Abstract:
The vadose zone typically comprises soil underlain
by fractured rock. Often, surface water and groundwater parameters
are readily available, but variably saturated flow
through soil and rock are oversimplified or estimated as input
for hydrological models. In this paper, a series of geotechnical
centrifuge experiments are conducted to contribute to the
knowledge gaps in: (i) variably saturated flow and dispersion
in soil and (ii) variably saturated flow in discrete vertical and
horizontal fractures. Findings from the research show that the
hydraulic gradient, and not the hydraulic conductivity, is
scaled for seepage flow in the geotechnical centrifuge.
Furthermore, geotechnical centrifuge modelling has been
proven as a viable experimental tool for the modelling of
hydrodynamic dispersion as well as the replication of similar
flow mechanisms for unsaturated fracture flow, as previously
observed in literature. Despite the imminent challenges of
modelling variable saturation in the vadose zone, the geotechnical
centrifuge offers a powerful experimental tool to physically
model and observe variably saturated flow. This can be
used to give valuable insight into mechanisms associated with
solid–fluid interaction problems under these conditions.
Findings from future research can be used to validate current
numerical modelling techniques and address the subsequent
influence on aquifer recharge and vulnerability, contaminant
transport, waste disposal, dam construction, slope stability and
seepage into subsurface excavations.
