Hydraulic properties of partially saturated rock fractures subjected to mechanical loading

• 3D laser scanning was used to obtain the aperture distribution of a fracture.
• A capillary pressure curve was proposed for rock fractures subjected to loading.
• A relative permeability model was proposed for fractures subjected to loading.

This study presents a methodology for estimating the unsaturated hydraulic properties of rock fractures under deformation conditions. The surface morphology of an artificial granite rock fracture was examined using a high-resolution three-dimensional laser scanner, and the aperture distribution of the fracture was found to follow a Gaussian distribution. By virtue of the aperture distribution function and applying the Young–Laplace equation to local apertures, a novel model was presented to predict the capillary pressure–saturation relationship and the relative hydraulic conductivity of rough-walled rock fractures subjected to normal and shear loading. The proposed model was partially validated against existing laboratory data on the unsaturated hydraulic properties of rock fractures, and can be readily applied to various engineering practices such as transport phenomena in fractures, landslide mitigation, or underground oil storage.