Excessive settlement caused by deep ground instability problem raised the alarm for a retaining wall founded on such problematic ground conditions. The reinforced soil retaining wall is over 10 m high and functions as a separation between two levels of high value residential properties. There were genuine concerns over potential sudden rupture of reinforcement induced by excessive settlement which could result in heavy concrete facing panels falling down and large scale slope movement. Performance assessment of the retaining wall was therefore undertaken by reviewing the original retaining wall design and construction, site inspection and investigation followed by numerical modelling which enabled the engineer to not only assess the wall condition at the time but also predict the future performance as a result of further settlement. The review of the original design shows that the local and global stability assessment gives adequate factors of safety based on the assumption that the wall was constructed to the design requirements. The site inspection and investigation revealed that the connection of the top level reinforcements were intact with no signs of overstressing. The numerical modelling results further confirm the adequacy of the original design. The deformation of the reinforced soils and the tensile forces of the reinforcing elements are acceptable for the retaining all construction to its full height. Results of further models by applying the settlement level that was thought to have occurred beneath the wall suggested consistent horizontal wall movements observed on site and sufficient level of safety factor in terms of mobilised tensile stress within the reinforcement. By applying further settlement the retaining wall would suffer further damage and may cause rupture of the connection between the facing panels and the reinforcement leading to instability of the facing panels. Pullout or breakage failures of the reinforcement were anticipated to occur should the ground settle further.
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