Abstract

VAN TONDER, W D  and  JACOBSZ, S W. Seepage column hydraulic conductivity tests in the geotechnical centrifuge. J. S. Afr. Inst. Civ. Eng. [online]. 2017, vol.59, n.3, pp.16-24. ISSN 2309-8775.  http://dx.doi.org/10.17159/2309-8775/2017/v59n3a3.

Provided that inter-particle flow remains laminar, hydraulic conductivity tests can be carried out in a centrifuge to accelerate flow, allowing the hydraulic conductivity of relatively impervious materials to be measured within a reasonable time. It is well documented that the inter-particle flow velocity in the centrifuge increases linearly with acceleration, and a debate in the literature deals with whether hydraulic conductivity also scales with acceleration or not. A number of hydraulic conductivity tests were carried out using seepage columns in the geotechnical centrifuge in which pore pressures were recorded within the samples during testing. When hydraulic conductivity is calculated from the hydrostatic potentials measured during testing, the hydraulic conductivity is found to be independent of the imposed acceleration. It is therefore advocated that the hydrostatic potential is scaled in the centrifuge rather than the hydraulic conductivity. It must therefore be recognised that the hydraulic gradient used in the conductivity calculation does not remain constant, but changes with the imposed acceleration.

Keywords : falling head; geotechnical centrifuge; hydraulic conductivity; seepage scaling laws; pore pressure transducer.

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