New insight into the compressibility and structured nature of Coode Island Silt

Daniel King, Abdelmalek Bouazza, Joel Gniel and Ha Bui

Abstract

As part of the Regional Rail Link (RRL) project in Melbourne, Australia, a number of geosynthetic reinforced (GR) embankments with ground improvement were constructed where the rail alignment passes over the Coode Island Silt (CIS), a well-known soft soil encountered around inner Melbourne. To better understand the behaviour and performance of the load transfer platform (LTP) at the base of these embankments, a field case study has been undertaken which has seen an extensive array of instrumentation installed within the North Dynon embankment. This paper presents and describes a significant amount of field and laboratory data gathered as part of the geotechnical site characterisation of the instrumented areas. Based on this data a description of the compressibility and permeability of the CIS is presented and insight into the structured nature of the CIS is described. In addition, it is shown that a far better characterisation of soft soil behaviour can be gained through the use of more sophisticated oedometer testing techniques.