Improved correction factor for indirect determination of permeability function

Capillary Barrier System has been widely utilized in geo-environmental engineering. Basically, the system consists of a fine-grained soil layer overlying a coarse-grained soil layer and requires good understanding of unsaturated soil mechanics, particularly on the unsaturated permeability characteristics of capillary barrier materials. This paper focuses on the estimation of permeability function from measured soil-water characteristic curve (SWCC). A statistical method proposed by Childs & Collis-George (1950), which was modified by Kunze et al. (1968), is usually used to calculate unsaturated permeability function from SWCC. However, Agus et al. (2005) suggested using Mualem (1976) statistical model with Fredlund & Xing (1994) SWCC equation based on the earlier works by Agus et al. (2003). In this paper, Mualem (1976) equation was modified to produce more accurate results with physically meaningful parameters for coarse-grained soils. The modified Mualem (1976) equation was verified against experimental data from the literature and the results indicated good agreement between the estimation and the experimental data.