Cascading Failures Of Interdependent Multilayer Network For Urban Critical Infrastructures

With the development of world economy and the constant breakthroughs in information technology,urban critical infrastructure(CI)network has become more complex.In emergencies such as natural disasters or deliberate attack,small parts of damage follow dense connection relations spread on the critical infrastructure in the city network,which is a network of tiny disturbance spread to the consequences of a wide range of the whole city.To understandthe cascade failure of urban multilayer critical infrastructure networks,this paper studied the simulation techenique,vulnerability and topological structure of multilayer independent networks form the research perspectives of the types and effects of critical infrastructure networks connection relationship.Then,vulnerability assessment for urban multilayer coupled networks is presented.We carried out the following research:(1)Based on the percolation theory of complex network,the effects of cascading failures of urban critical infrastructure corresponding to different interdependencies are discussed.Focus on the different characteristics of critical infrastructure network interdependencies,the unidirectional or bidirectional interdependencies,functional or geographical interdependencies were considered in two-layers cascading failure model research.The model verified the interdependencies between layers of the network layer in multilayer coupled network appear the phenomenon of extremely vulnerable,revealed the geographical relationship and the function relationship of the fragility of the significant impact of multilayer network,found jointly considering geographical and functional relationship can get more accurate simulation results.(2)The effect of interlayer relationship on the vulnerability of multilayer coupling network is analyzed from the perspective of structure and function.The index of interlayer topology structure,including interlayer degree,interlayer coefficient uniformity and coefficient compactness index,was constructed to measure the influence of interlayer topology structure pattern on the vulnerability of multilayer network.The interaction index of the vulnerability of multilayer coupled networks and the cross impact quantification formula based on the failure model are proposed.(3)Based on the characteristics of multilayer critical infrastructures,a vulnerability evaluation index and an urban loss estimation method are proposed.This method considers the cascading failure caused by the load distribution after the failure of the node of the single layer subnetwork,and emphasizes that different infrastructure networks share the function of urban service.The proportion of reserved service function area is used to replace the proportion of nodes of the giant connected component as the vulnerability evaluation index of urban infrastructure network.This method introduces the indexes of maximum weak functional area,maximum strong functional area,unaffected population proportion and gross product proportion,and describes the impact of cascading failures on cities from multiple angles and all directions.(4)The cascading failure simulation and control measures of multilayer critical infrastructure networks under uncertain failure are proposed.According to the characteristics of the regional and random damage of the explosion damage,a vulnerability evaluation method based on the expectation of the coupling network of the multilayer critical infrastructure networks is proposed.Aiming at the random failure of large-scale network nodes,the Monte Carlo method is adopted to simulate the failure uncertainty of each network node,and the cascading failure simulation of the multilayer critical infrastructure networks under explosion damage is realized.The reasons of cascading failure and the control measures of cascading failure are analyzed.Simulation of urban disaster spread,vulnerability estimation,identification of weak areas and cascading failure control measures are realized.