Approximately one billion people across the globe are living in informal settlements with a large potential fire risk. Due to the high dwelling density, a single informal settlement dwelling fire may result in a very serious fire disaster leaving thousands of people homeless. In this work, a simple physics-based theoretical model was employed to assess the critical fire separation distance between dwellings. The heat flux and ejected flame length were obtained from a full-scale dwelling tests with ISO 9705 dimension (3.6 m × 2.4 m × 2.4 m) to estimate the radiation decay coefficient of the radiation heat flux away from the open door. The ignition potential of combustible materials in adjacent dwellings are analyzed based on the critical heat flux from cone calorimeter tests. To verify the critical distance in real informal settlement fire, a parallel method using aerial photography within geographic information systems (GIS), was employed to determine the critical separation distances in four real informal settlement fires of 2014–2015 in Masiphumelele, Cape Town, South Africa. The fire-spread distances were obtained as well through the real fires. The probabilistic analysis was conducted by Weibull distribution and logistic regression, and the corresponding separation distances were given with different fire spread probabilities. From the experiments with the assumption of no interventions and open doors and windows, it was established that the heat flux would decay from around 36 kW/m² within a distance of 1.0 m to a value smaller than 5 kW/m² at a distance of 4.0 m. Both experiments and GIS results agree well and suggest the ignition probabilities at distances of 1.0 m, 2.0 m and 3.0 m are 97%, 52% and 5% respectively. While wind is not explicitly considered in the work, it is implicit within the GIS analyses of fire spread risk, therefore, it is reasonable to say that there is a relatively low fire spread risk at distances greater than 3 m. The distance of 1.0 m in GIS is verified to well and conservatively predict the fire spread risk in the informal settlements.

全球大约有十亿人居住在非正式的定居点中，潜在的火灾隐患很大。由于住宅密度高，一次非正式的定居住宅火灾可能会导致非常严重的火灾，使数千人无家可归。在这项工作中，使用了一个简单的基于物理的理论模型来评估住宅之间的临界火灾隔离距离。通过ISO 9705尺寸（3.6 m×2.4 m×2.4 m）的全尺寸住宅试验获得热通量和喷出的火焰长度，以估算远离敞开的门的辐射热通量的辐射衰减系数。根据锥形量热仪测试得出的临界热通量，分析了相邻住宅中可燃材料的着火电位。为了验证实际非正式定居点射击中的临界距离，采用了一种在地理信息系统（GIS）中使用航空摄影的并行方法来确定2014-2015年南非开普敦Masiphumelele发生的四次真正的非正式定居火中的关键间隔距离。火灾蔓延距离也是通过真实火灾获得的。通过Weibull分布和logistic回归进行概率分析，并给出了不同火势蔓延概率的相应间隔距离。通过在没有干预措施且没有打开门窗的情况下进行的实验，可以确定热通量将从约36 kW / m衰减 在南非开普敦的Masiphumelele，2014年至2015年的四次实际非正式定居火场中，被用来确定临界间隔距离。火灾蔓延距离也是通过真实火灾获得的。通过Weibull分布和logistic回归进行概率分析，并给出了不同火势蔓延概率的相应间隔距离。通过在没有干预措施且没有打开门窗的情况下进行的实验，可以确定热通量将从约36 kW / m衰减 在南非开普敦的Masiphumelele，2014年至2015年发生的四次真实的非正式定居火中，他们被用来确定临界间隔距离。火灾蔓延距离也是通过真实火灾获得的。通过Weibull分布和logistic回归进行概率分析，并给出了不同火势蔓延概率的相应间隔距离。通过在没有干预措施且没有打开门窗的情况下进行的实验，可以确定热通量将从约36 kW / m衰减 给出了不同的火势蔓延概率。通过在没有干预措施且没有打开门窗的情况下进行的实验，可以确定热通量将从约36 kW / m衰减 给出了不同的火势蔓延概率。通过在没有干预措施且没有打开门窗的情况下进行的实验，可以确定热通量将从约36 kW / m衰减²在1.0 m的距离内达到小于5 kW / m ^2的值在4.0 m的距离内。实验和GIS结果均吻合良好，表明在1.0 m，2.0 m和3.0 m距离处的点火概率分别为97％，52％和5％。尽管在工作中未明确考虑风，但在GIS火灾蔓延风险分析中却隐含了风，因此，可以合理地说，距离大于3 m时火灾蔓延风险相对较低。验证了GIS中1.0 m的距离，可以很好地保守地预测非正式住区的火灾蔓延风险。