Multifunctional ECC superimposed structure system for weak area of station tunnel structure and construction method of multifunctional ECC superimposed structure system

Abstract

The invention provides a multifunctional ECC superimposed structure system for a weak area of a station tunnel structure and a construction method of the multifunctional ECC superimposed structure system. The structural system comprises an outer-side crack control type ECC layer, a middle debonding softening layer and an inner-side bearing type ECC layer, and the outer-side ECC layer improves the crack control capacity and the self-healing performance by doping a tensile reinforcing material or a self-healing functional material; the debonding softening layer is made of a weak interface or low-friction material, so that the outer side ECC layer and the inner side ECC layer generate controllable interface slippage when the stress reaches a preset threshold value, and differential deformation is realized; a controlled yield micro-block unit is arranged in the inner side ECC layer and is used for forming a transferable plastic energy consumption zone; a guide and drainage micro-channel is arranged between the outer ECC layer and the debonding layer, local water pressure can be released when cracks or water pressure reaches a threshold value, and the leakage risk is reduced. The structural system achieves the synergistic effect of bearing, crack control, self-healing, waterproof and energy dissipation functions through bearing layer prefabrication and outer layer on-site overlapping, is suitable for station side walls, tunnel linings and other weak parts, and can remarkably improve the long-term safety, anti-seismic toughness and use performance of a station tunnel structure.

Description

Technical Field

[0001] This invention relates to the field of underground structure reinforcement and seismic resistance technology, and in particular to a multifunctional ECC composite structure system and its construction method for weak areas of station and tunnel structures, belonging to the field of underground structure crack prevention, waterproofing, energy dissipation and toughness improvement technology. Background Technology

[0002] Station-tunnel structures refer to continuous structures in which subway stations and tunnel sections are integrated in design, construction, and structural system. Under seismic loads and long-term service conditions, these structures are prone to cracking, leakage, and localized strain concentration, especially at weak points such as station-tunnel interfaces, the base of concealed columns, wall penetrations, and sidewalls. These defects not only affect the structural safety and performance but may also lead to a decline in long-term durability. Traditional reinforcement or waterproofing measures, such as concrete or reinforced concrete reinforcement, the application of external steel or FRP materials, and waterproof membranes or coatings, while improving local load-bearing capacity or surface waterproofing performance to some extent, generally suffer from long construction periods, high costs, limited crack control capabilities, and difficulties in balancing ductility and energy dissipation capacity.

[0003] In recent years, ECC (engineering cement-based composites) has shown great potential in the reinforcement and repair of complex underground structures due to its high ductility, controllable cracking, and self-healing properties. However, current research and applications mainly focus on the crack control or local repair functions of single-layer ECC. There is still a lack of systematic research on composite systems that achieve synergistic effects of load-bearing enhancement, crack control, self-healing, waterproofing, and energy dissipation in weak areas, especially in terms of controllable interfacial slip, the formation of plastic energy-dissipating zones, and the integration of conduction and drainage functions.

[0004] Therefore, there is an urgent need to develop a multifunctional ECC composite structure system that can simultaneously enhance load-bearing capacity, control cracks, provide self-healing, waterproofing, and dissipate energy during long-term service in weak underground structural zones and under seismic conditions, thereby significantly improving the safety, toughness, and durability of the structure and meeting the feasibility requirements for on-site construction. Summary of the Invention

[0005] This invention aims to propose a multifunctional ECC composite structure system that integrates crack control, self-healing, waterproofing, energy dissipation, and toughness enhancement, breaking through the limitations of existing technologies in waterproofing and seismic compatibility, and achieving long-term safe operation of weak areas in station and tunnel structures.

[0006] To solve the above-mentioned technical problems, the technical solution of this application is as follows: A multifunctional ECC composite structure system for weak areas of station and tunnel structures is characterized by comprising an outer crack-controlling ECC layer, an intermediate debonding and softening layer, and an inner load-bearing ECC layer; wherein, (1) the outer ECC layer is improved by incorporating tensile reinforcing materials or self-healing functional materials to enhance crack control and self-healing performance; (2) the debonding and softening layer is formed by a weak interface or low friction material, so that the outer ECC layer and the inner ECC layer can generate controllable interface slippage when the stress reaches a set threshold, thereby achieving differential deformation; (3) multiple discrete controlled yielding micro-block units are arranged inside the inner ECC layer, and the micro-block units are connected to the ECC matrix through a weak connection interface or a yieldable connection part to form a plastic energy dissipation zone in the weak area; (4) a drainage microchannel is provided between the outer ECC layer and the debonding and softening layer to drain seepage water or release local water pressure when the crack or water pressure reaches a preset threshold.

[0007] Preferably, the outer crack-controlled ECC layer uses an ECC ratio with high tensile strength and tensile strain, and the inner load-bearing ECC layer uses an ECC ratio with high compressive strength.

[0008] Preferably, the debonding softening layer is a continuous layer or a local isolation zone, so that the outer ECC layer and the inner ECC layer can slip relative to each other under shear or tension, thereby enhancing the controllability of the plastic energy dissipation zone and limiting the propagation of cracks into the load-bearing layer.

[0009] Preferably, the controlled yielding microblock unit is a prefabricated or in-situ formed block, strip, or sheet component, arranged in an array, strip, or group form along the circumferential, longitudinal, or local area of ​​the structure to form a migratable or extendable plastic energy dissipation path.

[0010] Preferably, the inner load-bearing ECC layer and the outer crack-controlling ECC layer are fixed and structurally stable by pre-embedded protruding steel bars or weak interface bonding.

[0011] Preferably, the drainage microchannels are arranged continuously or intermittently along the outer ECC layer or interface, and are connected to the external drainage system after the pouring is completed, so as to ensure effective drainage when the local water pressure or crack opening exceeds the threshold; after the construction is completed, the slip threshold and drainage performance are accepted.

[0012] A construction method for the above-mentioned multifunctional ECC composite structure system includes the following steps: (1) Clean and repair the surface of the weak area of ​​the substrate and set up templates or supports; (2) Cast or pre-support the inner bearing type ECC layer, and arrange controlled yield micro-block units according to the design spacing, while pre-embedding protruding steel bars or setting interface bonding positions on the bearing layer; (3) After the load-bearing layer has cured, lay a debonding softening layer (continuous or local isolation strip) on site and reserve the position of the drainage microchannel; (4) Cast an outer crack-controlling ECC layer on the debonding layer, and arrange self-healing capsules and drainage channel through sections in the layer; (5) Perform surface curing and acceptance to ensure that the composite structure system reaches the designed slip threshold and plastic energy dissipation function.

[0013] The beneficial effects of this invention are as follows: (1) By setting the outer ECC layer and the drainage microchannel, the traditional “sealing” waterproofing is transformed into “active drainage”, which effectively releases local water pressure and significantly improves the waterproofing performance of the structure; (2) The outer ECC layer, combined with microcapsule self-healing material, can automatically repair itself when microcracks occur, and has the functions of crack control, self-healing and waterproofing, thereby improving the long-term durability of the structure; (3) The intermediate debonding softening layer can trigger interface slip when the structure is subjected to shear or tension to the design threshold. It works with the inner discrete controlled yielding micro-block unit to form a controllable plastic energy dissipation zone. This energy dissipation zone can migrate along a predetermined path under repeated earthquake excitation, effectively concentrate energy dissipation and limit crack propagation, and improve the seismic toughness of the weak zone. (4) In terms of construction, it is compatible with conventional ECC construction method. The precast load-bearing layer and the on-site superimposed crack control layer are connected as a whole by pre-embedded protruding steel bars or interface bonding. There is no need to remove the original structure, which makes construction simple, convenient for rapid construction and quality control, while maintaining the crack control and load-bearing functions of layered ECC. Attached Figure Description

[0014] Figure 1 Schematic diagram of the cross-section of the composite structure Figure 2 Top view showing the arrangement of yield microblocks in the inner bearing type ECC layer. Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] Please refer to the following: Figures 1-2This application provides a multifunctional ECC composite structure system, which includes, along the thickness direction, an outer crack-controlling ECC layer 10, an intermediate debonding and softening layer 20, and an inner load-bearing ECC layer 30.

[0017] The outer crack-controlling ECC layer 10 is located on the side of the structure adjacent to the soil and rock mass, with a thickness ranging from 30 to 80 mm. The outer crack-controlling ECC layer 10 achieves a tensile strain of 2%-5% or higher and a tensile strength of 5 MPa or higher through optimized proportioning. The outer crack-controlling ECC layer 10 incorporates PVA fibers 40 and self-healing microcapsule material 50, which can trigger a self-healing reaction after microcracks appear, allowing the cracks to automatically close in humid environments, thus improving durability and impermeability. The PVA fiber volume fraction is 0.5-2%, and the self-healing capsules can be microcapsule-type epoxy or carbonate-based self-healing materials, with a total volume ratio of 0.1-2%.

[0018] The intermediate debonding and softening layer 20 is composed of a thin insulating material (e.g., PE film, slip coating, or controllable weak interface material). The thickness is preferably 0.1-5 mm, and the interface static friction coefficient is ≤0.25. The debonding layer can be arranged in continuous or partial isolation zones, allowing controllable slippage between the outer and inner ECC layers when shear or normal stress reaches a predetermined threshold. This achieves differential deformation, enhances the formation of plastic energy-dissipating zones in weak areas, and limits crack propagation into the inner ECC layer.

[0019] In this embodiment, a drainage microchannel 60 is provided on the outer ECC layer near the debonding layer. The drainage microchannel 60 can be formed using fine mortar pipes, fine aggregate concrete troughs, corrugated microtubes, or pre-embedded detachable mandrels. The channel diameter or equivalent width is 1-12 mm, and it is arranged along the outer crack control layer and connected to the external drainage system. The drainage channel adopts a passive differential pressure / capillary drive or a pre-set pressure-sensitive valve structure. When the local water pressure or crack opening exceeds a threshold (e.g., crack width ≥ 0.2 mm or water pressure ≥ 0.05 MPa), the drainage microchannel can quickly release water pressure, reducing the risk of leakage and deterioration.

[0020] The inner load-bearing ECC layer 30 is fabricated using precast composite slabs or precast shells, and its cross-section can be rectangular, arc-shaped, annular, or other shapes suitable for subway station side walls, arches, or tunnel linings. The precast load-bearing ECC layer 30 has embedded steel mesh or short steel bars, with protruding steel bars 70 at the edges for connection to the outer ECC layer assembled on site.

[0021] Specifically, the compressive strength of the inner load-bearing ECC layer 30 is 70-100 MPa, which enables it to maintain ductile deformation capacity under seismic loading.

[0022] Preferably, multiple discrete controlled yield micro-block units 80 are arranged inside the inner load-bearing ECC layer. The micro-blocks can be cubic, rectangular strips, or ring-shaped blocks, with a size range of 10-250 mm. The micro-blocks are connected to the ECC matrix through weak interfaces or designated vulnerable sections to form a positionable plastic energy dissipation band. The yield load of a single micro-block is 0.05-1.5 MPa. The micro-blocks are arranged in arrays, strips, or groups along the circumferential, longitudinal, or local regions of the structure to achieve the migratory or extended plastic energy dissipation path.

[0023] Implementation effect The composite structure system described in this embodiment can synergistically achieve functions such as load-bearing enhancement, crack control, self-healing, waterproofing, and energy dissipation. This structure is suitable for the sidewalls, linings, and other structurally weak areas of station and tunnel structures, and can significantly improve the long-term safety, seismic toughness, and service performance of station and tunnel structures.

[0024] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A multifunctional ECC composite structure system for weak areas of station and tunnel structures, characterized in that, It includes an outer crack-controlling ECC layer, an intermediate debonding and softening layer, and an inner load-bearing ECC layer; wherein, (1) the outer ECC layer is incorporating tensile reinforcing materials or self-healing functional materials to improve crack control and self-healing performance; (2) the debonding and softening layer is formed by a weak interface or a low-friction material, so that the outer ECC layer and the inner ECC layer can produce controllable interface slippage when the stress reaches a set threshold, thereby achieving differential deformation; (3) multiple discrete controlled yielding micro-block units are arranged inside the inner ECC layer, and the micro-block units are connected to the ECC matrix through a weak connection interface or a yieldable connection part, which is used to form a plastic energy dissipation zone in the weak area; (4) a drainage microchannel is provided between the outer ECC layer and the debonding and softening layer, which is used to drain seepage water or release local water pressure when the crack or water pressure reaches a preset threshold.

2. The composite structure system according to claim 1, characterized in that: The outer crack-controlled ECC layer uses an ECC ratio with high tensile strength and tensile strain, while the inner load-bearing ECC layer uses an ECC ratio with high compressive strength.

3. The composite structure system according to claim 1, characterized in that: The debonding softening layer is a continuous layer or a local isolation zone, which enables the outer ECC layer and the inner ECC layer to slip relative to each other under shear or tension, thereby enhancing the controllability of the plastic energy dissipation zone and limiting the propagation of cracks into the load-bearing layer.

4. The composite structure system according to claim 1, characterized in that: The controlled yielding micro-block units are prefabricated or in-situ formed block, strip, or sheet-like components, arranged in array, strip, or group form along the circumferential, longitudinal, or local areas of the structure to form a migratable or extendable plastic energy dissipation path.

5. The composite structure system according to claim 1, characterized in that: The inner load-bearing ECC layer and the outer crack-controlling ECC layer are fixed and structurally stable by pre-embedded protruding steel bars or weak interface bonding.

6. The drainage microchannels are arranged continuously or intermittently along the outer ECC layer or interface, and are connected to the external drainage system after the pouring is completed, so as to ensure effective drainage when the local water pressure or crack opening exceeds the threshold; after the construction is completed, the slip threshold and drainage performance are accepted.

7. A construction method for constructing the composite structural system of claim 1, characterized in that, Includes the following steps: (1) Clean and repair the surface of the substrate in the weak area and set up templates or supports; (2) Cast or pre-support the inner bearing type ECC layer, and arrange controlled yield micro-block units according to the design spacing, while pre-embedding protruding steel bars or setting interface bonding positions on the bearing layer. (3) After the load-bearing layer has cured, lay a debonding and softening layer (continuous or local isolation strip) on site and reserve the position of the drainage microchannel; (4) Cast an outer crack-controlling ECC layer on the debonding layer, and arrange self-healing capsules and drainage channel through sections in the layer; (5) Perform surface curing and acceptance to ensure that the composite structure system reaches the designed slip threshold and plastic energy dissipation function.

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