Investigation of the Sand Porosity Via Oedometric Testing

Investigation of the porosity of Klaipėda sand by oedometric test is presented. The Klaipėda sand is typical Baltic see-shore sand consisting of grains the average diameter of which varies from 1.18 mm to 0.3 mm. Variation of the porosity during oedometric compression of the whole mixture of the sand and of three separate fractions were investigated experimentally. Porosity was characterised by the maximal (initial) and minimal (after compression) values of the void ratio. It was proved experimentally that porosity of the sand mixture is practically predicted by the coarse-grained fraction with grain diameters ranging between 1.18 mm and 0.6 mm. The role of microstucture in the densification mechanism is explained by employing the discrete element method simulations. The spherical particles and commercial EDEM code were used for modelling purposes. Discrete element method simulations confirmed generally the macroscopic experimental results and yielded additional data on microscopic behaviour. The non-smooth deformation behaviour was observed during detailed numerical time-history analysis. The detected instabilities are explained by rearrangement of the sand grains.