METHODOLOGY OF USING CFD-BASED RISK ASSESSMENT IN ROAD TUNNELS

Abstract

The definition of the deterministic approach in the safety analyses comes from the need to understand the conditions that come out during the fire accident in a road tunnel. The key factor of the tunnel operations during the fire is the ventilation, which during the initial fazes of the fire, impact strongly on the evacuation of people and latter on the access of the intervention units in the tunnel. The paper presents the use of the computational fluid dynamics model in the tunnel safety assessment process. The model is validated by comparing data with experimental and quantifying the differences. The set-up of the initial and boundary conditions and the requirement for grid density found during the validation tests is used to prepare three kind of fire scenarios 20 MW, 50 MW, and 100 MW, with different ventilation conditions; natural, semi transverse, full transverse, and longitudinal ventilation. The observed variables, soot density and temperature, are presented in minutes time steps trough the entire tunnel length. Comparing the obtained data in a table, allows the analyses of the ventilation conditions for different heat releases from fires. The second step is to add additional criteria of human behaviour inside the tunnel (evacuation) and human resistance to the elevated gas concentrations and temperature. What comes out is a fully deterministic risk matrix that is based on the calculated data where the risk is ranged on five levels, from the lowest to a very danger level. The deterministic risk matrix represents the alternative to a probabilistic safety assessment methodology, where the fire risk is represented in detail as well as the computational fluid dynamics model results are physically correct.

Keywords

Dates

  • Submission Date2006-04-12
  • Revision Date2006-09-15
  • Acceptance Date2006-11-23

DOI Reference

10.2298/TSCI0702207M

References

  1. Cheng, L. H., Ueng, T. H., Liu, C. W., Simulation of Ventilation and Fire in the Underground Facilities, Fire Safety Journal, 18 (2003), 5, pp. 597-619
  2. Jojo, S. M. L., Chow, W. K., Numerical Studies on Performance Evaluation of Tunnel Ventilation Safety Systems, Tunnelling and Underground Space Technology, 18 (2003), 5, pp. 435-452
  3. Lowndes, I. S., Crossley, A. J., Yang, Z.-Y., The Ventilation and Climate Modelling of Rapid Development Tunnel Drivages, Tunnelling and Underground Space Technology, 19 (2004), 2, pp. 139-150
  4. Carvel, R. O., Beard, A. N., Jowitt, P. W., The Influence of Longitudinal Ventilation Systems on Fires in Tunnels, Tunnelling and Underground Space Technology, 16 (2001), 1, pp. 3-21
  5. Bread, A. N., A Model for Predicting Fire Spread in Tunnels, Journal of Fire Science, 15 (1997), 4, pp. 277-307
  6. Kunsch, J. P., Critical Velocity and Range of a Pre-Gas Plume in a Ventilated Tunnel, Atmospheric Environment, 33 (1998), 1, pp. 13-24
  7. Megret, O., Vauquelin, O., A Model to Evaluate Tunnel Fire Characteristics, Fire Safety Journal, 34 (2000), 4, pp. 393-401
  8. Haack A., Fire Protection in Traffic Tunnels: General and Results of the EUREKA Project, Tunnelling and Underground Space Technology, 13 (1998), 4, pp. 377-381
  9. Haack, A., Current Safety Issues in Traffic Tunnels, Tunnelling and Underground Space Technology 17 (2002), 2, pp. 117-127
  10. Amundsen, F. H., Ranes, G., Studies on Traffic Accidents in Norwegian Road Tunnels, Tunnelling and Underground Space Technology, 15 (2000), 1, pp. 3-11
  11. ***, Commision of the European Communities, Directive of the European Parliament and of the Council on minimum safety requirements for tunnels in the Trans-European Road Network, Brussels, 2004
  12. Kirchsteiger, C., On the Use of Probabilistic and Deterministic Methods in Risk Analysis, Journal of Loss Prevention in the Process Industries, 12 (1999), 5, pp. 399-419
  13. Gann, R. G., Hall, J. R., Fire Conditions for Smoke Toxicity Measurement, Fire and Materials, 18 (1994), 3, pp. 193-199
  14. ***, PIARC Technical Committee on Tunnel Operation, Fire and Smoke Control in Road Tunnels, Commission report, Paris, 2003
  15. Gasser, I., Struckmeier, J., Teleaga, I., Modelling and Simulation of Fires in Vehicle Tunnels, Computational Fluid Dynamics and Data Analyses (Ed. F. Reihe), No. 19, University of Hamburg, Hamburg, Germany, 2002
  16. Floyd, J. E., Wieczorek, C. J., Vandsburger, U., Simulation of the Virginia Tech. Fire Research Laboratory Using Large Eddy Simulations with Mixture Fraction Chemistry and Finite Volume Radiative Heat Transfer, Proceedings, International Symposium INTERFLAM 2001, Edinburgh, Scotland, UK, 2001, pp. 767-778
  17. Persson, M., Quantitative Risk Analysis, Procedure for the Fire Evacuation of a Road Tunnel, 2nd International Conference on Safe and Reliable Tunels, Lausanne, Switzerland, 2006
  18. Vidmar, P., Petelin, S., An Analysis of a Fire Resulting from a Traffic Accident, Journal of Mechanical Engineering (Strojniski Vestnik), 49 (2003), 5, pp. 1-13
  19. McGrattan, K., Baum, H., Rehm, R., Hamins, A., Forney, G. P., Floyd, J. E., Hostikka, S., Fire Dynamics Simulator, Technical reference guide, National Institute of Standard and Technology, NISTIR 6783, Gaithersburg, Md., USA, 2001
  20. Fletcher, C. A. J., Computational Techniques of Fluid Dynamics, 2nd ed., Vol. 2, Springer-Verlag, Berlin, Heidelberg, 1991
  21. Sagaut, P., Large Eddy Simulations for Incompressible Flows, 2nd ed., Springer-Verlag, Berlin, Heidelberg, 2002
  22. Lesieur, M., Turbulence in Fluids, Kluwer Academic Publisher, Dodrecht, The Netherlands, 1997
  23. Heskestad, G., SFPE Handbook, Chapter Fire Plumes, 2nd ed., National Fire Protection Association, Quincy, Ma., USA, 1995
  24. Drysdale, D., An Introduction to Fire Dynamics, John Wiley & Sons Ltd, New York, USA, 1998
  25. ***, Memorial Trunnel Fire Ventilation Test Program, Massachusetts Highway Department, Central Artery/Tunnel Project, Boston, Ma., USA, 1996
  26. McGrattan, K., Hamins, A., Numerical Simulation of the Howard Street Tunnel Fire, National Institute of Standard and Technology, Gaithersburg, Md., USA, 2002
  27. Woodburn, P. J., Britter, R. E., CFD Simulations of a Tunnel Fire, Fire Safety Journal, 26 (1996), 1, pp. 35-62
  28. Jang, H. M., Chen, F., A Novel Approach to the Transient Ventilation of Road Tunnels, Journal of Wind Engineering and Industrial Aerodynamics, 86 (2000), 1, pp. 15-36
  29. Trucano, T. G., Prediction and Uncertainty in Computational Modeling of Complex Phenomena, Sandia National Laboratories, Albuquerque, N. Mex., USA, 1998
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