## Abstract

The effect of shear displacement inclined relative to macroscopic water flow on the hydraulic conductivity of a rock fracture was estimated, using synthetic fractures that reproduce a tensile fracture in granite. The results showed that the hydraulic aperture normalized by the mean aperture increased with the angle between the directions of shear displacement and macroscopic water flow, according to a sinusoidal function of twice the angle. Formulae were established to estimate the hydraulic aperture of the fracture as a function of the mean aperture, the standard deviation of the initial aperture, the shear displacement, and the angle between the shear displacement and macroscopic water flow, based on results obtained in both this work and previous work, but neglecting scale effects. By assuming the mechanical properties of the fracture based on experimental results for granite, but neglecting scale effects, the hydraulic conductivity of the fracture with an arbitrary direction under a given state of stress (σ_{1}=29 MPa, σ_{2}=25 MPa and σ_{3}=13.5 MPa) was estimated for macroscopic water flow in the directions of both σ_{1} and σ_{2}. When the contour map of the transmissivity of the fracture is plotted on a stereonet of the normal direction of the fracture in the principal axes of stress, there is a ridge (line of the local maximum) of transmissivity in the circumferential direction, and the inclination angle of the ridge from the σ_{3}-axis decreases with shear displacement, since shear dilation increases with both a decrease in normal stress and an increase in shear displacement. Furthermore, for the condition of stress given in this study, the transmissivity for macroscopic water flow in the direction of σ_{1} is maximum for a fracture with a normal direction within the σ_{2}-σ_{3} plane, while that in the direction of σ_{2} is maximum for a fracture with a normal direction within the σ_{1}-σ_{3} plane.

Original language | English |
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Pages (from-to) | 436-449 |

Number of pages | 14 |

Journal | International Journal of Rock Mechanics and Mining Sciences |

Volume | 47 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2010 Apr |

## Keywords

- Anisotropy
- Fracture
- Hydraulic conductivity
- Hydraulic transmissivity
- In situ stress
- Shear displacement
- Synthetic fracture

## ASJC Scopus subject areas

- Geotechnical Engineering and Engineering Geology