Investigation of Soil-Water Characteristic Curves for Compacted
Bentonite Considering Dry Density
Abstract
Deep geological repositories are often considered for the disposal of
high-level radioactive waste (HLW). HLW should be disposed of safely and
permanently using two barrier systems: engineered barrier systems (EBS)
and natural barrier systems (NBS). An EBS is an artificially suggested
concept composed of various components. The buffer is one of the most
important components since it plays crucial roles in terms of the safety
of the entire disposal system, and compacted bentonite is considered a
highly adequate buffer candidate material. As groundwater flows into the
rock-mass and buffer, the degree of saturation of compacted bentonite
increases. A soil-water characteristic curve (SWCC) represents
saturation behavior, and thus it is essential to investigate SWCCs of
compacted bentonite. For this reason, this paper conducted SWCC tests of
Korean compacted bentonites according to dry density variations, as the
dry density of compacted bentonite also varies in actual repository
environments. The van-Genuchten fitting parameters (α, n) were obtained;
α decreased in exponential form and n increased linearly according to
dry density. Furthermore, using the obtained SWCC datasets, a simple
empirical model was suggested to estimate the van-Genuchten fitting
parameters. The mean relative error between the test results and the
empirical model was approximately 8.6%.