INFLUENCE OF PORE SIZE DISTRIBUTION ON PENETRATION RESISTANCE BEHAVIOUR AND DRY DENSITY OF CLAY-LOAM SOIL

A semi-empirical penetration resistance model is presented. The procedure utilizes a relationship based on the pore size distribution (in log-normal form) in terms of the change of soil dry density and gravimetric soil water content supporting correlations to penetration resistance per unit depth. Tests were performed using clay -loam as a standardized soil type for the soil water contents 14, 15, 17 and 19 %, respectively. Compacting levels 50, 75, 100 and 150 kPa were correlated to the changes in pore radius (using a log-normal pore size distribution model). The penetration resistance was measured below the centre of the load. The model was used to evaluate a uniformly precompacted soil profile and the compacting state at contact pressures of 300 kPa for the soil water content 17.5 % and 200 kPa for 19.5 % (corresponding to 75 and 85 % soil plastic limit) demonstrating correlations of 0.94 and 0.97, respectively, to the predetermined soil dry density.