Research On Cascading Failure Mechanism Of Rail Transit Based On Complex Network

With the rapid development of urban rail transit,rail transit gradually tends to network,scale and complexity,which makes the interdependent between the network site and site,site and line,line and line closer.When some nodes of the network are deliberately attacked,the network may collapse because of cascading failures.Therefore,it is very important to study the node importance evaluation algorithm of the rail transit network and the propagation mechanism of cascade failure behavior,which is of great significance to improve the operational efficiency and safety of the network.Firstly,it is proved that there are “small-world” and “scale-free characteristics of the complex network in the rail transit network,and a node importance evaluation algorithm based on the comprehensive index is put forward.A new similar betweenness is introduced by this method,and the contribution weight of m-order adjacency nodes is redefined.Through comparing and analyzing degree method,traditional number method,m-order adjacency nodes importance contribution algorithm and comprehensive index evaluation algorithm,the results show that the comprehensive evaluation algorithm can not only reflect the influence of network operation characteristics(traffic flow)on the importance of nodes,also reflects the important contribution of a node ’s m-order adjacent nodes for the node,which there is a certain improvement with other three methods.Secondly,considering the self-repair time factor,a DST Load-Capacity model is proposed to study the failure mechanism of the rail transit network.The model has been improved from three aspects:(1)Based on the existing degree attack strategy,betweenness attack strategy and the new node importance evaluation method,we propose two new attack strategies of MNI and SNI.(2)Redefine the load reassignment rule,it can be known that the more remaining capacity of the node adjacent nodes,the greater ability of attracting traffic flow.(3)the nodes are divided into three cases: normal state(NN state),deliberate attack failure state(IAN state),cascade failure state(CFN state),And the node state function is given according to the load digest function of the cascade affected site.The influence of the failure scale of rail transit network can be analyzed through node capacity adjustable parameters,attack strategy and self-repair time factor by simulation.It can be found that the DST load-capacity model is more in line with the actual situation than the cascade failure model without considering the self-repair time factor.Finally,considering the critical site evaluation algorithm and the cascade failure mechanism of the rail transit network,the weaknesses of the network can be determined,and appropriate measures should be taken to improve the operational efficiency and safety of the rail transit network.