Full-Scale Informal Settlement Dwelling Fire Experiments and Development of Numerical Models

摘要

While fire-related injuries and deaths decreased in the global north over the past few years, they have increased in the global south. With more than one billion people residing in informal settlements (sometimes known as slums, ghettos or shantytowns), it is necessary that greater effort be placed on addressing and developing means for improving fire safety in these areas. As a result of advances made in computer technologies, emerging performance-based regulations and an increase in building complexity in the global north, the use of computer models simulating enclosure fires have increased dramatically. In this work an experimental investigation is presented for (a) a full-scale corrugated steel sheeting clad informal dwelling experiment and (b) a full-scale timber clad informal dwelling experiment. The experimental results are then compared to numerical models consisting of both simple two-zone (OZone) and computational fluid dynamic models. Currently, there is negligible literature available on Fire Dynamic Simulator (FDS) modelling of informal settlement dwellings (sometimes known as shacks or shanties) fires. This paper evaluates the plausibility of using FDS v6.7 and zonal models to predict certain fire parameters (i.e. ceiling temperatures, heat fluxes, etc.) for Informal Settlement Dwellings (ISDs) and to study the plausibility of using FDS to estimate the probability of fire spread. In this paper an introduction to ISDs is given with details pertaining to construction materials and considerations needed for numerical modelling of informal dwellings (i.e. thin permeable boundaries or combustible boundaries). Models are based upon (a) a prescribed heat release rate per unit area in FDS using data obtained from a Fire Propagation Apparatus test, and (b) an empirical two-zone model using OZone. The FDS validation guide was used to quantify the model uncertainties in order to give a critical separation distance at which fire spread between dwellings will not occur. It was found that at 3 m spacing between ISDs there is a 6% chance (based on the model uncertainties) that fire spread can occur. This is an important finding that highlights the danger associated with these closely spaced dwellings and the hope is that it can guide local government and Non-Governmental Organizations in future decision making. Three meters spacing between dwellings, however, may not be possible due to the socio-cultural-political-economic issues associated with informal settlements. This is one of the first papers to demonstrate FDS models against full-scale ISD experiments.