EVALUATION OF MULTI-ZONE MODELLING FOR FIRE RISK ASSESSMENT IN TUNNELS

Sammanfattning: Abstract Tunnels are one of the most complex and delicate elements of the road system. Assessing fire behaviour and fire severity remains the biggest source of uncertainty in risk assessment and is an essential step in the tunnel design process. This study focuses on investigating the reliability and accuracy of different available tools to describe tunnel fire dynamics, with a focus on assessing the efficiency of the Multi-Zone (MZ) Fire model. This tool is under development thanks to a collaboration between Lund University and the Italian fire engineering company Cantene srl, with the aim of further developing a multi-zone modelling approach to be implemented in their tunnel risk analysis tool called ARTU®. The study consists of three phases. In the initial stage a literature review was performed to investigate what type of methods and tools are available to calculate gas temperatures and smoke layer height in tunnels. In the second phase, the three selected models, CFAST, MZ and FDS, were benchmarked in set of simple tunnel configurations to investigate the influence of varying Heat Release Rate (HRR), geometry and ventilation on the results. In the last phase the tools were validated against a set of experimental data from full scale tests performed in the Koralm Tunnel in Austria, provided by Graz University of Technology. The accuracy, the attributes, and the constraints of the tools were evaluated. The Multi-Zone (MZ) Fire model generally provided satisfying results and a good quality of agreement with more validated software. The accuracy of the tool was further discussed, recommendations for its use were provided, limitations and opportunities for further development were identified and presented in the study.