Underground green corridors are getting popular worldwide intending to integrate greenery into built environments. Green corridors provide greenery benefits and aesthetic pleasing view. Proper irrigation is necessary to maintain live plants in green walls. Automated irrigation with adequate amounts and proper drainage is vital to avoid overflows and drowning of plants. Due to improper irrigation plants in green walls can die quickly, creating a potential fire risk in underground green corridors. This paper aims at investigating the ignition, fire propagation and smoke propagation in underground green corridors. Numerical simulations with computational fluid dynamics (CFD) and physical scale modeling experiments were performed. The simulation has been completed based on heat release rate (HRR, kW/m²) data obtained from the cone calorimeter experiments for three plant species, namely; Hedera helix, Peperomia obtusifolia and Aglaonema commutatum. CFD simulations were conducted for an underground passage with a green wall. Results showed that a fire does not occur in underground corridors with fresh and live plants. However, fire risk increases gradually with drying out of plants. For dry plants, the surface temperature may reach above 850 °C. The fire spreads rapidly in about 20 s. An experimental study was carried out on a reduced-scale underground green corridor to investigate the fire and smoke propagation. It is observed that in the vertical direction fire spreads up to the ceiling rapidly. However, fire spreads slowly in the horizontal direction along the green wall. The experiments show that when the green wall is ignited, it may tremendously affect the evacuation due to smoke spread along the corridor and fire propagation in the vertical direction. It is recommended to decrease the fire risk in underground corridors with properly maintained green walls, especially in evacuation paths. This work is an initial study towards the analysis of fire and smoke propagation in underground green corridors.

中文翻译：

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地下绿色走廊火灾增长研究

地下绿色走廊在世界范围内越来越受欢迎，打算将绿色植物融入建筑环境中。绿色走廊可带来绿化效益，并提供美观的景观。必须进行适当的灌溉才能使绿色植物中的活植物保持健康。进行足够的自动灌溉和适当的排水对于避免植物溢出和淹死至关重要。由于灌溉不当，绿墙中的植物可能很快死亡，从而在地下绿色走廊中造成潜在的火灾隐患。本文旨在调查地下绿色走廊中的着火，火灾蔓延和烟雾蔓延。进行了具有计算流体动力学（CFD）和物理比例模型实验的数值模拟。根据放热率（HRR，kW / m ^2）完成了模拟）从锥形量热仪实验获得的三种植物的数据，即；常绿常春藤，百日草和百日草。对带有绿墙的地下通道进行了CFD模拟。结果表明，新鲜植物和有生命的植物在地下走廊中没有发生火灾。但是，随着植物变干，火灾风险逐渐增加。对于干燥植物，表面温度可能会达到850°C以上。火势在大约20 s内迅速蔓延。在缩小规模的地下绿色走廊上进行了一项实验研究，以研究火灾和烟雾的传播。观察到，火在垂直方向迅速扩散到天花板。但是，火势沿着绿墙沿水平方向缓慢蔓延。实验表明，点燃绿墙时，可能会极大地影响撤离，这是由于烟沿着走廊散布以及垂直方向的火势蔓延。建议降低带有适当维护的绿墙的地下走廊的火灾风险，尤其是在疏散路径中。这项工作是对分析地下绿色走廊中火灾和烟雾传播的初步研究。