  Network modelling of water retention and conductivity of porous geomaterials
based on filling and emptying of pores requires the use of a computational cell
which is a representative volume element of the material. The conditions for
the existence of a representative volume element are that with increasing cell
size the statistical results of multiple random cells approach a constant mean
and zero coefficient of variation of the macroscopic property. In this study,
random network analyses were carried out to determine the mean and coefficient
of variation of degree of saturation and conductivity for varying capillary
suction and cell size. For water retention, a representative volume element was
obtained for the entire range of capillary suction investigated. For
conductivity, a representative volume element was obtained for most of the
range of capillary suction, but there is a small range of capillary suction for
which the coefficient of variation does not reduce with increasing size of the
computational cell, due to onset and termination of percolation of the wetting
fluid (during wetting and drying, respectively).
