Investigation of the sand porosity via oedometric testing/Smelio poringumo ommetriniai tyrimai/Smilts porainibas petijums izmantojot odometrisko testesanu/Liiva poorsuse uurimine odomeetrikatsega

Investigation of the porosity of Klaipeda sand by oedometric test is presented. The Klaipeda 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. Keywords: sand, oedometer test, void ratio, discrete element method (DEM), spherical particles. Klaipedos smelio poringumo tyrimai odometru. Klaipedos smelis yra tipiskas Lietuvos pajurio smelis, kurio daleliu skersmuo yra nuo 1,18 mm ir 0,3 mm. Odometriniu testu eksperimentiskai tirtas smelio ir atskirtuju triju jo frakciju poringumo kitimas. Poringumo pokycius apibudina pradinis ir galutinis (suspaudus) poringumo koeficientai. Eksperimentiskai nustatyta, kad smelio poringuma praktiskai lemia didziausia jo frakcija, kurios daleliu skersmuo kinta tarp 1,18 mm ir 0,6 mm. Mikrostrukturinis smelio tankejimo mechanizmas nagrinetas panaudojant modeliavima diskreciuju elementu metodu (DEM). Modeliavimui pasirinktos sferines formos daleles, o skaiciavimai atlikti komerciniu paketu EDEM. Modeliavimas diskreciuju elementu metodu patvirtino eksperimentinius rezultatus ir suteike papildomos informacijos apie smelio elgsena mikrolygmeniu. Skaitiniai rezultatai atskleide netolyduji deformavimo pobudi, o nustatytus elgsenos nestabilumus leme smelio daleliu erdvine pertvarka. Reiksminiai zodziai: smelis, odometras, poringumo koeficientas, diskreciuju elementu metodas, sferines daleles. Raksta atainoti Kaipedas smilts porainibas izpetes rezultati, kas ieguti ar odometriska testa palidzibu. Klaipedas smilts ir