Normal joint stiffness a a function of spatial geometry

Normal joint stiffness was introduced by Goodman et al. (1968) as a parameter than can be used to describe the potential behavior of a joint. An advantage of joint stiffness as a prediction parameter is that it can be measured in the laboratory without detailed analysis of the joints themselves. Stiffness has been shown to be an important parameter in determining seismic wave propagation across joints (e.g. Hopkins, 1990, and Pyrak-Nolte et al., 1990) and is probably related to their hydraulic properties. While stiffness is a function of contact area, it will be shown that stiffness is not uniquely determined by contact area. The objective of this study is ti examine the relationships between normal joint stiffness and asperity dimensions, the spatial geometry of the asperities, and surface roughness