New Criterion for Shutter Designing by Dry Pluviation Method

Dry pluviation is a technique applied to prepare sandy soil samples for physical modeling. In this method, soil particles rainfall in the mold after passing through the mesh with certain opening sizes. In this study, a dry pluviation device was designed and manufactured to examine the effect of shutter properties, including the height of fall (HF), deposition intensity (DI), and gradation on relative density (RD). A two-piece mold was used to evaluate the homogeneity of the sample. The RD measured at the top and bottom of the mold is the same, indicating that the fabricated sample is homogeneous. The results indicate that HF and DI have a direct and indirect relation with RD, respectively, but RD is constant for HF≥1200 mm. In order to investigate the impact of shutter properties on DI and RD, α ratio (total area of the shutter holes to the area of the deposition surface) was defined, and a linear relationship is proposed between DI and α. The results revealed an indirect relation between RD and α, but for α≥0.130, RD is constant. In order to assess the simultaneous effect of grain size and shutter properties on RD, an independent grain size variable (i.e., α/D50) was defined, and a linear relationship was established between α/D50 and RD. The results showed that the variable α/D50 can be considered a useful criterion for designing a shutter to reconstitute sandy soils with different gradations.