FRACTAL ANALYSIS OF THE FABRIC CHANGES IN A CONSOLIDATING CLAY

Electron microscopy and mercury intrusion porosimetry studies on the f abric of clays undergoing consolidation tests have indicated that the clays have pores of different sizes and shapes. After pressure is appl ied to the clay samples, the larger pores change in size and shape, wi th the smaller pores being relatively unaffected. The size of the pore s and their distribution have been determined from mercury porosimeter tests. The shape of the pores and the changes they experience during the consolidation process have received only a qualitative evaluation from the photomicrographs obtained with the scanning electron microsco pe. In this study, a quantitative evaluation of the shape of the pores in a clay subjected to consolidation stresses is presented. This eval uation is done using fractal theory. Fractal theory employs the concep t of fractal dimension to evaluate the shape (roughness) of closed pro files such as pores. The larger the fractal dimension, the rougher is the shape of a closed profile. The fractal dimension of a pore in a cl ay sample undergoing consolidation changed progressively from 1.4623 ( very rough pore) to 0.9856 (very smooth pore). Thus, during consolidat ion, the pore, besides changing in size, also experienced a change in its degree of roughness. In addition, a theoretical analysis of the in fluence of the shape of the pores on the rate of water flow from a sat urated clay undergoing consolidation is presented.