Experimental investigation of dynamic behaviour of cantilever retaining walls

The dynamic behaviour of cantilever retaining walls under earthquake action is explored by means of 1-g shaking table testing. Following a brief review of available limit analysis solutions, the paper reports on a systematic investigation carried out on scaled models at the 3m x 3m shaking table of the Bristol Laboratory for Advanced Dynamics Engineering (BLADE), University of Bristol, UK, within the framework of the Seismic Engineering Research Infrastructures for European Synergies (SERIES project), funded by the 7th FP of the European Commission. The experimental program encompasses different combinations of retaining wall geometries, soil configurations and input ground motions (white noise, sine dwells and actual recorded motions from the Italian and American database). Aluminium wall models of height 0.6m were founded on a compliant base layer. Both the base layer and the backfill consisted of dry, coarse grained Leighton Buzzard sand at differing levels of densification (medium dense and loose respectively). The systems were tested dynamically using a large Equivalent Shear Beam container (“shear stack”) of dimensions 4.8m long by 1.15m high by 1m wide, installed on the shaking table of BLADE. The response analysis of the systems at hand aimed at shedding light onto the salient features of the problem, such as: (1) the magnitude of the soil thrust and its point of application; (2) the relative sliding as opposed to rocking of the wall base and the corresponding failure mode; (3) the importance/interplay between soil stiffness, wall dimensions, and excitation characteristics, as affecting the above. The results of the experimental investigations were in good agreement with the theoretical models used for the analysis and are expected to be useful for the better understanding and the optimization of earthquake design of this particular type of retaining structure.