Accounting for Void Ratio Variation in Determination of Grain Size Distribution by Soil Column Image Processing

摘要

Soil grain size determination by image processing necessitated development of a laboratory system to rapidly segregate soil grains by size to incrementally compile a grain size distribution curve. The segregation is essential since grain size determination by image processing is presently only accurate for images that contain relatively uniform particles. For this purpose, a soil sedimentation system was developed that allows sand grains to settle through water. The result is excellent segregation by size. The present paper investigated the potential errors associated with the sedimented soil column having a non-uniform void ratio. Variations in void ratio with depth due to increasing effective stress were not observed but the void ratio did decrease with increasing particle size. While the corrections are easily implemented, for practical purposes they do not make a significant difference in the grain size distribution.