基于系统动力学城市燃气管网动态风险评估体系研究

The dynamic risk assessment method of urban gas pipeline network presents the change trend of systemic risk, so its assessment result is more scientific and guidance significance than the static risk assessment methods. Based on the analysis of influence factors and relevance, the dynamic computing model of failure probability of urban gas pipeline network will be built through the experimental study on failure mechanism of gas pipeline network impacted by the coupling multiple factors. The dynamic evolution behavior will be imitated using simulation software, such as CFD and Phast when gas diffuses along the ground and ditches. Then the concentration distribution characteristic and the models of accident consequence analysis will be obtained. The fusion way will be explored between the system dynamics and dynamic risk assessment of urban gas pipeline network, and the dynamic risk assessment model of urban gas pipeline network based on System Dynamics will be set up. The data of spatial and temporal integration will be gotten real-time and dynamic by the combination between the monitoring systems of gas pipeline network and GIS. The risk control strategy will be analyzed by simulation experiments of risk assessment model. The key of research is to clarify the coupling mechanism of multiple factors and the failure mechanism of gas pipeline，and the method to propose real-time and dynamic the data for risk assessment. The main feature is to create the the dynamic risk assessment model of urban gas pipeline network based on System Dynamics by the mechanism analysis of risk change, and to solve effectively the problem of spatial and temporal variations of systemic risk. The dynamic risk assessment system of urban gas pipeline network can achieve to dynamic track in the risk of urban gas pipeline and risk control, and the target of "prevention" and "warning" in advance for gas accidents. It is very meaningful to obtain and apply the research achievements for revealing the dynamic response of urban gas pipeline risk state with the space-time change of the affecting factors. It can provide the theoretical basis for urban gas pipeline integrity management.

城市燃气管网动态风险评估呈现的是管网风险的动态变化趋势，相比静态风险评估更加科学和富有指导意义。本项目通过对管网失效影响因素及关联性分析，结合多因素耦合作用下管道失效机理的实验研究，构建燃气管网失效概率的动态计算模型。利用CFD和Phast等软件模拟燃气沿地面和沟渠扩散的动态演变行为，获得事故后果分析模型。从系统动力学与动态风险评估的融合方式入手构建基于系统动力学城市燃气管网动态风险评估模型，把燃气管网监测系统与GIS有机结合，实时动态获取风险评估所需数据；借助模型的仿真实验，分析其风险控制策略。研究关键在于理清多因素的耦合机制和管道的失效机理，提出实时动态获取风险评价所需数据的方法。主要特色是通过内在变化机理的分析，创建基于系统动动力学城市燃气管网的动态风险评估模型，有效解决系统风险的时空变化问题。所形成的城市燃气管网动态风险评估体系可实现对风险动态跟踪和风险控制的目标，能为城市燃气管道的完整性管理奠定理论基础。

本课题围绕城市燃气管网系统展开动态风险评估及风险控制技术研究，旨在掌握关键理论、方法和技术，为城市燃气管网风险的动态跟踪和控制提供理论依据。考虑燃气管网失效影响因素与时间的相关性，对于随着时间的推移具有较强规律性的腐蚀失效，本课题采用土壤腐蚀埋片实验、电化学实验与土壤腐蚀特征参数调研相结合的方法寻求燃气管道的土壤腐蚀规律，修正了幂函数腐蚀模型，综合考虑多载荷的耦合作用，采用结构可靠性的方法构建了燃气管道的腐蚀失效概率计算模型，并为之选择了高效可靠的计算方法--子集模拟法。在对欧洲燃气管道失效数据库（European Gas Pipeline Incident Data Group, EGIG）统计分析的基础上，利用修正系数法构建了第三方破坏等与时间无关的影响因素作用下燃气管网失效概率的计算模型。考虑到人为因素在燃气管道管理过程当中的干预作用而形成的动态反馈，提出多因素耦合作用下燃气管网动态失效概率的系统动力学计算模型。从城市建筑布局的实际情况出发，利用CFD（Computational Fluid Dynamics）三维模拟方法，分析不同的建筑布局情况下城市燃气泄漏后的动态扩散规律，并根据相似原理设计小尺寸实验模型，对模拟结果的准确性进行了验证。为掌握埋地燃气管道在覆土情况下的泄漏扩散规律，设计了土壤阻力系数测定的实验平台，获得了模拟所需要的关键参数，然后运用CFD三维模拟的方法，研究了不同管道埋深及泄漏孔径对燃气沿土壤—大气扩散的浓度分布和危险区域范围的影响。在获得燃气沿地面和土壤扩散的动态演变行为后，分别建立了喷射火、火球、爆炸几种燃气事故的后果分析模型。然后从失效概率和事故后果两个方面构建了基于系统动力学城市燃气管网动态风险评估模型，借助模型的仿真实验，分析其风险控制策略。并基于GIS平台开发了城市燃气管网动态风险评估软件系统，立体化显示燃气管道的动态风险。本项目共发表学术论文11篇，其中SCI论文6篇，获得授权专利1项，培养硕士研究生3名。