HR: 1330h
AN: H22A-0908    [PDF]
TI: Unsaturated hydraulic properties determined from geocentrifuge tests
AU: Nakajima, H
EM: nakah@iictr.com
AF: Geosciences Research Department, Idaho National Engineering and Environmental Laboratory, PO Box 1625 MS 2107, Idaho Falls, ID 83415-2107 United States
AU: Mattson, E D
EM: matted@inel.gov
AF: Geosciences Research Department, Idaho National Engineering and Environmental Laboratory, PO Box 1625 MS 2107, Idaho Falls, ID 83415-2107 United States
AU: * Stadler, A T
EM: stadat@iictr.com
AF: Geosciences Research Department, Idaho National Engineering and Environmental Laboratory, PO Box 1625 MS 2107, Idaho Falls, ID 83415-2107 United States
AB: The geocentrifuge is a useful tool for studying flow in unsaturated soil under well-controlled, repeatable conditions. The high-gravity field generated by the geocentrifuge increases the self-weight of pore fluids to produce: (1) very low saturation conditions at high capillary pressures, (2) a wide range of saturation profiles in multi-dimension, and (3) enhanced seepage velocities. Geocentrifuge experiments can be used to generate experimental data to validate mathematical models. However, if an unsaturated flow experiment is performed in the elevated gravity environment of the geocentrifuge, the unsaturated hydraulic properties must first be obtained at the target centrifugal acceleration. This information can be determined from relatively simple, one-dimensional column experiments and will provide the unsaturated hydraulic properties required as input into mathematical models. These one-dimensional column experiments will also provide insight into the influence of gravity on the flow field. In this study, a series of one-dimensional column experiments was performed to obtain the water retention characteristics of a uniform fine sand. Cumulative outflow and temporal changes of capillary pressures were measured during gravity driven drainage. The measured data were used as input data for an inverse analysis using HYDRUS 1-D to obtain unsaturated permeability and saturation-pressure parameters of the tested sand. The geocentrifuge experimental measurements were also compared with data obtained independently from conventional hanging-column tests. The suitability of the centrifuge test method was evaluated by comparing results from the two different experimental methods. In addition, the centrifuge experiments were conducted in different gravity fields to verify the scale similitude of the hydraulic properties in elevated gravity environments.
UR: http://www.inel.gov/env-energyscience/centrifuge/default.shtml
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting