Cast-in-situ bored pile head breaking device and method

Abstract

The invention discloses a cast-in-situ bored pile head breaking device and method, and the device comprises an engineering plastic sheet (1), a steel bar preformed hole conical rubber ring (2) welded with the engineering plastic sheet (1), a high-strength bolt bar (3) with a sleeve, a PVC sleeve (5), and wedge blocks (4) fixed at the two ends of the high-strength bolt bar in the high-strength bolt bar (3) with the sleeve through nuts (7), a circular guide pipe pouring reserved opening (6) is formed in the middle of the engineering plastic sheet (1), the high-strength bolt rods (3) with the sleeves are evenly and symmetrically distributed on the periphery of the guide pipe pouring reserved opening (6), the device is accurately pre-buried in the pile top elevation position, and the PVC sleeves (5) penetrate through steel bars to be inserted into the steel bar reserved hole conical rubber rings (2) to prevent concrete from being bonded with longitudinal steel bars. After pile body concrete reaches certain strength, torque is generated by screwing the bolt (7), the wedge-shaped block (4) is pushed to generate shearing force on the pile body, and efficient and accurate breaking of the pile head concrete is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of pile foundation construction, and more specifically, relates to a device and method for breaking a bored cast-in-place pile head. Background Art

[0002] In the field of civil construction, bored cast-in-place piles, as a mature and effective foundation treatment technology, have been widely used in the foundation construction of various construction projects due to their good bearing capacity and adaptability. In order to ensure the construction quality of bored cast-in-place piles and the overall stability of the structure, a certain height is usually over-cast above the designed pile top elevation, and this height range is usually controlled between 100 and 200 meters. Such over-casting measures are intended to compensate for errors that may occur during the construction process and ensure that the pile body can achieve the expected bearing effect in the subsequent superstructure construction. When the construction enters the construction stage of the pile foundation superstructure, it is necessary to break up this part of the over-cast concrete.

[0003] The traditional breaking method requires that after digging out the soil between the piles, a small crushing machine combined with manual breaking or a pile cutter with casing is used for overall breaking. Small machines combined with manual breaking produce loud noises, and the dust generated by breaking has a great impact on the health of the workers. The pile head breaking operation surface is uneven, the pile head steel bars are severely deformed, and the huge vibration can easily damage the lower pile body and its internal detection device of the bored pile. It requires a lot of manpower and material resources, is costly, and inefficient. The overall breaking of the pile cutter with casing requires a large operating space, the pile head breaking operation surface is uneven, and it is only suitable for breaking the bored pile heads with large pile spacing. It has great limitations and also has a large noise problem. In order to solve the problems existing in the traditional pile head breaking method, a variety of new pile head breaking technologies have been developed in recent years, such as the patent document with application number CN202010673640.4. The invention patent provides a method for breaking the bored pile head. Before the bored pile body concrete is initially set, a group of vertically inserted PVC pipes are buried in the pile head part. When the strength of the pile body concrete reaches more than 70%, the PVC pipe is poured with pre-cracking slurry that will gradually expand by self-heating. The pre-cracking slurry must be poured into the PVC pipe before heating. After the pouring is completed, the PVC pipe mouth is covered and blocked. The pre-cracking slurry gradually expands along the PVC pipe body, and the expansion pressure of the pre-cracking slurry is used to expand and crack the PVC pipe, so that the concrete around the PVC pipe body is expanded and cracked, the pile head is broken, and then the pile head is broken. The method of the present invention adopts the method of burying PVC pipes and pouring self-heating expansion pre-cracking slurry to break the pile head, which is simple to operate, fast and efficient, economical and practical, energy-saving and environmentally friendly, safe and reliable. However, this method uses the expansion cracking method, which takes a long time and the broken surface of the pile head is uneven.

[0004] Another example is the patent document with application number CN202223204429.1. The utility model provides a rapid breaking system for bored pile heads, including a bored pile body, a bored pile head, a breaking ring, a breaking pipe and a breaking rod; the bored pile head is arranged on the top of the bored pile body; the breaking ring is arranged at the connection between the bored pile body and the bored pile head; the breaking pipe is sleeved on the steel bars at the top of the bored pile body and connected to the breaking ring; the breaking rods are inserted in the breaking ring at intervals, and their ends extend out of the breaking ring to form a separation layer at the position where the bored pile body and the bored pile head are to be broken, and the breaking rod is pulled out of the breaking ring through the extended two ends, thereby leaving a plurality of broken pile holes between the bored pile body and the bored pile head. The staff can then use a steel chisel to drive into each broken pile hole and repeatedly hit the steel chisel back and forth to break the bored pile head at the annular broken pile hole. The utility model can form multiple broken pile holes at the connection between the cast-in-place pile body and the cast-in-place pile head by arranging a row of breaking rods in the breaking ring, eliminating the need to use a pneumatic drill to drill holes, simplifying the construction steps and improving work efficiency. However, the system device separates the cast-in-place pile body and the cast-in-place pile head by striking the steel chisel, which is prone to environmental pollution during the construction process, and the dust generated during the breaking has a greater impact on the health of the operators. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a bored cast-in-place pile head breaking device and method, which accurately embeds the device at the pile top elevation, inserts the PVC sleeve through the steel bar into the conical rubber ring of the steel bar reserved hole to prevent the concrete from adhering to the longitudinal steel bar, and after the pile body concrete reaches a certain strength, torque is generated by tightening the bolts to push the wedge block to generate shear force on the pile body, thereby achieving efficient and accurate breaking of the pile head concrete, ensuring the flatness of the pile top and reducing the noise pollution to the environment when the pile head is broken.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a bored pile head breaking device is provided, comprising a circular engineering plastic sheet, a conical rubber ring for a steel bar reserved hole located inside and fused to the sheet, a high-strength bolt rod with a sleeve, a PVC sleeve for isolating concrete and steel bars, and wedge blocks fixed to both ends of the high-strength bolt rod with a sleeve by nuts, wherein:

[0007] A circular conduit casting reserved opening is provided in the middle of the engineering plastic sheet, and the high-strength bolt rods with sleeves are evenly and symmetrically distributed around the conduit casting reserved opening. By accurately pre-burying the device at the elevation position of the pile top, the PVC sleeve passes through the longitudinal steel bar and is inserted into the conical rubber ring of the steel bar reserved hole to prevent the concrete from adhering to the longitudinal steel bar. After the concrete of the pile body reaches a certain strength, the torque is generated by tightening the bolt, which pushes the wedge block to generate shear force on the pile body, thereby realizing efficient and accurate breaking of the concrete at the pile head.

[0008] Furthermore, the diameter of the engineering plastic sheet is consistent with the diameter of the bored pile, and longitudinal and transverse ribs are arranged inside the sheet to facilitate the separation of the concrete below the pile top and the concrete above the pile top when the pile head is broken.

[0009] Furthermore, the conical rubber ring of the steel bar reserved hole is designed to be conical, ensuring a tight fit when the PVC sleeve is inserted.

[0010] Furthermore, the conical rubber rings of the steel bar reserved holes are arranged circumferentially along the engineering plastic sheet and are welded to the engineering plastic sheet, and the circumferential spacing is consistent with the spacing of the pile foundation steel bars in the design drawings.

[0011] Furthermore, the distance between the conical rubber ring of the steel bar reserved hole and the edge of the engineering plastic sheet is consistent with the distance between the longitudinal steel bar and the edge of the pile.

[0012] Furthermore, the surface of the sleeve of the high-strength bolt rod with sleeve is smooth and wear-resistant, and the wedge blocks are installed at both ends of the high-strength bolt rod inside it.

[0013] Furthermore, the high-strength bolt rod with sleeve can be replaced by a non-adhesive high-strength material.

[0014] Furthermore, a wedge block reserved hole is reserved in the center of the wedge block.

[0015] Furthermore, the wedge block is sleeved on both ends of the high-strength bolt rod through the reserved holes of the wedge block, and is tightened and fixed by the nut.

[0016] According to another aspect of the present invention, the present invention provides a method for breaking a bored cast-in-place pile head, which is implemented by using the bored cast-in-place pile head breaking device described above, and the specific implementation steps are as follows:

[0017] S100: Calculate and mark the top elevation of the steel cage pile: Calculate the top elevation of the steel cage pile in the pile foundation according to the design drawings and mark it on the steel cage;

[0018] S200: Embedded device: Pass the conical rubber ring of the reserved hole of the steel bar through the longitudinal steel bar in the pile foundation steel cage, adjust it to the pile top elevation, and use a tie wire to firmly tie the steel bar and the conical rubber ring of the reserved hole at the corresponding position;

[0019] S300: Insert PVC sleeve: Before lowering the steel cage, insert the PVC sleeve into the conical rubber ring of the steel bar reserved hole of the device to ensure that the pile head steel bar and concrete will not stick together when pouring concrete;

[0020] S400: Concrete pouring: lower the steel cage and conduit, pour the pile body concrete, slow down the pouring speed when the pile body concrete is close to the pile top concrete, and resume the normal pouring speed of the pile body after the concrete covers the connection between the PVC sleeve and the conical rubber ring of the steel reserved hole to prevent the PVC sleeve from floating due to excessive concrete pouring;

[0021] S500: Pile head breaking: When the concrete strength of the pile reaches 70% of the design strength and is not less than 15MPa, and the age is not less than 7 days, the torque generated by tightening the bolts drives the wedge block to apply shear force to the concrete, so that the concrete cracks at the predetermined position, and the pile head is lifted and removed by the lifting device to complete the pile head breaking work;

[0022] S600: Cleaning and inspection: Clean and trim the broken pile head to ensure that the quality of the pile body is not affected, and clean and maintain the device for next use.

[0023] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0024] 1. The torque generated by tightening the bolt drives the wedge block to generate shear stress on the pile body. The shear stress is transmitted along the direction of the engineering plastic film, so that the concrete below the pile top is separated from the concrete above the pile top, thereby solving the problem of insufficient flatness of the working surface of the pile top after the pile head is broken and the disturbance of the pile body below the pile top during breaking, thereby improving the efficiency of pile head breaking, having strong practicality, being easy to operate, being reusable, and reducing the cost of pile head breaking and environmental pollution.

[0025] 2. The device of the present invention arranges a conical rubber ring for a reserved hole for steel bars inside the engineering plastic sheet, and the spacing between the conical rubber ring for the reserved hole for steel bars and the pile side is fixed, which solves the problem of displacement of the steel bar cage at the pile head, achieves the technical effect of uniform thickness of the steel bar protective layer at the pile head, and ensures the quality of the pile.

[0026] 3. The device of the present invention solves the technical problem of adhesion between pile top concrete and steel bars by inserting the PVC sleeve into the conical rubber ring of the steel bar reserved hole, achieving the technical effect of quickly separating the pile head concrete and steel bars. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the three-dimensional structure of a bored pile head breaking device according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the top view of the bored pile head breaking device according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of a conical rubber ring for a steel bar reserved hole according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of a PVC casing according to an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of the combination of a wedge block and a high-strength bolt rod with a sleeve according to an embodiment of the present invention;

[0032] Figure 6 Schematic diagram of a top view and a side view of a wedge block according to an embodiment of the present invention;

[0033] Figure 7 The present invention is a schematic flow chart of a breaking method of a bored pile head breaking device according to an embodiment of the present invention.

[0034] In all the drawings, the same figure numbers represent the same technical features, specifically: 1-engineering plastic sheet, 2-conical rubber ring for steel bar reserved hole; 3-high-strength bolt rod with sleeve, 4-wedge block, 5-PVC sleeve, 6-conduit casting reserved opening, 7-nut, 8-wedge block reserved hole. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] In the present invention patent, the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprising..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a bored pile head breaking device, comprising an engineering plastic sheet 1, a conical rubber ring 2 for a steel bar reserved hole located at the inner edge thereof and welded thereto, a high-strength bolt rod 3 with a sleeve bonded to the engineering plastic sheet 1, wedge blocks 4 at both ends of the high-strength bolt rod 3 fixed to the high-strength bolt rod 3 with a sleeve by nuts 7, and a PVC sleeve 5 inserted into the conical rubber ring 2 for the steel bar reserved hole. By accurately pre-burying the device at the elevation position of the pile top, the PVC sleeve 5 is used to prevent the concrete from bonding with the longitudinal steel bar. After the pile body concrete reaches a certain strength, the bolt 8 is tightened to generate torque, which pushes the wedge block 4 to generate shear force on the pile body, thereby achieving efficient and accurate breaking of the pile head concrete. The device not only improves the efficiency of pile head breaking, reduces costs and environmental pollution, but also ensures the flatness of the pile top working surface and the pile body quality, and has good reusability.

[0040] like Figure 2 As shown, in this embodiment, the diameter of the engineering plastic sheet 1 is consistent with the diameter of the bored pile, and ribs with a spacing of 10 cm are arranged in the longitudinal and transverse directions thereof, and a circular conduit pouring reserved opening 6 with a diameter of 250 mm is arranged in the middle to facilitate the lowering of the grouting conduit for pouring concrete, which is helpful for separating the concrete below the pile top and the concrete above the pile top when the pile head is broken;

[0041] like Figure 3 As shown, in this embodiment, the conical rubber ring 2 of the steel bar reserved hole is designed to be conical, which ensures that the two are tightly sleeved when the PVC sleeve 5 is inserted to prevent gaps. The conical rubber ring 2 of the steel bar reserved hole can also be removed, and the gap between the bottom of the pile top PVC sleeve 5 and the steel bar can be sealed with polyurethane foam glue. Figure 2 As shown, the conical rubber ring 2 of the steel bar reserved hole is arranged circumferentially along the engineering plastic sheet 1 and is welded to the engineering plastic sheet 1, and the circumferential spacing is consistent with the spacing of the pile foundation steel bars in the design drawings, and the distance between it and the edge of the engineering plastic sheet 1 is consistent with the distance between the longitudinal steel bar and the edge of the pile, and it can pass through the longitudinal steel bars in the steel cage and be installed to the marked steel cage pile top elevation, and the steel bar and the corresponding conical rubber ring 2 of the reserved hole are tied firmly with a wire to prevent the steel bar from displacement;

[0042] like Figure 2 As shown, in this embodiment, the four high-strength bolt rods 3 with sleeves are evenly and symmetrically distributed around the reserved opening 6 for casting the conduit, and are bonded together with the engineering plastic sheet 1 through the sleeve, providing the main shear force transmission path of the device, and the wedge blocks 4 are installed at both ends of the high-strength bolt rods;

[0043] like Figure 5 As shown, a wedge block reserved hole 8 is reserved in the center of the wedge block 4, which is sleeved on the two ends of the high-strength bolt rod inside the high-strength bolt rod with sleeve 3 through the wedge block reserved hole 8, and is tightened and fixed by the nut 7, so that shear force is generated under the action of torque to separate the pile head concrete; the tightening power device can be a tool wrench or a through-type hydraulic jack, etc., and a large amount of dust and noise will not be generated in this process, reducing harm to human health and pollution to the environment.

[0044] like Figure 1 As shown, the PVC sleeve 5 passes through the longitudinal steel bar and is inserted into the conical rubber ring 2 of the steel bar reserved hole to isolate the steel bar and concrete, eliminate the gripping force of the concrete on the steel bar after solidification, and facilitate the rapid separation of the pile head.

[0045] When the device is used to break the shear of the pile head, since the engineering plastic sheet 1 and the PVC sleeve 5 are buried in the pile body, the longitudinal and transverse ribs on the engineering plastic sheet 1 separate the concrete below the pile top from the concrete above the pile top in the horizontal direction, and the PVC sleeve 5 cooperates with the conical rubber ring 2 of the steel bar reserved hole to separate the upper concrete of the pile top and the steel bar at the pile top, so a large shear force is not required.

[0046] Combination Figure 1-5 ,like Figure 6 As shown, an embodiment of the present invention provides a method for using a bored pile head breaking device, which is implemented by using a bored pile head breaking device as described above, and specifically includes the following steps:

[0047] Step 1: Calculate and mark the top elevation of the steel cage pile: Calculate the top elevation of the steel cage pile in the pile foundation according to the design drawings and mark it on the steel cage;

[0048] Step 2: Embedded device: Pass the conical rubber ring 2 of the reserved hole of the device through the longitudinal steel bars in the pile foundation steel cage, and adjust it to the elevation of the pile top, ensure that the elevation of the pile head position and the thickness of the steel bar protective layer meet the design requirements, and use a wire to tie the steel bar and the conical rubber ring 2 of the reserved hole at the corresponding position firmly to prevent displacement;

[0049] Step 3: Insert the PVC sleeve: Before lowering the steel cage, insert the PVC sleeve 5 into the conical rubber ring 2 of the steel bar reserved hole of the device to ensure that the pile head steel bars and concrete are not bonded when pouring concrete;

[0050] Step 4: Concrete pouring: lower the steel cage and conduit, pour the pile body concrete, slow down the pouring speed when pouring the pile body concrete close to the pile top concrete, and resume the normal pouring speed of the pile body after the concrete covers the connection between the PVC sleeve 5 and the conical rubber ring 2 of the steel bar reserved hole, in order to prevent the PVC sleeve 5 from floating due to excessive concrete pouring.

[0051] Step 5: Concrete solidification and pile head removal: When the concrete strength of the pile reaches 70% of the design strength and is not less than 15MPa, and the age is not less than 7 days, remove the soil between the piles, and at the position reserved for the high-strength bolt rod, remove the sleeves of the high-strength bolt rod blocked at both ends to expose the nuts 7 and wedge blocks 4, and use a tool wrench to symmetrically tighten the nuts 7 at both ends of the pile body. The torque generated drives the wedge blocks 4 to apply shear force to the concrete, so that the concrete cracks at the predetermined position, and the pile head is lifted and removed with a lifting device to ensure that the flatness of the working surface on the top of the pile meets the design requirements, and the pile head removal work is completed;

[0052] Step 6: Cleaning and inspection: Clean and trim the broken pile head to ensure that the quality of the pile body is not affected, and clean and maintain the device for next use.

[0053] The following further discloses a specific embodiment of the present invention based on a bored cast-in-place pile head breaking device and method of the present invention.

[0054] Example 1: In a high-rise building project, bored cast-in-place piles are used for foundation construction.

[0055] Specific implementation process:

[0056] Step 1: Calculation and marking: Based on the design drawings, the engineer calculates the pile top elevation of the steel cage in the pile foundation and clearly marks the position of the pile top elevation on the steel cage.

[0057] Step 2: Embedded device: During the steel cage production stage, the conical rubber ring of the steel bar reserved hole of the bored pile head breaking device of the present invention is passed through the longitudinal steel bar and adjusted to the pre-marked pile top elevation. The steel bar and the conical rubber ring of the reserved hole are firmly tied with a tie wire to prevent displacement during the hoisting and pouring process.

[0058] Step 3: Insert the PVC sleeve: Before lowering the steel cage, make sure that the PVC sleeve has been correctly inserted into each reserved hole conical rubber ring to ensure that there is no bonding between the pile head steel bars and the concrete during subsequent pouring.

[0059] Step 4: Concrete pouring: After the steel cage and conduit are lowered, start pouring the pile concrete. When pouring near the top of the pile, slow down the pouring speed to ensure that the concrete slowly covers the connection between the PVC sleeve and the conical rubber ring of the reserved hole, and then resume normal pouring speed.

[0060] Step 5: Concrete curing and pile head removal: After 7 days of curing, the concrete strength of the pile body reaches 70% of the design requirements and is not less than 15MPa. At this time, the soil between the piles is excavated to expose the reserved high-strength bolt rods. Use a tool wrench to symmetrically tighten the nuts at both ends of the pile body. The torque generated drives the wedge block to apply shear force to the concrete, separating the pile head concrete from the pile body concrete. Subsequently, use a crane to remove the pile head to ensure that the working surface on the top of the pile is flat.

[0061] Step 6: Cleaning and inspection: Thoroughly clean and trim the broken pile head to ensure that the quality of the pile body is not affected. At the same time, clean and maintain the device for reuse next time.

[0062] By using the pile head breaking device of the present invention, this embodiment successfully realizes the efficient and accurate breaking of the pile head, reduces costs, reduces environmental pollution, and at the same time ensures the flatness of the pile top working surface and the quality of the pile body.

[0063] Example 2: In a bridge construction project, bored cast-in-place piles are used for the piers. The bored cast-in-place piles require a large amount of construction and have strict requirements on the efficiency and quality of pile head removal.

[0064] Specific implementation process:

[0065] Step 1: Preparation stage: According to the design drawings, calculate the pile top elevation of the steel cage in the pile foundation and mark it on the steel cage. At the same time, prepare the improved pile head breaking device, including unbonded prestressed tendons and through-type hydraulic jacks.

[0066] Step 2: Embed the device: embed the engineering rubber ring device and adjust it to the pile top elevation.

[0067] Step 3: Inserting PVC sleeve and pouring concrete: Before lowering the steel cage, insert the end of the PVC sleeve to the pile top elevation, and use polyurethane foam glue to seal the gap between the bottom of the PVC sleeve at the pile top and the steel bar. Then lower the steel cage and pour concrete, the process is similar to that of specific example 1.

[0068] Step 4: Concrete solidification and pile head removal: After the concrete strength of the pile body reaches the design requirements, remove the soil between the piles to expose the unbonded prestressed tendons, start the hydraulic jack, and push the wedge block to apply shear force to the concrete. Since the hydraulic jack provides greater power, the pile head concrete separates from the pile body faster.

[0069] Step 5: Cleaning and inspection: After the pile head is removed by crane, it is cleaned and trimmed. At the same time, the device is cleaned and maintained, especially the hydraulic jack part, to ensure the reliability of the next use.

[0070] By adopting the improved pile head breaking device and method, the project further improves the accuracy and quality of pile head breaking while maintaining high efficiency. In addition, due to the use of hydraulic jacks, the labor intensity of manually tightening nuts is reduced, and the construction efficiency is improved.

[0071] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bored pile head breaking device, characterized in that: The invention comprises a circular engineering plastic sheet (1), a conical rubber ring (2) for a steel bar reserved hole located inside and welded to the circular engineering plastic sheet, a high-strength bolt rod with a sleeve (3), a PVC sleeve (5) for isolating concrete from steel bars, and wedge blocks (4) fixed to both ends of the high-strength bolt rod with a sleeve (3) via nuts (7), wherein: A circular conduit casting reserved opening (6) is provided in the middle of the engineering plastic sheet (1), and the high-strength bolt rods with sleeves (3) are evenly and symmetrically distributed around the conduit casting reserved opening (6). By accurately pre-burying the device at the elevation position of the pile top, the PVC sleeve (5) passes through the longitudinal steel bar and is inserted into the conical rubber ring (2) of the steel bar reserved hole to prevent the concrete from adhering to the longitudinal steel bar. After the concrete of the pile body reaches a certain strength, the bolt (7) is tightened to generate torque, which pushes the wedge block (4) to generate shear force on the pile body, thereby achieving efficient and accurate breaking of the pile head concrete.

2. A bored pile head breaking device according to claim 1, characterized in that: The diameter of the engineering plastic sheet (1) is consistent with the diameter of the bored cast-in-place pile, and longitudinal and transverse ribs are arranged inside the sheet to facilitate the separation of the concrete below the pile top and the concrete above the pile top when the pile head is broken.

3. A bored pile head breaking device according to claim 1 or 2, characterized in that: The conical rubber ring (2) of the steel bar reserved hole is designed to be conical, ensuring a tight fit when the PVC sleeve (5) is inserted.

4. A bored pile head breaking device according to claim 3, characterized in that: The conical rubber rings (2) for the reserved steel bar holes are arranged circumferentially along the engineering plastic sheet (1) and are welded to the engineering plastic sheet (1), and the circumferential spacing is consistent with the spacing of the pile foundation steel bars in the design drawings.

5. A bored pile head breaking device according to claim 4, characterized in that: The distance between the conical rubber ring (2) of the steel bar reserved hole and the edge of the engineering plastic sheet (1) is consistent with the distance between the longitudinal steel bar and the edge of the pile.

6. A bored pile head breaking device according to claim 1 or 2, characterized in that: The sleeve surface of the high-strength bolt rod with sleeve (3) is smooth and wear-resistant, and the wedge blocks (4) are installed at both ends of the high-strength bolt rod inside.

7. A bored pile head breaking device according to claim 6, characterized in that: The high-strength bolt rod with sleeve (3) can be replaced by a non-adhesive high-strength material.

8. A bored pile head breaking device according to claim 1 or 2, characterized in that: A wedge block reserved hole (8) is reserved at the center of the wedge block (4).

9. A bored pile head breaking device according to claim 8, characterized in that: The wedge block (4) is sleeved onto the two ends of the high-strength bolt rod with sleeve (3) through the wedge block reserved hole (8) and is tightened and fixed by the nut (3).

10. A method for breaking a bored pile head, which is implemented by using a bored pile head breaking device as claimed in any one of claims 1 to 9, characterized in that: The specific implementation steps are as follows: S100: Calculate and mark the top elevation of the steel cage pile: Calculate the top elevation of the steel cage pile in the pile foundation according to the design drawings and mark it on the steel cage; S200: Embedded device: The conical rubber ring (2) of the reserved hole for steel bars of the device is passed through the longitudinal steel bars in the pile foundation steel cage, and adjusted to the pile top elevation, and the steel bars are firmly tied to the conical rubber ring (2) of the reserved hole at the corresponding position with a tie wire; S300: Inserting the PVC sleeve: Before lowering the steel cage, insert the PVC sleeve (5) into the conical rubber ring of the steel bar reserved hole of the device to ensure that the pile head steel bar and the concrete are not bonded when pouring concrete; S400: pouring concrete: lowering the steel cage and the guide tube, pouring the pile body concrete, slowing down the pouring speed when the pile body concrete is close to the pile top concrete, and returning to the normal pouring speed of the pile body after the concrete has submerged the connection between the PVC sleeve (5) and the conical rubber ring (2) of the steel bar reserved hole, so as to prevent the PVC sleeve (5) from floating due to excessive concrete pouring; S500: Pile head breaking: When the concrete strength of the pile reaches 75% of the design strength and is not less than 15 MPa, and the age is not less than 7 days, the torque generated by tightening the bolt drives the wedge block (4) to apply shear force to the concrete, so that the concrete cracks at a predetermined position, and the pile head is lifted and removed by a lifting device, thus completing the pile head breaking work; S600: Cleaning and inspection: Clean and trim the broken pile head to ensure that the quality of the pile body is not affected, and clean and maintain the device for next use.

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