Trenchless Limitations on Postearthquake Repair and Rehabilitation of Unpressurized Networks: Christchurch, New Zealand

Abstract

Earthquakes are one of the most devastating natural disasters, annually causing severe damage to underground infrastructures, including unpressurized wastewater and stormwater networks. After intensive seismic damage has been inflicted, especially in municipal regions, application of a trenchless excavation technique is assumed to be an appropriate method for repair and rehabilitation. Trenchless techniques are well known as an appropriate method for new pipe installation, pipe rehabilitation, and pipe repair in populated areas because of their advantages over open-cut methods, although application of these techniques is limited in certain cases of postearthquake restoration of damaged pipelines. Earthquake shocks cause different types of damage to buried pipes, especially those in unpressurized networks where the application of trenchless techniques is very limited. The focus of this study is on these limitations with respect to which trenchless postearthquake techniques are to be applied for repair and rehabilitation of damaged unpressurized networks through a case study. A combination of a case study and direct observations was applied to show that some trenchless techniques like pipe bursting, cured-in-place pipe, and point repair methods cannot be applied to renovation and rehabilitation of damaged underground pipelines in some particular types of damage caused by earthquakes.