Road Tunnel Focus On The Ventilation Exhaust From The System

The tunnel fire occurred in all over the world frequently, and resulted in a large number of casualties and material damage. At present, the consensus of the importance and necessity of the study of tunnel fire, especially in the technology of tunnel ventilation under fire has been reached. In this paper, relied on the project of Cang-ling tunnel in Zhejiang province, the systematic study about the correlative problems of central exhaust system under long highway tunnel fire was carried on, and the content of this paper as follows:(1) On the basis of widely referring to the literatures of long highway tunnel ventilation under fire at home and abroad, pointing out the problems and the development trend of long highway tunnel ventilation under fire, and emphatically elaborated the design ideal of tunnel ventilation, that is to make the economical longitudinal ventilation under normal operation and the good effect of smoke control of central exhaust system under tunnel fire become harmony and unification.(2) According to the tunnel ventilation design, the general and reasonable tunnel fire scene was designed, and the FDS was selected to carry on the numerical simulation in order to analyze the effect of central exhaust system under fire, the numerical simulation includes the spread distance of first indication of smoke, the distributing of visibility and temperature of fire smoke in vertical section and transect.(3) For comparing the effects of central exhaust system under fire, the numerical simulation was also carried on in order to analyze the effects of vertical ventilation under the two most adverse conditions of all design fire scenes, and the findings indicated that the fire smoke was controlled in the range of 100-150m under central exhaust system, and the effect of stratified flow was in a small disturbance. However, under the vertical ventilation, the fire smoke was quickly spread in the whole range of tunnel ventilation with the ventilation airflow, and the effect of stratified flow was disturbed, the visibility was serious reduced.(4) The correlative FDS analysis results was used to setting the boundary condition of structure temperature field, and the ANSYS was selected to carry on the analysis of structure safety of the lining of tunnel, the top-clapboard and the bracket which connected the lining and top-clapboard of central exhaust system under fire, the findings showed that the structure system of smoke shaft could satisfy the operating requirements under tunnel fire.