Characteristic features of damage to the public sewerage systems in the Hanshin area

Abstract

Damage to the public sewerage systems for six cities in the Hanshin area due to the 1995 Hyogoken-Nanbu earthquake was summarized as 140 km pipelines, 19 treatment plants and 32 pumping stations. Characteristic features of the damage compared to those in past earthquakes were as follows: 1) distribution of damaged pipelines in Nishinomiya was concentrated both in liquefied zones of the coastal area surrounded by two faults, 2) three large concrete pipelines were heavily cracked longitudinally, 3) internal concrete linings in sewerage shield tunnels were cracked causing water leakage, and 4) the Higashinada treatment plant suffered serious damage due to liquefaction, whereas the Port Island plant was sound due to soil improvement to increase the soil's resistance for liquefaction.