• The Journal of Engineering Geology
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• v.31 no.1
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• pp.55-66
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• 2021

Hydraulic-mechanical (H-M) coupled numerical modeling was used to evaluate the evolution of hydrogeological properties in response to the installation and expansion of a borehole. A domain with a discrete fracture network was adopted for discontinuum modeling to simulate changes in fracture apertures. Comparison with real hydraulic test data shows that the effects of principal stress direction and expansion of borehole diameter were reasonably simulated by H-M coupled numerical modeling. The modeling confirmed that aperture changes depended on the principal stress direction, with an increase in aperture size due to vertical displacement being the dominant effect. A concentration of shear dilation around the borehole had an additional, subsidiary, effect on the hydrogeological evolution. These results show that the permeability of fractured rock can be increased by changing the hydraulic properties of a fracture through stress redistribution caused by the installation and expansion of a borehole.

• Tunnel and Underground Space
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• v.29 no.5
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• pp.318-331
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• 2019

A three-dimensional(3D) equivalent continuum modeling was performed to analyze hydraulic behavior of rock mass considering discontinuities by using DFN model and smeared fracture model. DFN model was generated by FLAC3D and smeared fracture model was applied by using FISH functions, which is built-in functions in FLAC3D, for equivalent continuum model of fractured rock mass. Comparative analysis with 3DEC, which is for discontinuum analysis, was conducted to verify reliability of equivalent continuum analysis by using FLAC3D. Similar results of hydraulic analysis under the same conditions could be achieved. Equivalent continuum analysis of fractured rock mass by using DFN model was implemented to compare with existing analytical methods for inflow into the tunnel.