Integrally implanted porous core pile group reinforced stiff composite pile and construction method

Abstract

The invention discloses an integrally implanted porous core pile group reinforced stiff composite pile which comprises a carbonizable cement soil mixing pile and a core pile group implanted in the carbonizable cement soil mixing pile at a time. The core pile group is formed by consolidating prefabricated high-strength concrete core piles through five cylindrical cast-in-place concrete connecting bodies which are uniformly arranged in the axial direction of the core piles; an axially-penetrating gas injection channel is reserved in the center of each high-strength concrete core pile, and a plurality of exhaust micropores communicating with the gas injection channels are evenly formed in the surface of a pile body in the circumferential direction. And the positions of the concrete connecting bodies and the distribution areas of the exhaust micropores are mutually staggered. During construction, the core pile group is implanted into the cement-soil mixing pile before initial setting, carbon dioxide is injected into the gas injection channel, gas is uniformly released from the exhaust micropores, and active, efficient and sufficient carbonization maintenance is performed on the cement-soil mixing pile. The method has construction convenience of one-time implantation, carbonization sufficiency of multi-source distribution and high strength of the whole structure, and unification of high construction efficiency, carbonization uniformity and high structural integrity is achieved.

Description

Technical Field

[0001] This invention belongs to the field of building foundation treatment and pile foundation engineering technology, and relates to an integrally implanted multi-hole core pile group reinforced stiff composite pile and its construction method. Background Technology

[0002] Reinforced composite piles combine the advantages of flexible and rigid piles by embedding high-strength rigid core piles (such as precast concrete piles or steel pipes) into cement-soil mixing piles. However, their cement-soil component suffers from drawbacks such as slow hardening, low early strength, and long-term performance heavily influenced by curing conditions. Currently, traditional natural curing methods have long cycles, impacting project progress.

[0003] Existing research attempts to apply accelerated carbonation technology to cement-based materials to rapidly improve strength and durability, but effectively implementing carbonation in underground cement-soil piles remains a major challenge. Therefore, there is an urgent need for an integrated solution that can achieve efficient and uniform carbonation, ensure the overall strength requirements of composite piles, and facilitate rapid on-site construction. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this invention is to provide an integrally implanted multi-hole core pile reinforced composite pile and its construction method.

[0005] The present invention provides an integrally implanted multi-hole core pile group reinforced composite pile, comprising: a carbonizable cement-soil mixing pile and a prefabricated core pile group;

[0006] The carbonizable cement-soil mixing pile is formed by on-site mixing and solidification of carbonizable cementitious slurry and foundation soil. The core pile assembly includes multiple precast high-strength concrete core piles, with the center-to-center shape of each core pile end face forming a regular polygon when the multiple high-strength concrete core piles are arranged. An axially penetrating air injection channel is reserved at the center of each core pile, with a diameter of 50mm. Four rows of venting micropores communicating with the air injection channel are evenly distributed circumferentially on the surface of the core pile, with a diameter of 15mm. Multiple high-strength concrete core piles are connected into a stable integral spatial structure by multiple cylindrical cast-in-place concrete connectors evenly arranged along their axial direction. The positions of the concrete connectors are staggered from the distribution areas of the venting micropores. The core pile assembly is inserted into the mixing pile body as a whole before the initial setting of the carbonizable cement-soil mixing pile.

[0007] This invention also provides a construction method for an integrally implanted multi-hole core pile reinforced composite pile, comprising the following steps:

[0008] S1: Factory-prefabricated core pile assembly: In the factory, high-strength concrete core piles with air injection channels and venting micropores are prefabricated. The horizontal bars and reinforcing bars at 5 predetermined elevation positions of multiple high-strength concrete core piles with air injection channels and venting micropores are tied together and concrete is poured to form a concrete connector. Multiple high-strength concrete core piles are connected into one unit through the concrete connector to form an integral core pile assembly.

[0009] S2: On-site preparation of carbonizable cement-soil mixing piles: Drill to the designed depth using mixing equipment, and simultaneously spray carbonizable cementitious material slurry to fully mix with the foundation soil to form carbonizable cement-soil mixing piles;

[0010] S3: Integrated implantation of precast core pile assembly: Before the initial setting of the carbonizable cement-soil mixing pile, the core pile assembly is vertically implanted into the carbonizable cement-soil mixing pile at the designed elevation position in one go using pile driving equipment.

[0011] S4: Precast core pile assembly connection and commissioning of the gas injection system: Connect the output end of the carbon dioxide supply device to the gas injection port at the top of each core pile through a branch pipeline with an independent valve. The branch pipeline is equipped with a flow meter and a pressure gauge to check the air tightness of the system.

[0012] S5: Staged pressure injection of CO2 gas and carbonization curing:

[0013] Initial diffusion stage: After the core pile group is implanted into the carbonizable cement-soil mixing pile, the gas supply device is connected. CO2 gas is continuously injected into the core pile group at a pressure of 0.1~0.15MPa for 2~4 hours. The CO2 gas flows through the gas injection channel and seeps out evenly from the exhaust micropores of each core pile, carbonizing and curing the surrounding cement-soil. In the initial stage, the gas initially establishes a diffusion path.

[0014] Main carbonization stage: The pressure is gradually increased to 0.25~0.3MPa, and the cycle mode of "injecting gas for 8 hours and stabilizing and standing for 4 hours" is adopted and continued for 36~60 hours. During this stage, gas continuously and evenly seeps out from a large number of exhaust micropores in each core pile and reacts fully with the carbonizable cement soil.

[0015] Later penetration stage: Adjust the pressure to 0.15~0.2MPa and continue injection for 8~12 hours to enhance the deep penetration effect;

[0016] S6: Carbonation process monitoring and curing completion: During the curing process, monitor the injection pressure, cumulative flow and pH value changes of the soil near the pile top; after reaching the predetermined curing time or strength growth index, stop the injection; slowly release the system pressure, disassemble the injection pipeline, and use special sealing material to permanently seal each injection port.

[0017] The present invention provides an integrally implanted multi-hole core pile group reinforced stiff composite pile and its construction method, which have the following beneficial effects:

[0018] (1) Construction efficiency is greatly improved: the core pile group can be prefabricated in the factory and multiple core piles can be installed on site as a whole at one time, realizing "one hoisting and one installation", which greatly reduces the number of hoisting and positioning, significantly shortens the construction period, and improves work efficiency.

[0019] (2) Uniform and efficient carbonization: Multiple core piles provide distributed gas sources. Combined with the staggered design of the concrete connector and the exhaust area, the gas is released and diffused without obstruction, and the carbonization is uniform and efficient to the optimal level.

[0020] (3) The overall structure and strength are significantly enhanced: Five 300mm thick cast-in-place concrete connectors are set at intervals to firmly connect multiple core piles into a spatial statically indeterminate structure. Its bending, shear, and torsional stiffness and stability are far superior to those of a single core pile or multiple unconnected core piles, which significantly improves the overall bearing capacity and seismic performance of the composite pile.

[0021] (4) High quality controllability: The core pile assembly is prefabricated in the factory, with high parameter accuracy (hole diameter, hole spacing, position and size of concrete connectors) and stable quality. The on-site implantation process is simplified, and the quality is easier to control. The air injection pressure and time for carbonation curing can be quantified and controlled, which is conducive to quality standardization.

[0022] (5) Material-process matching: Special carbonizable cement soil material is matched with staged air injection curing process to maximize the carbonization reaction speed and depth, and the early strength development is rapid (50%-70% of the design strength can be reached in 24-48 hours), and the long-term strength and durability are improved simultaneously.

[0023] (6) It has both economic and environmental benefits: improved construction efficiency reduces labor and machinery costs; enhanced structural performance allows for optimized design and material savings; carbon dioxide curing improves performance and sequesters carbon sinks. Attached Figure Description

[0024] Figure 1 This is a perspective view of an integrally implanted multi-hole core pile reinforced composite pile according to the present invention;

[0025] Figure 2 This is a top view of an integrally implanted multi-hole core pile reinforced composite pile according to the present invention;

[0026] Figure 3 This is a cross-sectional layout diagram of four high-strength concrete core piles;

[0027] Figure 4 This is a cross-sectional layout diagram of five high-strength concrete core piles;

[0028] Figure 5This is a flowchart of a construction method for an integrally implanted multi-hole core pile reinforced composite pile according to the present invention;

[0029] Figure 6 This is a schematic diagram of the carbonization curing of the integrally implanted porous core pile group reinforced composite pile of the present invention;

[0030] Among them, 1-carbonizable cement-soil mixing pile; 2-high-strength concrete core pile; 3-concrete connector; 4-air injection channel; 5-exhaust micropore; 6-sealing plug; 7-valve; 8-pressure gauge; 9-diversion pipeline; 10-pressure reducing valve. Detailed Implementation

[0031] like Figure 1 As shown, the present invention provides an integrally implanted porous core pile group reinforced composite pile, comprising: a carbonizable cement-soil mixing pile 1 and a prefabricated core pile group.

[0032] The carbonizable cement-soil mixing pile 1 is formed by mixing and solidifying carbonizable cementitious slurry with foundation soil on site.

[0033] The core pile assembly comprises multiple precast high-strength concrete core piles 2, with the center-to-center shape of each core pile's end face forming a regular polygon. Each high-strength concrete core pile 2 has an axially extending air injection channel 4 pre-installed at its center, the channel having a diameter of 50mm. Four rows of venting micro-holes 5, each with a diameter of 15mm, are evenly distributed circumferentially on the pile surface, communicating with the air injection channel 4. The multiple high-strength concrete core piles 2 are connected into a stable, integrated spatial structure by multiple cylindrical cast-in-place concrete connectors 3 evenly arranged along their axial direction. The positions of the concrete connectors 3 are staggered from the distribution areas of the venting micro-holes 5 to ensure unobstructed gas release paths. The core pile assembly is integrally implanted into the mixing pile body before the initial setting of the carbonizable cement-soil mixing pile 1.

[0034] like Figure 2-4 As shown, the number of precast high-strength concrete core piles 2 in the core pile group is 3, 4, or 5. When there are 3 high-strength concrete core piles, the shape of the center connection of the end faces of the 3 high-strength concrete core piles is an equilateral triangle; when there are 4 high-strength concrete core piles, the shape of the center connection of the end faces of the 4 high-strength concrete core piles is a square; and when there are 5 high-strength concrete core piles, the shape of the center connection of the end faces of the 5 high-strength concrete core piles is a regular pentagon.

[0035] In specific implementation, the exhaust microholes 5 are arranged radially along the high-strength concrete core pile 2 and connected to the air injection channel 4. The vertical spacing between adjacent exhaust microholes 5 in each row is 300~500mm.

[0036] In practice, five cylindrical cast-in-place concrete connectors 3 are provided, which are respectively set at the top, bottom and middle three-part points of the core pile group. No venting microholes 5 are set within the pile body section covered by the concrete connectors 3.

[0037] In practice, the cylindrical cast-in-place concrete connector is 300mm thick and is equipped with reinforcing bars that connect the horizontal bars of each core pile into one unit.

[0038] In specific implementation, the carbonizable cementitious material contains 50% to 70% silicate cement, 20% to 40% highly active magnesium oxide, 6% to 15% slag powder and 0.5% to 2% carbonation reaction catalyst by mass percentage, and its hydration products have high carbon dioxide reactivity; the concrete of the high-strength concrete core pile also contains active admixtures.

[0039] The carbonizable cementitious material of the present invention is designed to optimize the pore structure and alkaline environment of the slurry, so as to give it high carbon dioxide permeability and reactivity, and ensure that the carbonization reaction can proceed quickly and fully.

[0040] like Figure 5 As shown, the construction method of an integrally implanted multi-hole core pile reinforced composite pile according to the present invention includes the following steps:

[0041] S1: Factory-prefabricated core pile assembly: In the factory, high-strength concrete core piles with air injection channels and venting micropores are prefabricated. The horizontal bars and reinforcing bars at 5 predetermined elevation positions of multiple high-strength concrete core piles with air injection channels and venting micropores are tied together and concrete is poured to form a concrete connector. Multiple high-strength concrete core piles are connected into one unit through the concrete connector to form an integral core pile assembly.

[0042] In practice, during the prefabrication of the core pile assembly, the surface of its concrete connectors is roughened or shear keys are installed to enhance its adhesion and mechanical interlocking with the on-site cement and soil.

[0043] S2: On-site preparation of carbonizable cement-soil mixing piles: Drill to the designed depth using mixing equipment, and simultaneously spray carbonizable cementitious material slurry to fully mix with the foundation soil to form carbonizable cement-soil mixing piles.

[0044] S3: Integral implantation of precast core pile assembly: Before the initial setting of the carbonizable cement-soil mixing pile (approximately 1 hour), the core pile assembly is vertically implanted into the carbonizable cement-soil mixing pile at the designed elevation position in one go using pile driving equipment.

[0045] The implantation process must ensure the verticality of the core pile assembly and its position on the designed plane. The lifting ring or connector on the top of the core pile assembly can be used for lifting and positioning.

[0046] S4: Precast core pile assembly connection and commissioning of the gas injection system: Connect the output end of the carbon dioxide supply device to the gas injection port at the top of each core pile through the diversion pipeline 9 with independent valve 7, and check the air tightness of the system;

[0047] In practice, a flow meter and a pressure gauge 8 are installed on the diversion pipeline 9, and a pressure reducing valve 10 is also installed on the pipeline at the output end of the carbon dioxide supply device.

[0048] S5: Staged pressure injection of CO2 gas and carbonization curing: Figure 6 This is a schematic diagram of carbonization curing for integrally implanted porous core pile reinforced composite piles.

[0049] Initial diffusion stage: After the core pile group is implanted into the carbonizable cement-soil mixing pile, the gas supply device is connected. CO2 gas is continuously injected into the core pile group at a pressure of 0.1~0.15MPa for 2~4 hours. The CO2 gas flows through the gas injection channel and seeps out evenly from the exhaust micropores of each core pile, carbonizing and curing the surrounding cement-soil. In the initial stage, the gas initially establishes a diffusion path.

[0050] Main carbonization stage: The pressure is gradually increased to 0.25~0.3MPa, and the cycle mode of "injecting gas for 8 hours and stabilizing and standing for 4 hours" is adopted and continued for 36~60 hours. During this stage, gas continuously and evenly seeps out from a large number of exhaust micropores in each core pile and reacts fully with the carbonizable cement soil.

[0051] Later penetration stage: Adjust the pressure to 0.15~0.2MPa and inject continuously for 8~12 hours to enhance the deep penetration effect.

[0052] In practice, during the phased pressure injection of CO2 gas and carbonization curing process, a thick plastic film is covered over the top of the pile and sealed with geotextile to form a temporary top gas cover, reducing the upward escape of carbon dioxide and improving carbonization efficiency.

[0053] During the carbonization curing process, by adjusting the valves of each branch pipeline, it is possible to achieve differentiated gas injection into different core pile gas injection channels to meet the needs of uneven geological conditions or local reinforcement.

[0054] S6: Carbonation process monitoring and curing completion: During the curing process, monitor the changes in air injection pressure, cumulative flow and pH value of the soil near the pile top; after the predetermined curing time or strength growth index is reached, stop air injection; slowly release the system pressure, disassemble the air injection pipeline, and use a special sealing plug 6 to permanently seal each air injection port.

[0055] Twenty-four hours after the curing is completed, unconfined compressive strength or light penetration tests can be conducted on the pile body to verify the strengthening effect of carbonization curing.

[0056] Example 1 (3-core pile scheme)

[0057] In this embodiment, the core pile assembly comprises three cylindrical high-strength concrete core piles with a diameter of 300mm. The arrangement is as follows: Figure 2 As shown, a 50mm diameter air injection channel is prefabricated at the center of each core pile. Four rows of 15mm diameter venting microholes are evenly opened along the circumference of the pile body surface, with a vertical spacing of 400mm, and are connected to the air injection channel.

[0058] Five 300mm thick C40 micro-expansion concrete cylindrical connectors were poured along the pile length, located at the pile top, 2 / 5 pile length, 3 / 5 pile length, 4 / 5 pile length, and pile bottom, respectively (e.g., ...). Figure 1 As shown, the horizontal reinforcement bars at five predetermined elevation positions of the three core piles are tied to the reinforcement bars of the connecting body and then cast into a single unit with concrete to form an integral core pile assembly. No venting micropores are provided within the area covered by the concrete connecting body, creating a discontinuous zone approximately 400mm long.

[0059] The carbonizable cementitious material comprises 68% silicate cement, 18% highly active magnesium oxide, 13% slag powder, and 1% carbonation reaction catalyst by mass, with a water-cement ratio of 0.55. Its hydration products exhibit high carbon dioxide reactivity. It is mixed with on-site clay to form cement-soil mixing piles with a diameter of 1200 mm.

[0060] The construction method is as follows:

[0061] S1: Factory-prefabricated core pile assembly.

[0062] S2: On-site preparation of carbonizable cement-soil mixing piles.

[0063] S3: Integral implantation of precast core pile assembly. Before the initial setting of the cement-soil pile body (approximately 1 hour), the above-mentioned precast core pile assembly is hoisted as a whole and a large static pile driver is used to vertically press the entire core pile assembly into the center of the cement-soil mixing pile to the design elevation in one go.

[0064] S4: Precast core pile assembly connection and commissioning gas injection system: Connect the carbon dioxide gas supply system to the three gas injection ports at the top of each core pile (one for each core pile).

[0065] S5: Staged pressure injection of CO2 gas and carbonization curing:

[0066] Initial diffusion stage: Inject gas continuously at a pressure of 0.12 MPa for 3 hours.

[0067] Main carbonization stage: The pressure is raised to 0.28 MPa, and four complete cycles of "injecting gas for 8 hours and stabilizing pressure for 4 hours" are performed, for a total of 48 hours.

[0068] Late-stage permeation: Pressure is reduced to 0.18 MPa, and gas is continuously injected for 10 hours.

[0069] During the curing process, a sealing film is applied to the top of the pile to assist in curing. The total air injection time is approximately 61 hours.

[0070] S6: Carbonation process monitoring and curing completed. During the curing process, monitor the injection pressure, cumulative flow, and pH changes of the soil near the pile top; after reaching the predetermined curing time or strength growth index, stop the injection; slowly release the system pressure, disassemble the injection pipeline, and permanently seal each injection port with special sealing material.

[0071] Example 2 (4-core pile scheme)

[0072] The difference from Example 1 is that:

[0073] In this embodiment, the core pile assembly consists of four 300mm diameter cylindrical high-strength concrete core piles arranged in a square, with five 300mm thick C40 micro-expansion concrete connectors cast along the pile length. The air injection channels and exhaust micropores are arranged according to the same principles. The carbon dioxide injection method and curing mode are also the same.

[0074] Example 3 (5 core pile scheme)

[0075] The difference from Example 1 is that:

[0076] In this embodiment, the core pile assembly consists of five 300mm diameter cylindrical high-strength concrete core piles arranged in a regular pentagon. Five 300mm thick C40 micro-expansion concrete connectors are cast along the pile length. The air injection channels and exhaust micropores are arranged according to the same principles. The carbon dioxide injection method and curing mode are also the same.

[0077] The above embodiments demonstrate that the present invention, through the synergistic effect of a specific array of factory-prefabricated integral core pile groups, staggered connecting bodies, a porous venting system, special carbonizable materials, and a refined gas injection curing process, successfully constructs a high-performance, high-efficiency, and high-quality rigid composite pile technology system. This system resolves the inherent contradiction between construction efficiency, carbonization uniformity, and structural integrity, and has broad prospects for engineering applications.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the ideas of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of integrally implanted multi-hole core pile reinforced composite pile, characterized in that, include: Carbonizable cement-soil mixing piles and prefabricated core pile assemblies; The carbonizable cement-soil mixing pile is formed by mixing and solidifying a carbonizable cementitious slurry with the foundation soil on site. The core pile assembly comprises multiple precast high-strength concrete core piles. When the multiple high-strength concrete core piles are arranged, the center-to-center shape of each core pile end face is a regular polygon. An axially penetrating air injection channel is reserved at the center of each core pile, and the diameter of the air injection channel is 50mm. Four rows of venting microholes communicating with the air injection channel are evenly distributed circumferentially on the surface of the core pile, and the diameter of the venting microholes is 15mm. The multiple high-strength concrete core piles are connected into a stable integral spatial structure by multiple cylindrical cast-in-place concrete connectors evenly arranged along their axial direction. The positions of the concrete connectors are staggered from the distribution areas of the venting microholes. The core pile assembly is integrally implanted into the mixing pile body before the initial setting of the carbonizable cement-soil mixing pile.

2. The integrally implanted multi-hole core pile reinforced composite pile according to claim 1, characterized in that, The exhaust micropores are arranged radially along the high-strength concrete core pile and are connected to the air injection channel. The spacing between adjacent exhaust micropores in each row is 300~500mm.

3. The integrally implanted multi-hole core pile reinforced composite pile according to claim 1, characterized in that, Five cylindrical cast-in-place concrete connectors are provided, which are respectively set at the top, bottom and middle three-part points of the core pile group. No venting micropores are set within the pile body section covered by the concrete connectors.

4. The integrally implanted multi-hole core pile reinforced composite pile according to claim 1, characterized in that, The number of precast high-strength concrete core piles in the core pile group is 3, 4 or 5. When there are 3 high-strength concrete core piles, the shape of the center connection of the end faces of the 3 high-strength concrete core piles is an equilateral triangle; when there are 4 high-strength concrete core piles, the shape of the center connection of the end faces of the 4 high-strength concrete core piles is a square; when there are 5 high-strength concrete core piles, the shape of the center connection of the end faces of the 5 high-strength concrete core piles is a regular pentagon.

5. The integrally implanted multi-hole core pile reinforced composite pile according to claim 1, characterized in that, The cylindrical cast-in-place concrete connector is 300mm thick and has internal reinforcing bars that connect the horizontal bars of each core pile into a single unit.

6. The integrally implanted multi-hole core pile reinforced composite pile according to claim 1, characterized in that, The carbonizable cementitious material comprises 50% to 70% silicate cement, 20% to 40% highly active magnesium oxide, 6% to 15% slag powder, and 0.5% to 2% carbonation reaction catalyst by mass percentage, and its hydration products have high carbon dioxide reactivity; the concrete of the high-strength concrete core pile also contains active admixtures.

7. A construction method for an integrally implanted multi-hole core pile reinforced composite pile as described in claims 1 to 6, characterized in that, Includes the following steps: S1: Factory-prefabricated core pile assembly: In the factory, high-strength concrete core piles with air injection channels and venting micropores are prefabricated. The horizontal bars and reinforcing bars at 5 predetermined elevation positions of multiple high-strength concrete core piles with air injection channels and venting micropores are tied together and concrete is poured to form a concrete connector. Multiple high-strength concrete core piles are connected into one unit through the concrete connector to form an integral core pile assembly. S2: On-site preparation of carbonizable cement-soil mixing piles: Drill to the designed depth using mixing equipment, and simultaneously spray carbonizable cementitious material slurry to fully mix with the foundation soil to form carbonizable cement-soil mixing piles; S3: Integrated implantation of precast core pile assembly: Before the initial setting of the carbonizable cement-soil mixing pile, the core pile assembly is vertically implanted into the carbonizable cement-soil mixing pile at the designed elevation position in one go using pile driving equipment. S4: Connection and commissioning of precast core pile assembly and gas injection system: Connect the output end of the carbon dioxide supply device to the gas injection port at the top of each core pile through a branch pipeline with an independent valve. Install a flow meter and pressure gauge on the branch pipeline and check the air tightness of the system. S5: Staged pressure injection of CO2 gas and carbonization curing: Initial diffusion stage: After the core pile group is implanted into the carbonizable cement-soil mixing pile, the gas supply device is connected. CO2 gas is continuously injected into the core pile group at a pressure of 0.1~0.15MPa for 2~4 hours. The CO2 gas flows through the gas injection channel and seeps out evenly from the exhaust micropores of each core pile, carbonizing and curing the surrounding cement-soil. In the initial stage, the gas initially establishes a diffusion path. Main carbonization stage: The pressure is gradually increased to 0.25~0.3MPa, and the cycle mode of "injecting gas for 8 hours and stabilizing and standing for 4 hours" is adopted and continued for 36~60 hours. During this stage, gas continuously and evenly seeps out from a large number of exhaust micropores in each core pile and reacts fully with the carbonizable cement soil. Later penetration stage: Adjust the pressure to 0.15~0.2MPa and then inject continuously for 8~12 hours to enhance the deep penetration effect; S6: Carbonation process monitoring and curing completion: During the curing process, monitor the injection pressure, cumulative flow and pH value changes of the soil near the pile top; after reaching the predetermined curing time or strength growth index, stop the injection; slowly release the system pressure, disassemble the injection pipeline, and use a special sealing plug to permanently seal each injection port.

8. The construction method of the integrally implanted multi-hole core pile reinforced composite pile according to claim 7, characterized in that: In step S5, a thick plastic film is covered over the top area of ​​the pile and sealed with geotextile to form a temporary top air cover, reducing the upward escape of carbon dioxide and improving carbonization efficiency.

9. The construction method of the integrally implanted multi-hole core pile reinforced composite pile according to claim 7, characterized in that: In step S5, by adjusting the valves of each branch pipeline, differential gas injection can be achieved for different core pile gas injection channels to meet the needs of uneven geological conditions or local reinforcement.

10. The construction method of the integrally implanted multi-hole core pile reinforced composite pile according to claim 7, characterized in that: During the prefabrication of the core pile assembly, the surface of its concrete connectors is roughened or shear keys are installed to enhance its adhesion and mechanical interlocking with the on-site cement and soil.

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