Preparation of Sand Beds Using Fluidization

Reconstituting soil beds to a desired density is essential to geotechnical modeling tests. In this study, we apply and assess the method of air fluidization to prepare sand beds for geotechnical engineering studies. Through it, an automated bed preparation process can be realized. The details of device structure and design are presented as a reference for application of the methodology. By quantifying the average and local post-fluidization density of the bed, the performance of the fluidized bed device is characterized. With the addition of vibration and by changing the defluidization rate, the sand can be prepared with volume-based relative densities ranging from 10% to 92%. Local sand density, measured with a cone penetrometer, is nearly uniform across the bed: density variation is less than 13% (coefficient of variation with respect to relative density) for all protocols except for some beds prepared by defluidization only. The variation of local density and penetration resistance measured across the bed breadth is comparable to results from beds prepared by the commonly used method of pluviation. This suggests that sand beds reconstituted using air fluidization are suitable for geotechnical modeling tests.

Quantification of the Transparency of the Transparent Soil in Geotechnical Modeling

An indispensable process of geotechnical modeling with transparent soils involves capturing and analyzing images, in which favorable transparency is required for optical measurements. This paper proposes an objective framework for quantification of transparency in transparent soil based on its transmittance. Specifically, transparent soil with fused quartz serves as the soil sample for the detection of transmittance, and transmittance’s impact on imaging quality in geotechnical modeling with transparent soil is investigated through an evaluation function of image clarity. According to the results of research about transparent soil with fused quartz, viewing depth and refractive index matching are the dominant factors that affect variations in transmittance of transparent soil, and the variations of transmittance are subjected to exponential decay regarding viewing depth or refractive index matching based on the theoretical modeling’s function of curve fitting. Moreover, experimental results indicate that imaging quality of geotechnical modeling with transparent soil is enhanced with increasing transmittance, and imaging quality shows a remarkable improvement when transmittance is greater than 90%.