ABSTRACT:
Prediction of fluid flow through rock masses is important in mining and civil projects, oil and underground water extractions and geothermal and environmental issues. It is well known that the fractures in rock masses produce main paths of fluid flow, thus, the fracture properties such as normal stiffness, shear stiffness, aperture etc, govern flow through fractures in hydraulic (H) and hydro-mechanical (HM) analysis. In this study H and HM analysis of fractured rock masses were performed and water inflow into underground excavations were determined. Also, the effects of fracture properties such as normal stiffness, shear stiffness and aperture on inflow were studied. Results show that inflow increases with increasing normal stiffness, shear stiffness and aperture size. Furthermore, flow rate resulting from H analysis is greater than that from HM analysis. Finally, the inflow through fractures around the tunnel shows different distribution pattern in H and HM analysis. It is concluded that hydromechanical coupled analysis results are more realistic compared to uncoupled hydraulic analysis.
1 INTRODUCTION
Prediction of fluid flow through rock masses is significant in mining and civil projects, oil and underground water extraction, and when considering certain geothermal and environmental issues. The inflow into an excavation could affect the stability of the excavation and from an environmental point view, it can transport contaminants; minimum water inflow is therefore typically required. However in oil and underground water extraction, maximum flow is desirable. Therefore the prediction of inflow into an excavation and fluid flow main paths are important factors in underground construction, such as tunnels. It is well known that fractures are main paths for fluid flow in rock masses, thus fracture properties such as normal stiffness, shear stiffness, aperture, friction angle, dilation angle etc, could affect the inflow and hydraulic conductivity.
