CENTRIFUGE MODELING OF CONTAMINANT TRANSPORT THROUGH SOILS
Indiscriminate land disposal of hazardous chemicals and industrial wastes, in the due course of time, causes contamination of the ground water regime as well as the subsurface soil layers. Various complex geo-chemical processes and mechanisms control the transport of these contaminants when they come in contact with the soil-water system.
The transport of contaminants is often predicted with the help of mathematical models dealing with a set of governing equations, which are solved using either analytical or numerical methods. However, input parameters for these models can be obtained by conducting either controlled field experiments or laboratory column tests. Though controlled field experiments are found to be more reliable, as they facilitate inclusion of various complexities of the real life situation, these tests are quite expensive, tedious and offer little control over the boundary conditions. On the other hand, laboratory column tests are cost effective and relatively easy to perform. However, both these tests are not viable alternatives due to their limitation in modeling and simulating realistic prototype condition(s) since the time of interest may span decades of real time.
To overcome these limitations, researchers have employed a geotechnical centrifuge for modeling and simulating real life (prototype) conditions, in the recent past, quite efficiently. With this in view, a simple and efficient non-destructive testing methodology has been evolved to simulate and model contaminant transport through the soil mass, in a small geotechnical centrifuge. For the sake of validation of the results obtained, modeling of models has been demonstrated. Conventional column tests have also been conducted and an excellent matching of these results with that of the centrifuge tests is observed. As, factors like void ratio, degree of saturation, effect of clay content and the thickness of the barrier system play an important role in such studies, their influence has also been investigated in detail. Such a study would be very helpful for designing effective barrier/containment systems.
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