A time sequence adaptive bridge cable fire explosion cooperative defense system

Abstract

The application discloses a time sequence adaptive bridge cable fire and explosion cooperative defense system and belongs to the technical field of bridge catastrophe safety protection. The system is coated on the outer side of the anticorrosive layer of the bridge cable, and comprises, from inside to outside, an efficient aerogel felt heat insulation layer, an STF transient rheological armor layer, a multiphase foaming gas locking fire suppression wrapping belt layer and a weatherproof layer. The STF transient rheological armor layer comprises a high-strength fiber three-dimensional woven net, a shear thickening fluid impregnated in the net grid pores and two sides of flexible flow resistance sealing films. The multiphase foaming gas locking fire suppression wrapping belt layer comprises a flexible high polymer matrix, a thermal expansion foaming flame retardant and bimodal fire suppression microcapsules, and the microcapsule core encapsulates a liquid perfluorohexanone medium. The system is flexible and follows the movement in daily life, diffuses and spreads the impact stress by the STF transient rigidification when explosion impact occurs, and foams into carbon and locks the perfluorohexanone fire extinguishing medium when fire occurs, so that time sequence adaptive cooperative protection under fire, explosion and fire-explosion composite disasters is realized.

Description

Technical Field

[0001] This invention relates to the field of bridge structural disaster safety protection technology, specifically to a time-adaptive bridge cable fire and explosion collaborative defense system. Background Technology

[0002] Cable-stayed bridges are core load-bearing components of long-span bridges, and the risk of hazardous chemical vehicle fires and explosions on bridge decks has surged in recent years. Vehicle fires and explosions often exhibit significant temporal uncertainty, with the most typical and highly destructive evolution path being: initial localized fire, followed by a transient explosive impact, and then a prolonged fire. Currently, the mainstream main cable protection measure in the industry is a passive protection system consisting of "inner aerogel felt insulation + outer flame-retardant rubber / PE tape for corrosion protection." However, cables need to adapt to wind-induced micro-wind vibrations and live load deformation during daily service, therefore the outer protective layer must maintain extremely high flexibility (rigid sleeves may lock up). But when the flexible protective layer encounters a megapascal-level explosive impact or high-speed fragmentation, the impact load may instantly compact and pulverize the porous aerogel skeleton. Once the aerogel pulverizes, the cable will rapidly anneal and fail.

[0003] To address this issue, Chinese patent CN121519417A discloses an impact-fire protection system for the main cable system of a suspension bridge. This solution employs a flexible polyurea composite material sprayed onto the exterior of an existing fireproof layer for impact protection. However, its design logic is geared towards a specific sequence of "impact first, then fire," and has significant limitations when dealing with complex scenarios such as "fire first, then impact, then fire again." Firstly, the polyurea material of the external explosion-proof layer is flammable and easily loses its original protective function under high-temperature heat loads, thus failing to provide a continuous safety barrier for the internal fireproof layer. Secondly, the explosion-proof layer is located on the outermost side of the protection system, and it is prone to melting and dripping after being heated during combustion, posing a serious secondary safety hazard to the area below (such as pedestrians or vehicles on the bridge deck). Furthermore, this system is highly dependent on on-site high-altitude spraying technology, and is affected by strong winds and high humidity in cross-river and cross-sea environments, making it difficult to precisely control the construction quality and thickness.

[0004] Furthermore, to compensate for the limitations of passive protection mechanisms, some cutting-edge research has attempted to introduce active fire suppression mechanisms on the outside of bridge cables. However, those skilled in the art generally believe that setting active fire prevention measures on the outside of the cables is neither feasible nor effective. Specifically, the decks of large bridges are constantly exposed to open and complex wind fields with strong high-altitude convection. When an explosion occurs, not only will a violent overpressure shock wave be generated, but it will also inevitably be accompanied by extremely high-speed high-pressure airflow entrainment and turbulence effects. Under these extremely harsh flow field conditions, once existing active fire prevention devices trigger and release gaseous or particulate extinguishing media, the media will be rapidly diluted, dissipated, and completely blown away from the target area by the strong wind field and the explosion airflow within milliseconds. This extremely rapid mass diffusion effect means that the extinguishing media simply cannot establish and maintain the critical local extinguishing concentration required to extinguish the flames on the cable surface and in the surrounding space. Therefore, it is necessary to propose a composite defense system that balances daily flexibility with disaster-time rigidity and can achieve in-situ gas-locking fire suppression in open wind fields. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a time-adaptive bridge cable fire and explosion collaborative defense system to solve the problems in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a time-adaptive bridge cable fire and explosion collaborative defense system. The defense system covers the outside of the anti-corrosion layer of the bridge cable and includes, from the inside to the outside, a high-efficiency aerogel felt heat insulation layer, an STF transient rheological armor layer, a multiphase foamed air-locking fire-suppressing wrapping tape layer, and a weather-resistant protective layer. The high-efficiency aerogel felt insulation layer is disposed between the anti-corrosion layer and the STF transient rheological armor layer to form thermal insulation protection for bridge cables; The STF transient rheological armor layer covers the outside of the high-efficiency aerogel felt insulation layer and includes a high-strength fiber three-dimensional woven mesh, a shear thickening fluid impregnated in the mesh pores of the high-strength fiber three-dimensional woven mesh, and a flexible flow-blocking sealing membrane covering both sides of the high-strength fiber three-dimensional woven mesh. The multiphase foamed gas-locking flame-suppressing wrapping layer covers the outside of the STF transient rheological armor layer, including a flexible polymer matrix and a thermally expanding foaming flame retardant and a bimodal flame-suppressing microcapsule dispersed in the flexible polymer matrix. The core of the bimodal flame-suppressing microcapsule is encapsulated with a liquid perfluorohexanone medium. The multiphase foamed gas-locking fire-suppressing wrapping layer is configured to foam and carbonize upon heating to form a carbonized sponge shell layer, and to at least partially retain the perfluorohexanone medium released by the dual-mode fire-suppressing microcapsules within the pore channels of the carbonized sponge shell layer; the STF transient rheological armor layer is configured to undergo transient thickening and stiffening upon impact by an explosion or high-speed fragments, in order to disperse the impact load and reduce the local impact stress transmitted to the high-efficiency aerogel felt insulation layer.

[0007] In one embodiment, the flexible polymer matrix comprises ethylene-vinyl acetate copolymer and flexible acrylate rubber; the thermally expandable foaming flame retardant comprises at least two of expandable graphite, ammonium polyphosphate and melamine polyphosphate; and the bimodal flame-suppressing microcapsules are dispersed and embedded in the flexible polymer matrix in an island structure.

[0008] In one embodiment, the mass ratio of expandable graphite, ammonium polyphosphate, and melamine polyphosphate is 4:3:2; the shell of the bimodal fire-suppressing microcapsule is a double-layer composite shell composed of a melamine resin layer and a polyurethane layer; the particle size of the bimodal fire-suppressing microcapsule is 15μm to 35μm, the shell thickness is 1.2μm to 2.5μm, and the content of the liquid perfluorohexanone medium is 12% to 18% of the mass of the flexible polymer matrix.

[0009] In one embodiment, the dual-modal fire-suppressing microcapsule has a heat-triggered release mode and an impact-triggered release mode; Under the heat-triggered release mode, the dual-mode fire-suppressing microcapsule ruptures and releases its contents through the combined effects of the vapor pressure increase caused by the heat vaporization of the perfluorohexanone medium inside the capsule core and the heat softening of the capsule shell material. Under the impact-triggered release mode, the dual-mode fire-suppressing microcapsule is released through brittle fracture by the action of explosive impact pressure or high-speed fragment impact pressure on the capsule shell; Furthermore, the room temperature brittle fracture stress threshold of the dual-modal fire suppression microcapsule is greater than the maximum compressive stress generated by daily wind-induced vibration of bridge cables or vehicle live load vibration, and less than the preset explosive impact pressure threshold.

[0010] In one embodiment, the dual-modal fire-suppressing microcapsule possesses dual-threshold quantization trigger boundaries that simultaneously satisfy impact brittle fracture release and fire-induced vaporization release: For the heat-triggered release mode, the shell wall thickness t, the outer diameter r of the shell, and the thermal softening yield strength of the shell at the heating temperature T are considered. and the saturated vapor pressure of perfluorohexanone inside. Satisfying the critical rupture equation: ; For the impact-triggered release mode, the room-temperature tensile brittle fracture stress threshold of the capsule shell. It is less than the preset threshold for transient impact pressure caused by the explosion shock wave, and greater than the maximum compressive stress caused by the daily wind-induced vibration of the bridge.

[0011] In one embodiment, the multiphase foamed gas-locking and fire-suppressing wrapping layer generates a carbonized sponge shell layer under thermal triggering. The carbonized sponge shell layer has a porous and tortuous channel structure, which causes the released gaseous perfluorohexanone medium to form a blocked diffusion path within the carbonized sponge shell layer, thereby delaying the escape of the perfluorohexanone medium in the open wind field.

[0012] In a preferred embodiment, the carbonized sponge shell layer has the following quantitative pore topology and thermal property parameters: the overall porosity Φ of the carbonized sponge shell layer is not less than 80%, the volume ratio of micropores and mesopores with a pore size of 10μm to 100μm is not less than 70%, and the average tortuosity factor of the microchannels is greater than 2.5, so that the released gaseous perfluorohexanone medium forms an obstructed diffusion path in the carbonized sponge shell layer; the equivalent thermal conductivity of the fully cured carbonized sponge shell layer is less than 0.05 W / (m·K) to provide high transient thermal resistance isolation.

[0013] In one embodiment, the high-strength fiber three-dimensional woven mesh is one or more of aramid fiber three-dimensional woven mesh, ultra-high molecular weight polyethylene fiber three-dimensional woven mesh, basalt fiber three-dimensional woven mesh, or glass fiber three-dimensional woven mesh; the shear-thickening fluid includes nano-silica particles and a dispersion medium, the dispersion medium including polyethylene glycol and glycerol, the nano-silica particles having a particle size of 50nm to 200nm, and the solid content of the shear-thickening fluid being 35% to 50%.

[0014] In one embodiment, the flexible flow-blocking sealing film is a thermoplastic polyurethane film, which is heat-sealed onto the inner and outer surfaces of the high-strength fiber three-dimensional braided mesh to seal the shear-thickening fluid within the mesh openings of the high-strength fiber three-dimensional braided mesh, forming a composite armor unit; multiple composite armor units are spliced ​​and wrapped along the axial and / or circumferential direction of the bridge cable, and the splicing edges of adjacent composite armor units are sealed and connected by heat-melt welding, overlapping pressing, or sealant bonding.

[0015] In one embodiment, the high-efficiency aerogel felt insulation layer is a single layer or multiple layers of high-silica oxygen gel composite felt, with a single layer thickness of 3mm to 5mm; two adjacent layers of high-silica oxygen gel composite felt are wrapped around the outside of the anti-corrosion layer of the bridge cable in a staggered overlapping manner, and are radially constrained and fixed by fiberglass tape, flame-retardant wrapping tape or high-temperature resistant adhesive layer.

[0016] In one embodiment, the weather-resistant protective layer is a fluorocarbon topcoat sprayed onto the outside of the multiphase foamed gas-locking fire-suppressing wrapping tape layer.

[0017] In a preferred embodiment, the STF transient rheological armor layer possesses an impact unloading and targeted release mechanism based on dynamic characteristics and timing: For transient explosive impact pressure, the critical thickening trigger time of the shear-thickening fluid is no more than 1ms; after triggering the phase change, the dynamic energy storage modulus jumps by more than 1000 times. Through stress diffusion after stiffening by the intermediate STF layer, the residual impact stress transmitted to the indirect explosion-affected area is attenuated to below the microcapsule brittle fracture threshold. This restricts the external microcapsules to mechanically rupture only in the damaged, recessed core area.

[0018] In one embodiment, the defense system has an escape-proof and penetration-proof spatial topology layout based on alternating spiral directions and overlapping coverage; specifically, the high-efficiency aerogel felt insulation layer, STF transient rheological armor layer, and multiphase foamed air-locking fire-suppressing wrapping tape layer are all spirally wrapped on the outside of the anti-corrosion layer of the bridge cable, and the spiral winding directions of adjacent two layers of materials are opposite, that is, the left-hand and right-hand alternating laying method is adopted, so that the spiral joints of adjacent two layers of materials in space only form discrete intersections, and do not form continuous parallel radial straight gaps.

[0019] The overlap rate of each layer of material is not less than 50%, preferably 52%. Through the above-mentioned overlap coverage method, the spiral joint of any inner layer material is covered by the non-seamless solid area of ​​the adjacent outer layer material on the radially outer side, thereby reducing the formation of local pressure relief channels, obstructed gas escape channels and heat radial penetration and conduction channels, and improving the overall continuous protection capability of the defense system under fire, explosion impact and fire-explosion combined disasters.

[0020] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. The innovative dual-mode triggering and dynamic thermal resistance relay logic overcomes the technical bottleneck of uncertain timing in extreme complex disasters. In the heated mode, the surge in vapor pressure inside the microcapsule breaks through the softened shell, and in the exploded mode, the impact stress breaks through the room temperature brittle fracture limit of the shell. Whether dealing with "transient explosion followed by long-term fire" or "transient explosion induced in long-term fire", this system can maintain the explosion resistance and thermal insulation integrity of the defense structure through the timing relay of initial phase change isothermal anchoring, later dynamic thermal resistance isolation and core long-term passive heat insulation, without relying on external power or electronic sensing intervention, and achieves a purely physical adaptive response.

[0021] 2. This invention constructs a microporous air-locking and phase-change isothermal anchoring mechanism, overcoming the technical challenge of rapid dissipation of fire-suppressing media in open wind fields; it breaks the technical bias that external fire extinguishing agents disperse upon exposure to wind in the strong convection and combustion-explosive turbulent environment of the bridge deck. Through the confining effect of porous networks, tortuous channels, and local micropores, the fire-suppressing media, which originally tended to escape rapidly in the strong convection and combustion-explosive turbulence of the bridge deck, is transformed into a state of hindered diffusion and release, thereby forming a local fire-suppressing and oxygen-isolated environment near the outer surface of the cable; in the event of a fire... Initially, a porous sponge microstructure with a porosity greater than 80% and a tortuosity factor greater than 2.5 is generated on the periphery, which transforms the exhaust flow into obstructed Knudsen diffusion, enabling the release and controlled residence time of the perfluorohexanone medium to reach no less than 120s. During this period, the perfluorohexanone medium vaporizes and absorbs the latent heat of phase change, forming a heat-absorbing buffer environment of nearly 50°C between the multiphase foamed gas-locking fire-suppressing wrapping layer and the STF transient rheological armor layer, thereby reducing the risk of thermal damage to the intermediate explosion-proof layer from the heat in the early stage of the fire.

[0022] 3. This invention introduces a non-Newtonian fluid dynamics phase change armor and interlayer unloading, resolving the engineering contradiction between the need for flexibility in daily operation and the need for rigidity in disaster-prone conditions. It also addresses the engineering pain points of poor impact resistance of flexible aerogel felts and the impact of rigid metal sleeves on bridge vibration characteristics. This invention sets up a transient rheological armor dominated by non-Newtonian fluids on the outside of the core insulation layer. When faced with combustion and explosion impacts, the STF can achieve a fluid-solid phase change in a very short time, resulting in a significant step change in the energy storage modulus. This transient stiffening characteristic unloads and spreads the concentrated destructive force of high strain rate over a large area, protecting the integrity of the underlying aerogel skeleton. At the same time, the rigid support attenuates the surrounding stress, preventing the uncontrolled global rupture of the outer microcapsules and enabling on-demand targeted release from the damaged core area. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the three-dimensional peeling structure of the defense system of the present invention; Figure 2 This is a schematic diagram of the structure and impact response of the STF transient rheological armor layer of the present invention; Figure 3 This is a flowchart illustrating the collaborative response of the present invention under different disaster time sequences.

[0024] In the diagram: 1. Cable; 2. Anti-corrosion layer; 3. High-efficiency aerogel insulation layer; 4. STF transient rheological armor layer; 5. Multiphase foamed air-locking and fire-suppressing wrapping tape layer; 6. Fluorocarbon topcoat; 41. High-strength fiber three-dimensional woven mesh; 42. Shear thickening fluid STF. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0026] The following description, with reference to the accompanying drawings, describes a time-adaptive bridge cable fire and explosion collaborative defense system proposed in an embodiment of the present invention.

[0027] like Figures 1 to 3 As shown, the outer surface of the cable 1 is provided with an anti-corrosion layer 2. The defense system of this embodiment of the invention is covered on the outside of the anti-corrosion layer 2, including a high-efficiency aerogel heat insulation layer 3, an STF transient rheological armor layer 4, a multiphase foamed air-locking fire-suppressing wrapping tape layer 5, and a fluorocarbon topcoat 6 arranged sequentially from the inside to the outside.

[0028] The system comprises the following components: an anti-corrosion layer 2 is applied to the outer surface of the cable 1 to provide basic anti-corrosion, waterproofing, and sealing protection; a high-efficiency aerogel insulation layer 3 is applied to the outside of the anti-corrosion layer 2 to block external heat transfer to the cable 1 under continuous fire conditions; an STF transient rheological armor layer 4 is applied to the outside of the high-efficiency aerogel insulation layer 3 to generate a transient stiffening response under explosive or high-speed fragment impacts and to reduce the compaction or crushing damage of the high-efficiency aerogel insulation layer 3 caused by impact loads; a multiphase foamed gas-locking fire-suppressing wrapping layer 5 is applied to the outside of the STF transient rheological armor layer 4 to release fire-suppressing media and form a gas-locking insulation structure under fire or combustion / explosion conditions; and a fluorocarbon topcoat 6 is applied to the outside of the multiphase foamed gas-locking fire-suppressing wrapping layer 5 to improve the weather resistance and service stability of the entire defense system.

[0029] Specifically, the core of this embodiment lies in constructing a multi-layered composite defense system that combines daily flexibility, transient blast resistance, active fire suppression, and long-term heat insulation. The high-efficiency aerogel insulation layer 3 serves as the ultimate heat insulation line near the cable 1, primarily responsible for thermal barrier function under prolonged fire conditions. The STF transient rheological armor layer 4 serves as the intermediate blast resistance line, primarily responsible for stress diffusion and impact unloading under explosive impact. The multiphase foamed gas-locking fire-suppressing wrapping layer 5 serves as the external active fire suppression line, primarily responsible for the release of fire-suppressing media in the early stages of a fire, foaming and charring, and in-situ gas locking under open airflow conditions. Through the above interlayer coordination, this invention can adapt to different disaster sequences such as "explosion before fire," "fire before explosion," and "fire-explosion-further fire."

[0030] According to one embodiment of the present invention, a process for preparing a multiphase foamed gas-locking fire-suppressing wrapping layer 5 and an STF transient rheological armor layer 4 is provided.

[0031] First, a multiphase foamed gas-locking and fire-suppressing wrapping layer 5 is prepared; ethylene-vinyl acetate copolymer and flexible acrylate rubber are placed in a mixer or open mill for premixing, the mixing temperature is controlled at 80℃~110℃, and the mixing time is 5min~15min, so that the ethylene-vinyl acetate copolymer and flexible acrylate rubber are fully softened and form a uniform and continuous flexible polymer matrix.

[0032] Then, expandable graphite, ammonium polyphosphate, and melamine polyphosphate are added to the flexible polymer matrix; preferably, the mass ratio of expandable graphite, ammonium polyphosphate, and melamine polyphosphate is 4:3:2; after addition, mixing continues to ensure that the thermally expanding foaming flame retardant is evenly dispersed in the flexible polymer matrix; during the mixing process, the rotation speed and temperature are controlled to avoid local overheating that could cause the foaming flame retardant to react prematurely.

[0033] Subsequently, the mixing system is cooled to a temperature range that will not cause the bimodal flame-suppressing microcapsules to rupture or soften and fail, preferably to 30℃~45℃, and then the bimodal flame-suppressing microcapsules with liquid perfluorohexanone medium encapsulated in the core are added. After the bimodal flame-suppressing microcapsules are added, they are dispersed by low-shear stirring or low-speed open mixing. The stirring speed is preferably controlled at 20r / min~80r / min, and the mixing time is preferably 3min~8min, so that the bimodal flame-suppressing microcapsules are uniformly dispersed and embedded in the flexible polymer matrix, while avoiding the bimodal flame-suppressing microcapsules from breaking, leaking or prematurely releasing due to excessive temperature or excessive shear force.

[0034] Subsequently, a flexible polymer matrix containing a thermally expanding foaming flame retardant and bimodal fire-suppressing microcapsules is fed into a calendering device and calendered into a strip roll. The calendering temperature is controlled to be below the thermal trigger release temperature of the bimodal fire-suppressing microcapsules, preferably controlled to be 30℃~45℃, the calendering roller speed is preferably controlled to be 1m / min~5m / min, and the thickness of the calendered strip is preferably 1mm~3mm. During the calendering process, the strip thickness is kept uniform, and the calendering pressure and shear rate are controlled to avoid mechanical breakage or premature release of the bimodal fire-suppressing microcapsules during the calendering process. At the same time, it is also to avoid insufficient gas-locking capacity in the event of a fire due to excessively thin local thickness, or excessively thick local thickness affecting the on-site spiral winding adhesion. After calendering, the strip is cooled, cut, and wound up to obtain a prefabricated roll of multiphase foamed gas-locking fire-suppressing wrapping tape layer 5.

[0035] Secondly, a transient rheological armor layer 4 of STF is prepared; nano-silica particles are added to a compound dispersion medium of polyethylene glycol and glycerol, wherein the mass ratio of polyethylene glycol to glycerol is preferably 7:3, and the particle size of the nano-silica particles is preferably 50nm to 200nm; the dispersion is carried out by mechanical stirring, ultrasonic dispersion, or a combination of both to obtain shear thickening fluid STF 42; preferably, the solid content of shear thickening fluid STF 42 is controlled at 35% to 50% to balance daily flexibility and shear thickening ability under impact.

[0036] Then, the high-strength fiber three-dimensional braided mesh 41 is placed in a vacuum impregnation device to perform vacuum treatment on the high-strength fiber three-dimensional braided mesh 41 to remove the air in its mesh pores; then, the shear thickening fluid STF 42 is introduced into the vacuum impregnation device so that the shear thickening fluid STF 42 fully enters the mesh pores of the high-strength fiber three-dimensional braided mesh 41 under negative pressure; the vacuum degree is preferably controlled at -0.06MPa to -0.095MPa, and the impregnation time is preferably 10min to 30min; after impregnation, the vacuum is released and the mesh is rolled and leveled to make the shear thickening fluid STF 42 evenly distributed in the high-strength fiber three-dimensional braided mesh 41 and remove excess fluid from the surface.

[0037] Subsequently, a thermoplastic polyurethane flexible flow-blocking sealing film is applied to the inner and outer surfaces of the high-strength fiber three-dimensional braided mesh 41 impregnated with shear-thickening fluid STF 42. After application, a hot-pressing or hot-melt welding method is used for sealing, so that the shear-thickening fluid STF 42 is sealed within the mesh pores of the high-strength fiber three-dimensional braided mesh 41. The hot-pressing temperature is preferably 120℃~160℃, the hot-pressing pressure is preferably 0.2MPa~0.6MPa, and the hot-pressing time is preferably 10s~60s. After hot-melt sealing, the edge parts are subjected to secondary pressing or edge sealing treatment to reduce the risk of leakage of shear-thickening fluid STF 42 during long-term service, thus obtaining the prefabricated STF transient rheological armor layer 4.

[0038] Finally, the on-site layer-by-layer wrapping construction is carried out. First, the outer surface of cable 1 and anti-corrosion layer 2 are cleaned, dried and repaired for defects, so that the surface of anti-corrosion layer 2 is kept clean, continuous and flat; then, a high-efficiency aerogel insulation layer 3 is wrapped on the outside of anti-corrosion layer 2. The high-efficiency aerogel insulation layer 3 is set in a staggered overlapping manner and is radially constrained and fixed by fiberglass tape, flame-retardant wrapping tape or high-temperature resistant adhesive layer.

[0039] Next, the prefabricated STF transient rheological armor layer 4 is wrapped around the outside of the high-efficiency aerogel insulation layer 3; the edges of adjacent STF transient rheological armor layers 4 are arranged in an overlapping manner and sealed by hot melt welding, overlapping pressing or sealant bonding to ensure that the STF transient rheological armor layer 4 forms continuous impact protection on the outside of the cable 1.

[0040] Subsequently, a prefabricated roll of multiphase foamed air-locking fire-suppressing wrapping tape layer 5 is spirally wound around the outside of the STF transient rheological armor layer 4. During the winding process, the winding tension and overlap rate are controlled, with the overlap rate preferably not less than 50%, and more preferably 52%. The winding direction of adjacent functional layers is preferably alternating between left-handed and right-handed rotation, so that the joints of adjacent layers form discrete crosses, avoiding the formation of continuous radially penetrating weak gaps. After the winding is completed, fluorocarbon topcoat 6 is sprayed on the outside of the multiphase foamed air-locking fire-suppressing wrapping tape layer 5. The fluorocarbon topcoat 6 is preferably sprayed in two coats and cured at room temperature to form a continuous and uniform weather-resistant protective surface.

[0041] Through the above preparation process, the multiphase foamed gas-locking fire-suppressing wrapping layer 5 can maintain the flexible wrapping construction performance while having the ability to foam into carbon when heated and release perfluorohexanone medium; the STF transient rheological armor layer 4 can remain compliant under normal low shear conditions and undergo transient thickening and stiffening under explosive impact or high-speed fragment impact conditions, thus forming a fire and explosion synergistic defense structure together with the high-efficiency aerogel insulation layer 3.

[0042] According to one embodiment of the present invention, the anti-corrosion layer 2 can be an existing anti-corrosion layer of the bridge cable, or it can be a flame-retardant sealing wrapping tape, an anti-corrosion coating or a composite structure thereof; the anti-corrosion layer 2 is directly wrapped on the outer surface of the cable 1 to isolate external moisture, oxygen and corrosive media, and to provide a flat and continuous construction base for the high-efficiency aerogel insulation layer 3.

[0043] According to one embodiment of the present invention, the high-efficiency aerogel insulation layer 3 is a high-silica oxygen gel composite felt; the high-efficiency aerogel insulation layer 3 can be configured as a single layer or multiple layers; preferably, the high-efficiency aerogel insulation layer 3 is configured as two layers, each layer having a thickness of 3mm to 5mm; the adjacent two layers of high-efficiency aerogel insulation layer 3 are covered on the outside of the anti-corrosion layer 2 by staggered overlapping, so as to avoid the joints from being continuously connected in the radial direction, thereby reducing the possibility of local thermal bridge formation.

[0044] Specifically, the high-efficiency aerogel insulation layer 3 has a porous insulation structure inside, which can reduce the heat transfer rate from external flames or high-temperature smoke to cable 1. During a long-term fire, even if the outer multiphase foamed gas-locking fire suppression wrapping tape layer 5 and STF transient rheological armor layer 4 are partially damaged, the high-efficiency aerogel insulation layer 3 can still serve as the last insulation barrier near cable 1, delaying the temperature rise of cable 1 and reducing the risk of annealing failure of cable 1.

[0045] According to one embodiment of the present invention, the STF transient rheological armor layer 4 includes a high-strength fiber three-dimensional braided mesh 41 and a shear thickening fluid STF 42; the high-strength fiber three-dimensional braided mesh 41 serves as the main skeleton of the STF transient rheological armor layer 4, and the shear thickening fluid STF 42 is impregnated in the mesh pores of the high-strength fiber three-dimensional braided mesh 41.

[0046] Specifically, the high-strength fiber three-dimensional woven mesh 41 can be woven from one or more of aramid fibers, basalt fibers, glass fibers or ultra-high molecular weight polyethylene fibers; preferably, the high-strength fiber three-dimensional woven mesh 41 is woven from aramid fibers to improve the tensile strength, tear strength and impact diffusion resistance of the STF transient rheological armor layer 4.

[0047] The shear-thickening fluid STF 42 can be formed from nano-silica particles and a dispersion medium; the particle size of the nano-silica particles is preferably 50nm to 200nm; the dispersion medium is preferably a compound system of polyethylene glycol and glycerol, with a mass ratio of 7:3; the solid content of the shear-thickening fluid STF 42 is preferably 35% to 50%; at low shear rates, the shear-thickening fluid STF 42 remains in a flowing or compliant state, enabling the STF transient rheological armor layer 4 to adapt to the wind-induced vibration and live load deformation of the cable 1; at high shear rates, the shear-thickening fluid STF 42 undergoes hydrodynamic agglomeration and rapid thickening, enabling the STF transient rheological armor layer 4 to exhibit transient high stiffness and high damping characteristics.

[0048] Furthermore, the inner and outer sides of the STF transient rheological armor layer 4 can be heat-sealed with a thermoplastic polyurethane flexible flow-blocking sealing film to confine the shear thickening fluid STF 42 within the mesh pores of the high-strength fiber three-dimensional braided mesh 41, preventing leakage of the shear thickening fluid STF 42 during long-term service. Thus, the STF transient rheological armor layer 4 forms an independent flexible composite armor unit, which is convenient for prefabrication and also convenient for on-site wrapping construction on the outside of the cable 1.

[0049] According to one embodiment of the present invention, the multiphase foamed gas-locking flame-suppressing wrapping layer 5 is in the form of a strip roll, the main body of which is a flexible polymer matrix; thermally expanding foaming flame retardant and bimodal flame-suppressing microcapsules are dispersed and embedded in the flexible polymer matrix. The core of the bimodal flame-suppressing microcapsules is encapsulated with liquid perfluorohexanone medium for releasing the flame-suppressing medium under thermal or impact triggering conditions.

[0050] Specifically, the flexible polymer matrix can be formed by blending ethylene-vinyl acetate copolymer with flexible acrylate rubber, giving the multiphase foamed, air-locking, fire-suppressing wrapping layer 5 good flexibility, wrapping adhesion, and surface adaptability during construction. The thermally expanding foamed flame retardant can be a compound system of expandable graphite, ammonium polyphosphate, and melamine polyphosphate, with a preferred mass ratio of 4:3:2. The shell of the bimodal fire-suppressing microcapsules can be a double-layer composite shell material of melamine resin and polyurethane. The preferred particle size of the bimodal fire-suppressing microcapsules is 15μm to 35μm, the preferred shell thickness is 1.2μm to 2.5μm, and the content of perfluorohexanone medium is preferably 12% to 18% of the mass of the flexible polymer matrix.

[0051] When the multiphase foamed gas-locking fire-suppressing wrapping layer 5 is heated, the thermally expanding foaming flame retardant causes it to expand, foam, and carbonize rapidly, forming a porous carbonized sponge shell. At the same time, the liquid perfluorohexanone medium inside the dual-modal fire-suppressing microcapsule is heated and vaporized, the pressure inside the capsule increases, the capsule shell softens and ruptures, and the perfluorohexanone medium is released into the pores of the porous carbonized sponge shell. The released perfluorohexanone medium reduces the local temperature by absorbing heat through vaporization, and is retained around the cable 1 by the porous carbonized sponge shell, thus forming an in-situ fire-suppressing and oxygen-isolation microenvironment under the wind field of the open bridge deck.

[0052] Furthermore, the dual-mode fire suppression microcapsule also has an impact-triggered release function; when an explosive shock wave or high-speed fragments act on the multiphase foamed gas-locking fire suppression wrapping layer 5, the dual-mode fire suppression microcapsule located in the impact core region is subjected to transient impact pressure and undergoes mechanical brittle fracture, releasing perfluorohexanone medium to suppress the explosive fireball or initial flame; since the STF transient rheological armor layer 4 can thicken and stiffen and diffuse stress at the moment of impact, the residual impact stress in the non-directly impacted area is weakened, thereby reducing the global disordered rupture of the dual-mode fire suppression microcapsule and allowing the perfluorohexanone medium to be released preferentially in the damaged core region.

[0053] According to one embodiment of the present invention, the overall porosity of the porous carbonized sponge shell formed by the multiphase foamed gas-locking fire suppression wrapping layer 5 after heating is not less than 80%, wherein the volume ratio of micropores and mesopores with a pore size of 10μm to 100μm is not less than 70%, and the average tortuosity factor of the microchannels is greater than 2.5. Through the above-mentioned pore structure, the released gaseous perfluorohexanone medium can form an obstructed diffusion path in the porous carbonized sponge shell, slowing down its rapid removal by strong winds and combustion turbulence on the bridge deck, thereby improving the fire suppression sustainability under open wind fields.

[0054] According to one embodiment of the present invention, fluorocarbon topcoat 6 is sprayed onto the outer side of the multiphase foamed air-locked fire-suppressing wrapping layer 5; the fluorocarbon topcoat 6 can be applied by airless spraying and sprayed in two coats to form a continuous and uniform weather-resistant protective layer; the fluorocarbon topcoat 6 can improve the UV resistance, rain resistance, salt spray resistance, acid rain resistance and aging resistance of the protection system, so that the multiphase foamed air-locked fire-suppressing wrapping layer 5 can maintain good stability in the long-term bridge service environment.

[0055] According to one embodiment of the present invention, the construction method of the defense system includes the following steps: First, clean the outer surface of cable 1 to remove loose rust, oil, dust and impurities, and check the integrity of anti-corrosion layer 2. For any damaged, scratched or partially detached areas of anti-corrosion layer 2, repair them first to ensure that the surface of anti-corrosion layer 2 remains continuous, dry and clean.

[0056] Then, a high-efficiency aerogel insulation layer 3 is wrapped around the outside of the anti-corrosion layer 2. The high-efficiency aerogel insulation layer 3 can be set by spiral wrapping or sheet splicing; when using multiple layers of high-efficiency aerogel insulation layer 3, the joints of adjacent layers are staggered and radially constrained and fixed by fiberglass tape or flame-retardant wrapping tape, so that the high-efficiency aerogel insulation layer 3 is tightly bonded to the anti-corrosion layer 2.

[0057] Subsequently, the prefabricated STF transient rheological armor layer 4 is wrapped around the outside of the high-efficiency aerogel insulation layer 3. Since the STF transient rheological armor layer 4 is flexible as a whole under low shear conditions, it can conform to the arc shape of the cable 1; the edges of adjacent STF transient rheological armor layers 4 can be arranged in an overlapping manner and sealed by hot melt welding, overlapping pressing or sealant bonding to prevent leakage of shear thickening fluid STF 42.

[0058] Next, a multiphase foamed gas-locking fire-suppressing wrapping tape layer 5 is spirally wound around the outside of the STF transient rheological armor layer 4; during the winding process, the winding tension, winding pitch and overlap rate are controlled; preferably, the overlap rate of the multiphase foamed gas-locking fire-suppressing wrapping tape layer 5 is not less than 50%, and more preferably 52%; adjacent functional layers can be arranged in an alternating spiral direction, that is, the spiral winding directions of adjacent two layers are opposite, so that the spiral joints of adjacent layers form discrete intersections, thereby avoiding the formation of continuous radial through weak gaps.

[0059] Finally, fluorocarbon topcoat 6 is sprayed on the outside of the multiphase foamed air-locking fire-suppressing wrapping tape layer 5. After spraying, it is naturally cured at room temperature to form a continuous and uniform external weather-resistant surface.

[0060] According to an experimental example of the present invention, the gas-locking and release control effect and the phase change heat absorption and temperature control effect of the multiphase foamed gas-locking and fire-suppressing wrapping layer 5 are verified.

[0061] A steel circular tube with a diameter of 100 mm and a length of 400 mm was used as a simulated cable 1. An anti-corrosion layer 2, a high-efficiency aerogel insulation layer 3, an STF transient rheological armor layer 4, a multiphase foamed air-locking and fire-suppressing wrapping tape layer 5, and a fluorocarbon topcoat 6 were sequentially applied to its outer surface to form a test specimen. Among them, the high-efficiency aerogel insulation layer 3 is composed of two layers of high-silica oxygen gel composite felt with a single layer thickness of 3 mm. The thermal expansion foaming flame retardant in the multiphase foamed air-locking and fire-suppressing wrapping tape layer 5 is a compound system of expandable graphite, ammonium polyphosphate, and melamine polyphosphate, with a mass ratio of 4:3:2. The core of the dual-modal fire-suppressing microcapsule encapsulates liquid perfluorohexanone medium.

[0062] Temperature sampling points were set up on the test specimen. One temperature sampling point was set at the interface between the multiphase foamed gas-locking fire suppression wrapping layer 5 and the STF transient rheological armor layer 4 to record the temperature effect of the vaporization heat absorption of perfluorohexanone medium in the early stage of the fire on the interface of the intermediate layer. The other temperature sampling point was set at the interface between the STF transient rheological armor layer 4 and the high-efficiency aerogel insulation layer 3 to record the temperature change transmitted to the high-efficiency aerogel insulation layer 3. At the same time, a gas sampling port was set on the outside of the test specimen to collect the perfluorohexanone gas released by the multiphase foamed gas-locking fire suppression wrapping layer 5 after being heated.

[0063] The outer surface of the test specimen was heated by either radiant heating or flame heating, with a heat flux density of 50 kW / m². A transverse airflow of 3 m / s was applied to the outside of the specimen to simulate the wind field on the open bridge deck where the bridge cables are located. During the experiment, the interface temperature change and the perfluorohexanone gas concentration change were recorded simultaneously at a sampling frequency of 1 Hz.

[0064] Under the above experimental conditions, the multiphase foamed gas-locking fire-suppressing wrapping layer 5 foams and carbonizes upon heating, forming a carbonized sponge shell layer. The dual-mode fire-suppressing microcapsules rupture upon heating, releasing perfluorohexanone media. Part of the released perfluorohexanone media forms an obstructed diffusion path within the porous and tortuous channels of the carbonized sponge shell layer, while the other part vaporizes and absorbs heat, thereby reducing the interface temperature between the multiphase foamed gas-locking fire-suppressing wrapping layer 5 and the STF transient rheological armor layer 4.

[0065] The moment when the perfluorohexanone gas concentration first exceeds three standard deviations of the background concentration is recorded as the release control start time, and the moment when the perfluorohexanone gas concentration drops to below 10% of the peak concentration is recorded as the release control end time. The time difference between the two is defined as the release control residence time. The test results show that under the test conditions of a heat flux density of 50 kW / m² and a transverse airflow velocity of 3 m / s, the release control residence time is not less than 120 s, indicating that the carbonized sponge shell layer can delay the rapid dissipation of perfluorohexanone in an open wind field.

[0066] Meanwhile, during the initial phase change heat absorption stage of the fire, the interface temperature between the multiphase foamed gas-locking fire suppression wrapping layer 5 and the STF transient rheological armor layer 4 is maintained in the range of 45℃ to 60℃ for no less than 120s. This result indicates that the released perfluorohexanone medium can form a heat-absorbing buffer environment of close to 50℃ on the outside of the STF transient rheological armor layer 4 through vaporization heat absorption, thereby reducing the direct effect of heat on the STF transient rheological armor layer 4 during the initial stage of the fire.

[0067] In contrast, control samples were prepared using wrapping tape without dual-modal flame-suppressing microcapsules, wrapping tape without thermally expanding foaming flame retardant, and ordinary flame-retardant wrapping tape, respectively, and tested under the same heat flux density and transverse airflow conditions. Compared with the control sample, the multiphase foamed gas-locking flame-suppressing wrapping tape layer 5 containing thermally expanding foaming flame retardant and dual-modal flame-suppressing microcapsules can form a longer perfluorohexanone release control residence time and a more obvious interface temperature plateau, thereby verifying the gas-locking and release control effect of the carbonized sponge shell layer and the phase change endothermic effect of the perfluorohexanone medium.

[0068] Specifically, when extreme events such as vehicle explosions, hazardous chemical explosions, or bridge fires occur, the defense system of this invention generates different responses according to the sequence of events.

[0069] In a scenario of initial transient impact followed by prolonged fire, the explosive shock wave or high-speed fragments first act on the multiphase foamed gas-locking fire suppression wrapping layer 5. Some bimodal fire suppression microcapsules release perfluorohexanone media due to impact brittle fracture, which is used to suppress the explosive fireball or initial flame. At the same time, the impact load is transferred to the STF transient rheological armor layer 4, causing the shear-thickening fluid STF 42 to undergo transient thickening. The STF transient rheological armor layer 4 changes from a flexible state to a transient rigid state, spreading the local impact load along the circumferential and axial directions of the cable 1, thereby protecting the high-efficiency aerogel insulation layer 3 from being compacted or pulverized. In the subsequent prolonged fire stage, the high-efficiency aerogel insulation layer 3 continues to play a heat insulation role, reducing the annealing risk of the cable 1.

[0070] In the transient impact scenario during a long-term fire, the multiphase foamed gas-locking fire suppression wrapping layer 5 is first heated and foamed into carbon, forming a porous carbonized sponge shell; the dual-mode fire suppression microcapsules release perfluorohexanone medium upon heating, which is retained in the porous carbonized sponge shell and reduces the temperature of the outer and middle layers through vaporization heat absorption; when further explosive impact occurs during the fire, the STF transient rheological armor layer 4 can still undergo transient thickening and stiffening under high shear, weakening the impact load on the high-efficiency aerogel insulation layer 3; in the continuous fire stage after the explosion, the porous carbonized sponge shell and the high-efficiency aerogel insulation layer 3 work together to play a thermal barrier role.

[0071] In summary, the embodiments of the present invention, through the multi-level synergy of the anti-corrosion layer 2, the high-efficiency aerogel insulation layer 3, the STF transient rheological armor layer 4, the multiphase foamed air-locking fire-suppressing wrapping layer 5, and the fluorocarbon topcoat 6, enable the cable 1 to maintain flexibility and follow movement during daily service, achieve transient stiffening and unloading during combustion and explosion impacts, and achieve foaming air-locking, active fire suppression, and long-term heat insulation in fires, thereby improving the safety protection capability of bridge cables under combined fire and explosion disasters.

[0072] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] Furthermore, the terms "inner side," "outer side," "from inside to outside," and "covering" are used for descriptive purposes only and are relative positional descriptions based on the radial direction of cable 1, and should not be construed as limiting the invention. Those skilled in the art can adjust the thickness, material ratio, winding overlap rate, and construction method in the above embodiments according to the specific bridge cable structure, construction conditions, and protection level requirements.

[0074] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A time-adaptive bridge cable fire and explosion collaborative defense system, characterized in that, The defense system covers the outside of the anti-corrosion layer of the bridge cable and includes, from the inside out, a high-efficiency aerogel felt heat insulation layer, an STF transient rheological armor layer, a multiphase foamed air-locking fire-suppressing wrapping tape layer and a weather-resistant protective layer. The high-efficiency aerogel felt insulation layer is disposed between the anti-corrosion layer and the STF transient rheological armor layer to form thermal insulation protection for bridge cables; The STF transient rheological armor layer covers the outside of the high-efficiency aerogel felt insulation layer and includes a high-strength fiber three-dimensional woven mesh, a shear thickening fluid impregnated in the mesh pores of the high-strength fiber three-dimensional woven mesh, and a flexible flow-blocking sealing membrane covering both sides of the high-strength fiber three-dimensional woven mesh. The multiphase foamed gas-locking flame-suppressing wrapping layer covers the outside of the STF transient rheological armor layer, including a flexible polymer matrix and a thermally expanding foaming flame retardant and a bimodal flame-suppressing microcapsule dispersed in the flexible polymer matrix. The core of the bimodal flame-suppressing microcapsule is encapsulated with a liquid perfluorohexanone medium. The multiphase foamed gas-locking fire suppression wrapping layer is configured to foam and carbonize upon heating to form a carbonized sponge shell layer, and to at least partially retain the perfluorohexanone medium released by the dual-mode fire suppression microcapsules within the pore channels of the carbonized sponge shell layer. The STF transient rheological armor layer is configured to undergo transient thickening and stiffening upon impact from an explosive shock or high-speed fragments, in order to disperse the impact load and reduce the local impact stress transmitted to the high-efficiency aerogel felt insulation layer.

2. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The flexible polymer matrix includes ethylene-vinyl acetate copolymer and flexible acrylate rubber; the thermally expandable foaming flame retardant includes at least two of expandable graphite, ammonium polyphosphate and melamine polyphosphate; the bimodal flame-suppressing microcapsules are dispersed and embedded in the flexible polymer matrix in an island structure.

3. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 2, characterized in that, The mass ratio of expandable graphite, ammonium polyphosphate, and melamine polyphosphate is 4:3:2; the shell of the bimodal fire-suppressing microcapsule is a double-layer composite shell composed of a melamine resin layer and a polyurethane layer; the particle size of the bimodal fire-suppressing microcapsule is 15μm to 35μm; the shell thickness is 1.2μm to 2.5μm; and the content of the liquid perfluorohexanone medium is 12% to 18% of the mass of the flexible polymer matrix.

4. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The dual-modal fire-suppressing microcapsule has a heat-triggered release mode and an impact-triggered release mode; Under the heat-triggered release mode, the dual-mode fire-suppressing microcapsule ruptures and releases its contents through the combined effects of the vapor pressure increase caused by the heat vaporization of the perfluorohexanone medium inside the capsule core and the heat softening of the capsule shell material. Under the impact-triggered release mode, the dual-mode fire-suppressing microcapsule is released through brittle fracture by the action of explosive impact pressure or high-speed fragment impact pressure on the capsule shell; Furthermore, the room temperature brittle fracture stress threshold of the dual-modal fire suppression microcapsule is greater than the maximum compressive stress generated by daily wind-induced vibration of bridge cables or vehicle live load vibration, and less than the preset explosive impact pressure threshold.

5. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The carbonized sponge shell layer has a porous and tortuous channel structure, which causes the released gaseous perfluorohexanone medium to form an obstructed diffusion path within the carbonized sponge shell layer.

6. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The high-strength fiber three-dimensional woven mesh is one or more of aramid fiber three-dimensional woven mesh, ultra-high molecular weight polyethylene fiber three-dimensional woven mesh, basalt fiber three-dimensional woven mesh, or glass fiber three-dimensional woven mesh; the shear thickening fluid includes nano-silica particles and a dispersion medium, the dispersion medium includes polyethylene glycol and glycerol, the particle size of the nano-silica particles is 50nm to 200nm, and the solid content of the shear thickening fluid is 35% to 50%.

7. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 6, characterized in that, The flexible flow-blocking sealing membrane is a thermoplastic polyurethane film. The thermoplastic polyurethane film is heat-sealed onto the inner and outer surfaces of the high-strength fiber three-dimensional braided mesh to seal the shear-thickening fluid within the mesh openings of the high-strength fiber three-dimensional braided mesh, forming a composite armor unit. Multiple composite armor units are spliced ​​and wrapped along the axial and / or circumferential direction of the bridge cable, and the splicing edges of adjacent composite armor units are sealed and connected by heat-melt welding, overlapping pressing, or sealant bonding.

8. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The high-efficiency aerogel felt insulation layer is a single layer or multiple layers of high-silica oxygen gel composite felt, with a single layer thickness of 3mm to 5mm; two adjacent layers of high-silica oxygen gel composite felt are wrapped around the outside of the anti-corrosion layer of the bridge cable in a staggered overlapping manner, and are radially constrained and fixed by fiberglass tape, flame-retardant wrapping tape or high-temperature resistant adhesive layer.

9. The time-adaptive bridge cable fire and explosion collaborative defense system according to claim 1, characterized in that, The high-efficiency aerogel felt insulation layer, the STF transient rheological armor layer, and the multiphase foamed air-locking fire-suppressing wrapping tape layer are all spirally wrapped on the outside of the anti-corrosion layer of the bridge cable. The spiral winding directions of adjacent two layers are opposite, so that the spiral joints of adjacent two layers form discrete intersections. The overlap rate of each layer is not less than 50%, so that any inner layer joint is covered by the non-joint solid area of ​​the adjacent outer layer in the radial direction. The weather-resistant protective layer is a fluorocarbon topcoat sprayed on the outside of the multiphase foamed air-locking fire-suppressing wrapping tape layer.

10. The defense system according to claim 4, characterized in that, The dual-modal fire-suppressing microcapsule possesses dual threshold quantization trigger boundaries that simultaneously satisfy impact brittle fracture release and fire-induced vaporization release: For the heat-triggered release mode, the shell wall thickness t, the outer diameter r of the shell, and the thermal softening yield strength of the shell at the heating temperature T are considered. and the saturated vapor pressure of perfluorohexanone inside. Satisfying the critical rupture equation: ； For the impact-triggered release mode, the room-temperature tensile brittle fracture stress threshold of the capsule shell. It is less than the preset threshold for transient impact pressure caused by the explosion shock wave, and greater than the maximum compressive stress caused by the daily wind-induced vibration of the bridge.

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