Determination of failure zone of vane shear test using artificial transparent soil

The vane shear test method is used extensively in a variety of geotechnical exploration to determine the undrained shear strength fine grained clays and silts. A small scale physical model was developed to study the failure mechanism during the vane shear test. The soil was simulated using a mixture of amorphous silica and mineral oil, which becomes transparent when the refractive indices the oil and the silica are well matched. A special fabricated row cell equipped with vane shear device was developed to determine the strength of the transparent soil. One dimensional consolidation test was carried out to obtain the consolidation properties of the transparent soil. The laboratory vane shear test used is similar to the field vane shear test but is on smaller scale. The vane was mounted vertically at the centre of the rowe cell based which the vertical section aligned with the vane centerline was illuminated with laser light and sequence of digital image was recorded using a digital camera. Particle image velocimetry (PIV) was used to analyze the failure mechanism during vane shear test. The result obtained and the observation made in this study suggested that the failure zone was close to the conventional assumption of a uniform shear stress distribution at the vertical sides of the failure surface.