Quantitative Evaluation And Promotive Strategy Of Seismic Resilience For Lifeline Pipe Networks

The "Urban and Rural Resilience" was included in the "National Earthquake Science and Technology Innovation Project" in 2017,and was also a guideline for the construction of the "Nine Projects for Natural Disaster Prevention and Control".It is of great significance to quickly restore normal operation after the earthquake.With the rise of resilient urban and rural areas,research on resilience has gradually deepened from focusing on individual units to systems.As underground pipeline systems seriously affected by earthquakes,the gas distribution system and water supply network system lack systematic quantitative evaluation in the research on seismic resilience,and operational resilience improvement strategies are urgently needed.Therefore,this paper proposes the quantitative evaluation of the seismic damage index,connectivity vulnerability,and resilience of the pipeline network system,and shows strategies to enhance the resilience of the pipeline network: adding an earthquake emergency disposal system and improving the health of the existing pipeline network.The main content of the paper are as follows:(1)From the theoretical analysis of resilience,the quantitative assessment process of pipeline network resilience from the perspective of organizational dimension is given.This paper reviews the quantitative assessment and improvement strategies of resilience and resilience city to pipeline network resilience,and discusses seven factors that affect pipeline network resilience: robustness,connectivity vulnerability,recovery rate,recovery time,recovery path,recovery strategy,and interaction effects.The connotation connection is given,and the perspective of improving the resilience of the pipeline network in this paper is given: earthquake resilience assessment,disaster prevention preparation,earthquake emergency response and earthquake resistance recovery.First,the calculation process and grading standard of the seismic damage index of the pipe network system are given.Secondly,construct the seismic connection vulnerability assessment process of water supply network considering the uncertainty of earthquake damage situation.Based on the ground motion prediction equation,the ground motion parameters of each location of the water supply network are input,and Monte Carlo simulation is used to calculate the failure probability of the water supply pipeline and nodes.Exceed probability of seismic connectivity vulnerability curve and loss index under simulated earthquake intensity.The earthquake damage index and the connectivity vulnerability index are calculated and analyzed based on the data of a city’s water supply network in South China.The results show that: the smaller the magnitude,the stronger the correlation between the two indicators.Finally,the vulnerability of the network connectivity is used as the organizational dimension performance to calculate the resilience of the water supply network.The results show that the initial state of the system has a greater impact on the connectivity performance during the repair process.(2)From the perspective of technology dimension and cost dimension,a quantitative assessment framework for gas distribution system resilience considering multi-link uncertainty is proposed.The Monte Carlo simulation was used to evaluate the post-earthquake damage state of the gas distribution system after introducing the concepts of disordered distribution of pipe network rupture points,random allocation of repair order,parallel repair of multiple repair resources,and diversification of repair methods.The repair resources are repaired through random simulation.The distribution obtains the real-time repair process of the gas distribution system under each simulated failure condition,and obtains the technical dimension performance recovery curve.The seismic resilience of the pipeline network is evaluated from multiple angles by using the centroid of the recovery trajectory and the total recovery time.This framework is used to quantitatively evaluate the seismic resilience of a city gas distribution system in North China,and three types of post-earthquake maintenance,i.e.,point-by-point maintenance,whole pipe replacement and mixed maintenance are discussed from the perspectives of repair efficiency,repair time and repair cost.The most efficient repair path is obtained,thereby improving the resilience of the pipe network system.The results show that the influence of different restoration paths on restoration efficiency increases with the increase of intensity;the increase in the number of restoration resources can reduce the influence of different restoration paths on restoration efficiency.Hybrid repairs are the least expensive.The reliability of the results of the calculation example is verified by the actual repair situation of the gas distribution system after a strong earthquake abroad.The framework is universal and can be extended to other pipe network systems.To delve deeper into its relevance,a quantitative assessment of the resilience of water network system in medium-and small-sized cities was first conducted.We calculated the earthquake damage index,analyzed the reasons for the difference between the two types of cities,and investigated the impact on the resilience of the restoration process.The results show that the water supply network restoration resources have greater redundancy for small cities than medium-sized cities,which provides a reference for decision makers to plan resources for reserve scheduling.Then,the correlation and difference between the resilience of the water supply and gas distribution system in a city in central China and the repair cost are analyzed,and the repair cost is verified by earthquake cases at home and abroad.Finally,the weight method and the interpolation method are used to judge the contribution of the water supply and gas distribution system to the improvement of urban resilience.The results show that the contribution of the gas distribution system to the improvement of urban macro resilience is greater than that of the water supply pipeline network.If only from the perspective of more effectively improving urban resilience,and more inclined to restore resources to the gas distribution system,it will be more effective and faster to improve the macro resilience of the city.(3)From the perspective of disaster prevention decision-making,the strategy for improving the seismic resilience of the pipeline network system is expounded,and the early intervention measures to install earthquake emergency response valves in the gas distribution system are given.Determine the threshold value and installation position according to the principle of the gas distribution system earthquake emergency response valve and the pipeline network information,and calculate the recovery situation of the three conditions of installation of valves in all gas pressure regulating stations,installation of valves in some gas pressure regulating stations and no installation of gas valves.,combined with the resilience quantitative assessment framework to analyze the change of the installation of the valve on the repair path and whether the influence of the pipe diameter factor on the resilience is considered.The resilience classification standard of the gas distribution system is given,and the improvement of the resilience level of the pipeline network by installing the valve is intuitively evaluated.The results show that the installation of valves in the gas pressure regulating station can improve the resilience of the pipe network system,and the best improvement strategy is to install all the gas pressure regulating stations and only a part of them.Stable,not in line with the expected value of input and output.(4)Revise the resilience assessment process based on the perspective of pre-earthquake disaster preparedness,and add resilience improvement strategies for assessing the health of existing pipelines.The analysis of the pipeline network resilience assessment framework reveals the weak links in the resilience assessment process.The seismic damage performance of existing gas distribution systems varies widely due to the laying time and damage conditions,but the previous resilience assessment process was failed to distinguish them.For this problem,the key element of "pipe network health evaluation index" is introduced to improve the accuracy of the resilience simulation of the pipe network state based on the existing pipe network resilience model.The index weighting method is used to select the main influencing factors of pipe network resilience as evaluation indexes,and the weights are calculated.A pipeline scoring method based on the subjective-objective coupling weight method is established to comprehensively evaluate the health status of the pipe network.The Monte Carlo method is used to randomly distribute the rupture and leakage points of the pipe network according to the pipe network score.On the basis of scoring the health degree of the pipe network,its resilience is evaluated,and further analyzed and compared whether considering the health degree of the pipe network to the resilience.Impact.The results show that considering the health of the pipe network can improve the system resilience,and the improvement effect is more obvious when the damage is serious.A complete urban pipeline network resilience assessment framework can be formed by taking pre-earthquake physical measures,integrating the health of the pipeline network before the disaster,the random distribution of post-disaster rupture and leakage points,and the selection of the optimal repair sequence.