5.2.6 Pore fluid used for dynamic tests of soil-water interaction problem

When a model test is conducted under the centrifugal acceleration of n G, time duration for pore water pressure migration by consolidation is scaled to 1/n² of the prototype behaviour. Whereas the period of dynamic deformation is scaled to 1/n. One may use highly viscous fluid, such as silicone oil, a glycerin-water solution and a methyl cellulose-water solution, as a substitute for pore water for the purpose of reducing permeability of soils, by which to avoid conflict between the aforementioned time scalings. Note that these fluid should have similar density to water. Allard and Schenkeveld (1994) developed another type of water-based chemical solution, so-called 'Delft Geotechnics model pore fluid', and investigated mechanical properties of sand saturated with the fluid with reference to those of the water-saturated soils.

According to the similitude for dynamic model tests under the n-g centrifugal field, fluid with the viscosity of n times larger than that of water should be used as a substitute. Sakemi et al.(1995) carried out "in-flight" permeability tests, and observed that the permeability coefficient to silicone oil of n cSt viscosity under n-g centrifugal condition was properly scaled to 1/n that to water (Figure 2).

Allard, M.A. and Schenkeveld, F.M. (1994) : The Delft Geotechnics model pore fluid for centrifuge tests, Proc. of CENTRIFUGE 94, pp. 133-136.

Sakemi, T., Tanaka, M., Higuchi, Y., Kawasaki, K. and Nagura, K. (1995) : Permeability of pore fluids in centrifuge field, Proc. of 10th Asian Reg. Conf. on SMFE, pp. 481-484.