Centrifuge modelling of flow and contaminant transport through partially saturated soils

Centrifuge modelling is presented herein as a tool which may be used in conjunction with numerical modelling, provided a means of validating computer models for flow through unsaturated fine-grained soils. Because of the slow flow rates involved, field validation would in many cases require years of monitoring before sufficient data were available to validate a computer model. Centrifuge models, on the other hand, because of the reproduction of prototype stress distributions, could act as miniature prototypes, providing data on flow and transport at a time scale reduced from the field by the square of the geometric scale factor.;Dimensional analysis indicates that, as long as certain restrictions on flow velocities are met, the processes involved in both unsaturated flow and transport can be accurately modelled in the centrifuged. In order to demonstrate that such modelling is possible in practice as well as in theory, a number of column drainage tests and tracer infiltration tests were carried out at two different acceleration levels. Results of these tests indicate that the processes are in fact modelled correctly in the centrifuge.;A number of piece of equipment were developed for the experimental program, including a centrifuge flow monitoring apparatus, which is used to monitor flow quantities and maintain a constant water level in the model while in flight.