Reliable prediction of rock mass deformation, mine stability, mine water inflow is not only essential for improving mine safety and reduction of coal produc-tion costs, but also important for the assessment of environmental impact of mining. This prediction requires the accurate simulation of complex, highly non-linear and irreversible processes including the mechanics of rock deformation and failure due to coal mining and the consequent water flow. This paper describes a three-dimensional numerical code, called COSFLOW. It uses a Cosserat continuum approach for the efficient description of mechanical stress changes and deformation in weak layered rock, typical of coal measures. This me-chanical model is coupled with a two-phase dual porosity fluid flow model to describe flow of water and gas through porous rock. The coupling includes simulation of per-meability and porosity changes with rock deformation. As an example, a simulation of water inflow in an Australian mine is presented. The model is calibrated using existing extensive mine water inflow measurements and used to make predictions for future longwall panels.
In Australia, the ability to accurately predict the behavior of water in longwall opera-tions has become a pressing issue. While higher capacity longwall mines are putting pressure on dewatering requirements, environmental concerns about loss of water supply overshadow some of our existing and new projects. This paper describes a three dimensional finite element code, called COSFLOW, developed to simulate longwall mining water inflow problems. A COSFLOW simula-tion of water inflow at an Australian longwall mine is presented. Rock strata in a coal mining environment are essentially bedded and this has a large impact on load-deformation characteristics. Mining may induce shearing as well as separation along the bedding planes, which may result in bending and subsequent fracturing of the rock layer.
