Seismic Behaviour of Retaining Walls with Adjacent Structures

Abstract

Container cranes are essential to the local economy due to their functions in goods transportation. However, container cranes are vulnerable to earthquakes and tend to suffer damage caused by the failure of their foundations embedded in liquefiable soils. Additionally, despite the importance and seismic vulnerability of container cranes, a comprehensive understanding of their failure mechanisms has not been developed to produce reliable seismic designs of such structures. Therefore, this research aims to investigate the failure mechanisms and seismic behaviour of container cranes considering soil-structure interaction to provide some insightful suggestions in the seismic design standards of engineering practice. The primary methodology in this research is centrifuge modelling. Five centrifuge models use a simplified eccentric structure representing a container crane, a cantilever retaining wall, and liquefiable sand. Two models without a structure behind the retaining wall are considered benchmark tests. Seven dynamic centrifuge tests were conducted to study the effects of various factors on the behaviour of the structure-soil-wall systems. The factors include the soil condition, the distance from the structure to the retaining wall, the water table, and the stiffness of the backfill structure. In addition to centrifuge modelling, numerical modelling is employed using a finite-element code called Swandyne. In the numerical analysis, the prototypes represented by the centrifuge models were simulated to evaluate the accuracy and reliability of the constitutive models implemented in Swandyne. From the dynamic centrifuge tests, it is found that the factors considered affect the failure mechanisms of the structure-soil-wall systems to different degrees. The most substantial impact is from the distance between the structure and the retaining wall. When the structure is close to the retaining wall, it may experience uplift failure. With an increased distance, bearing capacity failure, rather than uplift failure, became dominant. With different water tables, the structure experienced excessive settlement and rotation subjected to strong earthquake loading, but the lowered water table inhibited the shear failure in the free field. Additionally, structural stiffness mainly influenced the backfill structure’s dynamic behaviour, with a minimal impact on dynamic soil behaviour. When compared to the experimental results, the numerical analysis produced reasonably good simulation in terms of soil and structural accelerations, especially in dry sand cases. However, further research may be needed to develop more advanced constitutive models to simulate the dynamic behaviour of liquefiable soils.