Abstract:Modern societies are becoming increasingly dependent on critical infrastructure systems to provide essential services that support economic prosperity, governance, and quality of life. A nation's health, wealth, and security rely on the production and distribution of certain goods and services. Critical infrastructures are the physical assets, processes, and organizations across which these goods and services move. Earthquakes have highlighted the importance of stable electric, gas and oil, water, transportation, banking and finance, and control and communication infrastructure systems. The frequency of earthquakes has been increasing in recent years; hence, the vulnerability of lifeline networks in the event of an earthquake must be studied. In this study, we analyzed the seismic vulnerability of lifeline networks. First, we present the status of domestic and international research on the seismic vulnerability of lifeline networks. Although numerous studies have been conducted on the seismic vulnerability of lifeline networks, most of them considered the seismic vulnerability of lifeline networks in the event of an earthquake to be a series of consequences. In this study, we consider that the lifeline network vulnerability in terms of the consequences of the network after the earthquake as well as network connectivity. Second, we redefined the concept of seismic vulnerability of lifeline networks as the ability of connectivity and enduring failure consequences in the event of an earthquake. Third, on the basis of the new definition of lifeline network vulnerability, we evaluate the lifeline network vulnerability using the risk matrix theory method. This study considers two aspects:lifeline network connectivity and failure consequences. Because network connectivity probability and failure probability have a complementary relationship, connectivity probability represents the possibility of occurrence of a risk in the risk matrix. The failure consequences of a lifeline network can be characterized by the network topology and function change; therefore, we used these two indicators to represent network failure consequences. Hence, this improved method is employed in this study to comprehensively assess lifeline network vulnerability. The improved risk matrix method can completely represent the lifeline earthquake vulnerability as defined in this study. By considering lifeline network connectivity and failure consequences in the event of an earthquake, we can determine the corresponding level. Therefore, we can determine the lifeline network level of seismic vulnerability in a most direct and convenient way. Finally, we use a gas pipeline to illustrate the effectiveness and rationality of this improved risk matrix method. The highest vulnerability level nodes in this gas supply pipe network are nodes 3, 7, and 9 primarily because nodes 7 and 9 are located at the end of the network; therefore, the connectivity with the source point is very low. The highest vulnerability grade of node 3 can be attributed to its poor connectivity and high water level. Therefore, in the future, we must focus on these nodes for seismic protection.
