Bridge performance during the 2010/2011 Canterbury Earthquakes

The 4 September 2010 Darfield earthquake and the 22 February 2011 Christchurch earthquake caused extensive damage to the city of Christchurch and adjacent areas due to soil liquefaction and related phenomena, such as settlement and lateral spreading. Following the earthquakes, the authors performed reconnaissance work and investigated the performance of road bridges in Christchurch, especially those crossing Avon River where liquefaction and lateral spreading were extensive. In general, the performance of bridge foundations, abutments, and approach fills during the September 2010 earthquake was satisfactory, although several road bridges were out of service in the days following the earthquake mainly due to damage on the approaches to the bridge induced by liquefaction, lateral spreading, and settlement of approach fills. However, none of the road bridges were damaged to the extent that they needed immediate replacement. Following the February 2011 earthquake, more bridges suffered damage due to liquefaction-induced lateral spreading at the abutments, although no bridge collapsed. Several bridges already damaged by the previous earthquake were again damaged. Detailed descriptions of the liquefaction observed following the earthquakes and the overall performance of bridges are presented in the paper.