Unsaturated hydraulic properties of rock fractures have been widely studied in geotechnical

energy and environmental engineering. In this study

the three-dimensional laser scanning testing is used to obtain the morphology properties of a granite fracture; and then the influences of morphology properties on the unsaturated hydraulic properties are analyzed. By analyzing the variation of aperture distribution under various stresses including tensile stress

compressive stress

shear stress

a model is established to describe the relationships between capillary pressure and saturation of rock fractures under complex loading. A relative permeability model for unsaturated fractures is developed based on the analysis of the surface microcosmic features. The model is verified by experimental data subsequently. Finally

a variational relative permeability model for unsaturated fractures is established. This work is helpful for the research on hydro-mechanical coupling mechanism of unsaturated fractured rock masses.