Study On Influence Factors Of Fire Smoke Spread In Utility Tunnel

Utility Tunnel,as a kind of public facilities,is used to collect cables,water supply and drainage pipes,gas line and other pipelines in the city.Although it makes the city more beautiful and convenient,it also brings many new challenges for fire prevention and control.Because of the function and structure of the Utility Tunnel,it is necessary to always open the ventilator machine.In addition,the cables and pipelines stored in it make the fire risk increased.Therefore,it is of great significance to study the layout of the inner cable of the Utility Tunnel and the ventilation rate of the ventilator machine.In this paper,we study how the cable connection point and the ventilation rate of ventilator machine effect the maximum temperature,longitudinal temperature field and flue gas flow field in the pipe corridor.The methods include shrinkage length channel test and FDS simulation.The specific works in this paper are summarized as follows:First,in the shrinkage length channel test,we change the position of fire source and analyzed its influence on the maximum temperature and longitudinal temperature field distribution in the long channel.In this experiment,we use the oil pool as the fire source,whose combustion rate not only indicates the burning speed,but also affects the flame height,temperature,thermal radiation and other important parameters.By changing the location of the fire source,the temperature curves of each point in the long channel are measured.Results show that,within the distance between ventilator machine and the closed end,as the fire source locates close to the smoke exhauster,its maximum temperature will gradually decrease.While in the distance between ventilator machine and theexport,the maximum temperature increases gradually as the fire source approaches the export.At the same time,the closer the fire source is to the ventilator machine,the greater the change of the fire source stability period.Second,the reliability of FDS simulation is confirmed.Experiments demonstrate that,the results of FDS simulation are similar with shrinkage length channel test in terms of the maximum temperature in the long channel and the variation curve of the longitudinal temperature field.As a result,the FDS simulation software can be used to simulate the fire of the Utility Tunnel.In the simulation experiment of the full-size Utility Tunnel with FDS,we change both the fire source location and ventilator rate.It can be found that,when the ventilation rate is 13 times per hour,plug-holing occurs,which limited the efficiency of ventilation machine on the contray.When changing the location of fire source,as the two ends of the pipe corridor are both closed,the source of fire(i.e.,cable connection point)arranged in the lower reaches of the ventilator machine makes flue gas spread slowly and also makes the maximum temperature is lower than other positions.Third,combining with shrinkage length channel test and FDS simulation,our paper puts forward the conclusion that,in the Utility Tunnel,the wind speed of the ventilator machine should not be greater than 4.5m/s,and the cable connection points should be arranged in the downstream of the ventilator machine.Figure[42] table[9] reference[55]...