Centrifugal modeling of capillary rise and drainage in sandy soils

Within the frame of the NECER program the scaling of capillary phenomena in a centrifuge has been investigated by cross-testing at several laboratories, using similar sample sizes and the same Congleton Sand. Drainage tests were carried out in Manchester, Lyngby and Bordeaux. The moisture retention profile was measured after the test and in-flight measurement of water content was also attempted, using radiotracers and tensiometers (Manchester) as well as dielectric FD and TDR probes (Lyngby and Bordeaux). Infiltration tests were conducted in Bochum, Manchester and Nantes. The movement of the water front was observed visually, and in some cases pore pressure transducers and tensiometers were also used. The test results indicate that the different laboratories get comparable results and that it appears to be possible to model the entire capillary zone in a centrifuge with the vertical dimension reduced by the g-factor N. Time dependant phenomena appear to be accelerated by the factor N squared.