Fire Characteristics And Evacuation In Cable Cabin Of Utility Tunnel

With the development of society,the comprehensive degree of urban architecture has been greatly improved,and utility tunnel has become an indispensable part of the modern urban infrastructure construction system.The utility tunnel integrates power cables,communication cables and other municipal pipelines.Once a fire accident occurs in the corridor,it will cause the interruption of power and communication lines,directly affect the normal use of surrounding buildings,bring great inconvenience to people's lives,and cause incalculable losses to the economy of the whole city.Most of the comprehensive corridors are located in the underground,and the space is narrow and closed.It is not only unsuitable to detect fire in time,but also brings great difficulty to rescue and evacuation.Based on FDS numerical simulation software,different ventilation wind speed and different fire power research schemes were adopted to analyze the smoke spread,temperature change and CO volume concentration in the corridor,and the smoke counter-current length,critical wind speed and the available safe evacuation time ASET under different fire power were analyzed.Aiming at the vertical cross section of cable cabin,the influence of different cabin fire conditions on cabin and another cabin was analyzed by using different cabin fire research methods.Aiming at personnel evacuation,based on Pathfinder simulation evacuation software,a fire protection zone without intersection section of cable cabin is selected to study.The concept of equivalent time is introduced.By setting different fire protection zone lengths and maintenance channel widths,RSET,the necessary safe evacuation time for personnel evacuation,is analyzed.By comparing with ASET studied in the previous part,the cable cabin of integrated corridor is obtained.The main contents of this paper are as follows:(1)A full scale numerical model of single fire zone in cable compartment without intersection is established.The large eddy simulation method is used to study the fire characteristics of single fire zone in cable compartment without intersection.Considering the flue gas spread and visibility,temperature change and CO volume concentration change under different longitudinal ventilation wind speed,the countercurrent length of flue gas and the corresponding critical wind speed under different longitudinal wind speed were obtained.The ASET curve of safe evacuation time for personnel in a single fire zone without cross section in cable cabin is obtained through research.(2)The full scale numerical model of the vertical cross section of cable cabin is established and its fire characteristics are studied.The 30 m length sections of the upper and lower cabin are selected for the study.The upper cabin is widened at the intersection and 1 m x 1 m repair holes are set in the middle of the intersection.By simulating and analyzing the fire in the cabin of the upper and lower cabins,the smoke spread,temperature change and CO volume concentration in the intersection under different working conditions were obtained.(3)Referring to the existing research on fire evacuation in highway tunnels,the evacuation in single fire zone without intersection in cabin was studied by using Pathfinder simulation evacuation software and Agent-base continuity model.By establishing equivalent time method,the evacuation mode of cable cabin without intersection section is obtained under the influence of different fire zone length,maintenance channel width and evacuation personnel parameters.