水幕屏蔽系统在地下道路火灾防控中的试验研究

Experimental Study on Effect of Water Curtain Shielding System in Fire Prevention and Control of Underground Road

合理的水幕屏蔽设计,可保证隧道有效排烟和烟气层的稳定性,为人员安全疏散提供有利环境。为研究水幕屏蔽系统在地下道路火灾防控中的作用,文章提出了基于水幕屏蔽作用的隧道消防灭火系统,并以弗劳德相似准则为理论依据,结合北横通道工程实际情况,选取隧道300 m中间段进行1:15的水幕屏蔽系统防灾性能缩尺模型试验研究。以水喷头流量为主要变量,设计5组试验工况(含1组对照工况),分别从烟气扩散及温度场两方面论证水幕屏蔽系统的防灾有效性。试验表明,水幕屏蔽对火灾中的烟气扩散起到了明显的阻隔作用,当水喷淋流量达到一定数值(模型试验中为300 L/h),烟气前锋被打断,向远端蔓延受阻,水幕内外侧完全隔离;同时,水幕屏蔽引起了火灾工况下隧道内的温度场变化,隧道中远端热环境改善,水喷头外侧温度曲线趋缓,且温度随水喷淋流量增大而降低。

Reasonable design of water curtain shielding can guarantee the effective smoke exhaust and the stability of the smoke layer in the tunnel to provide a favorable environment for safe evacuation of personnel.In order to study the role of water curtain shielding system in fire prevention and control of underground roads,a tunnel fire extinguishing system based on water curtain shielding was proposed in this paper.Then,based on Froude similarity criterion and combined with actual situation of North Cross Passage Project,a 300 m-long middle section of the tunnel was selected to perform the 1:15-scale model test for disaster prevention performance of the water curtain shielding system.With water nozzle flow as a major variable,five groups of test cases(including a group of control case)were designed to demonstrate the disaster prevention effectiveness of the water curtain shielding system from two aspects of smoke diffusion and temperature field.The test indicates that the water curtain shielding has an obvious barrier effect on smoke diffusion in the fire.When the water spray flow is up to a certain value(300 L/h in the model test),the smoke front is interrupted and prevented from spreading to the far end,so that inner and outer sides of the water curtain are completely isolated;Meanwhile,the water curtain shielding causes the change of temperature field in the tunnel in case of a fire.The thermal environment is improved at the middle and far ends of the tunnel.The temperature curve is flattening outside the water nozzle and the temperature decreases along with the increase of water spray flow.