This paper briefly describes an integrated approach to mine ground water simulation and prediction using an in-house finite element code called COSFLOW developed in CSIRO of Australia. COSFLOW uses a Cosserat continuum theory for the efficient description of load deformation behavior of layered coal measure rocks. Both coupled mechanical deformation and fluid flow model and uncoupled fluid flow model have been used to assess the impact of mining on regional groundwater resources. The coupled model is used to estimate the mining induced permeability and porosity changes in the rock mass and provided inputs to the regional scale fluid flow only model. Comparisons of numerical predictions with mine measurements demonstrate the suitability of such an approach in accurately predicting coalmine water inflow and impact on water resources. First, the model is calibrated using existing extensive mine water inflow and piezometer measurements and then used to make predictions for future longwall panels.
Reliable prediction of rock mass deformation, mine stability, mine water inflow and mine gas emission is not only essential for improving mine safety and reduction of coal production costs, but also important for the assessment of environmental impact of mining. This prediction requires the accurate simulation of complex, highly nonlinear and irreversible mining induced processes including the mechanics of rock deformation and fracture and the consequent water flow and gas desorption and flow.
This paper presents an integrated approach to mine groundwater simulation and prediction using an in-house finite element code called COSFLOW developed in CSIRO of Australia. COSFLOW incorporates (a) Cosserat continuum theory (Cosserat & Cosserat 1909) in its formulation for describing the load deformation of layered coal measure rocks and (2) two phase double porosity fluid flow formulation that can be coupled with either the mechanical model or run separately in isolation. A full description of the COSFLOW code is presented in Adhikary and Guo (2002) and the references cited there.
Both coupled mechanical deformation and fluid flow model and uncoupled fluid flow model have been used to assess the impact of mining on regional groundwater resources. First smaller scale three-dimensional coupled mechanical models were run to estimate the change in permeability and porosity in the strata surrounding the longwall mines and then this information was input into a single-phase regional scale groundwater flow model. The coupled model is fully described in Adhikary & Wilkins (2012) and will not be discussed here.