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Large-scaled fire testing for long-sized road tunnel
Tunnelling and Underground Space Technology incorporating Trenchless Technology Research
Tunnelling and Underground Space Technology 21 (2006) 282
www.elsevier.com/locate/tust
Large-scaled fire testing for long-sized road tunnel Z.G. Yan a, H.H. Zhu a, Q.X. Yang a b
b
Department of Geotechnical Engineering, Tongji University, Shanghai, China School of Civil Engineering, Southwest Jiaotong University, Chengdu, China
The Qinling Long Sized Road Tunnel (Qinling Tunnel) is the longest road tunnel in China. It consists of two tubes (two-lane carriageway per tube) with each tube 18.0 km in length. The longitudinal forced ventilation mode is utilized and the tunnel is divided into four regions by three ventilation shafts. To investigate the behaviours of fire in tunnel and to propose an effective ventilation measure to fight fires in the Qinling Tunnel, two large-scaled model tunnel were established and a series of fire testing were conducted between 2001 and 2004. The testing titled testing I was carried out to understand the general behaviour of tunnel fire, and another testing called testing II conducted by the model tunnel with ventilation shafts was to investigate how various ventilation measures interact with fire in a long sized road tunnel, and to thereby propose effective ventilation measure to fight fires in the Qinling Tunnel. For testing I, a total of 18 tests were performed, and for testing II, a total of 33 tests were performed. The model tunnels have a circular cross-section with an inner diameter of 1.8 m and measures 100 m long. The air velocity produced by the axial fans varies within 0–10 m/s in the different tests. Three different fire loads, i.e., fire load A, B and C are used to simulate the different fire scenarios. Numerous K-typed thermocouples and pitot tubes are installed at various cross sections within the tunnel to measure temperatures, air velocity and air pressure. All of the measurements are continuously recorded by the data acquisition system of controller area network (CAN). The scopes of the testing are as follows: (1) general behaviours of fire in long-sized road tunnel, such as chronological and spatial distribution of temperature, flowage of combustion gases and fluctuation of air pressure; (2) applicable fire ventilation measures for the Qinling Tunnel when fire occurs at the various positions in the tunnel. Based on the results of the testing, the following important findings have been established: (1) the temperature, pressure and smoke flow in the tunnel vary significantly with air velocity and fire load; (2) according to the fire load and ventilation condition, the temperature reaches the maximum value within 2–10 min after ignition; (3) the forced ventilation has both positive and negative effects on fires. In general, proper ventilation can prevent the backlyering of smoke and maintain a clear atmosphere on the leeward side of fire for evacuation. Furthermore, the ventilation improves the working conditions for fire fighters; and (4) when a fire occurs in the Qinling Tunnel, the primary objective of fire ventilation in the stage of evacuation is to control the smoke propagation and to prevent the backlayering of smoke. While in the stage of fire fighting, the fire ventilation serves to cause the fire to burn out faster, to allow relatively safe access for firefighters and to minimize the damage to the structure. To satisfy this objective the effective ventilation measures should be applied according to fire position, fire load and evacuation procedures. This paper describes the details of the large-scaled fire testing procedures and results. Keywords: Tunnel; Fire; Testing; Ventilation
doi:10.1016/j.tust.2005.12.142
Tunnelling and Underground Space Technology 21 (2006) 282
www.elsevier.com/locate/tust
Large-scaled fire testing for long-sized road tunnel Z.G. Yan a, H.H. Zhu a, Q.X. Yang a b
b
Department of Geotechnical Engineering, Tongji University, Shanghai, China School of Civil Engineering, Southwest Jiaotong University, Chengdu, China
The Qinling Long Sized Road Tunnel (Qinling Tunnel) is the longest road tunnel in China. It consists of two tubes (two-lane carriageway per tube) with each tube 18.0 km in length. The longitudinal forced ventilation mode is utilized and the tunnel is divided into four regions by three ventilation shafts. To investigate the behaviours of fire in tunnel and to propose an effective ventilation measure to fight fires in the Qinling Tunnel, two large-scaled model tunnel were established and a series of fire testing were conducted between 2001 and 2004. The testing titled testing I was carried out to understand the general behaviour of tunnel fire, and another testing called testing II conducted by the model tunnel with ventilation shafts was to investigate how various ventilation measures interact with fire in a long sized road tunnel, and to thereby propose effective ventilation measure to fight fires in the Qinling Tunnel. For testing I, a total of 18 tests were performed, and for testing II, a total of 33 tests were performed. The model tunnels have a circular cross-section with an inner diameter of 1.8 m and measures 100 m long. The air velocity produced by the axial fans varies within 0–10 m/s in the different tests. Three different fire loads, i.e., fire load A, B and C are used to simulate the different fire scenarios. Numerous K-typed thermocouples and pitot tubes are installed at various cross sections within the tunnel to measure temperatures, air velocity and air pressure. All of the measurements are continuously recorded by the data acquisition system of controller area network (CAN). The scopes of the testing are as follows: (1) general behaviours of fire in long-sized road tunnel, such as chronological and spatial distribution of temperature, flowage of combustion gases and fluctuation of air pressure; (2) applicable fire ventilation measures for the Qinling Tunnel when fire occurs at the various positions in the tunnel. Based on the results of the testing, the following important findings have been established: (1) the temperature, pressure and smoke flow in the tunnel vary significantly with air velocity and fire load; (2) according to the fire load and ventilation condition, the temperature reaches the maximum value within 2–10 min after ignition; (3) the forced ventilation has both positive and negative effects on fires. In general, proper ventilation can prevent the backlyering of smoke and maintain a clear atmosphere on the leeward side of fire for evacuation. Furthermore, the ventilation improves the working conditions for fire fighters; and (4) when a fire occurs in the Qinling Tunnel, the primary objective of fire ventilation in the stage of evacuation is to control the smoke propagation and to prevent the backlayering of smoke. While in the stage of fire fighting, the fire ventilation serves to cause the fire to burn out faster, to allow relatively safe access for firefighters and to minimize the damage to the structure. To satisfy this objective the effective ventilation measures should be applied according to fire position, fire load and evacuation procedures. This paper describes the details of the large-scaled fire testing procedures and results. Keywords: Tunnel; Fire; Testing; Ventilation
doi:10.1016/j.tust.2005.12.142