Centrifuge modeling of one-dimensional subsurface contamination

One-dimensional contaminant transport through a saturated soil is modeled u sing a 1.2-m radius geotechnical centrifuge. Small-scale physical modeling in the centrifuge is achieved in relatively short time, at stress distribut ions that are similar to those experienced in the prototype (actual site). A 0.05 mol/l of sodium chloride solution is used as a contaminant and condu ctivity cells measure the concentration of the contaminant throughout the p orous medium. Scaling analysis for centrifuge modeling and l-g modeling are briefly discussed and it is concluded that centrifuge modeling simulates t he effect of molecular diffusion; however, scaling of the effect of mechani cal dispersion may be violated in the centrifuge if the interstitial fluid velocity is high. Centrifuge test results show good agreement with the pred icted relationship between the coefficient of hydrodynamic dispersion and t he Peclet number using column tests. Centrifuge modeling can be used as a c omplement of numerical modeling although the effect of mechanical dispersio n may be overestimated in the former.