ABSTRACT:

When stresses in fractured rock masses are changed due to engineering intrusion, then initial fracture apertures are changed leading to variation in permeability and fluid flow. Prediction of stress-dependent permeability and water flow behaviors is one of the essential tasks of rock engineering design. In mining engineering, due to coal extraction, stress redistribution and rock deformations will occur in the host rocks changing the original permeability values. Water inrush and the methane outburst that take place in coal mines are results of groundwater or methane along zones of the increasing permeability. Therefore, it is very important to study the coupling of stresses and fluid flow through rocks for hazard control during coal mining.

In this paper, fracture aperture and permeability changes due to three-dimensional stress variations in fractured media were studied and theoretical relationships between stress and permeability were derived. The surface subsidence due to stress changes and drainage in porous aquifers were studied. A finite element model with coupling stress and water flow for fractured porous media was developed. The model was applied to examine permeability changes, and surface subsidence in a coal mine for various mining geometries.

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