Research On Design Of The Large Interchange Tunnel Ventilation And Smoke Extraction System

With the increase of the tunnel length and quantity in China, the higher requirements are put forward in all aspects on tunnel technology. The large interchange tunnel can relieve traffic pressures and insure the fast traffic of city. Considering of the large scale and complex situation with more branches.the ventilation design of the interchange tunnel,which is more complex than ordinary tunnel,hhas become an important issue that must be studied during its construction and security operations.This paper introduces the basic knowledge of graph theory and the important matrix in the large interchange tunnel’s ventilation network calculation software. According to the theoretical knowledge on ventilation network and the practical situation of tunnel ventilation, the influence factors,such as tunnel frictional resistance,local resistance, natural ventilating pressure, traffic piston effect, jet fans’ blowing pressure and fire resistance, etc,on the state of tunnel wind pressure were determined. The large interchange tunnel ventilation network calculation model are established. The main results were as follows:(1) Based on the ventilation network theory, The large interchange tunnel’s ventilation network calculation software is compiled,which can calculate a varieties of complex forms of the large interchange ventilation system.(2) According to a large interchange tunnel in Shenzhen, this paper calculate the required airflow of each branch in the southern and northern route with the traffic speeds are 30km/h、40km/h、50km/h、60km/h in 2020 and 2032 which is necessary for normal operation and fire condition.(3) The normal operation which includes the southern and northern route’s ventilation network diagrams and the fire condition’s ventilation network diagrams which include 16 positions where the fire may break out are built.(4) Under the natural ventilating pressure and required airflow in the same direction、 reverse direction conditions of different years and traffic speeds in normal operation and different fire conditions when the fire break out in different tunnel branches, this paper carries out wind flow organization research, the ventilation network calculation software compiled in this paper is used for ventilation calculation in order to gain the arrangement of jet fans to achieve the wind flow balance and meet the normal operational ventilation and smoke extraction’s requirements.Through research in the paper, it provides technical support for design of tunnel ventilation with using ventilation network in the large interchange tunnel.