A precast concrete element with a targeted repair channel and a method of repairing the same

Abstract

The application relates to the technical field of precast concrete components, and discloses a precast concrete component with a targeted repair channel and a repair method thereof, which comprises a component body, the inside of the component body is provided with a plurality of hollow pipes, a plurality of grouting interfaces are equidistantly arranged on the outside of the hollow pipes, a plurality of grout outlets are arranged on the outside of the hollow pipes, a temporary sealing layer is arranged on one side of the inner cavity of the grout outlet, a sealing plug is arranged at one end of the temporary sealing layer, and the sealing plug is slidingly connected to the inner wall of the grout outlet; the plurality of hollow pipes and the grout outlets are distributed in a grid or branch shape in the inner cavity of the component body; and the material of the hollow pipes is selected from one or a combination of polyvinyl chloride, polypropylene, polyethylene, stainless steel, galvanized steel, polyvinyl alcohol and polylactic acid. The temporary sealing layer and the sealing plug arranged at the end of the grout outlet solve the technical problem that the pre-embedded repair channel is easily damaged during the preparation of the component.

Description

Technical Field

[0001] This invention relates to the field of precast concrete component technology, specifically to a precast concrete component with targeted repair channels and its repair method. Background Technology

[0002] Precast concrete components are widely used in infrastructure construction, but due to the brittle nature of concrete, these components inevitably develop microcracks under load during service, affecting the structure's durability. To address this issue, embedding fluid delivery pipelines within the components to create a self-healing system has become a technological approach. This technology aims to fill and heal cracks by delivering a repair agent through the embedded pipelines when cracks appear.

[0003] However, the effective construction of pre-embedded repair channel systems in existing technologies faces significant technological challenges, primarily concentrated in the component casting stage. Concrete pouring involves high-intensity mechanical vibration and lateral hydrostatic pressure generated by the liquid concrete. Existing pre-embedded pipes typically only use tape or a thin film to simply cover the surface at the grout outlet to prevent concrete intrusion. Because the pipe's internal structure is hollow, this simple film covering lacks effective backing support. Under the impact load of concrete pouring and continuous vibration, the film covering the grout outlet is highly susceptible to inward collapse, rupture, or shear failure due to excessive internal and external pressure differences.

[0004] Once the seal fails, the highly fluid concrete grout will penetrate the pipe under pressure and harden as the component solidifies, causing irreversible physical blockage of the repair channel. This blockage not only renders the repair channel inoperable before the component enters service, but also makes it difficult to clean or unclog using conventional methods because the blockage is located deep within the component. Furthermore, while using a permanent solid plug can solve the pressure resistance problem, it prevents the establishment of a connection between the fluid inside the pipe and the external crack without damaging the component itself, thus preventing the repair agent from flowing out. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a precast concrete component with targeted repair channels and its repair method. This solves the technical problem in existing technologies where the port closure structure of the pre-embedded repair channels is prone to cracking and failure under the high-pressure impact environment of concrete pouring and vibration due to the lack of effective rigid support, which leads to the intrusion and solidification of concrete slurry, causing irreversible blockage of the channels.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a precast concrete component with a targeted repair channel, comprising a component body, wherein a plurality of hollow tubes are provided inside the component body, a plurality of grouting ports are provided at equal intervals on the outside of the hollow tubes, a plurality of grout outlet pipes are provided on the outside of the hollow tubes, a pre-sealing layer is provided on one side of the inner cavity of the grout outlet pipe, a sealing plug is abutted at one end of the pre-sealing layer, and the sealing plug is slidably connected to the inner wall of the grout outlet pipe.

[0007] According to the above technical solution, the structural integrity of the pre-embedded repair channel is protected during the component casting and vibration stages by utilizing the combination of a temporary sealing layer and a rigid sealing plug located at the end of the grout outlet pipe. The rigid sealing plug provides backing support for the temporary sealing layer, effectively resisting the lateral pressure and impact of the concrete grout, preventing damage or subsidence of the temporary sealing layer. After the initial setting of the concrete, removing the sealing plug creates a clean cavity leading to the temporary sealing layer, ensuring the unobstructed flow and usability of the repair channel throughout the entire pre-embedding process.

[0008] Preferably, the plurality of hollow tubes and slurry outlet tubes are distributed in a grid-like or dendritic pattern within the internal cavity of the component body.

[0009] Preferably, the hollow tube is made of one or more of the following materials: polyvinyl chloride, polypropylene, polyethylene, stainless steel, galvanized steel, polyvinyl alcohol, and polylactic acid. The outer wall surface of the hollow tube is provided with a friction-enhancing structure, which includes threads, ridges, a frosted layer, or a corrugated structure.

[0010] A method for repairing precast concrete components includes the following steps: S1. Based on the mechanical analysis of the component body, connect the hollow pipes with predetermined stiffness and external wall friction-enhancing structure into a grid-like or tree-like repair channel network, set several grout outlet pipes at intervals along the axial direction on the hollow pipes, and install the grouting interface at one or both ends of the hollow pipes. S2. Cover the end port of each slurry outlet with a pre-sealing layer to form an initial seal, and then insert the sealing plug into the slurry outlet so that its end face is tightly against the inner surface of the pre-sealing layer. S3. All sealing plugs are connected in series by a flexible traction component and led out to the grouting interface through the inner cavity of the hollow pipe. S4. Fix the hollow pipe after installation onto the steel reinforcement skeleton inside the component body mold, position it in the crack-prone area of ​​the component, pour concrete into the mold and vibrate it. S5. After the concrete reaches the preset strength and forms the component body, open the grouting interface and pull it outward with the flexible traction component to remove all the sealing plugs in the hollow pipe and the grout outlet pipe through the grouting interface in sequence. S6. When cracks are detected or observed on the surface of the component body, determine the location of one of the hollow tubes by the direction of the cracks. S7. Unscrew the top sealing cap of the grouting interface of the hollow pipe in the corresponding area and connect the output pipe of the high-pressure grouting equipment to the grouting interface; S8. Start the grouting equipment and pump the low-viscosity repair grout into the hollow pipe. As the grouting pressure increases, the grout fills the entire channel network. When the pressure reaches the preset threshold, the repair grout breaks through the pre-sealed layer at the end of the grout pipe from the inside. The repair grout automatically diverts and permeates under pressure. S9. Stop grouting and maintain pressure. After the grout has initially solidified, remove the grouting equipment, reseal the grouting interface, and complete the repair after the repair grout has fully solidified.

[0011] According to the above technical solution: based on the mechanism of different fluid penetration resistance in different media, automatic diversion and targeted penetration of the repair grout are achieved by controlling the grouting pressure and grout viscosity. After the grouting pressure breaks through the sealing layer, the crack area forms a low fluid resistance path due to its connection with the outside, guiding the grout to preferentially flow in and fill the crack space; while the dense concrete interface of the intact area forms a high fluid resistance boundary, effectively preventing the grout from flowing out, thus completing the precise repair of the damaged area of ​​the component without the need for complex control equipment. In addition, the friction-enhancing structure of the hollow pipe's outer wall strengthens the mechanical bond between the pipe and the concrete matrix, preventing interface debonding and slippage.

[0012] Preferably, the thickness of the pre-sealing layer is 0.05 mm to 0.2 mm, and the pre-sealing layer is made of polyethylene or polyvinyl chloride film.

[0013] Preferably, the sealing plug is removed in step S5 after the concrete has reached its initial setting state and before its final setting state.

[0014] Preferably, the initial viscosity of the repair grout is 100 cP to 500 cP, and the grouting pressure is controlled to be 0.2 MPa to 1.0 MPa.

[0015] Preferably, the repair grout includes low-viscosity epoxy resin grout, low-viscosity polyurethane grout, or ultrafine cement-based grout.

[0016] Preferably, in step S8, the automatic diversion and infiltration includes the following: for the grout outlet at the location of the crack, because the crack provides a low-resistance path, the repair grout flows into the crack space from the inside and fills the crack from the inside out. For the grout outlet pipe in the intact area, because the outside is tightly wrapped by the dense component body, the repair grout cannot flow out.

[0017] Preferably, the pressure holding time in step S9 is 10 min to 30 min.

[0018] This invention provides a precast concrete component with targeted repair channels and a repair method thereof. It has the following beneficial effects: 1. This invention solves the technical problem of easy damage to pre-embedded repair channels during component preparation by setting a pre-sealing layer and a sealing plug at the end of the grout outlet pipe. During concrete pouring and vibration, the rigid sealing plug effectively supports the pre-sealing layer, preventing it from cracking or sinking due to external pressure or impact. After the concrete has solidified, the sealing plug can be controllably removed, leaving a cavity in the grout outlet pipe, thus ensuring the integrity of the pre-sealing layer before grouting and ensuring the structural reliability of the repair channel system throughout the entire process of pre-embedding, pouring, and solidification.

[0019] 2. This invention achieves automatic diversion and permeation of the repair grout by controlling the performance of the repair grout and the pressure of the grouting equipment during the repair stage, and by utilizing the permeability differences of fluids in different media. When the grout breaks through the pre-sealing layer, the presence of the crack provides a low fluid resistance path for the grout, allowing it to preferentially and primarily flow towards the crack area for filling; while the dense concrete in the intact area provides high fluid resistance, effectively preventing non-target permeation of the grout.

[0020] 3. This invention applies a friction-enhancing structure and ring stiffness constraint to the pre-embedded hollow pipe. The friction-enhancing structure on the outer wall significantly strengthens the mechanical bond between the pipe and the concrete, effectively preventing the pipe from debonding or slipping when the component shrinks, temperature changes, or cracks under load, thus ensuring the long-term stability of the repair channel network. Simultaneously, the predetermined ring stiffness of the pipe resists the lateral pressure during concrete pouring and vibration, preventing structural deformation or collapse of the pipe. Attached Figure Description

[0021] Figure 1 This is a schematic cross-sectional view of the component body of the present invention; Figure 2 This is a schematic diagram of the side cross-sectional structure of the hollow tube of the present invention; Figure 3 For the present invention Figure 2 Enlarged view of point A; Figure 4 This is a schematic diagram of the process steps of the present invention.

[0022] The components include: 1. Component body; 2. Hollow pipe; 3. Grouting interface; 4. Grout outlet pipe; 5. Sealing plug; 6. Pre-sealing layer. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0024] Please see the appendix Figure 1 -Appendix Figure 3 This invention provides a precast concrete component with a targeted repair channel, including a component body 1. The component body 1 has multiple hollow pipes 2 inside. Multiple grouting ports 3 are equidistantly opened on the outside of the hollow pipes 2. Multiple grout outlet pipes 4 are arranged on the outside of the hollow pipes 2. A temporary sealing layer 6 is arranged on one side of the inner cavity of the grout outlet pipe 4. One end of the temporary sealing layer 6 abuts against a sealing plug 5. The sealing plug 5 is slidably connected to the inner wall of the grout outlet pipe 4.

[0025] Specifically, the component body 1 is a structural load-bearing body made of cured concrete material. Multiple hollow pipes 2 are installed inside the component body 1. These pipes form a pre-set fluid transport network inside. The outer wall surface of the hollow pipes 2 is provided with a friction-enhancing structure, such as a threaded, raised, or corrugated structure, to improve the mechanical interlocking force between the pipes and the surrounding concrete material, so as to maintain the structural interface stability during the service of the component. Multiple grout outlet pipes 4 are connected axially at intervals to the hollow pipes 2. The end ports of the grout outlet pipes 4 face the concrete entity of the component body 1. Multiple grouting ports 3 are equidistantly opened on the outside of the hollow pipes 2. The grouting ports 3 are used to connect to external fluid pumping equipment to realize the input of repair grout.

[0026] A pre-sealing layer 6 is provided on one side of the inner cavity of the slurry outlet pipe 4. The pre-sealing layer 6 is a thin film material with a preset tensile strength and fracture strain, which physically isolates the fluid space inside the slurry outlet pipe 4 from the external concrete matrix.

[0027] The pre-sealing layer 6 ensures the cleanliness and integrity of the repair channel system in its unrepaired state. One end of the pre-sealing layer 6 abuts against a sealing plug 5, which is an elastic component. The contact surface between the sealing plug 5 and the pre-sealing layer 6 is treated to ensure uniform rigid support for the pre-sealing layer 6 in the assembled state. The sealing plug 5 is located on the inner wall of the slurry outlet pipe 4 and is slidably connected, allowing the sealing plug 5 to move axially within the pipe.

[0028] During the casting and molding process of component body 1, the sealing plug 5 provides crucial backing support for the temporary sealing layer 6 through its tight contact with the temporary sealing layer 6. This support function is designed to resist the lateral pressure exerted on the temporary sealing layer 6 by the poured concrete grout, as well as the impact load generated by the vibration operation, preventing the temporary sealing layer 6 from cracking during component molding and thus avoiding premature intrusion of concrete grout into the repair channel. The sealing plug 5 is connected and led out to the grouting interface 3 via a traction component, so that it can be completely extracted and removed after the component strength meets the requirements. After the sealing plug 5 is removed, a reserved cavity is formed in the grout outlet pipe 4 leading to the temporary sealing layer 6. This cavity creates fluid space for the subsequent grouting repair stage and ultimately puts the repair channel in a ready state.

[0029] When a crack appears in component 1 and requires repair, low-viscosity repair grout is pumped in through grouting interface 3. Driven by pressure, the grout fills the hollow pipe 2 and outlet pipe 4, eventually breaking through the pre-sealing layer 6. Due to the presence of the crack, a low fluid permeability resistance path is formed at the end of the outlet pipe in the crack area, guiding the repair grout into the crack space; while in the dense area without cracks, the concrete provides high fluid permeability resistance, effectively preventing non-targeted penetration of the grout. This technical mechanism based on fluid resistance differences ensures that the repair grout can automatically divert and fill the cracked area.

[0030] Multiple hollow pipes 2 and slurry outlet pipes 4 are distributed in a grid-like or dendritic pattern within the inner cavity of the component body 1.

[0031] Specifically, this distribution pattern is designed based on the geometric shape of the component body 1 and the distribution characteristics of the internal stress field. For large-area planar components such as plates and walls, the hollow tube 2 usually adopts a crisscrossing grid layout to cover the entire stress plane. For long, narrow structural members such as beams and columns, the hollow tubes 2 tend to adopt a tree-like layout with a main trunk and branches, extending along the main stress axis of the member. The technical principle behind this design is to increase the probability of the repair channels intersecting with the plane of potential cracks. Since concrete cracks typically occur in stress concentration areas, pre-embedding the channel network at these critical locations ensures that when the member body 1 cracks, the crack path can be interrupted or connected to at least one grout outlet pipe 4. This connectivity design also allows for the supply of grout to a large area through a single or a small number of grouting interfaces 3. Under pressure, the repair grout can be transported along the connected network to any location at the end of the network, thus ensuring effective coverage and accessibility of repair for potentially damaged areas of the member.

[0032] The material of hollow tube 2 is selected from one or more combinations of polyvinyl chloride, polypropylene, polyethylene or stainless steel, galvanized steel or polyvinyl alcohol, and polylactic acid. The outer wall surface of the hollow tube 2 is provided with a friction-enhancing structure, which includes threads, ridges, abrasive layers, or corrugated structures.

[0033] Specifically, the materials used for hollow pipe 2 are diverse, and their selection depends on the type of component body 1, the pre-embedded environment, and the required structural durability. Materials can be selected from rigid plastics such as polyvinyl chloride, polypropylene, and polyethylene, which have good corrosion resistance and low cost; or metal materials such as stainless steel and galvanized steel can be used to obtain higher ring stiffness and strength, and resist more stringent pouring and vibration conditions.

[0034] In addition, to meet certain specific engineering requirements, materials can also be selected from one or more combinations of biodegradable or soluble materials such as polyvinyl alcohol and polylactic acid.

[0035] The friction-enhancing structure is a physical irregularity formed during the manufacturing process of the pipe, including one or more of the following: threads, ridges, frosted layers, or corrugated structures. The mechanism of this friction-enhancing structure is to increase the mechanical interlocking force at the interface between the pipe and the poured concrete. This mechanical interlocking effect significantly improves the hollow pipe's pull-out resistance and anti-slip performance in the cured concrete matrix, ensuring that the embedded pipe will not detach from the concrete matrix when the component is subjected to temperature stress, shrinkage deformation, or external loads causing minor cracks. This maintains the long-term structural stability of the repair channel network and guarantees the durability of the repair function. Example

[0036] Please see the appendix Figure 4 This embodiment, based on a precast concrete component with targeted repair channels from Embodiment 1, provides a method for repairing precast concrete components, including the following steps: S1. Based on the mechanical analysis of the component body 1, the hollow pipes 2 with predetermined stiffness and external wall friction-enhancing structure are connected into a grid-like or tree-like repair channel network. Several grout outlet pipes 4 are arranged at intervals along the axial direction on the hollow pipes 2, and the grouting interface 3 is installed at one or both ends of the hollow pipes 2. S2. Cover the end port of each slurry outlet pipe 4 with a temporary sealing layer 6 to form an initial seal. Then, insert the sealing plug 5 into the slurry outlet pipe 4 so that its end face is tightly against the inner surface of the temporary sealing layer 6. The thickness of the temporary sealing layer 6 is 0.05mm to 0.2mm, and the temporary sealing layer 6 is made of polyethylene or polyvinyl chloride film.

[0037] S3. All sealing plugs 5 are connected in series by a flexible traction component and led out through the inner cavity of the hollow pipe 2 to the grouting interface 3. S4. Fix the hollow pipe 2 after installation onto the steel reinforcement skeleton inside the mold of the component body 1, position it in the crack-prone area of ​​the component, pour concrete into the mold and vibrate it. S5. After the concrete reaches the preset strength and forms the component body 1, open the grouting interface 3 and pull it outward with the flexible traction component to remove all the sealing plugs 5 in the hollow pipe 2 and the grout outlet pipe 4 in sequence through the grouting interface 3. The timing for removing the sealing plugs 5 in step S5 is after the concrete reaches the initial setting state and before the final setting state.

[0038] S6. When a crack is detected or observed on the surface of the component body 1, the location of one of the hollow tubes 2 is determined by the direction of the crack. S7. Unscrew the top sealing cap of the grouting interface 3 of the hollow pipe 2 in the corresponding area, and connect the output pipe of the high-pressure grouting equipment to the grouting interface 3. S8. Start the grouting equipment and pump the low-viscosity repair grout into the hollow pipe 2. As the grouting pressure increases, the grout fills the entire channel network. When the pressure reaches the preset threshold, the repair grout breaks through the pre-sealed layer 6 at the end of the grout outlet pipe 4 from the inside. Under pressure, the repair grout automatically diverts and permeates. The initial viscosity of the repair grout is 100 cP to 500 cP, and the grouting pressure is controlled at 0.2 MPa to 1.0 MPa. The repair grout includes low-viscosity epoxy resin grout, low-viscosity polyurethane grout, or ultrafine cement-based grout. In step S8, the automatic diversion and permeation means that for the grout outlet at the location of the crack, because the crack provides a low-resistance path, the repair grout flows into the crack space from the inside and fills the crack from the inside out. However, for the grout outlet pipe 4 in the intact area, because it is tightly wrapped by the dense component body 1, the repair grout cannot flow out.

[0039] S9. Stop grouting and maintain pressure. After the grout has initially solidified, remove the grouting equipment and reseal grouting interface 3. After the repair grout has completely solidified, the repair is complete. The pressure holding time in step S9 is 10 to 30 minutes.

[0040] Specifically, the method first performs a repair network assembly step, determining stress concentration and potential cracking areas based on the mechanical analysis results of the component body 1. Based on this analysis, hollow pipes 2 with predetermined ring stiffness and external wall friction-enhancing structures are selected and connected to form a grid-like or dendritic repair channel network to ensure coverage of critical stress areas. Several grout outlet pipes 4 are spaced apart along the axial extension direction of the hollow pipes 2, and grouting interfaces 3 are installed and fixed at the ends of the hollow pipes 2.

[0041] After the channel network is assembled, sealing and support operations are performed. A polyethylene film or polyvinyl chloride film with a thickness of 0.05mm to 0.2mm is selected as the pre-sealing layer 6 and covers the end port of each grout outlet pipe 4 to form an initial physical seal. Then, a rigid sealing plug 5 is placed into the inner cavity of the grout outlet pipe 4 and adjusted until the end face of the sealing plug 5 tightly abuts against the inner surface of the pre-sealing layer 6. At this time, the sealing plug 5 provides a rigid backing for the pre-sealing layer 6 to resist external pressure. Next, all the sealing plugs 5 in the pipeline network are connected in series by a flexible traction device, and the end of the traction device is led out through the inner cavity of the hollow pipe 2 to the grouting interface 3, preparing for the subsequent removal process.

[0042] The casting and molding stage then begins. The hollow pipe 2, with its sealing components installed, is fixed to the reinforcing steel frame inside the mold, precisely positioned in the pre-analyzed crack-prone area. Concrete is poured into the mold and vibrated. During this process, the sealing plugs 5 support the temporary sealing layer 6 to resist the lateral pressure of the concrete slurry. After the concrete reaches its initial setting state but before its final setting state—that is, within the time window when the concrete matrix has achieved initial shape stability but is not yet fully hardened—the operator opens the grouting interface 3 and, by pulling the pre-installed flexible traction component, sequentially removes all the sealing plugs 5 from the hollow pipe 2 and the grout outlet pipe 4 through the grouting interface 3. After this step, a clean cavity leading to the temporary sealing layer 6 is formed inside the grout outlet pipe 4, and the temporary sealing layer 6 is positioned and encased by the surrounding hardened concrete.

[0043] When component body 1 is put into use and surface cracks are monitored or observed, the location of a specific hollow pipe 2 intersecting with the crack is determined based on the direction and distribution of the crack. The sealing cap on the top of the grouting interface 3 corresponding to that area is unscrewed, and the output pipeline of the high-pressure grouting equipment is airtightly connected to the grouting interface 3. The grouting equipment is started, and a low-viscosity repair grout with an initial viscosity between 100 cP and 500 cP is pumped in. The repair grout material is selected from one or more of low-viscosity epoxy resin grout, low-viscosity polyurethane grout, or ultrafine cement-based grout.

[0044] As the grouting operation proceeds, the grouting pressure is controlled within the range of 0.2 MPa to 1.0 MPa. As the fluid pressure inside the pipe increases and reaches a preset threshold, the repair grout breaks through the pre-sealed layer 6 at the end of the grout outlet pipe 4 from the inside. At this time, the system utilizes the difference in fluid resistance to achieve automatic diversion and penetration: for the grout outlet located at the crack location, since the crack space provides a low fluid resistance path connecting to the outside, the repair grout preferentially flows into the crack under pressure and completes the filling from the inside to the outside along the direction of crack extension; while for the grout outlet pipe 4 located in the intact concrete area, its exterior is tightly wrapped by the dense component body 1, forming a high fluid resistance interface, and the repair grout is blocked and cannot flow out.

[0045] After the grout fills the cracks, pumping is stopped but system pressure is maintained for 10 to 30 minutes. This pressure-holding process aims to compensate for grout shrinkage and penetration into microcracks. After the grout has initially cured, the grouting equipment is removed and the grouting interface 3 is resealed. Once the repair grout has fully cured, the structural repair of the component is complete.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A precast concrete component with targeted repair channels, comprising a component body (1), characterized in that: The component body (1) has multiple hollow pipes (2) inside. Multiple grouting ports (3) are equidistantly opened on the outside of the hollow pipes (2). Multiple grout outlet pipes (4) are provided on the outside of the hollow pipes (2). A sealing layer (6) is provided on one side of the inner cavity of the grout outlet pipe (4). A sealing plug (5) is abutted at one end of the sealing layer (6). The sealing plug (5) is slidably connected to the inner wall of the grout outlet pipe (4).

2. A precast concrete component with targeted repair channels according to claim 1, characterized in that: The hollow tubes (2) and the slurry outlet tubes (4) are distributed in a grid or dendritic pattern within the inner cavity of the component body (1).

3. A precast concrete component with targeted repair channels according to claim 1, characterized in that: The hollow tube (2) is made of one or more of the following materials: polyvinyl chloride, polypropylene, polyethylene or stainless steel, galvanized steel or polyvinyl alcohol, polylactic acid. The outer wall surface of the hollow tube (2) is provided with a friction-enhancing structure, which includes threads, ridges, frosted layers or corrugated structures.

4. A method for repairing precast concrete components, used in any one of claims 1-3 of a precast concrete component with a targeted repair channel, characterized in that, Includes the following steps: S1. Based on the mechanical analysis of the component body (1), the hollow pipe (2) with predetermined stiffness and external wall friction enhancement structure is connected into a grid-like or tree-like repair channel network. Several grout outlet pipes (4) are set at intervals along the axial direction on the hollow pipe (2), and the grouting interface (3) is installed at one or both ends of the hollow pipe (2). S2. Cover the end port of each slurry outlet pipe (4) with a pre-sealing layer (6) to form an initial seal. Then, place the sealing plug (5) into the slurry outlet pipe (4) so ​​that its end face is tightly against the inner surface of the pre-sealing layer (6). S3. All sealing plugs (5) are connected in series by a flexible traction member and led out to the grouting interface (3) through the inner cavity of the hollow pipe (2). S4. Fix the hollow pipe (2) after installation onto the steel reinforcement skeleton inside the mold of the component body (1), position it in the crack-prone area of ​​the component, pour concrete into the mold and vibrate it. S5. After the concrete reaches the preset strength and forms the component body (1), open the grouting interface (3), and pull it outward through the flexible traction component to remove all the sealing plugs (5) in the hollow pipe (2) and the grout outlet pipe (4) in sequence through the grouting interface (3). S6. When a crack is detected or observed on the surface of the component body (1), the location of one of the hollow tubes (2) is determined by the direction of the crack. S7. Unscrew the top sealing cap of the grouting interface (3) of the hollow pipe (2) in the corresponding area, and connect the output pipe of the high-pressure grouting equipment to the grouting interface (3). S8. Start the grouting equipment and pump the low-viscosity repair grout into the hollow pipe (2). As the grouting pressure increases, the grout fills the entire channel network. When the pressure reaches the preset threshold, the repair grout breaks through the sealing layer (6) at the end of the grout pipe (4) from the inside. The repair grout automatically diverts and permeates under pressure. S9. Stop grouting and maintain pressure. After the grout has initially solidified, remove the grouting equipment and reseal the grouting interface (3). After the repair grout has completely solidified, the repair is complete.

5. A method for repairing precast concrete components according to claim 4, characterized in that: The thickness of the pre-sealing layer (6) is 0.05 mm to 0.2 mm, and the pre-sealing layer (6) is made of polyethylene or polyvinyl chloride film.

6. A method for repairing precast concrete components according to claim 4, characterized in that: The sealing plug (5) in step S5 is removed after the concrete has reached its initial setting state and before its final setting state.

7. A method for repairing precast concrete components according to claim 4, characterized in that: The initial viscosity of the repair grout is 100 cP to 500 cP, and the grouting pressure is controlled to be 0.2 MPa to 1.0 MPa.

8. A method for repairing precast concrete components according to claim 4, characterized in that: The repair grout includes low-viscosity epoxy resin grout, low-viscosity polyurethane grout, or ultrafine cement-based grout.

9. A method for repairing precast concrete components according to claim 4, characterized in that: In step S8, automatic diversion and infiltration include the grout outlet at the location of the crack. Because the crack provides a low-resistance path, the repair grout flows into the crack space from the inside and fills the crack from the inside out. However, for the grout outlet pipe (4) in the intact area, the repair grout cannot flow out because it is tightly wrapped by the dense component body (1).

10. A method for repairing precast concrete components according to claim 4, characterized in that: The pressure holding time in step S9 is 10 to 30 minutes.

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