Case study: Embankment failure of Cable-Ski Lake development in Cairns

摘要

This paper presents the results of case studies into a slip that occurred during constructionof a Cable-Ski Lake that will eventually form part of a residential development in Cairns. The slip measuresabout 100 m by 50 m overall and occurred within a 6 m high partially cut and partially filled profile. Groundconditions in the slip area generally comprise stiff clays to a depth of 3 m,over soft marine clay to a depthof 15 m. The scope of the studies included drilling two boreholes with SPT and U50 sampling,installationof two standpipes,performance of a series of CPTu tests within the failure area and stability back analyses.Remedial work presents special challenges due to the extent of the failure that occurred and high cost involvedfor conventional stabilization methods. A staged remedial plan was proposed that considered the nature of thesensitive clay and project timing of the future residential development,which would not happen at least withinthe following five years. The initial stage of the remedial work involved reshaping the failed embankment toallow the Cable-Ski Lake development to proceed as proposed. The ultimate remedial work would allow thefuture residential development,however would be a gradual process depending on the strength recovery of thedisturbed soft sensitive clay.