Comparative Study on Strategies for the Division of Earthquake-Proof Strengthening Segments to Reinforce the Reliability of Water Supply Systems

Abstract

It is very important to secure the sustainability of physical and non-physical social infrastructure facilities in the event of a disaster. The water supply network is particularly vulnerable to seismic damage, and so physical earthquake resistance is very necessary to adapt to or withstand disaster situations. This study evaluated various strategic methods to improve the reliability of water distribution network systems in the event of an earthquake disaster with a focus on structural earthquake-proofing methods for pipelines. For this purpose, three major flow-, diameter- and connection-hierarchy-based earthquake proofing strategies are proposed. We quantified the extent to which earthquake reliability improved after the strengthening of the earthquake-proofing of the pipeline segments, which had been divided based on the proposed strategies. The proposed methodology of dividing the pipeline segments for earthquake-proof strengthening was applied to the water supply system of the Republic of Korea and analyzed thereafter. As a result, it was confirmed that the associated costs and the extent of the improvement in the reliability of earthquake proofing for each strategy and scenario need to be precisely analyzed. Thus, it is necessary to execute strategic earthquake proofing of pipelines with medium size diameters and which occupy most of the length of a mainline, in order to simultaneously satisfy the reliability and cost efficiency of the relevant water supply. However, additional earthquake proofing for segments of a higher level of flowrate is required because a marked drop in overall reliability is caused if they are damaged. In addition, because the effect of an increase in reliability in comparison with the costs incurred is insignificant in the case of some low demand and small-diameter pipeline segments, it is reasonable to exclude earthquake resistance strategies for these sections. The proposed study results—determining the level of importance of each resistance method—can be utilized to make a combined plan for optimal earthquake-proofing strategies.