This study focuses on the prediction of the porosity of nonuniform sediment mixtures,considering the effects of particle packing.A random particle packing model has been developed for the porosity of bimodal mixtures by extending the existing random particle filling theory.Coefficients in the developed model are calibrated by fitting the model to measured data for a variety of bimodal mixtures,including spherical glass particles,rounded quarry grains,and natural sediments.The model coefficients are found to be functions of the diameter ratio of coarse and fine particles,separately for spherical glass particles and natural sediments due to differences in particle shapes,The bimodal mixture model is then extended to trimodal particle mixtures in three approaches:two based on serial packing and one based on random packing.These models are tested against experimental data of six trimodal mixtures with spherical glass beads.The results show that the random packing model and the fine-medium-coarse particle serial packing model predict well the observed trimodal mixture porosities.