Structure for enhancing lateral resistance of flexible pile and construction method thereof

Abstract

The invention discloses a structure for enhancing lateral resistance of a flexible strong screw pile and a construction method of the structure. The structure comprises a pile body, the spiral blades surround the surface of the pile body; the pile cap is fixed to the top of the pile body and comprises a side wall plate and a cover plate, a through hole is reserved in the center of the cover plate, the top of the pile body penetrates out of the through hole and is fixed to the cover plate, and the penetrating-out part forms an extending-out section; the rib plates are fixed to the periphery of the extending section at intervals in the annular direction, one side of each rib plate is fixed to the outer surface of the extending section, and the other side of each rib plate is fixed to the upper surface of the cover plate. The pile cap is arranged above the spiral pile, the rib plate is fixed to the top of the pile cap, and the rib plate and the pile body are fixed, so that the contact face between the spiral top and a shallow soil body is increased, a multidirectional load transmission path is formed, more shallow soil bodies are forced to evenly share loads, local bending deformation of the pile body is effectively restrained, and lateral stiffness is remarkably improved; the problem that the bearing capacity of a traditional flexible spiral pile is insufficient due to shallow soil body debonding is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of pile foundation engineering, and particularly relates to a structure for enhancing the lateral resistance of flexible and strong spiral piles and a construction method thereof. Background Art

[0002] Screw pile foundations significantly enhance their overall load-bearing performance through the three-dimensional interlocking effect between the spiral blades of the pile and the soil. However, flexible piles with a slenderness ratio exceeding 1 / 30 exhibit significant flexibility. Under horizontal loads, the pile's displacement and rotation are primarily concentrated in the wedge-shaped flow zone near the soil surface, making it difficult to mobilize the resistance of the deeper soil layers. This results in a heavy reliance on shallow soil layers for lateral bearing capacity, which is susceptible to strength degradation due to cyclic wind-induced vibration. This can lead to the accumulation of residual displacements in the pile and even overall instability. Summary of the Invention

[0003] The present invention provides a structure for enhancing the lateral resistance of flexible spiral piles, which can force more shallow soil to evenly share the load, effectively suppress local bending deformation of the pile body, significantly improve the lateral stiffness, and overcome the problem of insufficient bearing capacity of traditional flexible spiral piles caused by debonding of shallow soil.

[0004] The present invention provides a structure for enhancing the lateral resistance of a spiral pile, comprising: a pile body; spiral blades spirally surrounding the surface of the pile body, the number of the spiral blades being multiple and the multiple spiral blades being spaced apart; a pile cap fixed to the top of the pile body, the pile cap comprising a side wall plate surrounding the pile in a ring and a cover plate sealing the top of the side wall plate, a through hole being reserved at the center of the cover plate, the top of the pile body passing through the through hole and being fixed to the cover plate, the protruding portion forming an extension section, the multiple spiral blades being located below the cover plate; and multiple ribs, the multiple ribs being fixed to the outer circumference of the extension section at intervals along the annular direction, one side of each rib being fixed to the outer surface of the extension section, and the other side of each rib being fixed to the upper surface of the cover plate.

[0005] A further improvement of the present invention is that a plurality of ribs are fixed to the outer periphery of the extension section at uniform intervals along the circumferential direction.

[0006] A further improvement of the present invention is that the side wall plate is annular, and the axis of the side wall plate and the axis of the pile body are parallel to each other.

[0007] A further improvement of the present invention is that the surface of the pile cap is coated with a wear-resistant layer.

[0008] A further improvement of the present invention is that the pile body is made of high-strength steel pipe.

[0009] A further improvement of the present invention is that a composite reinforcement layer is formed at the fixed connection between the pile body and the cover plate.

[0010] The present invention provides a construction method for a structure for enhancing the lateral resistance of a flexible and strong spiral pile, comprising the following steps:

[0011] S1, prefabricating the pile body and the spiral blades, pile cap and multiple ribs on its surface in a factory;

[0012] S2, passing the pile body through the through hole on the cover plate of the pile cap to form an extended end, and fixedly connecting the cover plate to the pile body; fixing a plurality of ribs along annular intervals on the outer side of the extended end of the pile body, and fixing the plurality of ribs to the cover plate;

[0013] S3. Driving the pile body together with the pile cap into the soil, ensuring that the lower surface of the cover plate is in close contact with the shallow soil.

[0014] A further improvement of the present invention is that when the cover plate and the rib plate are fixed to the pile body, the cover plate and the rib plate are welded to the surface of the pile body.

[0015] A further improvement of the present invention is that after the cover plate is welded to the pile body, foamed concrete is injected into the welding point, and after solidification, a composite reinforcement layer is formed.

[0016] A further improvement of the present invention is that after the ribs are welded to the pile body, ultrasonic flaw detection is performed on the weld seams.

[0017] The present invention arranges a pile cap above the spiral pile and fixes a rib plate on the top of the pile cap and fixes it to the pile body to increase the contact surface between the spiral top and the shallow soil, forming a multi-directional load transfer path, forcing more shallow soil to evenly share the load, effectively suppressing local bending deformation of the pile body, significantly improving lateral stiffness, and overcoming the problem of insufficient bearing capacity of traditional flexible spiral piles caused by debonding of shallow soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the pile cap above the present invention;

[0020] Figure 3 This is a schematic diagram of the bottom of the pile cap of the present invention;

[0021] Figure 4 This is a schematic diagram of the pile cap decomposition structure of the present invention;

[0022] Figure 5 The schematic diagram below shows the pile cap decomposition structure of the present invention.

[0023] Figure 6 It is a schematic diagram of the pile structure of the present invention;

[0024] In the figure: 1. cover plate; 2. rib plate; 3. side wall plate; 4. hollow area; 5. spiral blade; 6. pile body; 7. connection surface between rib plate and pile body; 8. connection surface between rib plate and cover plate. DETAILED DESCRIPTION

[0025] like Figures 1 to 6 As shown, a structure for increasing the flexibility and strengthening the lateral resistance of a spiral pile comprises: a pile body 6; a plurality of spiral blades 5 spirally wrapped around the surface of the pile body, with the plurality of spiral blades 5 spaced apart; a pile cap fixed to the top of the pile body 6, the pile cap comprising a ring-shaped side wall plate 3 and a cover plate 1 fixedly arranged on the top of the side wall plate 3, a through hole being reserved at the center of the cover plate 1, the top of the pile body 6 passes through the through hole and is fixed to the cover plate 1, the passing portion forming an extended section, and the plurality of spiral blades 5 are all located below the cover plate 1; a plurality of ribs 2, the plurality of ribs 2 extending along the ring The ribs 2 are fixed at intervals on the outer periphery of the extended section. One side of each rib 2 is on the outer surface of the extended section, and the other side, the rib 2 and the cover plate connection surface 8 are fixed to the upper surface of the cover plate 1. The ring-shaped side wall plate 3 is not a ring in the strict sense, but can be a closed geometric shape such as a rectangle or a polygon. The side wall plate 3 is spaced a certain distance between the pile body 6 so that an annular space is formed between the side wall plate 3 and the pile body 6. By forming the annular space, when the pile body 6 is inserted into the soil, the soil is located in the annular space, thereby increasing its horizontal pull-out resistance in the shallow soil. Preferably, as Figure 2 As shown, multiple ribs 2 are fixed to the outer periphery of the extended section at uniform intervals along the circumferential direction. In this embodiment, six ribs 2 are included, and each rib 2 is arranged at a 60° interval around the outer periphery of the extended section. By evenly arranging the ribs 2, the load is evenly distributed to the surrounding soil to avoid excessive load concentration.

[0026] Preferably, if Figures 1 to 6 As shown, the side wall plate 3 is annular, and the axis of the side wall plate 3 and the axis of the pile body 6 are parallel to each other. In this embodiment, the side wall plate 3 and the pile body 6 are both arranged in the vertical direction to reduce the disturbance to the surrounding soil during the driving process, thereby reducing the difficulty of driving the pile body 6 and the pile cap into the soil.

[0027] Preferably, the surface of the pile cap is coated with a wear-resistant layer. In this embodiment, the surface of the pile cap is coated with a wear-resistant tungsten carbide coating to reduce interface wear under long-term wind vibration loads.

[0028] Preferably, the pile body 6 is made of high-strength steel pipe.

[0029] A construction process for a structure for enhancing the lateral resistance of flexible and strong spiral piles, comprising the following steps:

[0030] S1, prefabricate the pile body 6 and the spiral blades 5 on its surface, the pile cap and the multiple ribs 2 in the factory;

[0031] S2, the pile body 6 is passed through the through hole on the cover plate 1 of the pile cap to form an extended section, and the cover plate 1 is fixedly connected to the pile body 6; a plurality of ribs 2 are fixed to the outer side of the extended section of the pile body 6 along annular intervals, and the plurality of ribs 2 are fixed to the cover plate 1;

[0032] S3. Drive the pile body 6 together with the pile cap into the soil, ensuring that the lower surface of the cover plate 1 is in close contact with the shallow soil.

[0033] Preferably, when fixing the cover plate 1, the rib plate 2 and the pile body 6, the cover plate 1 and the rib plate 2 are welded to the surface of the pile body 6. In this example, a laser-MAG composite welding process is adopted, combined with sandblasting pretreatment and multi-layer weld control, and non-destructive testing is performed to ensure the strength and corrosion resistance of the weld.

[0034] Preferably, after the cover plate 1 is welded to the pile body 6 , foamed concrete is injected into the welding point, and a composite reinforcement layer is formed after solidification.

[0035] Preferably, after the ribs 2 are welded to the pile body 6, ultrasonic testing is performed on the weld seam, ie, the connection surface 7 between the ribs and the pile body, to ensure that there are no defects such as pores and slag inclusions.

[0036] Preferably, the coaxiality of the pile cap and pile body 6 is calibrated by a total station during installation, and the deviation is controlled within ±3 mm.

[0037] In this embodiment, Figures 1 to 6 As shown, the pile body 6 is made of prefabricated high-strength steel pipe (Q355B), with an outer diameter of 76mm and a wall thickness of 4mm. Three sets of spiral blades 5 are welded axially along the pile body 6 at intervals. The spiral blades 5 have a diameter of 228mm, the pile diameter, and are spaced 1.05m apart. The edges of the spiral blades 5 are coated with ultra-high molecular weight polyethylene wear-resistant sleeves.

[0038] The pile cap consists of a side wall plate 3 and a cover plate 1. The cover plate 1 has an outer diameter of 350mm and a wall thickness of 15mm. The side wall plate 3 is annular, 300mm high, and 10mm thick. The pile cap surface is coated with a tungsten carbide wear-resistant coating.

[0039] Hexagonally distributed triangular ribs 2 are welded to the top surface of the cover plate 1. The thickness of the ribs decreases from 10 mm to 6 mm from the center to the edge, and the angle between adjacent ribs is 60 degrees. The ribs 2 are fixed to the outer wall of the spiral pile through continuous fillet welds, forming a rigid connection node.

[0040] The embodiments of the present invention have the following beneficial effects:

[0041] (1) Enhanced lateral resistance of shallow soil: The combined design of the pile cap and ribs 2 significantly expands the contact area between the pile body 6 and the shallow soil, forming a multi-directional load transfer path. Under horizontal loads, the close fit between the pile cap and the shallow soil and the distributed support of the ribs 2 force more shallow soil to evenly share the load, effectively suppressing local bending deformation of the pile body 6 and significantly improving lateral stiffness. This overcomes the insufficient bearing capacity of traditional flexible screw piles due to debonding of the shallow soil.

[0042] (2) Modular construction and efficient assembly: The pile body 6 and pile cap can be prefabricated in sections, with each component prefabricated in the factory. This design greatly simplifies the construction process and eliminates the need for complex equipment. It is particularly suitable for projects in remote areas or with tight deadlines. At the same time, the lightweight pile cap and the parallel alignment of the sidewall plate 3 to the axis of the pile body 6 reduce the difficulty of the driving process.

[0043] (3) Uniform load transfer and fatigue resistance optimization: The hexagonally distributed triangular ribs 2 are designed with a symmetrical geometric layout (adjacent angles are 60°) to evenly distribute the horizontal load to the shallow soil, avoiding stress concentration at the edge of the spiral blade 5. The pile cap surface is coated with a high-strength alloy, combined with the buffering effect of the filling layer, which significantly reduces the interface wear and fatigue damage under wind-induced vibration loads. It is especially suitable for scenarios where shallow soil dominates the lateral resistance under alternating wind loads, such as offshore structures and sandy areas.

[0044] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A structure for enhancing the lateral resistance of flexible and strong screw piles, characterized in that: include: pile body; A spiral blade spirally surrounds the surface of the pile body, the number of the spiral blades is multiple, and the multiple spiral blades are arranged at intervals; a pile cap fixed to the top of the pile body, the pile cap includes a side wall plate surrounding the ring and a cover plate sealing the top of the side wall plate, a through hole is reserved in the center of the cover plate, the top of the pile body passes through the through hole and is fixed to the cover plate, the passing part forms an extended section, and the multiple spiral blades are all located below the cover plate; a plurality of ribs, the multiple ribs are fixed to the outer periphery of the extended section at intervals along the annular direction, one side of each rib is fixed to the outer surface of the extended section, and the other side is fixed to the upper surface of the cover plate.

2. The structure for enhancing the lateral resistance of flexible and reinforced screw piles according to claim 1, characterized in that: A plurality of ribs are fixed to the outer periphery of the extension section at uniform intervals along the circumferential direction.

3. The structure for enhancing the lateral resistance of flexible and reinforced screw piles according to claim 1, characterized in that: The side wall plate is in the shape of a circular ring, and the axis of the side wall plate and the axis of the pile body are parallel to each other.

4. The structure for enhancing the lateral resistance of flexible and reinforced screw piles according to claim 1, characterized in that: The surface of the pile cap is coated with a wear-resistant layer.

5. The structure for enhancing the lateral resistance of flexible and reinforced screw piles according to claim 1, characterized in that: The pile body is made of high-strength steel pipe.

6. The structure for enhancing the lateral resistance of flexible and reinforced screw piles according to claim 1, characterized in that: A composite reinforcement layer is formed at the fixed connection between the pile body and the cover plate.

7. A construction method for a structure for enhancing the lateral resistance of flexible and strong screw piles according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, prefabricating the pile body and the spiral blades, pile cap and multiple ribs on its surface in a factory; S2, passing the pile body through the through hole on the cover plate of the pile cap to form an extended section, and fixedly connecting the cover plate to the pile body; fixing a plurality of ribs along annular intervals to the outer side of the extended end of the pile body, and fixing the plurality of ribs to the cover plate; S3. Driving the pile body together with the pile cap into the soil, ensuring that the lower surface of the cover plate is in close contact with the shallow soil.

8. The construction method for a structure for enhancing the lateral resistance of flexible and strong screw piles according to claim 7, characterized in that: When fixing the cover plate, the rib plate and the pile body, the cover plate and the rib plate are welded to the surface of the pile body.

9. The construction method for a structure for enhancing the lateral resistance of flexible and strong screw piles according to claim 7, characterized in that: After the cover plate is welded to the pile body, foamed concrete is injected into the welding position, and a composite reinforcement layer is formed after solidification.

10. The construction method for a structure for enhancing the lateral resistance of flexible and strong screw piles according to claim 7, characterized in that: After the ribs are welded to the pile body, ultrasonic flaw detection is performed on the welds.

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