Observed Damage of Wastewater Pipelines and Estimated Manhole Uplifts during the 2004 Niigataken Chuetsu, Japan, Earthquake

After the 2004 Niigata-ken Chuetsu, Japan, earthquake, an open-cut survey of damaged wastewater systems was conducted by the Nagaoka city government. The survey compiled valuable datasets for sewer pipeline damage due to strong shaking. The main feature of the collected data includes locations of damaged sections and inclination of pipes before and after the earthquake. In the present study, by using the datasets and the SPT borehole logs in the affected area, both provided by the Nagaoka city government, the cause of damage to wastewater systems is investigated. Correlation analysis between the pipeline damage and the geological settings in the affected area reveals that ground water depth and native soils are the key parameters for manhole uplift behavior. The simple method for estimation of the maximum uplift of a manhole, is compared with the observed data recorded in Nagaoka.