Discrete Fracture Network and Equivalent Hydraulic Conductivity for Tunnel Seepage Analysis in Rock Mass

摘要

This paper discusses the applicability of stochastic discrete fracture network (DFN) realizations forrnequivalent continuum hydraulic conductivity and tunnel seepage analysis in rock mass. Based onrndetailed geological investigation results, three DFN models were generated at divided equivalentrndomains showing the same statistics of fracture geometry. Two-dimensional hydro-mechanicalrnmodelling with UDEC was carried out to determine the amount of groundwater into a tunnel usingrnDFN model from the equivalent hydraulic conductivity. Numerical results show that the hydraulicrnconductivity of fractured rocks decreases with using the disturbed aperture by an initial stress whenrnthe stress is not large enough to cause shear dilation of fractures, and that the flow rates increase withrnincreasing the difference between the horizontal and vertical stresses. It is revealed from the studyrnthat equivalent hydraulic conductivity from DFN model can be widely used for tunnel seepagernanalysis including the effect of in-situ stresses to minimize uncertainties from complicated structure ofrnrock fractures.