An expansive clay for centrifuge modelling.

This paper explores the development of an expansive soil which can be repeatedly reproduced for use in centrifuge models to investigate soil-structure interaction problems involving expansive soils. The study considered two materials, namely a sand-bentonite mixture and a naturally occurring, highly expansive clay. For the natural material, two approaches were explored to create a scaled down fissured structure for use in centrifuge testing. The swell behaviour of the two candidate materials was first investigated by means of oedometer tests and then by centrifuge modelling. The centrifuge tests consisted of layers of compacted clay slabs separated by free draining layers. The study revealed that while the sand-bentonite mixture possessed the potential to swell significantly, the time required to do so was impractical for centrifuge studies. It was however found that the approach used to create a scaled down fissured structure in the naturally occurring clay facilitated rapid ingress of water which allowed for significant heave to take place in a much shorter time frame. The results obtained from the centrifuge test conducted on the reworked clay were compared with an empirical heave prediction method and it was found that the swell obtained from the fissured clay matched the predicted heave profile within three hours.