Three-dimensional numerical models of groundwater flow and solute transport in fractured granites: Impact of tunnel construction in the groundwater system at the Aspo island, Sweden

摘要

The Aspo Hard Rock Laboratory (HRL) is an underground facility operated by the Swedish Nuclear Waste Company, SKB. The Aspo tunnel was constructed between October 1990 and June 1995, reaching a maximum depth of 450 m. In order to simulate the impact of the tunnel construction on the hydro-geology of the Aspo island, a 3-D transient groundwater flow and multi-component solute transport numerical model was carried out. The model accounts for 20 major fracture zones and extends over 6 years. The tunnel front advancement was simulated dynamically by means of internal time-varying boundary conditions. Model results were compared to measured data at 45 control points. The calibrated flow model provides an excellent fit of both water inflows into the tunnel and drawdown at selected boreholes. The transport model, which was constructed with no calibration, is in a very good agreement with measured concentrations of conservative species breaking through the tunnel and boreholes. Observed discrepancies for reactive species such as calcium, sulfate, bicarbonate and sodium are attributed to hydrochemical processes.