PORE SIZE DISTRIBUTION OF SANDY SOILS AND THE PREDICTION OF PERMEABILITY

The soils used in this study were a sand and two sand-clay mixtures. Kneading compaction was used to prepare samples of sand-clay mixtures while pluvial compaction was used to prepare compacted samples of sand. The testing program consisted of the permeability test and the pore size distribution (PSD) test. A technique for the preparation of PSD specimens of cohesionless sands has been developed. The mercury intrusion technique was used to conduct PSD test. Falling head tests under back pressure were used to measure permeability. Mathematical interpretations of PSD were given in detail. For the soils studied, both the pore size distributions and pore size density functions were presented. Pore size density function of sand studied showed a single modal characteristic on a log diameter scale while that of sand-clay mixtures showed bimodal characteristics on a log diameter scale. The influence of varying water content and compactive effort on the fabric of the sandy soils studied was characterized by their pore size distributions and pore size density functions. A permeability model which related the pore size distribution to the permeability of soils has been proposed. The prediction of permeability by the proposed model was excellent (e.g. R(,a)(\u272) = 0.98) for both the author\u27s and Garcia-Bengochea\u27s (1978) data. In other words, the proposed permeability model can provide an excellent predictive tool. Thus a functional relationship between the PSD and the permeability of compacted soils is clearly demonstrated