  Geometry of the rock joint is a governing factor for joint mechanical and
hydraulic behavior. A new method of evaluating aperture distribution based on
measurement of joint surfaces and three dimensional characteristics of each
surface is developed. Artificial joint of granite surfaces are
measured,processed, analyzed and three dimensional approaches are carried out
for surface characterization. Parameters such as asperity's heights, slope
angles, and aspects distribution at micro scale,local concentration of elements
and their spatial localization at local scale are determined by Geographic
Information System (GIS). Changes of aperture distribution at different normal
stresses and various shear displacements are visualized and interpreted.
Increasing normal load causes negative changes in aperture frequency
distribution which indicates high joint matching. However, increasing shear
displacement causes a rapid increase in the aperture and positive changes in
the aperture frequency distribution which could be due to unmatching, surface
anisotropy and spatial localization of contact points with proceeding shear.
