FRACTAL APPROACH TO MEASURING ROUGHNESS OF GEOMEMBRANES

Fractal analysis was used to evaluate the roughness of four commercially available geomembranes used in waste-containment systems. Fractal analysis uses the concept of the fractal dimension D as a way to calculate the roughness of simple and complex profiles. In the present study, it was determined that the fractal dimension D of the geomembrane profiles increased as the roughness of their profiles increased. For example, the smoothest of the four geomembrane profiles had a fractal dimension D equal to 1.001: the roughest of the geomembrane profiles had a fractal dimension D equal to 1.1345. The difference in the fractal dimension D for the four geomembrane profiles was found to be relatively small. Thus, when the fractal dimension D is used to evaluate the roughness of geomembranes, at least four-digit precision after the decimal point is advisable. The sensitivity of the fractal dimension to inputs such as the direction of measurement and cut as well as the size of the segment length used to cover the geomembrane profiles were also analyzed.