JBA Trust, Skipton, North Yorkshire, UK.
Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, UK.
Risk Anal. 2019 Nov;39(11):2457-2478. doi: 10.1111/risa.13370. Epub 2019 Jul 18.
Scour (localized erosion by water) is an important risk to bridges, and hence many infrastructure networks, around the world. In Britain, scour has caused the failure of railway bridges crossing rivers in more than 50 flood events. These events have been investigated in detail, providing a data set with which we develop and test a model to quantify scour risk. The risk analysis is formulated in terms of a generic, transferrable infrastructure network risk model. For some bridge failures, the severity of the causative flood was recorded or can be reconstructed. These data are combined with the background failure rate, and records of bridges that have not failed, to construct fragility curves that quantify the failure probability conditional on the severity of a flood event. The fragility curves generated are to some extent sensitive to the way in which these data are incorporated into the statistical analysis. The new fragility analysis is tested using flood events simulated from a spatial joint probability model for extreme river flows for all river gauging sites in Britain. The combined models appear robust in comparison with historical observations of the expected number of bridge failures in a flood event. The analysis is used to estimate the probability of single or multiple bridge failures in Britain's rail network. Combined with a model for passenger journey disruption in the event of bridge failure, we calculate a system-wide estimate for the risk of scour failures in terms of passenger journey disruptions and associated economic costs.
冲刷（由水引起的局部侵蚀）是世界范围内许多桥梁以及基础设施网络的重要风险因素。在英国，冲刷已导致超过 50 次洪水事件中河流上的铁路桥梁失效。这些事件已经过详细调查，为我们开发和测试模型提供了数据集，以量化冲刷风险。风险分析是根据通用的、可转移的基础设施网络风险模型制定的。对于一些桥梁失效，已经记录或可以重建引发的洪水的严重程度。将这些数据与背景失效率以及未失效的桥梁记录相结合，构建了定量描述洪水事件严重程度条件下失效概率的脆弱性曲线。生成的脆弱性曲线在一定程度上对将这些数据纳入统计分析的方式敏感。使用从英国所有河流水位测量站点的极端河流水流空间联合概率模型模拟的洪水事件对新的脆弱性分析进行了测试。与洪水事件中预期的桥梁失效数量的历史观测相比，综合模型表现出稳健性。该分析用于估计英国铁路网络中单个或多个桥梁失效的概率。结合桥梁失效时乘客行程中断的模型，我们以乘客行程中断和相关经济成本的形式计算了冲刷失效的系统范围风险的估计值。
