An investigation of the failure mechanism of a cantilever retaining wall under earthquake loading

The seismic behaviour of retaining walls is of continuing interest to geotechnical engineers as many of these structures were found to fail following recent earthquakes. In this study an investigation of the development of the failure of a cantilever retaining wall subjected to dynamic loading in dry sand was performed. The small-scale plane strain models produced for this purpose were tested using a new shaking table facility at Cambridge University. Images of the cross-section of the model for each one of these events were recorded by means of a high-speed and high-resolution image-capturing device, which allowed for the complete information on the displacement field to be recorded. The principles of Particle Image Velocimetry, as applied by the GeoPIV software package developed at Cambridge, were then used to process this data by removing the base displacement of the model and calibrating the images from pixel to real space. In this way it was possible to produce displacement and strain plots for any time interval, allowing for the real-time development of the failure mechanism for such a structure to be investigated for the first time. In particular, it was possible to isolate time intervals as small as 10 ms and hence obtain a visualisation of a nearly instantaneous failure mechanism for the structure.