Damage to sewerage systems during the 2004 Earthquake in Niigata-ken Chuetsu, Japan

The 2004 earthquake in Niigata-ken Chuetsu, Japan, caused widespread damage to sewer pipelines due to uplift behaviors caused by ground settlement after liquefaction. Sewer pipelines, which are important lifelines, suffer damage when sewerage systems cease to operate over a long period of time. Manholes ejected from the groundʹs surface can disrupt traffic. To study the failure mechanism after the earthquake, the Nagaoka city government conducted an open-cut survey of the damaged sewerage systems. The main features of the collected data included the locations of damaged sections and the inclination of the sewer pipes before and after the earthquake. In the present study, the cause of damage to the sewerage systems was investigated using the datasets and the standard penetration test (SPT) borehole logs. The relationship between the sewer pipeline damage and the geological settings in the affected area reveals that the groundwater depth and the geotechnical properties of the original subsoils acted as the key parameters influencing the manhole uplift behavior. Also, the uplift mechanism was investigated through centrifuge modeling tests, and these findings agree well with the test results obtained in this study.