2.0 Features of MINEDW¶
The MINEDW software includes special features that facilitate the 3-D simulation of dewatering operations in open-pit and underground mines. Some of these features are as follows:
The progressive excavation of an open pit can be simulated in the model by changing the elevation of the nodes affected by mining over time.
A groundwater flow problem is simulated as saturated-unsaturated groundwater flow. This allows the finite-element mesh to remain fixed with time (except for excavations) and the saturated flow domain to adjust with time in accordance with changes in the position of the water table. The fixed mesh, in contrast to a deforming mesh, facilitates the representation of the spatial hydrogeologic variability of a groundwater system by the finite-element mesh.
MINEDW provides 3-D graphic representations of geology, model domain, pit geometry, groundwater heads, groundwater flux, recharge and evaporation zones, particle tracking, and pore pressures.
Specified-head boundary conditions can be imposed using heads that are either invariable with time or variable with time. In the latter case, the boundary heads are specified in terms of tables representing a hydrograph of the heads.
Specified-flux boundary conditions and internal source-sink terms are defined by a group of data sets that can be combined in different configurations for each time step.
Variable-flux boundary conditions can be imposed to simulate time-variant boundary fluxes in response to changing boundary heads. This boundary condition allows the finite volume of the modeled flow domain to be “extended” to infinity by “attaching” the analytical solution for a semi-infinite, linear aquifer to the boundary of the flow domain. [II]
The interaction between the groundwater system and river networks can be realistically simulated. Streams are simulated as a river network (or networks) that consists of a main river channel and tributary channels. The model accounts for streamflow depletions or additions by simulating the exchange of water between the stream and the groundwater system.
In addition, evapotranspiration of groundwater from vegetated areas or evaporation from bare-soil areas can be simulated. The evapotranspiration rate is assumed to be inversely proportional to the depth from the ground surface to the water table elevation. MINEDW uses the maximum evaporation rate and the extinction depth as constraints.
Spatial and temporal variation in precipitation across the model domain can be simulated. In areas with steep relief, MINEDW has the capability to simulate orographically controlled precipitation.
Open-pit excavation, open-pit backfilling, and pit-lake formation can be efficiently simulated within a MINEDW model.
MINEDW can efficiently simulate the formation of a zone of relaxation (ZOR) around a pit excavation or underground mining operation through time according to the mining schedule.
Outputs of pore-pressure distribution can be seamlessly used in both two-dimensional (2-D) and 3-D geomechanical models using Itasca’s geomechanical codes.