As an underground laying system for power and communication cables, the fire-retardant performance of prefabricated lightweight cable trenches directly affects the safety and stability of cable operation. In the event of a fire, if the cable trench cannot effectively prevent the spread of fire, it may lead to cable burnout, system paralysis, or even secondary disasters. Therefore, improving its fire-retardant performance is a crucial aspect of ensuring infrastructure safety. The following discusses strategies for improving the fire-retardant performance of prefabricated lightweight cable trenches from four dimensions: material selection, structural design, fireproofing measures, and construction and maintenance.
Material selection is fundamental to improving fire-retardant performance. The main material of prefabricated lightweight cable trenches must possess characteristics such as high fire resistance, low smoke, and non-toxicity. While traditional concrete materials have a certain degree of fire resistance, they are heavy, have long construction cycles, and are prone to cracking and spalling at high temperatures. The application of novel inorganic high-performance fiber composite materials (UCFC) provides a better solution for cable trenches. These materials, meeting the R130 mechanical property standard, possess high compressive strength, bending resistance, and chemical corrosion resistance. Their fire resistance temperature can reach over 1000 degrees Celsius, and they do not release toxic gases during combustion, significantly enhancing the passive fire protection capability of cable trenches. Furthermore, the inner walls of the cable trench can be coated with fire-retardant paint, such as intumescent perchloroethylene fire-retardant paint, which forms a dense heat-insulating layer upon contact with fire, further slowing the spread of fire.
The structural design must consider both fire-resistant partitioning and heat dissipation requirements. Prefabricated lightweight cable trenches can adopt a modular design, enabling rapid assembly through flexible interfaces. Each section of the cable trench contains an independent fire-resistant compartment. The compartments are filled with soft fire-retardant materials such as rock wool blocks and foamed asbestos, effectively blocking flame and heat transfer while facilitating future cable capacity expansion or replacement. In addition, a U-shaped drainage channel is designed at the bottom of the cable trench to prevent water accumulation and short circuits caused by moisture. The slope design guides water drainage, reducing the risk of electrical faults caused by dampness. In cable support design, a combination of metal supports and fireproof partitions is used to arrange cables of different voltage levels or uses in layers, preventing the fire from spreading longitudinally along the cables.
Fireproof isolation measures are a crucial element in preventing fire spread. Where cable trenches enter buildings or critical equipment areas, prefabricated fireproof partitions must be installed. These partitions are integrally formed with the cable trench and use fire-resistant materials with a fire resistance rating of not less than 3 hours, such as silicate fiber felt or slag wool, to form a physical barrier. Simultaneously, fireproof tape or fire-retardant paint is wrapped around the cables on both sides of the partition within a 0.5 to 1 meter radius, forming "double protection." Even if a local cable fire occurs, it can effectively prevent flames from escaping through doorways or gaps, preventing the fire from spreading. For long cable trenches, fire-resistant sections can be installed at regular intervals, using fire-resistant bags, fireproof putty, and other materials to construct and seal the trench, dividing it into multiple independent fire-resistant units.
The standardization of construction and maintenance directly affects the durability of fire resistance performance. During the construction phase, strict quality control of materials is essential to ensure that fire-retardant coatings, fire-resistant bags, and other materials meet national standards, preventing fire resistance failure due to material defects. When laying cables, maintain proper spacing to avoid excessive density that could lead to poor heat dissipation. Also, avoid contact between cables and sharp objects to prevent short circuits caused by insulation damage. In routine maintenance, regularly check the integrity of fire-resistant materials in the cable trench, promptly replacing aged or detached fire-resistant tapes and sealing strips; clean accumulated dust and debris from the trench to prevent the accumulation of flammable materials; and check the drainage system for blockages to prevent water accumulation that could corrode cables or fire-resistant materials.
Improving the fire resistance and flame retardancy of prefabricated lightweight cable trenches requires a coordinated approach from four aspects: materials, structure, isolation measures, and construction and maintenance. By selecting highly fire-resistant materials, optimizing structural design, improving fire isolation systems, and strengthening construction and maintenance standards, fire risks can be significantly reduced, ensuring the safe and stable operation of cable systems and providing solid support for the safety of urban power grids, rail transit, and other infrastructure.
