Pile pulling device and pile pulling method suitable for precast pile with large burial depth

Abstract

The invention provides a pile pulling device and a pile pulling method suitable for a precast pile with a large burial depth. The precast pile pulling device comprises a pile pulling sleeve, a pile pulling frame, at least one turning plate set and a cover plate. The pile pulling frame is located below the pile pulling casing pipe, the pile pulling frame and the pile pulling casing pipe are coaxially arranged and communicate with each other, and a pile body channel which communicates in the axial direction of the pile pulling casing pipe and can allow a precast pile to be inserted therein is formed. The turning plate set comprises two turning plates, and the two turning plates are rotationally connected with the two opposite plate bodies of the pile pulling frame correspondingly. The cover plate is arranged on the side, corresponding to the opening, of the pile pulling sleeve, and one end of the cover plate is rotationally connected with the pile pulling frame. And the turning plate set avoids the precast pile in the storage state, sleeving of the device is facilitated, a traditional mechanical clamping structure is replaced, and extrusion damage to the pile body is avoided. The cover plate further fixes the position of the pile body, the pile body is prevented from being disengaged from the opening side, device installation is facilitated in the open state, the overall structure is suitable for a large-burial-depth scene, and the pile pulling stability and efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of building construction, and in particular to a pile extraction device and method suitable for precast piles with large burial depths. Background Technology

[0002] With the acceleration of urbanization, land resources in urban core areas are becoming increasingly scarce, making river-crossing tunnel projects one of the core means to alleviate traffic pressure and optimize urban road networks. However, the construction of river-crossing tunnels requires crossing flood control walls on both banks, inevitably leading to conflicts with the flood control wall pile foundations. This necessitates the removal and modification of the existing flood control wall pile foundations. Traditional direct pile extraction methods have disadvantages such as low efficiency and slow speed, and are also prone to problems such as pile breakage, making pile extraction difficult. Summary of the Invention

[0003] The main objective of this invention is to provide a precast pile extraction device suitable for deep burial, in order to solve the technical problems of low efficiency, slow speed, and easy pile fracture in the direct pile extraction method.

[0004] To achieve the above objectives, the present invention provides a precast pile extraction device suitable for deep burial, comprising:

[0005] When the pile casing is pulled out, one of the circumferential walls is missing, forming an opening.

[0006] A pile extraction frame is located below the pile extraction sleeve. The pile extraction frame is coaxially arranged and connected with the pile extraction sleeve, forming a pile channel that is axially connected along the pile extraction sleeve and allows for the insertion of precast piles.

[0007] At least one flap assembly, the flap assembly including two flaps, the two flaps being rotatably connected to two opposite plates of the pile extraction frame, having an upward rotating and retracted state to avoid the precast pile at the edge of the pile channel, and a downward rotating and extended state to restrict the precast pile within the pile channel.

[0008] A cover plate is disposed on the side of the pile extraction sleeve corresponding to the opening. One end of the cover plate is rotatably connected to the pile extraction frame. The cover plate has a limited state that rotates towards the side closer to the pile channel and an open state that rotates away from the pile channel.

[0009] According to an embodiment of this application, the pile extraction frame includes two opposing side panels, and the two side panels are connected one-to-one with the two flip plates. Each side panel includes a plate body, a set of mounting plates disposed on the outside of the plate body, and a plate body pivot. The plate body has an installation opening corresponding to the position of the mounting plate. One end of the flip plate passes through the installation opening and is mounted on the mounting plate through the plate body pivot, and rotates around the axis relative to the plate body pivot.

[0010] According to an embodiment of this application, the lower side of the flap near the pile channel is an upwardly inclined wedge-shaped surface.

[0011] According to an embodiment of this application, the lower side of the flap has a reinforcing plate at the end away from the pile channel, and when the flap is in the unfolded state, the reinforcing plate abuts against the plate body.

[0012] According to an embodiment of this application, the plate body includes an outer side plate, an inner side plate, and a connecting plate. The outer side plate and the inner side plate are disposed opposite to each other and connected by the connecting plate. The mounting plate is mounted on the outer side plate.

[0013] The outer side plate has an outer opening, and the inner side plate has an inner opening corresponding to the outer opening, which together form the mounting opening. The upper edge of the inner opening is higher than the upper edge of the outer opening, and the lower edge of the inner opening is flush with the lower edge of the outer opening, thus limiting the flap when it is unfolded.

[0014] According to an embodiment of this application, the pile extraction frame is a frame structure with an opening on the same side as the pile extraction sleeve, and the pile extraction frame has a back panel, which is connected to the two side panels.

[0015] According to an embodiment of this application, the pile extraction sleeve includes a back wall and two flange walls, which are connected to the back wall and are arranged symmetrically.

[0016] According to an embodiment of this application, both flange walls are provided with arc-shaped grooves, the two arc-shaped grooves are arranged opposite each other, and the height of the arc-shaped grooves gradually decreases from the side away from the back wall to the side closer to the back wall.

[0017] The cover plate has a lower rotating shaft assembly and an upper rotating shaft assembly. The lower rotating shaft assembly is rotatably connected to the two plate bodies, and the upper rotating shaft assembly extends into two arc-shaped sliding grooves respectively.

[0018] According to an embodiment of this application, the two flange walls have flange portions and flat portions, the flat portions are connected to the pile extraction frame, the arc-shaped groove is located in the flat portions, the width of the flange portions gradually increases from top to bottom, and the lower end is flush with the flat portions.

[0019] This application also provides a method for extracting precast piles with large burial depth, including the following steps:

[0020] The aforementioned precast pile extraction device is inserted along the axial direction of the precast pile.

[0021] The precast pile extraction device is struck and vibrated downwards, causing it to penetrate the soil layer to a depth of more than 1 meter greater than the tip of the precast pile.

[0022] Increase the intensity of vibration so that at least one flap group of the precast pile extraction device is in an unfolded state and the cover plate is in a limited state.

[0023] The precast pile extraction device is pulled upwards, causing the precast pile to be pulled out.

[0024] In the aforementioned precast pile extraction device suitable for deep burial, the pile channel provides precise guidance for the extraction of the precast pile, preventing the pile from shifting or tilting during extraction and reducing the risk of pile breakage. The flap assembly, in its retracted state, avoids the precast pile, facilitating device insertion; in its extended state, it restricts the pile, transmits extraction force, and replaces traditional mechanical clamping structures, avoiding crush damage to the pile. The cover plate, located on the open side, surrounds the extraction sleeve in the restricted state, further fixing the pile position and preventing the pile from detaching from the open side; in the open state, it facilitates device installation. The overall structure is adaptable to deep burial scenarios, improving the stability and efficiency of pile extraction. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 This is a front view of a precast pile extraction device suitable for deep burial, according to one embodiment of this application.

[0027] Figure 2 This is a left view of a precast pile extraction device suitable for deep burial, according to one embodiment of this application.

[0028] Figure 3 This is a schematic diagram of the usage state of a precast pile extraction device suitable for deep burial, according to one embodiment of this application.

[0029] Figure 4 This is a schematic diagram of the unfolded state of the flip panel according to one embodiment of this application.

[0030] Figure 5 This is a schematic diagram from another perspective showing the unfolded state of the flap according to one embodiment of this application.

[0031] Figure 6 This is a schematic diagram from one perspective of the storage state of the flap according to one embodiment of this application.

[0032] Figure 7 This is a schematic diagram from another perspective of the storage state of the flap according to one embodiment of this application.

[0033] Figure 8 This is a schematic diagram of the flap, cover plate and rotating shaft structure according to one embodiment of this application.

[0034] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0035] 1. Pile extraction sleeve; 2. Pile extraction frame; 3. Plate pivot; 4. Flip plate; 5. Cover plate; 2-1. Back panel; 2-2. Side panel; 2-3. Mounting plate; 2-4. Mounting port; 2-5. Inner side panel; 2-6. Connecting plate; 2-7. Outer side panel; Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0038] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0039] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0040] This invention provides a precast pile extraction device suitable for deep burial, see [link to relevant documentation]. Figures 1-3 It includes a pile extraction sleeve, a pile extraction frame, at least one flap assembly, and a cover plate. The pile extraction sleeve has a circumferentially missing wall section, forming an opening.

[0041] The pile extraction sleeve consists of multiple walls, with one wall missing. The pile extraction sleeve is a tubular structure fitted over the outside of the precast pile to provide vertical guidance and protection, reducing the frictional resistance of the surrounding soil during pile extraction.

[0042] The pile extraction frame is located below the pile extraction sleeve. The pile extraction frame and the pile extraction sleeve are coaxially arranged and connected to each other, forming a pile channel that is axially connected along the pile extraction sleeve and allows for the insertion of precast piles.

[0043] The pile extraction frame is a frame structure that connects the pile extraction sleeve and the flap assembly, providing installation support for the flap assembly and forming a pile channel together with the pile extraction sleeve. The pile extraction frame and the pile extraction sleeve can be connected by welding. The size of the pile channel is larger than the size of the precast pile.

[0044] At least one flap assembly, the flap assembly including two flaps, the two flaps being rotatably connected to two opposite plates of the pile extraction frame, having an upward rotating and retracted state to avoid the precast pile at the edge of the pile channel, and a downward rotating and extended state to restrict the precast pile within the pile channel.

[0045] The flap assembly consists of two rotatable flaps that switch states by rotation to avoid or limit the precast piles. It is used to clamp the pile body and transmit the pile extraction force during pile extraction.

[0046] The flap assembly can be a single flap assembly (suitable for precast piles with smaller diameters) or a double flap assembly (set at intervals between the upper and lower flaps to suit precast piles with larger diameters or longer lengths, enhancing the stability of the limit position).

[0047] See Figure 6 and Figure 7 The two flaps of the flap assembly can rotate upwards and be stored at the edge of the pile channel. In this way, when the precast pile extraction device is inserted downwards into the precast pile, it is blocked by the precast pile and stored in the storage state, without interfering with the precast pile, and the precast pile can pass smoothly through the pile channel.

[0048] See Figure 4 and Figure 5 The two flaps can rotate downwards and unfold, thereby extending into the pile channel to restrict the precast pile. When the precast pile extraction device penetrates deep below the precast pile, the flaps automatically open under their own weight and soil compression by means of vibration hammer, etc., pressing against the lower pile tip of the precast pile to clamp the pile body and transmit the extraction force.

[0049] See Figure 3 For ease of explanation, the direction of the opening of the pile extraction sleeve is set as the length direction. The flap assembly can be set along the length direction or along the width direction. If set along the width direction, the two flaps are distributed along the width direction and set on the two walls respectively.

[0050] See Figure 3A cover plate is disposed on the side of the pile extraction sleeve corresponding to the opening. One end of the cover plate is rotatably connected to the pile extraction frame. The cover plate has a limited state that rotates towards the side of the pile channel and an open state that rotates away from the side of the pile channel.

[0051] The cover plate is set on the opening side of the pile extraction sleeve. It is a plate-shaped structure that helps to limit the position of the pile or facilitates the insertion of the device into the pile by rotating to switch states.

[0052] When the precast pile extraction device is inserted into the precast pile, the cover plate is held in place by the precast pile and rotates to the side away from the pile body channel, thus opening up the precast pile without interfering with it. The precast pile can then pass smoothly through the pile body channel.

[0053] When the precast pile extraction device penetrates deep beneath the precast pile, the cover plate, under its own weight and the pressure of the soil, is rotated towards the side of the pile channel by means of vibration from a vibratory hammer, thus pressing against the side of the precast pile. This, together with the extraction sleeve, encloses the precast pile circumferentially, preventing it from detaching from the open side.

[0054] In the aforementioned precast pile extraction device suitable for deep burial, the pile channel provides precise guidance for the extraction of the precast pile, preventing the pile from shifting or tilting during extraction and reducing the risk of pile breakage. The flap assembly, in its retracted state, avoids the precast pile, facilitating device insertion; in its extended state, it restricts the pile, transmits extraction force, and replaces traditional mechanical clamping structures, avoiding crush damage to the pile. The cover plate, located on the open side, surrounds the extraction sleeve in the restricted state, further fixing the pile position and preventing the pile from detaching from the open side; in the open state, it facilitates device installation. The overall structure is adaptable to deep burial scenarios, improving the stability and efficiency of pile extraction.

[0055] In some embodiments, see Figure 4 , Figure 5 , Figure 6 and Figure 7 The pile extraction frame includes two opposing side panels, which are connected one-to-one with two flip plates. Each side panel includes a plate body, a set of mounting plates disposed on the outside of the plate body, and a plate body pivot. The plate body has an installation opening corresponding to the position of the mounting plate. One end of the flip plate passes through the installation opening and is mounted on the mounting plate via the plate body pivot, rotating around the pivot relative to the plate body pivot.

[0056] The side panel is a major component of the pile extraction frame, a plate-like structure used to install the flapper, providing rotational support and limiting its position. The mounting plate is an auxiliary plate structure located on the outside of the plate body, used to install the plate's rotating shaft and limit the flapper's rotation range. The plate's rotating shaft is a shaft-like component that passes between the flapper and the mounting plate, allowing the flapper to rotate around it. The mounting opening is an opening structure formed on the plate body, allowing one end of the flapper to pass through and rotate.

[0057] The split design of the side panel (panel body, mounting plate, and panel pivot) facilitates the installation and maintenance of the flip panel; the mounting port provides rotation space for the flip panel, avoiding interference between the flip panel and the panel body; the mounting plate limits the rotation trajectory of the flip panel, ensuring accurate positioning of the flip panel in both the retracted and unfolded states, improving the reliability of the flip panel's operation, thereby ensuring the stability of the precast pile's positioning, avoiding uneven transmission of pile extraction force due to flip panel offset, and reducing the risk of pile breakage.

[0058] In some embodiments, see Figure 4 , Figure 5 , Figure 6 and Figure 7 The lower side of the flap, near the end of the pile channel, is an upwardly inclined wedge-shaped surface.

[0059] A wedge-shaped surface refers to the inclined surface on the underside of the flap, near the end of the pile channel, which serves a guiding function. Its angle is not limited, such as a 30° inclination angle or a 45° inclination angle.

[0060] When the device is inserted into the precast pile, the upward-sloping wedge-shaped surface can guide the flap to rotate automatically upward to the storage state through the jacking action of the pile body. There is no need for manual adjustment of the flap position, which simplifies the device installation process and improves installation efficiency. At the same time, the wedge-shaped surface structure reduces the contact stress between the flap and the pile body, avoids damage to the pile surface, and is suitable for precast piles with different surface conditions.

[0061] In some embodiments, see Figure 4 , Figure 5 , Figure 6 and Figure 7 The lower side of the flap is provided with a reinforcing plate at the end away from the pile channel. When the flap is in the unfolded state, the reinforcing plate abuts against the plate body.

[0062] The reinforcing plate significantly improves the bending strength of the flap, preventing deformation or breakage when subjected to pile extraction force and extending the service life of the device. When the flap is unfolded, the reinforcing plate abuts against the plate body, forming a stable force transmission path. The pile extraction force is transmitted through the reinforcing plate to the pile extraction frame and then to the external pile extraction equipment, ensuring uniform transmission of the pile extraction force, avoiding excessive local stress on the flap and preventing damage, thus improving the overall load-bearing capacity of the device and adapting to the extraction requirements of deep-buried precast piles.

[0063] In some embodiments, see Figure 4 , Figure 5 , Figure 6 and Figure 7 The plate body includes an outer side plate, an inner side plate, and a connecting plate. The outer side plate and the inner side plate are arranged opposite to each other and connected by the connecting plate. The mounting plate is installed on the outer side plate.

[0064] The outer side plate has an outer opening, and the inner side plate has an inner opening corresponding to the outer opening, which together form the mounting opening. The upper edge of the inner opening is higher than the upper edge of the outer opening, and the lower edge of the inner opening is flush with the lower edge of the outer opening, thus limiting the flap when it is unfolded.

[0065] The three-layer structure of the plate body (outer side plate, inner side plate, and connecting plate) significantly improves its overall rigidity and deformation resistance, adapting to the complex stress environment during deep pile extraction; the design of the upper edge of the inner opening being higher than the upper edge of the outer opening provides ample space for the flap rotation, avoiding interference with the flap when it is in the retracted state, and ensuring the reliability of the flap operation.

[0066] When the flap unfolds, the reinforcing plate abuts against the lower edge of the outer opening of the outer plate and the lower edge of the inner opening of the inner plate, forming a precise limit and preventing the flap from rotating excessively and causing the limit to fail.

[0067] In some embodiments, see Figure 4 , Figure 5 , Figure 6 and Figure 7 The pile extraction frame is a frame structure with an opening on the same side as the pile extraction sleeve. The pile extraction frame has a back panel, which is connected to the two side panels.

[0068] The back panel connects the two side panels to form a stable frame structure, which improves the torsional and bending resistance of the pile extraction frame and prevents the frame from deforming during pile extraction. At the same time, the back panel prevents the pile from shifting to the opposite side of the opening, and together with the cover plate, further limits the position of the pile in the pile channel, ensuring the stability of the pile during extraction and reducing the risk of pile tilting and breakage.

[0069] In some embodiments, see Figures 1-3 The pull-out sleeve includes a back wall and two flange walls, which are connected to the back wall and are arranged symmetrically.

[0070] The back wall is the wall opposite the opening of the pile extraction sleeve. It provides back support and guidance for the pile, reducing the pile's deviation to the back side during extraction.

[0071] The flange wall is a wall structure that is symmetrically arranged on both sides of the back wall, and together with the back wall, forms the main body of the pull-out sleeve, enhancing the rigidity of the sleeve and providing an installation foundation for the cover plate.

[0072] The pile extraction casing structure, consisting of the back wall and two symmetrical flange walls, balances rigidity and lightweight design. While ensuring that the casing can withstand the soil pressure and frictional resistance during deep pile extraction, it reduces the overall weight of the device, facilitating transportation and installation. The symmetrical flange walls provide symmetrical support for the subsequent installation of the cover plate, ensuring smooth rotation of the cover plate, avoiding jamming due to uneven stress, improving the overall reliability of the device, and adapting to the complex construction environment of riverside silt areas.

[0073] In some embodiments, see Figure 1 , Figure 2 and Figure 3 Both flange walls are provided with arc-shaped sliding grooves, which are arranged opposite each other. The height of the arc-shaped sliding grooves gradually decreases from the side away from the back wall to the side closer to the back wall. The cover plate has a lower rotating shaft assembly and an upper rotating shaft assembly. The lower rotating shaft assembly is rotatably connected to the two plate bodies, and the upper rotating shaft assembly extends into the two arc-shaped sliding grooves respectively.

[0074] The arc-shaped groove is a groove-like structure formed on the flange wall, which is arc-shaped and gradually changes in height. It provides a sliding path for the rotating shaft assembly on the cover plate and guides the rotation of the cover plate.

[0075] The lower and upper rotating shaft assemblies are located at both ends of the cover plate and cooperate with the plate body and the arc-shaped slide groove, respectively, so that the cover plate can rotate around the lower rotating shaft assembly while the upper rotating shaft assembly slides along the arc-shaped slide groove.

[0076] The gradually changing arc-shaped chute guides the cover plate to rotate along a preset arc trajectory through the sliding of the upper rotating shaft assembly, preventing the cover plate from shifting or jamming when switching states. The dual-shaft cooperation between the lower and upper rotating shaft assemblies makes the rotation of the cover plate more stable and prevents deformation caused by uneven force on one side. No additional drive device is required; the cover plate state can be switched simply by manual pushing or slight lifting by external pile extraction equipment, simplifying the operation process. It is especially suitable for construction scenarios with limited space in riverside silt areas.

[0077] In some embodiments, see Figure 1 , Figure 2 and Figure 3 The two flange walls have flange portions and flat portions. The flat portions are connected to the pile extraction frame. The arc-shaped groove is located in the flat portions. The width of the flange portions gradually increases from top to bottom, and the lower end is flush with the flat portions.

[0078] The flange section is the upper region of the flange wall. The gradually changing width design is used to enhance the wall rigidity while reducing the volume of the upper part of the device.

[0079] The leveling section is the lower area of ​​the flange wall, with a flat surface, which is used to connect with the pile extraction frame and to form an arc-shaped sliding groove.

[0080] The gradually changing width design of the flange section enhances the bending stiffness of the wall while avoiding an overly bulky upper part of the device, reducing interference in narrow construction spaces. The flat section provides a stable installation base for the arc-shaped chute, ensuring the precise positioning of the chute and guaranteeing the flatness of the connection between the flange wall and the pile extraction frame, preventing the cover plate from rotating and jamming due to misalignment. The lower end of the flange section is flush with the flat section, making the wall more evenly stressed, extending the service life of the device, and adapting to the long-term loads during deep pile extraction.

[0081] This application also provides a method for extracting precast piles with large burial depths, see [link to relevant documentation]. Figure 1 , Figure 2 and Figure 3 This includes the following steps:

[0082] S100: Insert the precast pile extraction device along the axial direction of the precast pile.

[0083] S200: The precast pile extraction device is struck and vibrated downwards, causing it to penetrate the soil layer to a depth greater than 1 meter above the tip of the precast pile.

[0084] For example, a vibratory pile driver and vibratory sinking method are used to sink the pile extraction sleeve along the side wall of the precast pile. Since the flip-up and cover plates can rotate through corresponding shafts, they open upwards during sinking, facilitating the sinking of the pile extraction sleeve and reducing sinking resistance. During this process, two theodolites are used for observation to control the perpendicularity of the pile extraction sleeve to the precast pile, and the sinking depth must be at least 1 meter greater than the tip of the old pile.

[0085] S300: Increase the intensity of vibration so that at least one flap group of the precast pile extraction device is in an unfolded state and the cover plate is in a limited state.

[0086] For example, once in place, increase the vibration intensity of the vibratory hammer to cause the flaps and covers to open automatically under their own weight and soil compression. Figure 3 As shown, with openings 2-4 as support, the flap extends horizontally to block the lower tip of the old pile.

[0087] S400: Pull out the precast pile pulling device upwards, driving the precast pile out.

[0088] For example, a vibratory pile driver is used to pull up the pile extraction sleeve, and a flapping plate pulls the pile out together, while the cover plate restricts the movement of the pile during the extraction process.

[0089] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A precast pile extraction device suitable for deep burial, characterized in that, include: When the pile casing is pulled out, one of the circumferential walls is missing, forming an opening; A pile extraction frame is located below the pile extraction sleeve. The pile extraction frame is coaxially arranged and connected with the pile extraction sleeve to form a pile channel that is axially connected along the pile extraction sleeve and allows for the insertion of precast piles. At least one flap assembly, the flap assembly including two flaps, the two flaps being rotatably connected to two opposite plates of the pile extraction frame, having an upward rotating and retracted state to avoid the precast pile at the edge of the pile channel, and a downward rotating and extended state to restrict the precast pile within the pile channel. A cover plate is disposed on the side of the pile extraction sleeve corresponding to the opening. One end of the cover plate is rotatably connected to the pile extraction frame. The cover plate has a limited state that rotates towards the side closer to the pile channel and an open state that rotates away from the pile channel.

2. The precast pile extraction device suitable for deep burial as described in claim 1, characterized in that, The pile extraction frame includes two opposing side panels, which are connected one-to-one with two flip plates. Each side panel includes a plate body, a set of mounting plates disposed on the outside of the plate body, and a plate body pivot. The plate body has an installation opening corresponding to the position of the mounting plate. One end of the flip plate passes through the installation opening and is mounted on the mounting plate via the plate body pivot, rotating around the pivot relative to the plate body pivot.

3. The precast pile extraction device suitable for deep burial as described in claim 2, characterized in that, The lower side of the flap, near the end of the pile channel, is an upwardly inclined wedge-shaped surface.

4. The precast pile extraction device suitable for deep burial as described in claim 2, characterized in that, The lower side of the flap, away from the pile channel, has a reinforcing plate. When the flap is in the unfolded state, the reinforcing plate abuts against the plate body.

5. The precast pile extraction device suitable for deep burial as described in claim 2, characterized in that, The plate body includes an outer side plate, an inner side plate, and a connecting plate. The outer side plate and the inner side plate are arranged opposite to each other and connected by the connecting plate. The mounting plate is installed on the outer side plate. The outer side plate has an outer opening, and the inner side plate has an inner opening corresponding to the outer opening, which together form the mounting port; the upper edge of the inner opening is higher than the upper edge of the outer opening, and the lower edge of the inner opening is flush with the lower edge of the outer opening, thus limiting the flap when it is unfolded.

6. The precast pile extraction device suitable for deep burial as described in claim 2, characterized in that, The pile extraction frame is a frame structure with an opening on the same side as the pile extraction sleeve. The pile extraction frame has a back panel, which is connected to the two side panels.

7. The precast pile extraction device suitable for deep burial as claimed in any one of claims 2 to 6, characterized in that, The pull-out sleeve includes a back wall and two flange walls, which are connected to the back wall and are arranged symmetrically.

8. The precast pile extraction device suitable for deep burial as described in claim 7, characterized in that, Both flange walls are provided with arc-shaped grooves, which are arranged opposite each other. The height of the arc-shaped grooves gradually decreases from the side away from the back wall to the side closer to the back wall. The cover plate has a lower rotating shaft assembly and an upper rotating shaft assembly. The lower rotating shaft assembly is rotatably connected to the two plate bodies, and the upper rotating shaft assembly extends into two arc-shaped sliding grooves respectively.

9. The precast pile extraction device suitable for deep burial as described in claim 8, characterized in that, The two flange walls have flange portions and flat portions. The flat portions are connected to the pile extraction frame. The arc-shaped groove is located in the flat portions. The width of the flange portions gradually increases from top to bottom, and the lower end is flush with the flat portions.

10. A method for extracting precast piles with large burial depth, characterized in that, Includes the following steps: The precast pile extraction device according to any one of claims 1 to 9 is inserted along the axial direction of the precast pile; The precast pile extraction device is struck and vibrated downwards, causing it to penetrate the soil layer to a depth of more than 1 meter greater than the tip of the precast pile. Increase the intensity of vibration so that at least one flap group of the precast pile extraction device is in an unfolded state and the cover plate is in a limited state. The precast pile extraction device is pulled upwards, causing the precast pile to be pulled out.

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