Study of Seismic Design of Lifeline System Considering System Performance after an Earthquake

本文研究了地震后供水系统的系统性能和改造的优先级。1995年神户地震后，神户市的供水系统完全中断，失去了主要功能。大约用了三个月的时间才完全恢复供水。由于在像1995年神户地震这样非常罕见的大地震中完全防止地震破坏是不现实的，因此应该在生命线系统中引入基于性能的设计。此外，由于管道长度较大，从系统性能的角度出发，需要对系统进行优化改造。首先，进行了供水管道的流量分析，以估计情景地震后管网的供水点。本研究以日本金泽市供水管网为个案。从系统性能的角度估计了地震后停水和供水不足对民间社会的影响。以1995年神户地震资料为基础，给出了震后日与供水主要目的的关系，并给出了供水量的最小目标。然后定义了缺水损失，以评估缺水对公民生活的影响程度。缺水损失，即供水量与最低目标之间的差额，是用金钱价值来评价的。为了减少地震后因停水和供水不足而造成的缺水损失，对供水管道的加固进行了研究。结果表明，缺水损失总量可作为评价改造优先度的指标之一。

This study deals with a system performance of water supply system after an earthquake and prioritization of the retrofit. After the 1995 Hyogoken Nambu (Kobe) earthquake, the water supply system of Kobe City was completely disrupted and its principal functions were lost. It took about three months for complete recovery of water supply. Since it is not realistic that the earthquake damages were perfectly prevented against very rare but great earthquake like the 1995 Kobe earthquake, performance based design should be introduced into the lifeline system. Moreover, the retrofit prioritization is required in the system strengthening From the point of system performance because of the enormous piping length.First, a flow analysis of water supply pipelines was conducted in order to estimate under water supply points of a network after a scenario earthquake. The water supply pipeline network of Kanazawa City in Japan was adopted as a case study in this study. An effect of suspension and under supply of water on a civil society after an earthquake was estimated from the point of system performance. Based on the data in the 1995 Kobe earthquake, the relation between the day after the event and main purpose of water was shown and the minimum objective of water supply volume was given. Then a loss for water shortage was defined to evaluate the degree of effects of water shortage on a civic life. A loss of water shortage, which was a difference between supplied water volume and the minimum objective was evaluated by the value of money. The strengthening of water supply pipelines was studied to reduce the loss for water shortage due to the suspension and under supply of water after an earthquake. The results revealed that the total loss for water shortage seems to be one of the indices for evaluation of retrofit prioritization.