Prefabricated prestressed spiral anti-floating pile and construction method thereof

Abstract

The present invention is applicable to the technical field of anti-floating piles, and provides a prefabricated prestressed spiral anti-floating pile and a construction method thereof. The anti-floating pile includes: a pile body structure, including a steel cage and a pile body; anchoring and connecting components, including an anchor head, an anchor pad 1, an anchor pad 2, and a clip; force-bearing and prestressed components, including a steel strand; auxiliary and functional components. The surface of the pile body is provided with a pile body thread; the anchor pad 1 is located at the pile head, bearing the force transmitted from the bottom plate and dispersing the stress; the anchor head, the anchor pad 1, the steel strand, and the clip form an anchor connection at the pile head; the anchor pad 2 is located at the pile end, applying compressive stress to the pile body concrete. The present invention solves the problems of long construction period, environmental pollution, and quality control of on-site cast anti-floating piles by prefabricating the spiral pile body in the factory and assembling the prestress on site; the present invention gives full play to the tensile properties of the steel strand and the compressive properties of the concrete, and by setting up the spiral pile body, greatly improves the anti-floating ability and anti-floating stability of the anti-floating pile.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-floating piles, and in particular relates to a prefabricated prestressed spiral anti-floating pile and a construction method thereof. Background Art

[0002] With the rapid development of urban construction and the continued development of underground space, the scale and depth of underground structures have continued to increase, and the buoyancy of groundwater has posed a serious threat to structural stability. In particular, the continued rise in groundwater levels, driven by regional water diversion projects and frequent extreme rainfall, has placed even more stringent demands on the anti-buoyancy design of buildings.

[0003] In current anti-floating design, anti-floating piles are a commonly used anti-floating measure, and most of these anti-floating piles are pull-out piles. However, these pull-out piles present numerous challenges in practice. Firstly, the piles primarily bear tensile forces, hindering the full potential of concrete's strong compressive strength. Secondly, their construction often involves wet on-site construction, resulting in a harsh working environment. The quality of these anti-floating piles depends on the quality of the on-site grouting, which not only prolongs construction time but also makes it difficult to ensure effective quality assurance.

[0004] In recent years, precast, prestressed anti-floating piles have been increasingly used in engineering anti-floating projects. Factory-based production ensures pile strength and quality, avoiding the uncertainties associated with on-site casting. Prestressed steel strands improve the pile's pullout resistance, reducing the amount of reinforcement and, to a certain extent, addressing some of the issues associated with cast-in-place anti-floating piles. However, precast, prestressed anti-floating piles also have some drawbacks. First, most precast, prestressed anti-floating piles are cylindrical in shape, resulting in a small contact area with the soil and limited pullout capacity. Second, during operation, in addition to the tensile forces acting on the steel bars, the concrete cover also experiences significant tensile forces, making crack control difficult. Third, most precast, prestressed anti-floating piles currently use a pre-tensioning method that relies on the bond between the steel bars and concrete to transmit prestress. This bond can easily fail due to inadequate curing conditions and groundwater grouting, compromising the anti-floating effectiveness. Furthermore, the core load-bearing component of existing precast, prestressed steel bars, while the concrete is primarily subjected to tension, still fails to fully utilize their compressive strength. Therefore, how to effectively improve the pile structure of prefabricated prestressed anti-floating piles, increase the contact area between the pile body and the soil, give full play to the compressive strength of the pile concrete, enhance the construction quality and crack resistance of the anti-floating piles, and improve the anti-floating ability and anti-floating stability of the anti-floating piles has become an urgent problem to be solved. Based on this, the present invention proposes a prefabricated prestressed spiral anti-floating pile and its construction method. Summary of the Invention

[0005] The object of the present invention is to provide a prefabricated prestressed spiral anti-floating pile and a construction method thereof, in order to solve the problems raised in the above-mentioned background technology.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A prefabricated prestressed spiral anti-floating pile, comprising:

[0008] Pile structure, including steel cage and pile body;

[0009] Anchoring and connecting components, including anchor head, anchor pad 1, anchor pad 2, pile head steel plate, U-shaped steel pad, steel ring and clip;

[0010] Load-bearing and prestressed components, including pressure-bearing steel pipes and steel strands;

[0011] Auxiliary and functional components, including bellows, spiral steel drill bits, polymer self-adhesive waterproof membranes, water-swelling waterstops, and grouting pipes;

[0012] The surface of the pile body is provided with a pile body thread to increase the contact area between the pile body and the soil body and enhance the friction force and mechanical bite force;

[0013] The anchor plate 1 is located at the pile head, bears the force transmitted from the bottom plate and disperses the stress; the anchor head, anchor plate 1, steel strand and clip at the pile head form an anchor connection; the anchor plate 2 is located at the pile end, cuts into the steel cage, and applies compressive stress to the pile concrete.

[0014] Furthermore, the steel cage is internally provided with spiral stirrups and longitudinal structural steel bars to form a pile skeleton.

[0015] Furthermore, in the anchoring and connecting components:

[0016] The anchor head and the clip cooperate to fix the steel strand after the anchor connection is completed, and then perform the tensioning operation;

[0017] The pile head steel plate is provided with grouting holes, and pile head steel plates are installed at both ends of the steel cage;

[0018] The U-shaped steel plate is welded to the anchor plate 2, and a positioning groove is provided on the U-shaped steel plate for positioning the bellows;

[0019] The steel ring is used to assist the U-shaped steel plate in positioning and installing the corrugated pipe.

[0020] Furthermore, the first anchor plate is square and has a thickness of ≥20 mm; the second anchor plate is circular and has three holes.

[0021] Furthermore, in the stressed and prestressed components:

[0022] The pressure-bearing steel pipe is located at the pile head, and the pressure-bearing steel pipe is connected to the steel cage through the pile head steel plate, and the pile head steel plate is welded to the pressure-bearing steel pipe. The pressure-bearing steel pipe bears part of the pressure, and the anchor plate is directly placed on the pressure-bearing steel pipe;

[0023] The steel strands bear the tension and provide prestressing force for the anti-floating piles.

[0024] Furthermore, in the auxiliary and functional components:

[0025] The bellows passes through the steel ring and is clamped in the positioning groove of the U-shaped steel plate to protect the steel strands and inject anti-corrosion grease; the bellows is parallel to the inner wall of the steel cage when installed, and after being connected to the pressure-bearing steel pipe, it is parallel to the inner wall of the pressure-bearing steel pipe;

[0026] The spiral steel drill bit is welded to the pile end after the pile body is transported to the construction site;

[0027] The water-swelling waterstop strips and polymer self-adhesive waterproof membrane are laid around the contact surface between the pile body and the base plate for waterproofing;

[0028] The grouting pipe is used for grouting between the pile body and the foundation. When installed, the grouting pipe is parallel to the inner wall of the steel cage and the inner wall of the pressure-bearing steel pipe.

[0029] A construction method of the prefabricated prestressed spiral anti-floating piles according to the above-mentioned method comprises the following steps:

[0030] Step 1: Design the pile length, diameter, and prestressing parameters based on the anti-floating requirements, and select the steel strands, pressure-bearing steel pipes, anchor pad 1, anchor pad 2, anchor head, and U-shaped steel pad;

[0031] Step 2: Use a spiral steel mold, insert spiral stirrups and longitudinal structural steel bars to make a steel cage as the skeleton of the pile;

[0032] Step 3: Weld the U-shaped steel plate with steel ring and the anchor plate 2 into a whole;

[0033] Step 4: Pre-embed the corrugated pipe, pass it through the steel ring and lock it in the positioning groove, ensure that the second anchor plate is inscribed in the steel cage, and complete the threading of the steel strand;

[0034] Step 5: Install the pile head steel plates at both ends and reserve grouting holes, install the grouting pipe, and ensure that the grouting pipe and corrugated pipe are parallel to the inner wall of the steel cage;

[0035] Step 6: Pour early-strength concrete with a strength of C40 or above, cover and maintain after vibrating and compacting, and demould after the strength reaches 100% of the design value. Inspect the appearance of the pile and the patency of the corrugated pipe and grouting pipe;

[0036] Step 7: Weld the pile head steel plate to the pressure-bearing steel pipe on site, complete the anchor connection of the anchor head, anchor plate 1, steel strand, and clip at the pile head, inject mortar into the pressure-bearing steel pipe, and ensure that the corrugated pipe and grouting pipe are parallel to the inner wall of the pressure-bearing steel pipe;

[0037] Step 8: After the mortar solidifies, inject anti-corrosion grease into the bellows and use a jack to tension it until the prestressing design requirements are met;

[0038] Step 9: Transport the main components to the construction site, weld the spiral steel drill bit at the pile end, use a spiral pile driver to drive the pile into the soil, and inject grout into the grouting pipe to form a whole with the pile and foundation;

[0039] Step 10: After the pile is buried in the ground, water-swelling waterstop strips and polymer self-adhesive waterproof membrane are laid around the contact surface between the pile and the base plate for waterproofing.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention has practical significance in the actual application of anti-floating design in buildings. Compared with on-site cast anti-floating piles, it avoids problems such as on-site environmental pollution, long construction period, difficulty in ensuring pile body quality, and unstable anti-floating ability. Compared with ordinary prefabricated prestressed anti-floating piles, the present invention adopts a post-tensioning method with controllable on-site quality to apply prestress, giving full play to the strong tensile strength of the steel strand. At the same time, by separating the pile head anchor gasket 1 from the pressure-bearing steel pipe and pre-buried anchor gasket 2 at the bottom of the pile body, prestress is applied to the steel strand, converting the concrete that was originally under tension into compression, giving full play to the compressive properties of the concrete, and improving the anti-floating ability and stability of the anti-floating pile. The present invention adopts a factory-prefabricated spiral pile body and on-site assembly and tensioning prestressing method, which ensures the construction quality of the pile body, reduces the prestress loss caused by concrete shrinkage, creep and temperature difference, and improves the prestressing efficiency. The pile body adopts a spiral external structure, which not only reduces the construction difficulty, but also increases the friction with the soil and generates additional mechanical bite force, greatly improving the anti-floating ability and stability. During actual construction, if the soil quality is poor or the foundation is relatively hard, you can choose to install a grouting pipe, drill it through the guide hole to form a partial soil-squeezing pile, and then grout it into the soil to provide sufficient friction resistance to ensure anti-floating ability and anti-floating stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the main view of the prefabricated prestressed spiral anti-floating pile.

[0043] Figure 2 This is the main cross-sectional view of the prefabricated prestressed spiral anti-floating pile.

[0044] Figure 3 This is a side cross-sectional view of a prefabricated prestressed spiral anti-floating pile.

[0045] Figure 4 This is a top view of prefabricated prestressed spiral anti-floating piles.

[0046] Figure 5 Schematic diagram of waterproofing measures between the pile and the base plate.

[0047] Figure 6 Schematic diagram of pile end anchor.

[0048] Figure 7 Schematic diagram of the U-shaped steel pad at the pile end.

[0049] In the figure: 1-anchor head; 2-anchor pad 1; 3-pressure-bearing steel pipe; 4-corrugated pipe; 5-steel strand; 6-rebar cage; 7-pile thread; 8-pile body; 9-anchor pad 2; 10-pile head steel plate; 11-U-shaped steel pad; 12-steel ring; 13-spiral steel drill bit; 14-clamp; 15-positioning groove; 16-polymer self-adhesive film waterproof membrane; 17-water-expanding waterstop; 18-grouting pipe. DETAILED DESCRIPTION

[0050] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0051] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0052] like Figure 1-Figure 7 As shown, one embodiment of the present invention provides a prefabricated prestressed spiral anti-floating pile, comprising:

[0053] The pile structure includes a steel cage 6 and a pile body 8;

[0054] The anchoring and connecting parts include an anchor head 1, an anchor pad 2 (thickened and enlarged square, thickness ≥ 20 mm), an anchor pad 9 (round with three holes), a pile head steel plate 10, a U-shaped steel pad 11, a steel ring 12 and a clip 14.

[0055] The load-bearing and prestressed components include pressure-bearing steel pipes 3 and steel strands 5.

[0056] Auxiliary and functional components include a corrugated pipe 4, a spiral steel drill bit 13, a polymer self-adhesive film waterproofing coil 16, a water-swelling waterstop strip 17 and a grouting pipe 18.

[0057] like Figure 1-Figure 3 As shown in FIG. 1 , as a preferred embodiment of the present invention, in the pile structure:

[0058] The steel cage 6 has spiral stirrups and longitudinal structural steel bars built into it, forming the skeleton of the pile body 8, thereby enhancing the overall strength of the pile body;

[0059] The surface of the pile body 8 is provided with a pile body thread 7, which increases the contact area between the pile body 8 and the soil compared to ordinary anti-floating piles, enhances friction and mechanical bite force, and thus improves anti-floating ability and anti-floating stability.

[0060] like Figure 1-Figure 7 As shown in FIG. 1 , as a preferred embodiment of the present invention, in the anchoring and connecting components:

[0061] The anchor head 1 and the clip 14 cooperate to fix the steel strand 5 after the anchor connection is completed, and then the tensioning operation is performed.

[0062] The anchor plate 1 2 is located at the pile head, bearing the force transmitted from the bottom plate and dispersing the stress. The anchor head 1, anchor plate 1 2, steel strand 5 and clip 14 at the pile head form an anchor connection.

[0063] The anchor plate 2 9 is located at the pile end and is inscribed in the reinforcement cage 6 to apply compressive stress to the pile concrete.

[0064] The pile head steel plate 10 is provided with grouting holes, and the pile head steel plates 10 are installed at both ends of the reinforcement cage 6 .

[0065] The U-shaped steel plate 11 is welded to the anchor plate 2 9, and a positioning groove 15 is provided on the U-shaped steel plate 11, and the positioning groove 15 can clamp the bellows 4;

[0066] The steel ring 12 is used to assist the U-shaped steel backing plate 11 in positioning and installing the corrugated tube 4 and enhance the connection stability.

[0067] like Figure 1 and Figure 2 As shown, as a preferred embodiment of the present invention, in the stressed and prestressed components:

[0068] The pressure-bearing steel pipe 3 is located at the pile head. The pressure-bearing steel pipe 3 is connected to the steel cage 6 through the pile head steel plate 10, and the pile head steel plate 10 is welded to the pressure-bearing steel pipe 3. The pressure-bearing steel pipe 3 bears part of the pressure, and the anchor plate 2 is directly placed on the pressure-bearing steel pipe 3.

[0069] The steel strand 5 is made of high-strength, low-relaxation steel strand 5 and is coated with an epoxy coating. It is a key component that withstands tension and provides prestress for the anti-floating pile.

[0070] like Figure 2-Figure 7 As shown in FIG. 1 , as a preferred embodiment of the present invention, in the auxiliary and functional components:

[0071] The corrugated tube 4 passes through the steel ring 12 and is stuck in the positioning groove 15 of the U-shaped steel pad, which is used to protect the steel strand 5 and facilitate the injection of anti-corrosion grease. During installation, it is necessary to ensure that it is parallel to the inner wall of the steel cage 6, and after being connected to the pressure-bearing steel pipe 3, it is ensured that it is parallel to the inner wall of the pressure-bearing steel pipe 3.

[0072] The spiral steel drill bit 13 is welded to the pile end after the pile body 8 is transported to the construction site, so as to facilitate the pile body 8 to be buried in the soil.

[0073] The water-swellable waterstop strip 17 and the polymer self-adhesive waterproof membrane 16 are laid around the contact surface between the pile body 8 and the base plate to play a waterproof role.

[0074] The grouting pipe 18 is used to inject grout between the pile body and the foundation. During installation, ensure that it is parallel to the inner wall of the steel cage 6 and the inner wall of the pressure-bearing steel pipe 3 to enhance the integrity of the pile and the foundation.

[0075] One embodiment of the present invention provides a construction method for prefabricated prestressed spiral anti-floating piles, comprising the following steps:

[0076] Step 1: Design the pile length, diameter, and prestressing parameters according to the specific anti-floating requirements, and select appropriate high-strength, low-relaxation steel strands 5 (epoxy-coated), pressure-bearing steel pipes 3, anchor pads 1 and 2, anchor pads 9, anchor heads 1, and U-shaped steel pads 11.

[0077] Step 2: Use a spiral steel mold to embed spiral stirrups and longitudinal structural steel bars to make a steel cage 6 as the skeleton of the pile body 8.

[0078] Step 3: Weld the U-shaped steel plate 11 with the steel ring 12 and the anchor plate 2 9 into a whole.

[0079] Step 4: Pre-embed the corrugated pipe 4, pass it through the steel ring 12 and get it stuck in the positioning groove 15, ensure that the anchor plate 9 is inscribed in the steel cage 6, and complete the threading of the steel strand 5.

[0080] Step 5: Install the pile head steel plates 10 at both ends (with reserved grouting holes), and install the grouting pipe 18, ensuring that the grouting pipe 18, the corrugated pipe 4 and the inner wall of the steel cage 6 are parallel.

[0081] Step 6: Pour early-strength concrete of C40 or above, cover and maintain after vibrating to make it dense, and demould after the strength reaches 100% of the design value. Check the appearance of the pile body 8 and the patency of the corrugated pipe 4 and the grouting pipe 18, and clear the pipe if necessary.

[0082] Step 7: Weld the pile head steel plate 10 to the pressure-bearing steel pipe 3 to complete the anchor connection of the anchor head 1, anchor plate 2, steel strand 5, and clip 14 at the pile head, and inject mortar into the pressure-bearing steel pipe 3 to ensure that the corrugated pipe 4 and the grouting pipe 18 are parallel to the inner wall of the pressure-bearing steel pipe 3.

[0083] Step 8: After the mortar solidifies, inject anti-corrosion grease into the corrugated pipe 4 and use a jack to tension it until the prestressing design requirements are met. The injection of anti-corrosion grease and the threading and tensioning of the steel strands 5 can also be carried out at the construction site.

[0084] Step 9: Transport the main structure to the construction site, weld the spiral steel drill bit 13 to the pile end, and use a spiral pile driver to drive the pile body 8 into the ground. If penetration is difficult or the foundation is solid, a pilot hole can be used to convert the pile body 8 into a partial soil-squeezing pile. Grout is then injected into the grouting pipe 18 to integrate the pile with the foundation and ensure sufficient pullout resistance.

[0085] Step 10: After the pile body 8 is buried, a water-swellable waterstop strip 17 and a polymer self-adhesive waterproof membrane 16 are laid around the contact surface between the pile body 8 and the base plate (below the anchor plate 2) for waterproofing.

[0086] Working Principle: After the prefabricated prestressed spiral anti-floating pile is installed, the pile head anchor pad 2 is located within the base plate. When groundwater creates buoyancy on the base plate, the anchor pad 2 at the top of the pile head has no special connection to the pressure-bearing steel pipe 3. The base plate, subject to the buoyancy, tensions the internal prestressed steel strands 5 through the anchor pad 2, leveraging the strands' strong tensile strength. Simultaneously, the anchor pad 2 9 at the pile end applies compressive stress to the pile concrete, leveraging the concrete's strong compressive resistance to effectively control the development of concrete cracks and extend the component's service life. Furthermore, the pile body 8 is a spiral pile, with a larger contact area with the soil than conventional anti-floating piles. This generates not only greater friction but also mechanical engagement, significantly improving the pile's anti-floating capability and stability.

[0087] The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention. These should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A prefabricated prestressed spiral anti-floating pile, characterized in that: include: The pile structure comprises a steel cage and a pile body; the steel cage is internally provided with spiral stirrups and longitudinal structural steel bars to form a pile body skeleton; the surface of the pile body is provided with pile threads to increase the contact area between the pile body and the soil and enhance friction and mechanical bite force; The anchoring and connection components include an anchor head, a first anchor plate, a second anchor plate, a pile head steel plate, a U-shaped steel plate, a steel ring, and a clip. The first anchor plate is located at the pile head, bearing the force transmitted from the bottom plate and dispersing the stress. The anchor head, the first anchor plate, the steel strand, and the clip form an anchor connection at the pile head. The second anchor plate is located at the pile end, intersecting the steel cage, and applying compressive stress to the pile concrete. In the anchoring and connecting components: The anchor head and the clip cooperate to fix the steel strand after the anchor connection is completed, and then perform the tensioning operation; The pile head steel plate is provided with grouting holes, and pile head steel plates are installed at both ends of the steel cage; The U-shaped steel plate is welded to the anchor plate 2, and a positioning groove is provided on the U-shaped steel plate for positioning the bellows; The steel ring is used to assist the U-shaped steel plate in positioning and installing the bellows; The first anchor plate is square and has a thickness of ≥20 mm; the second anchor plate is circular and has three holes; Load-bearing and prestressed components, including pressure-bearing steel pipes and steel strands; of the load-bearing and prestressed components: The pressure-bearing steel pipe is located at the pile head, and the pressure-bearing steel pipe is connected to the steel cage through the pile head steel plate, and the pile head steel plate is welded to the pressure-bearing steel pipe. The pressure-bearing steel pipe bears part of the pressure, and the anchor plate is directly placed on the pressure-bearing steel pipe; The steel strands bear tension and provide prestress for the anti-floating piles; Auxiliary and functional components, including bellows, spiral steel drill bits, polymer self-adhesive waterproof membranes, water-swelling waterstops, and grouting pipes; Among the auxiliary and functional components: The bellows passes through the steel ring and is clamped in the positioning groove of the U-shaped steel plate to protect the steel strands and inject anti-corrosion grease; the bellows is parallel to the inner wall of the steel cage when installed, and after being connected to the pressure-bearing steel pipe, it is parallel to the inner wall of the pressure-bearing steel pipe; The spiral steel drill bit is welded to the pile end after the pile body is transported to the construction site; The water-swelling waterstop strips and polymer self-adhesive waterproof membrane are laid around the contact surface between the pile body and the base plate for waterproofing; The grouting pipe is used for grouting between the pile body and the foundation. When installed, the grouting pipe is parallel to the inner wall of the steel cage and the inner wall of the pressure-bearing steel pipe.

2. A construction method for prefabricated prestressed spiral anti-floating piles according to claim 1, characterized in that: The following steps are involved: Step 1: Design the pile length, diameter, and prestressing parameters based on the anti-floating requirements, and select the steel strands, pressure-bearing steel pipes, anchor pad 1, anchor pad 2, anchor head, and U-shaped steel pad; Step 2: Use a spiral steel mold, insert spiral stirrups and longitudinal structural steel bars to make a steel cage as the skeleton of the pile; Step 3: Weld the U-shaped steel plate with steel ring and the anchor plate 2 into a whole; Step 4: Pre-embed the corrugated pipe, pass it through the steel ring and lock it in the positioning groove, ensure that the second anchor plate is inscribed in the steel cage, and complete the threading of the steel strand; Step 5: Install the pile head steel plates at both ends and reserve grouting holes, install the grouting pipe, and ensure that the grouting pipe and corrugated pipe are parallel to the inner wall of the steel cage; Step 6: Pour early-strength concrete with a strength of C40 or above, cover and maintain after vibrating and compacting, and demould after the strength reaches 100% of the design value. Inspect the appearance of the pile and the patency of the corrugated pipe and grouting pipe; Step 7: Weld the pile head steel plate to the pressure-bearing steel pipe, complete the anchor connection of the anchor head, anchor plate 1, steel strand, and clip at the pile head, inject mortar into the pressure-bearing steel pipe, and ensure that the corrugated pipe and grouting pipe are parallel to the inner wall of the pressure-bearing steel pipe; Step 8: After the mortar solidifies, inject anti-corrosion grease into the corrugated pipe and use a jack to tension it until the prestressing design requirements are met; Step 9: Transport the main components to the construction site, weld the spiral steel drill bit at the pile end, use a spiral pile driver to drive the pile into the soil, and inject grout into the grouting pipe to form a whole with the pile and foundation; Step 10: After the pile is buried in the ground, water-expanding waterstop strips and polymer self-adhesive waterproof membrane are laid around the contact surface between the pile and the base plate for waterproofing.

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