Monitoring of an encapsulated embankment for the validation of a dimensionless model for soil swelling

In road projects where expansive materials are used for construction of an embankment, it is crucial to control soil swelling in order to ensure the long term durability and serviceability of the embankment structure and pavement. This may be achieved by placing compacted layers of expansive soil in the inner part of embankment with of non-expansive capping and outer zone materials to encapsulate in order to limit moisture movement within the fill and provide overburden pressure to counter-balance the swell pressure from the placed expansive materials. Accurate prediction of the soil swelling in order to develop a design solution for encapsulation and specification for placement of the expansive materials in the embankment is a challenge for the geotechnical designers. This paper presents a dimensionless swelling model which may potentially become a design tool for the designers of encapsulated embankments for use in the future. The model, which is detailed in the first part of the paper, has been validated at the laboratory scale and is proposed to be applied to an actual embankment structure at a prototype scale for site validation. An encapsulated embankment of the Hunter Expressway has been selected for this purpose. The second part of the paper presents the instrumentation of the selected embankment and the properties of the expansive materials that are used in the encapsulated layers in this newly constructed highway. The validation of the model will be based on monitoring of the instrumented embankment during construction and in the operation phase of the project.