As shown, the cross-section of the screw thread 3 is trapezoidal, and the trajectory of the screw thread 3 winding around the pile body 2 is an Archimedean spiral. The screw thread 3 is evenly distributed, which can bear the load evenly in engineering applications and avoid stress concentration that could damage the pile body.

[0037] like Figure 2 As shown, the pile tip 4 includes a steel pile tip 401 and a concrete pile tip 402. The top of the concrete pile tip 402 is connected to the concrete pile body 202. The steel pile tip 401 is sleeved on the outside of the concrete pile tip 402 and the top of the steel pile tip 401 is connected to the steel pile body 201. The top diameter of the pile tip is 500mm. The concrete pile body 202 forms a pile tip cavity 403. The pile tip is set at the bottom, which increases the overall airtightness of the screw pile and facilitates the screw pile body to penetrate into the soil.

[0038] As a preferred embodiment: The steel-concrete composite hollow bolt pile provided in this embodiment can also use the following dimensional parameters, as shown in Table 1: Table 1 Common Dimensions of Steel-Concrete Composite Hollow Bolts

[0039] The working principle of this embodiment: The screw pile provided in this embodiment is made of steel on the outside and has a hollow design inside the pile body 2, which has a strong bearing capacity when used as a foundation pile; the screw threads 3 are wrapped around the pile body 2, making the screw pile more stable in the soil.

[0040] Example 2 like Figure 1-6 As shown, this embodiment, based on the steel-concrete composite hollow screw pile provided in Embodiment 1, provides a method for preparing a steel-concrete composite hollow screw pile, including the following steps: S1: Fabrication of steel structure mold 5; specifically including: S101: As Figure 3-4 As shown, steel structure outer mold 501 and steel structure inner mold 502 are manufactured; both steel structure outer mold 501 and steel structure inner mold 502 are hollow rotating structures; steel structure outer mold 501 is provided with steel structure mold rotating shaft 504 at the bottom; S102: Apply release agent to the inner surface of the steel structure outer mold 501; and hoist and fix the steel structure outer mold 501 inside the centrifuge tank so that the steel structure mold shaft 504 is connected to the lower end of the centrifuge tank; S103: Apply a release agent to the outer surface of the inner steel mold 502; and hoist and fix the inner steel mold 502 inside the outer steel mold 501, forming a steel mold cavity 503 between the outer steel mold 501 and the inner steel mold 502.

[0041] In this embodiment, an outer steel mold 501 and an inner steel mold 502 are made for casting the outer layer of the steel structure. The steel mold rotating shaft 504 is designed to facilitate vibration through a centrifugal tank, ensuring high density of the outer layer of the steel structure. Applying a release agent facilitates subsequent demolding.

[0042] S2: Casting the outer layer of the steel structure using steel structure mold 5; specifically including: S201: Inject molten steel into the inner cavity 503 of the steel structure mold; the thickness of the inner cavity 503 of the steel structure mold is the thickness of the outer layer of the steel structure. S202: After the molten steel has solidified and formed, the inner mold 502 and the outer mold 501 of the steel structure are removed in sequence to obtain the outer layer of the steel structure. S203: Perform maintenance and repair on the outer layer of the steel structure.

[0043] In this embodiment, a steel structure mold cavity 503 is formed between the outer steel structure mold 501 and the inner steel structure mold 502. Molten steel is poured into the inner steel structure mold cavity 503 to obtain an integrated steel structure outer layer, which has strong load-bearing capacity.

[0044] S3: Concrete mold making 6; specifically including: S301: As Figure 5-6 As shown, a pile cap model 601 and a pile body cavity model 604 are prepared. The pile cap model 601 is a hollow rotating body structure. The internal dimensions of the hollow rotating body structure are the same as the dimensions of the pile cap. The bottom of the pile cap model 601 is open and the top is provided with a semi-closed rolled edge 602. S302: A concrete mold shaft 603 is vertically installed inside the pile body cavity model 604, and the concrete mold shaft 603 is connected to the top of the pile cap model 601 through a rod; thus completing the preparation of the concrete mold 6.

[0045] In this embodiment, a pile cap model 601 and a pile body cavity model 604 are designed. The pile cap and concrete pile body are poured in one go, eliminating the need for multiple pours of the pile cap and concrete pile body, thus improving energy efficiency and reducing construction time.

[0046] S4: Using concrete mold 6, pour the inner layer of concrete inside the outer layer of the steel structure to obtain the bolt pile; specifically including: S401: Hoist the outer layer of the steel structure into the interior of the outer formwork 501 of the steel structure and fix it in place; S402: Hoist the concrete mold 6 into the inner part of the outer layer of the steel structure; align the concrete mold shaft 603 with the upper end of the centrifuge tank; S403: Secure the pile cap model 601 to the top of the steel structure outer formwork 501 using bolts; S404: Inject concrete from the semi-closed opening of the rolled edge 602 and allow the concrete to flow into the gap between the concrete mold 6 and the outer layer of the steel structure; during the concrete pouring process, the centrifugal tank is activated intermittently to ensure that the screw pile has a uniform and dense texture. S405: Concrete pouring is complete. Restart the centrifuge tank to vibrate the concrete. S406: After the concrete has solidified and set, the concrete mold and the steel outer mold 501 are removed in sequence to obtain the complete screw pile; S407: Maintain and repair the bolt piles, and apply an anti-rust protective layer to the outer surface of the steel structure.

[0047] In this embodiment, the concrete mold 6 is set inside the outer layer of the steel structure, and concrete is poured between the outer layer of the steel structure and the concrete mold 6. The poured inner layer of concrete is directly connected to the outer layer of the steel structure. This pouring method can make the inner layer of concrete and the outer layer of steel structure fit more tightly, increase the connection strength between the two, and improve the overall integrity of the steel-concrete composite screw pile.

[0048] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed herein without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the invention.

Claims

1. A method for preparing a steel-concrete composite hollow screw pile, characterized in that: The steel-concrete composite hollow screw pile includes a pile cap (1), a pile body (2), screw threads (3), and a pile tip (4); the pile cap (1) is a solid disc structure, and the pile body (2) is connected to the bottom of the pile cap (1). The pile body (2) is a conical column structure with a larger diameter at the top and a smaller diameter at the bottom, and the conical column structure is hollow inside; the screw threads (3) are coiled and wrapped around the pile body (2); the pile tip (4) is provided below the pile body (2), and the pile tip (4) is a conical structure with the cone tip facing downwards; The pile body (2) includes a steel pile body (201) and a concrete pile body (202), both of which are hollow structures; the top of the concrete pile body (202) is connected to the pile cap (1), the steel pile body (201) is sleeved on the outside of the concrete pile body (202), and the interior of the concrete pile body (202) forms a pile body cavity (203). The threaded thread (3) includes a steel threaded thread (301) and a concrete threaded thread (302). The concrete threaded thread (302) is evenly wound and coiled around the concrete pile body (202). The steel threaded thread (301) is wrapped around the concrete threaded thread (302). The steel threaded thread (301) is connected to the steel pile body (201). The steel threaded thread (3) formed by the steel threaded thread (301) wrapping the concrete threaded thread (302) increases the contact area between the steel pile body (201) and the concrete pile body (202). The concrete threaded thread (302) is embedded inside the steel threaded thread (301), making the connection between the steel pile body (201) and the concrete pile body (202) more secure and improving the overall stability of the screw pile. The pile tip (4) includes a steel pile tip (401) and a concrete pile tip (402). The top of the concrete pile tip (402) is connected to the concrete pile body (202). The steel pile tip (401) is sleeved on the outside of the concrete pile tip (402). The top of the steel pile tip (401) is connected to the steel pile body (201). The concrete pile body (202) forms a pile tip cavity (403). The method for preparing steel-concrete composite hollow screw piles includes the following steps: S1: Make steel structure molds (5); the steps are as follows: S101: Fabricate a steel structure outer mold (501) and a steel structure inner mold (502); both the steel structure outer mold (501) and the steel structure inner mold (502) are hollow rotating structures; the bottom of the steel structure outer mold (501) is provided with a steel structure mold rotating shaft (504). S102: Apply a release agent to the inner surface of the steel structure outer mold (501); and hoist and fix the steel structure outer mold (501) inside the centrifuge tank, so that the steel structure mold shaft (504) is connected to the lower end of the centrifuge tank; S103: Apply a release agent to the outer surface of the inner steel mold (502); and hoist and fix the inner steel mold (502) inside the outer steel mold (501), forming a steel mold cavity (503) between the outer steel mold (501) and the inner steel mold (502). S2: Use the steel structure mold (5) to cast the outer layer of the steel structure; the steps are as follows: S201: Molten steel is injected into the inner cavity (503) of the steel structure mold; the thickness of the inner cavity (503) of the steel structure mold is the thickness of the outer layer of the steel structure. S202: After the molten steel has solidified and formed, the inner mold (502) and the outer mold (501) of the steel structure are removed in sequence to obtain the outer layer of the steel structure; S203: Perform maintenance and repair on the outer layer of the steel structure; S3: Making concrete molds (6); the steps are as follows: S301: Make a pile cap model (601) and a pile body cavity model (604); the pile cap model (601) is a hollow rotating body structure, the internal dimensions of the hollow rotating body structure are the same as the dimensions of the pile cap (1), the pile cap model (601) has an open bottom and a semi-closed rolled edge (602) on the top. S302: A concrete mold rotating shaft (603) is vertically installed inside the inner cavity model (604) of the pile body, and the concrete mold rotating shaft (603) is connected to the top of the pile cap model (601) through a rod; thus completing the preparation of the concrete mold (6); S4: Using the concrete mold (6), pour the inner layer of concrete inside the outer layer of the steel structure to obtain the bolt pile; the steps are as follows: S401: Hoist the outer layer of the steel structure into the interior of the outer formwork (501) and fix it; S402: Hoist the concrete mold (6) into the inner part of the outer layer of the steel structure; make the rotating shaft (603) of the concrete mold connect with the upper end of the centrifugal tank; S403: Fix the pile cap model (601) to the top of the steel structure outer formwork (501) by bolts; S404: Inject concrete from the semi-closed opening of the rolled edge (602) and allow the concrete to flow into the gap between the concrete mold (6) and the outer layer of the steel structure; intermittently start the centrifugal tank during the concrete pouring process; S405: After the concrete pouring is completed, restart the centrifuge tank to vibrate the concrete. S406: After the concrete has solidified and formed, the concrete mold (6) and the steel structure outer mold (501) are removed in sequence to obtain a complete screw pile; S407: The bolt piles are maintained and repaired, and an anti-rust protective layer is applied to the outer surface of the outer layer of the steel structure.

2. The method for preparing steel-concrete composite hollow screw piles according to claim 1, characterized in that: The cross-section of the screw thread (3) is trapezoidal, and the trajectory of the screw thread (3) winding around the pile body (2) is an Archimedean spiral.

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