Validation of contaminant transport process using modflow and centrifuge model test results

Abstract

A geotechnical centrifuge is a powerful testing tool for modeling the transport of contaminants in soils. The simulation of identical effective stress states in scaled centrifuge model and equivalent prototype ensures the modeling of soil properties including hydraulic conductivity. Centrifuge modeling is particularly applicable in replicating the physical transport of dense pollutants due to gravitational gradients. The increased acceleration field is essential to correctly study such phenomena in reduced scale models. This thesis presents a validation of the contaminant transport process by using the MODFLOW computer program and the centrifuge model test results. The modular finite-difference groundwater flow model well known as MODFLOW has been developed for simulating confined and unconfined, saturated flow in one, two or three dimensions. The program allows both steady-state and transient simulations. In centrifuge modeling, scaling laws are very important. First, the computer code MODFLOW is used to verify scaling laws for centrifuge tests using the series of one dimensional tests with various soils and reasonable results are obtained. Next, MODFLOW predictions are validated using a two dimensional centrifuge test of a non-sorbing dense pollutant leaking from a landfill into a homogenous saturated silt layer. Again, reasonable comparisons are obtained between the MODFLOW predictions and the centrifuge model test results.