HR: 1340h
AN: H53F-1487    [Abstracts]
TI: Geotechnical Centrifuge Studies of Unsaturated Transport
AU: * Smith, R W
EM: smithbob@uidaho.edu
AF: University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83402, United States
AU: Mattson, E D
EM: Earl.Mattson@inl.gov
AF: Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415, United States
AU: Palmer, C D
EM: Carl.Palmer@inl.gov
AF: Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415, United States
AB: Improved understanding of contaminant migration in heterogeneous, variably saturated porous media is required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose-zone barriers to contaminant migrations. A geotechnical centrifuge provides an experimental approach to explore vadose zone transport over a wide range of relevant conditions in time frames not possible for conventional bench-top experiments. Our research to date resulted in the design, construction, and testing of in-flight experimental apparatus allowing the replication of traditional bench top unsaturated transport experiments using the 2-meter radius geotechnical centrifuge capabilities at the Idaho National Laboratory. Additionally we conducted a series of unsaturated 1-dimenstional column experiments using conservative tracers to evaluate the effects of increased centrifugal acceleration on derived transport properties and assessing the scaling relationships for these properties. Our experimental results indicated that breakthrough times for a conservative tracer decreased significantly and systematically as a function of increased centrifugal acceleration. Differences between these experimental results and estimates based on predictive scaling rules are due to slight moisture content differences between experiments at different centrifugal accelerations. In contrast, dispersion coefficients varied systemically with centrifugal acceleration in accordance with predictive scaling rules. The results we obtained in this study indicate that the centrifuge technique is a viable experimental method for the study of subsurface processes where gravitational acceleration is important. The geotechnical centrifuge allows experiments to be completed more quickly than tests conducted at 1-gravity and can be used to experimentally address important scaling issues, and permits experiments under a range of conditions that would be difficult or impossible using conventional approaches.
DE: 1832 Groundwater transport
DE: 1839 Hydrologic scaling
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting