Author(s)

A. de Lieto Vollaro, S. Grignaffini & A. Vallati

Abstract

The purpose of this work is to assess through numerical analysis the thermothidynamic conditions in underground railway and road tunnels following a fire, so as to implement a mathematical model that could be used in the future to identify a security indicator associated with every tunnel. The phenomenon of the thermal field has been assessed through a numerical analysis by way of the software Fluent 5.3. The mathematical model utilized has been applied in comparing the results available in literature relative to noted experiments taken in a tunnel, in relation to a fire of small dimensions, reaching a maximum power of 2.5MW for reasons tied to the feasibility of the carrying out of measurement in the field. Our mathematical model though, once validated, will be able to simulate fires of greater dimensions in which the thermal field and the temperatures reach the limit values of the stability of the structures. The comparisons were made between some points positioned at different distances from the hearth and at different heights from the road. An attempt was made to reproduce the natural ventilation conditions present within the tunnel and special attention was given to the discretitation grid to which an independent solution was obtained from what was chosen. The results reached were in accordance with the amount experimented with, allowing to assume the possibility to utilize this mathematical model for other underground and road tunnels, assessing in particular, the eventual labor necessary to carry out complete security.

Keywords