Pile-anchor composite foundation for improving single-pile bearing capacity and construction method

Abstract

The invention relates to the technical field of pile foundation engineering, in particular to a pile-anchor composite foundation for improving the bearing capacity of a single pile and a construction method, the pile-anchor composite foundation comprises the single pile and an anchoring body, the anchoring body is arranged on the single pile in a sleeving mode, the anchoring body comprises a pile embracing disc and an anchor fluke, and the anchor fluke is installed on the pile embracing disc in the circumferential direction and extends downwards. The device can be installed in a rear-mounted mode after primary sinking of a single pile, the pile sinking procedure does not need to be additionally added, and the device is suitable for the complex construction environment of ocean engineering. The anchor flukes are uniformly distributed along the circumferential direction, can bear wave and tidal current loads in multiple directions, and are adaptive to a complex marine environment; the buckling resistance of an anchoring body is enhanced through a triangle-like area formed by the supporting arches, and effective transmission of force is ensured through rigid connection of the sleeve and the single pile.

Description

Technical Field

[0001] This application relates to the field of pile foundation engineering technology, and in particular to a pile-anchor composite foundation and construction method for improving the bearing capacity of a single pile. Background Technology

[0002] In the construction of offshore wind power, cross-sea bridges, and other marine engineering projects, the surface soil of the seabed often exhibits weak characteristics of high compressibility and low strength. When traditional monopile foundations are driven into such weak soil, they are prone to problems such as lateral displacement, settlement, or overall instability of the pile foundation due to insufficient bearing capacity of the surface soil, which seriously affects the safety and durability of the engineering structure.

[0003] To address the aforementioned issues, various solutions for enhancing the bearing capacity of monopile have been proposed in existing technologies, such as using expanded diameter piles or adding lateral support structures. However, these solutions generally suffer from drawbacks: expanded diameter piles are difficult to construct, especially in large-diameter pile foundation projects, easily increasing pile driving resistance; lateral support structures have poor adaptability and are difficult to accommodate complex ocean wave and tidal loads. Furthermore, another technology enhances bearing capacity by adding a suction cylinder composite structure to the bottom of the monopile, but this structure has stringent requirements for the uniformity of the foundation soil layer, and is prone to instability or long-term settlement in uneven soft soil foundations. Additionally, the suction cylinder alters local hydrodynamic conditions, exacerbating seabed erosion and further threatening foundation stability.

[0004] In view of the shortcomings of existing technologies, there is an urgent need for a monopile bearing capacity enhancement scheme that is easy to construct, adaptable to soft soil environments, and can take into account multi-directional load bearing capacity, so as to meet the green and efficient construction requirements of marine engineering. Summary of the Invention

[0005] This application provides a pile-anchor composite foundation and construction method for improving the bearing capacity of a single pile, in order to solve the problems of insufficient bearing capacity of single piles in soft soil environments, and the complexity or poor adaptability of reinforcement schemes in the prior art.

[0006] On the one hand, this application provides a pile-anchor composite foundation for enhancing the bearing capacity of a single pile, comprising: Single pile; An anchor body is fitted onto a single pile. The anchor body includes a pile gripping plate and anchor claws. The anchor claws are installed circumferentially on the pile gripping plate and extend downwards.

[0007] In one possible design, the pile clamping plate includes a tray and a sleeve. The tray has a clearance hole in the center, and the sleeve is located at the upper end of the clearance hole and is coaxial with the clearance hole. The sleeve and the tray are fixed on the pile by being fitted together.

[0008] In one possible design, the pallet includes two symmetrically arranged half-pallets, and the sleeve includes two symmetrically arranged half-sleeves. The side walls of the two half-pallets and the side walls of the two half-sleeves are detachably connected and together secured to the monopile.

[0009] In one possible design, multiple connecting blocks are arranged radially at intervals on the upper end face of the half-tray near the side wall. The connecting blocks have screw holes, and adjusting studs are inserted into the screw holes. The adjusting studs adjust the distance between the side walls of the two half-trays by engaging with the screw holes. A set nut is fitted at the end of the adjusting stud.

[0010] In one possible design, the anchor body also includes multiple circumferentially distributed support arches, with the upper end of the support arches connected to the outer wall of the sleeve and the lower end connected to the edge of the tray, and the middle part of the support arches having an upward-curving arch structure.

[0011] In one possible design, the lower end of the tray is provided with radially distributed radial ribs and circumferentially distributed annular ribs. And / or, the upper surface of the tray is provided with lifting rings.

[0012] In one possible design, the cross-section of the anchor claw gradually decreases from top to bottom.

[0013] In one possible design, a grouting channel is provided inside the anchor claw and on the tray. The inlet of the grouting channel is connected to the grouting pump and the grout tank through a pipe, and the outlet of the grouting channel extends to the middle of the anchor claw.

[0014] In one possible design, a release hole is provided at the lower end of the tray. The opening of the release hole is covered with a filter screen, and a curing agent capsule is provided in the release hole. The curing agent capsule includes a capsule wall and a curing agent filled in the capsule wall. The capsule wall is made of a water-swellable rubber layer.

[0015] On the other hand, this application also provides a construction method for the pile-anchor composite foundation for improving the bearing capacity of a single pile, as described above, the method comprising: A single pile is driven to a preset depth using pile driving equipment; The anchor body is aligned with the single pile and inserted using a lifting device; Adjust the anchor body so that the pile clamping disc is fixed to the outer wall of the single pile; The single pile and the anchor body are lowered as a whole, so that the anchor claw sinks into the soil and the pile sinks to the predetermined depth, thus completing the pile driving.

[0016] The beneficial effects of this application are as follows: The pile-anchor composite foundation of this application for improving the bearing capacity of a single pile adopts a modular semi-pallet and semi-sleeve design for the anchor body, which can be installed after the initial sinking of the single pile without the need for additional pile driving procedures; the adjustment of the mating structure of the stud and the set nut reduces the requirements for installation accuracy and is suitable for the complex construction environment of marine engineering.

[0017] The anchor claws are evenly distributed circumferentially, which can withstand wave and tidal loads from multiple directions and are suitable for complex marine environments; the triangular area formed by the support arch enhances the buckling resistance of the anchor body, and the rigid connection between the sleeve and the monopile ensures the effective transmission of force.

[0018] The anchor claws of the anchor body work together with the single pile to effectively reinforce the weak surface soil. Combined with the grouting reinforcement body and the surface curing agent, a three-layer reinforcement system of "deep anchor claws - middle grouting body - surface solidified soil" is formed, which increases the bearing capacity of the single pile by 80%-100% and significantly enhances its overturning resistance.

[0019] The construction method provided in this application incorporates all the advantages of the pile-anchor composite foundation for enhancing the bearing capacity of a single pile as described in this application. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the pile-anchor composite foundation provided in the embodiments of this application; Figure 2 A top view of a pile-anchor composite foundation provided in an embodiment of this application; Figure 3 A bottom view of the pile-anchor composite foundation provided in the embodiments of this application; Figure 4 A cross-sectional view of a pile-anchor composite foundation provided in an embodiment of this application; Figure 5 A schematic diagram of the pile-anchor composite foundation in the pre-assembled state provided in the embodiments of this application; Figure 6 A schematic diagram of the pile-anchor composite foundation in the locked state provided in the embodiments of this application; Figure 7 This is a schematic diagram of the construction process of the pile-anchor composite foundation provided in the embodiments of this application.

[0022] Figure label: 1. Monopile; 2. Anchor body; 21. Pile clamping plate; 211. Pallet; 2111. Half pallet; 212. Sleeve; 2121. Half sleeve; 22. Anchor claw; 23. Support arch; 3. Connecting block; 4. Adjusting stud; 5. Set nut; 6. Radial rib; 7. Annular rib; 8. Lifting ring; 9. Release hole. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The following is combined with Figures 1-7 This describes the pile-anchor composite foundation provided in the embodiments of this application for enhancing the bearing capacity of a single pile 1.

[0025] Reference Figure 1 , Figure 2 , Figure 3 As shown in the embodiment of this application, the pile-anchor composite foundation for improving the bearing capacity of a single pile 1 includes a single pile 1 and an anchor body 2. The anchor body 2 is sleeved on the single pile 1 and the bearing capacity is improved by cooperating with the single pile 1 to bear the force.

[0026] Single pile 1 is a commonly used cylindrical pile foundation in engineering, made of high-strength steel. Its diameter and length are determined according to the engineering load requirements and geological conditions. The function of single pile 1 is to serve as the main load-bearing structure of the foundation, transferring the vertical and horizontal loads of the superstructure (such as wind turbine towers and bridge piers) to the deep soil.

[0027] The anchor body 2 is a modular structure, including a pile clamping plate 21 and anchor claws 22. The anchor claws 22 are evenly installed on the pile clamping plate 21 in the circumferential direction and extend downward to form lateral support and soil anchoring effect for the single pile 1.

[0028] In some embodiments, the pile clamping plate 21 includes a pallet 211 and a sleeve 212, which are integral structures to ensure effective force transmission. The pallet 211 has an annular structure with a clearance hole in its center that matches the diameter of the single pile 1 for mounting the single pile 1. The lower end face of the pallet 211 is provided with radially distributed radial ribs 6 and annular ribs 7 distributed circumferentially. The radial ribs 6 and annular ribs 7 are interlaced to form a grid-like reinforcing structure, which can reduce the thickness of the pallet 211 cover plate while ensuring rigidity, reducing steel consumption, and uniformly transmitting the pile driving force to the anchor claw 22.

[0029] The sleeve 212 is coaxially disposed at the upper end of the clearance hole, and its inner wall is in contact with the outer wall of the single pile 1. It is fitted onto the single pile 1 together with the tray 211 to achieve the fixation of the anchor body 2 on the single pile 1. The height of the sleeve 212 is determined according to the diameter of the single pile 1 and the fixing requirements, usually 300-500mm, to ensure the connection stability between the anchor body 2 and the single pile 1.

[0030] Anchor claws 22 are evenly arranged around the circumference of the tray 211, for example, six in total. The upper end of each anchor claw 22 is welded and fixed to the clearance groove on the edge of the tray 211, and the lower end extends downward and is pointed. Along the top-to-bottom direction, the cross-section of the anchor claws 22 gradually decreases, forming a streamlined structure similar to a blade. This structure can reduce the penetration resistance when the anchor claws 22 enter the soil, facilitate the coordinated sinking of the anchor body 2 and the single pile 1, and at the same time increase the contact area and friction between the anchor claws 22 and the soil, thereby improving the anchoring effect.

[0031] In some embodiments, the pallet 211 includes two symmetrically arranged half-pallets 2111211, and the sleeve 212 includes two symmetrically arranged half-sleeves 2121212. The sidewalls of the two half-pallets 2111211 and the sidewalls of the two half-sleeves 2121212 are respectively fixed to the monopile 1 by a detachable connection structure, which facilitates post-installation after the monopile 1 has been initially driven. Specifically, a plurality of connecting blocks 3 are arranged radially at intervals near the sidewalls on the upper end face of the half-pallets 2111211, with 3-4 blocks on each half-pallet 2111211. The connecting blocks 3 are provided with screw holes, and adjusting studs 4 are inserted into the screw holes. The adjusting studs 4 can adjust the distance between the sidewalls of the two half-pallets 2111211 by threading with the screw holes. The end of the adjusting studs 4 is fitted with a set nut 5. After the monopile 1 is fitted onto the anchor body 2, the distance is locked by tightening the set nut 5, thereby achieving a rigid connection between the pile clamping plate 21 and the monopile 1.

[0032] In addition, a lifting ring 8 is provided on the upper surface of the pallet 211 along the circumferential direction to cooperate with the lifting device to lift the anchor body 2; the lifting rings 8 located on the side walls of the two half pallets 2111 and 211 are in corresponding positions, so that the same hook can lift the two lifting rings 8 simultaneously, ensuring the levelness of the anchor body 2 during the lifting process and avoiding tilting.

[0033] The anchor body 2 also includes multiple circumferentially distributed supporting arches 23. The number of supporting arches 23 is the same as that of the anchor claws 22, typically six. The upper end of the supporting arch 23 is welded and fixed to the outer wall of the sleeve 212, and the lower end is welded and fixed to the edge of the tray 211. The middle part of the supporting arch 23 has an upward-curving arched structure. This arched structure not only enhances the connection stiffness between the sleeve 212 and the tray 211, but also extends to the anchor claws 22, forming a triangular-like stable area together with the anchor claws 22 and the tray 211. The triangular-like structure has excellent buckling resistance, which can effectively disperse the stress generated during pile driving, prevent the tray 211 from buckling during pile penetration, and distribute the pile driving force more evenly to the half-tray 211 and the anchor claws 22.

[0034] Furthermore, the edge of the pallet 211 is provided with clearance grooves that are adapted to the support arch 23 and the anchor claw 22. The lower end of the support arch 23 and the upper end of the anchor claw 22 are respectively welded and fixed in the clearance grooves, and the lower end of the support arch 23 and the upper end of the anchor claw 22 are connected to each other by welding to form an integrated force-bearing system of "support arch 23-anchor claw 22-pallet 211", which further improves the overall stability of the anchor body 2.

[0035] To further enhance the reinforcement effect on the surface soft soil, a connecting grouting channel is provided inside the anchor claw 22 and on the tray 211. The inlet of the grouting channel is located on the upper end face of the tray 211 and is connected to the external grouting pump and grout tank through a pipe; the outlet of the grouting channel extends to the middle of the anchor claw 22, and a one-way valve is installed at the outlet to prevent soil particles from flowing back and clogging the channel. During construction, cement-water glass dual-liquid grout and other grouts are injected into the soil through the grouting pump, forming a middle layer of grouting reinforcement around the middle of the anchor claw 22, thus expanding the reinforcement range.

[0036] Meanwhile, the lower end face of the tray 211 has multiple release holes 9, and the openings of the release holes 9 are covered with filter screens. A curing agent capsule is placed in each release hole 9. The curing agent capsule includes a capsule wall and a curing agent filled within the capsule wall. The capsule wall is made of a water-swellable rubber layer. When the anchor body 2 sinks to the seabed surface, the water-swellable rubber layer slowly expands upon contact with seawater, breaking through the capsule wall within 3-7 days, releasing the curing agent, reducing the surface soil moisture content, increasing soil cohesion, and forming a surface reinforcement layer.

[0037] When a single pile 1 is subjected to wave and wind loads, the load is first transferred to the ring anchoring system, and then transferred to the middle grouting body through the anchor claw 22. Because the grouting body is combined with a large area of ​​soil, it disperses the load to the surface reinforcement layer and the deep soil, avoiding the soil shear failure caused by the load being concentrated at the tip of the anchor claw 22 in traditional structures.

[0038] The curing agent and grouting material not only improve the soil but also fill the gap between the anchor claw 22 and the soil, making the anchor claw 22 and the improved soil form an integrated bearing unit. Compared with the original contact between the anchor claw 22 and the natural soft soil, the friction between the improved soil and the anchor claw 22 can be increased by 40%-60%, and the pull-out bearing capacity is significantly enhanced.

[0039] Based on the above-mentioned pile-anchor composite foundation, this application embodiment also provides a construction method, including the following steps: Initial sinking of monopile 1: Using pile driving equipment such as a pile driving vessel, monopile 1 is vertically sunk to a preset depth (usually 2.0-3.0m below the seabed surface) to give monopile 1 initial stability and prevent tilting during subsequent installation of anchor body 2.

[0040] Pre-assembly and hoisting of anchor body 2: On the construction platform or transport ship, anchor body 2 is pre-assembled: the two half pallets 2111211 and the two half sleeves 2121212 are initially connected by adjusting studs. At this time, the set nut 5 is not tightened, leaving a gap of 10-20mm to facilitate the installation of monopile 1; then, the hook of the hoisting device is hooked onto the lifting ring 8 on the upper end of the pallet 211 to ensure that the lifting rings 8 in symmetrical positions are stressed synchronously, and the anchor body 2 is lifted smoothly by the cable and moved directly above the monopile 1.

[0041] Anchor 2 installation and fixing: Adjust the position of the lifting device so that the clearance hole of the anchor 2 is aligned with the monopile 1, and slowly lower the anchor 2 to the preset height (usually 0.5-1.0m above the seabed surface); then, by adjusting the studs, reduce the distance between the two half trays 2111211 and the two half sleeves 2121212 so that the inner wall of the sleeve 212 fits against the outer wall of the monopile 1, tighten the set nut 5, lock the relative position of the anchor 2 and the monopile 1, and complete the fixing of the pile clamping plate 21.

[0042] Integral pile driving: Remove the lifting device and use the pile driving equipment to continue to drive the single pile 1 and the anchor body 2 as a whole. During the sinking process, the anchor claw 22 can smoothly penetrate the soil due to its gradually decreasing cross-section. At the same time, the radial rib 6 and the annular rib 7 at the lower end of the tray 211 can help to disperse the pile driving force. The pile driving is completed when the single pile 1 is driven to the predetermined depth. Grouting and Curing Agent Release: If the geological conditions are extremely soft soil, start the grouting pump, control the grouting pressure at 0.5-2.0MPa, and inject the grout into the surrounding soil of the middle part of the anchor claw 22 through the grouting channel to form a middle layer grouting body; At the same time, the curing agent capsule in the release hole 9 at the lower end of the tray 211 has come into contact with seawater, and the capsule wall begins to slowly expand. Subsequently, the curing agent in the capsule wall will be automatically released to form the surface reinforced soil.

[0043] After the pile driving is completed, it is cured for 7-10 days until the grouting and surface curing agent reach the design strength. The strength of the reinforced soil is tested by static cone penetration test, and the verticality of single pile 1 is monitored by inclinometer. After ensuring that all indicators meet the project requirements, the acceptance is completed.

[0044] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A pile-anchor composite foundation for enhancing the bearing capacity of a single pile, characterized in that, include: Single pile; An anchor body, which is fitted onto the single pile, includes a pile gripping plate and anchor claws, with the anchor claws circumferentially mounted on the pile gripping plate and extending downwards.

2. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 1, characterized in that, The pile clamping plate includes a tray and a sleeve. The tray has a clearance hole in the center. The sleeve is located at the upper end of the clearance hole and is coaxial with the clearance hole. The sleeve and the tray are fixed on the single pile by being fitted together.

3. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 2, characterized in that, The pallet includes two symmetrically arranged half-pallets, and the sleeve includes two symmetrically arranged half-sleeves. The side walls of the two half-pallets and the side walls of the two half-sleeves are detachably connected and together fixed to the monopile.

4. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 3, characterized in that, Multiple connecting blocks are arranged radially at intervals on the upper end face of the half-tray near the side wall. Each connecting block has a screw hole, and an adjusting stud passes through the screw hole. The adjusting stud adjusts the distance between the side walls of the two half-trays by threading with the screw hole. A set nut is fitted at the end of the adjusting stud.

5. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 2, characterized in that, The anchor body also includes multiple circumferentially distributed support arches. The upper end of the support arch is connected to the outer wall of the sleeve, and the lower end is connected to the edge of the tray. The middle part of the support arch has an upward-curving arch structure.

6. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 2, characterized in that, The lower end of the tray is provided with radial ribs distributed in the radial direction and annular ribs distributed in the circumferential direction. And / or, the upper surface of the tray is provided with a lifting ring.

7. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 1, characterized in that, The cross-section of the anchor claw gradually decreases from top to bottom.

8. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to any one of claims 2-6, characterized in that, A grouting channel is provided inside the anchor claw and on the tray. The inlet of the grouting channel is connected to the grouting pump and the grout tank through a pipe, and the outlet of the grouting channel extends to the middle of the anchor claw.

9. The pile-anchor composite foundation for enhancing the bearing capacity of a single pile according to claim 8, characterized in that, The tray has a release hole at the lower end, the opening of the release hole is covered with a filter screen, and a curing agent capsule is placed in the release hole. The curing agent capsule includes a capsule wall and a curing agent filled in the capsule wall. The capsule wall is made of a water-swellable rubber layer.

10. A construction method, characterized in that, The method of using the pile-anchor composite foundation for enhancing the bearing capacity of a single pile as described in any one of claims 1-9 includes: A single pile is driven to a preset depth using pile driving equipment; The anchor body is aligned with the single pile and inserted using a lifting device; Adjust the anchor body so that the pile clamping disc is fixed to the outer wall of the single pile; The single pile and the anchor body are lowered as a whole, so that the anchor claw sinks into the soil and the pile sinks to the predetermined depth, thus completing the pile driving.

Images