Technology Development of Anti-seismic Structures for Sewer Networks

Japan has experienced several major earthquakes in the past two decades: the Southern Hyogo Earthquake (1995), the Niigata-Chuetsu Earthquake (2004) and the Great East Japan Earthquake (2011). These earthquakes damaged many kinds of infrastructure, including sewage facilities, and resulted in a major long-term impact on civic life and urban activities.Almost 90 years has passed since the Great Kanto Earthquake of 1923, and there is a 70 percent chance that a shallow-focus earthquake could hit directly under Tokyo within the next 30 years.The Tokyo Bureau of Sewerage is working to develop seismic technologies to maintain sewerage infrastructure as well as ensure safe evacuation and toilet usability in the event of a major earthquake.Here, we would like to introduce our seismic retrofitting measures for the joints connecting sewage pipes to manholes (which have shown significant damage during earthquakes) and a trenchless seismic retrofitting technology to prevent the manhole uplifting that results from liquefaction. We would also like to briefly introduce a new technology currently under development that prevents sediment influx into manholes during earthquakes.