Liquefaction potential of the micaceous lake sediments in the Queenstown area

Queenstown is a known seismically-active area. Following the September 2010 Canterbury earthquake, the local authorities in Queenstown have taken more initiative to improve their knowledge of the regional subsoils in order to better determine the liquefaction risk and the potential impact posed to the functionality of buildings and infrastructure should liquefaction-induced ground deformation occur. The authors carried out in-situ and laboratory testing and evaluated the liquefaction risk of the inter-bedded silt/ sandy silt laminated lake sediment layers overlying the schist bedrock. Despite a comprehensive list of assessment methods used, the data retrieved from conventional liquefaction analysis did not neatly consolidate towards a definitive conclusion and engineering judgement was needed to better interpret the body of evidence. In this paper, the authors present their liquefaction assessment and outline their findings. This paper is intended to provide readers an introduction to the topic and recommendations are given for further research to better understand the cyclic behaviour of these soils.