PERFORMANCE OF REINFORCED EARTH (R) BRIDGE ABUTMENT WALLS IN THE 2010-2011 CANTERBURY EARTHQUAKES

Reinforced Earth bridge abutment walls were subjected to strong ground shaking in one or more of the earthquakes in the Canterbury earthquake sequence of September 2010 to December 2011. Although the walls at three sites were subjected to ground motions of intensity greater than the design level none of the walls were damaged by the earthquakes. The paper describes the earthquake design procedure used for the Reinforced Earth abutment walls and back-analyses carried out after the earthquakes to investigate their performance. Calculations based on probable material strengths rather than the dependable design values, and assuming no strip corrosion, gave critical accelerations to initiate sliding movements of the walls that were about 20% greater than predictions based on the design parameters. No significant outward movements of the walls were observed following the earthquakes. This was consistent with the predicted critical acceleration levels for the walls in their condition at the time of the earthquakes.