This research investigates the use of artificial ground freezing as a means of containing and consolidating hazardous waste. A two dimensional finite element simulation of soil solidification is proposed. The numerical strategy utilizes innovative techniques for representing dendrite curvature, finite element grid deployment and numerical heat and mass conservation. The solidification model is based on the coupled, transient heat and mass equations in both frozen and unfrozen phases. Boundary conditions account for the interfacial energy, kinetics and solute rejection effects. The adaptive finite element mesh continually tracks the phase front such that boundary conditions are applied directly on the interface. An automatic rediscretization routine is employed which requires no user intervention during the simulation. The numerical simulations will be compared to existing, large-scale experimental data for situations involving the solidification of soils with and without sodium chloride and soils spiked with hazardous wastes (chloroform, benzene, toluene and tetrachloroethylene). Artificial ground freezing has been in practice for over a century in civil engineering applications. Its ability to form impermeable barriers, dewater sludge, and consolidate solids has been demonstrated. However, predicting or controlling the location of the frozen barrier as a function of time for arbitrary geometries is unsolved. Inherent in the coupled heat and mass transfer system lie instabilities associated with the growth of dendrites due to undercooling and constitutional supercooling. The coupled transport system dealing with solidification of the soil is unamendable to analytical solutions beyond one dimensional situations. Consequently, this proposal research holds great promise if illuminating the solution to the control of ground freezing.
