| With the development of society,the city scale is more and more large,and land resources become increasingly tense.In order to improve the utilization rate of the city underground space and realize more functions,people put forward the construction of utility tunnel.The utility tunnel includes the water pipe,gas pipe,heating pipe,sewage,electricity lines,communications lines,waste vacuum pipe and television lines,etc.More than two kinds of pipeline in one set,and provides a unified platform for city pipeline,the implementation of unified planning,design,construction and management.The utility tunnel can improve the appearance of a city,and avoid direct buried pipeline maintenance in the expansion of repeated excavation of pavement,which can avoid the cable hanging over the city,and at the same time improve the pipeline service life.With the increase of investment in the construction of utility tunnel project,the design reliability and safety of utility tunnel should be paid more attention.The fire risk of the cable compartment is the largest,and the power and communication plays an important role in the modern social and economic life.According to the utility tunnel’s actual 3-D size in the Liupanshui City,experimental model is established using FDS simulation software,which can simulate of cable fire in the sealed cable tunnel.During the simulation of observation,there show that fire development,smoke diffusion and temperature variations.There are three factors on the smoke effect exhaust air velocity,whether string induced fant,and vent position.The orthogonal experiment table obtained 9 experimental conditions,which established by the factors,followed by simulation experiment.The condition 1 show that the cable fire in sealed tunnel last about 10 min,and burn the cable about 20 m,which did not bring much property damage to the utility tunnel,So the use of fire self-extinguishing methods is feasible.After cooling for half an hour,the temperature in the gallery decreased gradually(average temperature was 29.5 degrees Celsius).If it with automatic fire extinguishing system,fire losses will be smaller.The conditions of 2~9 show that the negative pressure scale is the main reason for the scale of the wind speed in the utility tunnel.That the negative pressure increases,the average wind speed in the cabin porch is bigger,and it more conducive to ventilation.Setting induced fan plays a important role for the efficiency of smoke exhaust.Induced fan is bad for exhaust efficiency,which the speed is 2m/s on one side into the side vent position form row.Meanwhile,induced fan is good for exhaust efficiency,which the speed is 2m/s on the middle row into the vents on both sides.Whether setting the induced fan should be consider carefully to avoid the negative effect on the exhaust efficiency. |
