Centrifuge testing of dual row retaining walls in dry sand: The influence of earthquake sequence and multiple flights

Abstract

Multi-hazard threats from tsunami events preceded by large earthquakes have been put into sharp focus in recent times. Dual row retaining walls are soil-structure systems that can have large lateral capacity with a small horizontal extent, making them ideal for the next generation of coastal protection. However, the dynamics of their behaviour is a complex interaction problem. Centrifuge tests, with multiple earthquakes within a single flight as well as multiple flights with varied embedment ratio were conducted to elucidate the mechanics of these systems when founded in dry sand. The structural response shows permanent, plastic deformations during the early cycles dependent mainly on the PGA superposed with more elastic vibrations during prolonged shaking. The development of the soil stresses and stiffnesses mobilised are used to explain the overall system response. Finally, the recorded structural and soil behaviour during swing up and down are combined to show that the soil stress and strain state is effectively reset between flights. Overall, useful methods for judging the progressive response of a complex soil-structure system are presented which can help justify future comparisons between experimental datasets and understand the implications of practical dynamic design.