Bonded prestressed concrete cast-in-place pile construction method

Abstract

The invention relates to the technical field of cast-in-place pile construction, and provides a bonded prestressed concrete cast-in-place pile construction method which comprises the following steps that S1, a plurality of steel strand bundles are arranged in a steel sleeve in a penetrating mode, a bottom end pipe opening and a top end pipe opening of the steel sleeve are plugged through a first sealing piece and a second sealing piece correspondingly, and fixed end anchorage devices are installed at the tail ends of the steel strand bundles; s2, the steel sleeve is moved into the inner circumference of the pile body reinforcement cage and fixed; s3, the pile body reinforcement cage is hung into the pile hole; s4, concrete is poured into the pile hole to form a cast-in-place pile; s5, the pile cap of the cast-in-place pile is forcibly disassembled, and the second sealing piece at the pipe opening of the top end of the steel sleeve is disassembled; s6, anchor bearing plates are installed; s7, a bearing platform structure is poured; s8, prestress tensioning is conducted, specifically, a clamping piece type anchorage device is installed on the steel strand bundle stretching out of the anchor bearing plate, and the steel strand bundle is tensioned; and S9, grouting materials are injected into the steel sleeve through the grouting holes in the anchor bearing plate. The method has the effect of reducing microcracks easily generated in the pile body concrete of the cast-in-place pile.

Description

Technical Field

[0001] The present application relates to the field of bored pile construction, and in particular to a method for constructing bonded prestressed concrete bored piles. Background Art

[0002] During the construction of underground buildings, in order to prevent the subsequent buoyancy caused by groundwater and affect the overall structural stability of the building, a number of pull-out piles will be driven underground in the early stage of the main construction of the building and a foundation structure will be cast on top of the pull-out piles to form an anti-floating component.

[0003] At present, the pile structure of pull-out piles mainly adopts cast-in-place pile structure. When cast-in-place piles are used as pull-out piles, under the action of the axial tension of the main building on the pile top, the pile body concrete of the cast-in-place pile is in a tensile state as a whole, and micro cracks are easily generated in the pile body. As the micro cracks expand, the steel structure inside the cast-in-place pile is easily damaged by rust.

[0004] In the existing technology, in order to limit the occurrence of microcracks in the concrete of the bored pile body, the reinforcement amount of the steel cage is usually increased. However, the above measures not only increase the difficulty and cost of manufacturing the pile body steel cage, but also increase the difficulty of hanging and installing the steel cage during the subsequent bored pile construction process. Therefore, there is room for improvement. Summary of the Invention

[0005] In order to better limit the occurrence of micro cracks in the pile body concrete when the bored pile is used as a pull-out pile, the present application provides a construction method for a bonded prestressed concrete bored pile.

[0006] This application provides a method for constructing bonded prestressed concrete piles, which adopts the following technical solution: A method for constructing bonded prestressed concrete piles, comprising the following steps: S1: Prestressed component assembly: several steel strands are passed through the steel casing, the bottom and top openings of the steel casing are sealed with the first and second seals respectively, and fixed end anchors are installed at the ends of the steel strands; S2: Prestressed component installation: move the steel casing into the inner periphery of the pile reinforcement cage and fix it; S3: Hoisting the pile reinforcement cage: hoist the pile reinforcement cage into the pile hole; S4: Pile body concrete pouring: pour concrete into the pile hole to form a cast-in-place pile; S5: demolish the pile cap and remove the second seal at the top end of the steel casing; S6: Anchor plate installation: insert the anchor plate into the top of the steel strand bundle and install and connect the anchor plate to the top end of the steel casing; the anchor plate is formed with a grouting hole, and the grouting hole is connected to the inner cavity of the anchor plate; S7: Casting of the foundation structure; S8: Prestressing: Install clip-type anchors on the steel strands extending out of the anchor pad, and tension the steel strands to apply bonding prestress to the cast-in-place pile body; S9: Inject grouting material into the steel casing through the grouting holes on the anchor plate.

[0007] By adopting the above technical solution, after installing a clip-type anchor at the top of the steel strand bundle, the steel strand bundle is tensioned, and the steel strand bundle, the fixed end anchors located at both ends of the steel strand bundle, and the clip-type anchor cooperate to apply bonded prestress to the bored pile, so that the bored pile is placed in a state of compression as a whole. This helps to limit the occurrence of micro-cracks in the pile body concrete due to the axial tension of the pile top structure during subsequent use of the bored pile. Compared with the traditional method of increasing the reinforcement of the steel cage, this method helps to reduce the increase in the difficulty and cost of the steel cage production due to the increase in reinforcement, and at the same time, it affects the overall lifting of the steel cage. By passing the steel strand bundle through the steel casing and sealing both ends of the steel casing, it helps to reduce the damage of the steel strand bundle during the bored pile casting process. By using the first and second seals, the contact between groundwater and concrete slurry during the bored pile casting process is reduced except for the bottom end of the steel strand bundle, which facilitates the subsequent tensioning of the steel strand bundle.

[0008] Preferably, the first sealing member comprises a sealing plate, and the sealing plate is provided with a perforation corresponding to the steel strand bundle; In step S1, when the bottom end pipe of the steel casing is sealed by the first sealing member, the sealing plate is sleeved on the steel strand bundle through the perforation, and the sealing plate is welded to the bottom end pipe opening of the steel casing.

[0009] By adopting the above technical solution, the bottom end of the steel casing is sealed with a sealing plate to prevent the steel strand bundle from being exposed to the concrete slurry except the bottom end during the subsequent pouring of the cast-in-place pile concrete slurry, thereby affecting the subsequent tensioning of the steel strand bundle.

[0010] Preferably, the second sealing member comprises a sealing sleeve, the inner bottom of the sealing sleeve is provided with an internal thread; the top of the steel casing is provided with an external thread, and the internal thread and the external thread cooperate with each other; In step S1, when the top pipe opening of the steel casing is sealed by the second sealing member, the thread of the sealing sleeve is sleeved on the top of the steel casing.

[0011] By adopting the above technical solution, the top of the steel casing can be sealed by threading the sealing sleeve onto the top of the steel casing, so as to limit the influx of concrete slurry from the top of the steel casing during the subsequent pouring of concrete for the pile body. At the same time, when subsequently installing the anchor plate at the top of the steel casing, it is only necessary to unscrew the sealing sleeve from the top of the steel casing to open the top pipe opening of the steel casing and expose the steel strand bundle, without the need to cut or dismantle the steel casing, thereby facilitating the rapid installation of the anchor plate.

[0012] Preferably, in step S1, after the bottom end of the steel casing is sealed by a sealing plate, grouting holes are drilled on the outer periphery of the bottom end of the steel casing, and then the steel casing is tilted and lifted, and grouting material is poured into the bottom end of the steel casing through the grouting holes to form a sealing structure.

[0013] By adopting the above technical solution, a sealing structure is formed at the bottom end of the inner cavity of the steel casing by pouring grouting material through the grouting holes to seal the gap between the sealing plate perforation and the steel strand bundle, thereby limiting the subsequent groundwater and pile body concrete slurry from entering the steel casing through the gap between the sealing plate perforation and the steel strand bundle, which is conducive to better improving the sealing effect of the bottom end of the steel casing.

[0014] Preferably, in step S4, before pouring the pile body concrete, a pearl cotton layer is wrapped around the outer periphery of the sealing sleeve, and the pearl cotton layer covers the connection between the sealing sleeve and the steel casing; and then a PVC casing is sleeved around the outer periphery of the pearl cotton layer.

[0015] By adopting the above technical solution, by arranging a pearl cotton layer and a PVC sleeve on the outer periphery of the sealing sleeve, on the one hand, the sealing sleeve can be wrapped, protected and cushioned by the PVC sleeve in combination with the pearl cotton layer, which is beneficial to reduce the damage to the sealing sleeve when the pile cap of the bored pile is broken, resulting in the difficulty in removing the sealing sleeve from the top of the steel casing; on the other hand, it can limit the subsequent pile body concrete slurry from contacting the connection between the sealing sleeve and the steel casing, and after the bored pile anchor is broken, it is convenient to remove the sealing sleeve from the steel casing.

[0016] Preferably, in step S1, a fixed grouting pipe is laid in the steel casing, and the bottom end of the grouting pipe is extended to the bottom of the steel casing; In step S6, when the anchor plate is installed on the top of the steel casing, the grouting pipe is connected to the grouting hole on the anchor plate.

[0017] By adopting the above technical solution, the concrete slurry subsequently poured through the grouting holes of the anchor plate can be introduced into the bottom of the inner cavity of the steel casing via the grouting pipe, which is conducive to the poured grouting material to better fill the inner cavity of the steel casing.

[0018] Preferably, in step S2, when the steel casing is fixed to the inner periphery of the steel cage, the fixed end anchors of the steel strand bundles exposed at the bottom ends of adjacent steel casings are staggered.

[0019] By adopting the above technical solution, by staggering the fixed end anchors at the ends of adjacent steel casing steel strand bundles up and down, it is helpful to reduce the situation where the grouting pipe used to pour the pile body concrete slurry is difficult to lower to the bottom of the pile hole due to the fixed end anchors at the ends of the steel strand bundles being located on the same horizontal plane.

[0020] Preferably, the anchor plate is further formed with an exhaust hole, and the exhaust hole is connected to the inner cavity of the anchor plate.

[0021] By adopting the above technical solution, when grouting material is subsequently injected into the steel casing through the grouting port on the anchor plate, the air in the steel casing can be discharged through the exhaust holes on the anchor plate, which is beneficial to reducing the pressure in the steel casing and making it easier for the grouting material to better fill the steel casing.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. By tensioning the steel strand bundle, the steel strand bundle is used in conjunction with the fixed end anchor and the tensioning end clip-type anchor to apply bonding prestress to the pile body, so that the entire pile is under compression, which is beneficial to reduce the subsequent influence of the axial tension on the pile top, which may cause micro cracks in the pile body concrete.

[0023] 2. By threading the sealing sleeve onto the top of the steel casing, on the one hand, the top of the steel casing is temporarily blocked to limit the influx of concrete slurry into the steel casing when pouring the pile body concrete of the bored pile. At the same time, when the anchor plate is subsequently installed on the top of the steel casing, the sealing sleeve can be unscrewed from the steel casing to quickly open the pipe opening at the top of the steel casing without breaking the top of the steel casing, thereby facilitating the rapid installation of the anchor plate.

[0024] 3. There are exhaust holes formed on the anchor plate. When the grouting material is subsequently injected into the steel casing through the grouting holes on the anchor plate, the air in the steel casing can be discharged in time through the exhaust holes, which facilitates the grouting material to better enter the steel casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of an embodiment of the present application for installing a fixed end anchor at the bottom end of a steel strand bundle.

[0026] Figure 2 This is a schematic diagram of an embodiment of the present application used to illustrate the state of injecting grouting material into the inner cavity of the steel casing through the grouting hole.

[0027] Figure 3 This is a schematic diagram of the connection relationship between the steel casing and the sealing sleeve used in an embodiment of the present application.

[0028] Figure 4 yes Figure 3 Enlarged schematic diagram of part A in the middle.

[0029] Figure 5 This is a schematic diagram used in an embodiment of the present application to illustrate how to fix the steel casing to the inner circumference of the steel cage.

[0030] Figure 6 This is a schematic diagram used in an embodiment of the present application to illustrate the positional relationship between the steel casing and the steel cage.

[0031] Figure 7 This is a schematic diagram of an embodiment of the present application used to illustrate the state of installing a pearl cotton layer and a PVC casing on the top of a steel casing.

[0032] Figure 8 This is a schematic diagram of an embodiment of the present application used to illustrate the state of installing an anchor plate on the top of a steel casing.

[0033] Figure 9 It is a structural diagram used to illustrate the anchor pad in an embodiment of the present application.

[0034] Figure 10 It is a schematic diagram used to illustrate the state of the tensioned steel strand bundle in an embodiment of the present application.

[0035] Description of reference numerals: 1. Steel casing; 10. Grouting hole; 11. Sealing plate; 12. Sealing sleeve; 13. Grouting pipe; 14. Limiting ring; 141. Limiting bolt; 15. Pearl cotton layer; 16. PVC casing; 2. Steel strand bundle; 21. Fixed end anchor; 22. Anchor plate; 221. End plate; 222. Cylinder; 223. Grouting hole; 224. Exhaust hole; 23. Spiral reinforcement; 24. Clip-type anchor; 3. Steel cage; 4. Cast-in-place pile; 5. Cap. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1-10 This application is described in further detail.

[0037] The present invention discloses a method for constructing bonded prestressed concrete piles, comprising the following steps: S1: Prestressed component assembly: refer to Figure 1 and Figure 2 , pass several steel strand bundles 2 through the steel casing 1, and seal the bottom pipe opening and the top pipe opening of the steel casing 1 respectively through the first seal and the second seal; install a fixed end anchor 21 at the end of the steel strand bundle 2.

[0038] The first sealing member includes a sealing plate 11, which has a through-hole corresponding to the steel strand bundle 2, and is used to pass through the steel strand bundle 2. The second sealing plate 11 includes a sealing sleeve 12, and the open end of the sealing sleeve 12 is provided with an internal thread. The outer periphery of the top end of the steel casing 1 is provided with an external thread, and the internal and external threads are arranged in a coordinated manner.

[0039] Reference Figure 3 and Figure 4 A limiting ring 14 is fixed at the top of the inner cavity of the steel casing 1. The axial direction of the limiting ring 14 is parallel to the axial direction of the steel casing 1. A limiting bolt 141 is threaded through the outer periphery of the limiting ring 14. One end of the limiting bolt 141 extends into the inner cavity of the limiting ring 14.

[0040] The specific steps of step S1 are as follows: S1.1: Anti-corrosion treatment of steel strand bundle 2: Apply epoxy resin on the outer periphery of steel strand bundle 2 to form an anti-corrosion layer; S1.2: Stranded wire bundle 2 threading: refer to Figure 1 and Figure 2 , pass the steel strand bundle 2 through the steel casing 1, and make the two ends of the steel strand bundle 2 extend out of the two ends of the steel casing 1 respectively; S1.3: Sealing the bottom end of the steel casing 1: Insert the sealing plate 11 through the perforation to the end of the steel strand bundle 2, and move the sealing plate 11 along the steel strand bundle 2 until the sealing plate 11 fits the bottom end of the steel casing 1. Weld the sealing plate 11 to the steel casing 1. S1.4: Grouting at the bottom of the steel casing 1: Drill grouting holes 10 on the outer periphery of the bottom end of the steel casing 1. Then, keep the grouting holes 10 facing upward and tilt the grouting opening upward, and pour grouting material into the bottom end of the inner cavity of the steel casing 1 through the grouting holes 10 until the grouting material overflows from the grouting opening; seal the grouting opening and keep the steel casing 1 tilted until the poured grouting material forms a sealing structure at the bottom end of the steel casing 1, thereby further sealing the gap between the perforation on the sealing plate 11 and the steel strand bundle 2. In this embodiment, the grouting material forming the sealing structure is epoxy resin; S1.5: Grouting pipe 13 installation: refer to Figure 3 and Figure 4 , insert the grouting pipe 13 into the limiting ring 14 inside the steel pipe, and move the grouting pipe 13 until the bottom end of the grouting pipe 13 extends above the sealing structure at the top of the steel casing 1, and screw the limiting bolt 141 on the outer periphery of the limiting ring 14 until the limiting bolt 141 is tightly pressed against the outer periphery of the grouting pipe 13 to limit the movement of the grouting pipe 13 in the limiting ring 14.

[0041] S1.6: Sealing the top of the steel casing 1: Screw the sealing sleeve 12 onto the top of the steel casing 1 to seal the top opening of the threaded sleeve; S1.7: Installation of fixed end anchor 21: refer to Figure 1 and Figure 2 A fixed end anchor 21 is installed at the end of the steel strand bundle 2. In this embodiment, the fixed end anchor 21 is an extruded anchor. In other embodiments, an embossed anchor may also be used.

[0042] S2: Prestressed component installation: refer to Figure 5 and Figure 6The steel casing 1 is moved into the inner periphery of the pile body reinforcement cage 3 and fixed to the inner periphery of the reinforcement cage 3 by tying with steel wire ropes. During the tying process, the fixed end anchors 21 of the exposed steel strand bundles 2 at the bottom ends of adjacent steel casings 1 are staggered with each other.

[0043] S3: Hoisting of pile reinforcement cage 3, refer to Figure 6 and Figure 7 , the specific steps are as follows: S3.1: Use a crane to hoist and install the pile reinforcement cage 3 into the pile hole; S3.2: Wrap waterproof tape around the connection between the sealing sleeve 12 and the steel casing 1; S3.3: Wrap a layer of pearl cotton 15 around the outer periphery of the sealing sleeve 12, and ensure that the pearl cotton 15 covers the connection between the sealing sleeve 12 and the steel casing 1; S3.4: PVC sleeve 16 is installed on the outer periphery of the pearl cotton layer 15.

[0044] S4: Pile body concrete pouring: pour concrete into the pile hole to form a cast-in-place pile 4.

[0045] S5: demolish the pile cap of cast-in-place pile 4 and remove the second seal at the top end of steel casing 1; Figure 6 and Figure 7 , the specific steps are as follows: S5.1: Anchor cap removal: Use tools to break the concrete structure in the area of the pile cap of the bored pile 4 until the top area of the steel casing 1 is exposed; S5.2: Remove the PVC sleeve 16 and the pearl cotton layer 15 from the top of the steel sleeve 1; S5.3: Remove the sealing sleeve 12 on the top of the steel casing 1.

[0046] S6: Anchor plate 22 installation: refer to Figure 8 and Figure 9 , insert the anchor plate 22 into the top of the steel strand bundle 2, and install and connect the anchor plate 22 to the top pipe opening of the steel casing 1.

[0047] The anchor plate 22 includes an end plate 221 and a cylinder 222 ; the anchor plate 22 is formed with a grouting hole 223 and an exhaust hole 224 ; both the grouting hole 223 and the exhaust hole 224 are communicated with the inner cavity of the anchor plate 22 .

[0048] The specific steps of S6 are as follows: S6.1: Put the anchor plate 22 in place: Put the spiral reinforcement 23 on the cylinder 222 of the anchor plate 22, move the anchor plate 22 so that the anchor plate 22 is inserted into the steel strand bundle 2, and make the end of the cylinder 222 of the anchor plate 22 butt against the top end of the steel casing 1; S6.2: Connect the grouting pipe 13 to the grouting hole 223 on the anchor plate 22 through a hose; S6.3: Fixing the anchor plate 22: Welding the cylinder 222 of the anchor plate 22 to the steel casing 1.

[0049] S7: Casting of the foundation 5 structure; Figure 8 and Figure 10 , the specific steps are as follows: S7.1: Tie the reinforcement structure of the cap 5; S7.2: Support the pouring formwork structure of the pedestal 5; S7.3: Pour concrete for cap 5 to form the cap structure.

[0050] S8: Prestressing: Reference Figure 10 , the specific steps are as follows: S8.1: Install clip-type anchors 24 on the strands 2 extending beyond the anchor pad 22. S8.2: Apply bonded prestressing to the cast-in-place pile shaft by tensioning the steel strands 2 using tensioning jacks.

[0051] S9: Reference Figure 4 and Figure 9 Grouting material is injected into the steel casing 1 through the grouting holes 223 on the anchor plate 22 and the grouting pipe 13 inside the steel casing 1. In this embodiment, the grouting material is cement mortar with a water-cement ratio of less than or equal to 0.4 and a cement mortar strength greater than 40 MPa. The injected grouting material protects the steel strands 2 within the steel casing 1, thereby reducing subsequent corrosion damage to the strands 2.

[0052] By installing a sealing plate 11 at the bottom end of the steel casing 1 and cooperating with the grouting material subsequently poured into the bottom of the inner cavity of the steel casing 1 to form a sealing structure, the bottom end of the steel casing 1 is effectively sealed. This helps to reduce the situation in which the concrete slurry enters the inner cavity of the steel casing 1 through the bottom end of the steel casing 1 and adheres to the steel strand bundle 2 located therein during the subsequent pouring of the cast-in-place pile 4, affecting the subsequent tensioning of the steel strand bundle 2.

[0053] By threading the sealing sleeve 12 onto the bottom of the steel casing 1, on the one hand, effective sealing of the top of the steel casing 1 is achieved, and on the other hand, it is convenient to quickly remove the anchor plate 22 from the steel casing 1 when it is subsequently installed.

[0054] By wrapping the pearl cotton layer 15 around the outer periphery of the sealing sleeve 12 and installing the PVC sleeve 16 before pouring the concrete of the bored pile 4, on the one hand, it is beneficial to achieve the wrapping protection of the sealing sleeve 12 and reduce the damage to the sealing sleeve 12 during the subsequent demolition of the pile cap. On the other hand, it is beneficial to limit the concrete slurry from entering the connection between the sealing sleeve 12 and the steel casing 1 during the pouring of the bored pile 4, which facilitates the subsequent removal of the sealing sleeve 12 from the top of the steel casing.

[0055] By setting the exhaust hole 224 on the anchor plate 22, when the grouting material is subsequently injected into the steel casing 1 through the grouting hole 223 on the anchor plate 22, the air in the steel casing 1 can be discharged in time through the exhaust hole 224, so that the grouting material can better fill the inner cavity of the steel casing 1.

[0056] In this application, the steel strand bundle 2 and the fixed end anchor 21 are pre-embedded in the bored pile 4, and after the foundation structure is cast, the clip-type anchor 24 is installed at the bottom end of the steel strand bundle 2 and the steel strand bundle 2 is tensioned, so that the steel strand bundle 2 cooperates with the fixed end anchor 21 and the clip-type anchor 24 at the tensioning end to apply bonding prestress to the bored pile 4, so that the bored pile 4 is in a compressed state, reducing the subsequent axial tension on the pile top of the bored pile 4, which causes micro cracks in the pile body of the bored pile 4.

[0057] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for constructing bonded prestressed concrete piles, characterized by: The following steps are involved: S1: Assembling the prestressed component: inserting a plurality of steel strand bundles (2) into the steel casing (1), sealing the bottom and top pipe openings of the steel casing (1) respectively with a first seal and a second seal, and installing a fixed end anchor (21) at the end of the steel strand bundle (2); S2: Prestressed component installation: move the steel casing (1) into the inner periphery of the pile body reinforcement cage (3) and fix it; S3: Hoisting the pile body reinforcement cage (3): hoisting the pile body reinforcement cage (3) into the pile hole; S4: Pile body concrete pouring: pouring concrete into the pile hole to form a cast-in-place pile (4); S5: The pile cap of the bored pile (4) is broken and the second sealing member at the top end of the steel casing (1) is removed; S6: Anchor plate (22) installation: insert the anchor plate (22) into the top end of the steel strand bundle (2), and install and connect the anchor plate (22) to the top end of the steel casing (1); a grouting hole (223) is formed on the anchor plate (22), and the grouting hole (223) is communicated with the inner cavity of the anchor plate (22); S7: Casting of the foundation (5) structure; S8: Prestressing: Installing a clip-type anchor (24) on the steel strand bundle (2) extending out of the anchor pad (22), and tensioning the steel strand bundle (2) to apply bonding prestressing to the cast-in-place pile body; S9: injecting grouting material into the steel casing (1) through the grouting hole (223) on the anchor plate (22).

2. A method for constructing bonded prestressed concrete piles according to claim 1, characterized in that: The first sealing member comprises a sealing plate (11), and the sealing plate (11) is provided with a perforation corresponding to the steel strand bundle (2); In step S1, when the bottom end pipe of the steel casing (1) is sealed by the first sealing member, the sealing plate (11) is sleeved on the steel strand bundle (2) through the perforation, and the sealing plate (11) is welded to the bottom end pipe opening of the steel casing (1).

3. The method for constructing bonded prestressed concrete piles according to claim 1, wherein: The second sealing member comprises a sealing sleeve (12), the inner bottom of the sealing sleeve (12) is provided with an internal thread; the top of the steel casing (1) is provided with an external thread, the internal thread and the external thread cooperate with each other; In step S1, when the top pipe opening of the steel casing (1) is sealed by the second sealing member, the thread of the sealing sleeve (12) is sleeved on the top of the steel casing (1).

4. The method for constructing bonded prestressed concrete piles according to claim 2, wherein: In step S1, after the bottom end of the steel casing (1) is sealed by a sealing plate (11), a grouting hole (10) is drilled on the outer periphery of the bottom end of the steel casing (1), and then the steel casing (1) is tilted and lifted, and grouting material is poured into the bottom end of the steel casing (1) through the grouting hole (10) to form a sealing structure.

5. The method for constructing bonded prestressed concrete piles according to claim 3, characterized in that: In step S4, before pouring the pile body concrete, a pearl cotton layer (15) is wrapped around the outer periphery of the sealing sleeve (12), and the pearl cotton layer (15) covers the connection between the sealing sleeve (12) and the steel casing (1); and then a PVC casing (16) is sleeved around the outer periphery of the pearl cotton layer (15).

6. The method for constructing bonded prestressed concrete piles according to claim 1, characterized in that: In step S1, a fixed grouting pipe (13) is laid in the steel casing (1), and the bottom end of the grouting pipe (13) is extended to the bottom of the steel casing (1); In step S6, when the anchor plate (22) is installed on the top of the steel casing (1), the grouting pipe (13) is connected to the grouting hole (223) on the anchor plate (22).

7. The method for constructing bonded prestressed concrete piles according to claim 1, characterized in that: In step S2, when the steel casing (1) is fixed to the inner periphery of the steel cage (3), the fixed end anchors (21) of the exposed steel strand bundles (2) at the bottom ends of adjacent steel casings (1) are staggered.

8. The method for constructing bonded prestressed concrete piles according to claim 6, characterized in that: An exhaust hole (224) is also formed on the anchor plate (22), and the exhaust hole (224) is communicated with the inner cavity of the anchor plate (22).

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