Investigation of clay smear formation in laboratory-prepared layered soil specimens

The purpose of this study was to investigate the impact of layering geometry on the formation of clay smears in laboratory prepared soil specimens. Digitized video clips of specimen deformation under vertical shear were reviewed. New conventions and definitions were developed to describe and measure the onset of clay smear. Measurements for a variety of sample layering geometries were taken. Specimen geometry was compared with its respective smear development properties to derive general relationships.; The study showed that as the sand thickness within a specimen increased, the required amount of vertical displacement and sand layer displacement prior to smear also increased. Ratios of sand to clay within a specimen did not alone provide a consistent indicator on the development of smear. However, by normalizing the sand layer displacement required for smear, a nearly constant value for all samples was achieved.