Roughness of rock joint surfaces is known to be one of the most significant factors to determine the shear strength of joint surfaces, and it has been widely investigated in various ways. A recent research on roughness quantification of rock joints revealed that various 3-dimensional methods could replace the conventional 2-dimensional methods. In its 3-dimensional application to field cases, however, roughness of rock joints was not easily quantified owing to the lack of well-defined criteria. As a complement on this problem the natural joint surfaces of rock have been rated numerically at intervals of 0.5 mm using 3-dimensional laser profiler. The measuring interval of 0.5 mm has been known to show a high correlation factor in previous study.
The numerically rated joint surfaces have been quantified using surface angularity and surface roughness coefficient. And also the correlation of each parameter has been analyzed. Because the joint surface tortuosity can affect the roughness parameters, the gradient of natural joint surfaces should be corrected by applying this tortuosity to the numerically rated joint surfaces. Accordingly, the effect of surface tortuosity on 3-dimensional quantification methods has been analyzed by comparing the corrected parameters with the original parameters.