Simulation of Post-earthquake Restoration for Lifeline Systems

Abstract

To have a national methodology for pre-earthquake planning, a model for predicting the post-earthquake behavior of city lifeline systems was developed. We discussed three factors in the model: structural damage, functional damage, and the restoration process after the earthquake. The restoration process is basically described by a differential equation applicable to a service area represented by a census mesh, and is applied to the lifelines (i.e., supply systems of gas, electric power, and water) of Sendai city in Japan. The model, in addition, indicates the lifeline network properties, and serviceability indices are defined in order to assess the functional damage of each system. In the case of the 1978 Off-myagi earthquake, a computer simulation of the restoration process was carried out by using step by step calculations and the Monte Carlo method. The simulated results, using indices as a function of time, were well in agreement with actual results, which indicates that the model is capable of predicting the restoration process. Through further simulations which varied the restoration strategies of the Emergency Headquarters, we show that the recovery of the gas system is sensitively affected by the strategy used. However, the electric power and the water systems were more influenced by the network properties rather than the strategies used. Our approach can provide useful information in undertaking pre-earthquake countermeasures for city lifeline systems.