Volume 29, Issue 3 (May 2006)
New Sample Holder for the Preparation of Undisturbed Fine-Grained Soil Specimens for Laboratory Element Testing
The paper describes a new soil sample holding device, the undisturbed soil sample holder (USSH), which has the ability to minimize potential sample disturbance during the preparation of relatively soft fine-grained cylindrical soil specimens. The USSH is capable of providing suitable external, uniform lateral confinement to a sample of soil extruded from a field sampling tube. The device comprises a split hollow cylindrical aluminum housing that is internally lined with a flexible synthetic foam material. The foam lining allows the diameter of the cylindrical cavity of the USSH to be variable, while maintaining the shape of the cavity cylindrical. The device has the ability to essentially eliminate the sample freestanding period that is commonly associated with conventional preparation methods and to reduce potentially significant soil deformations that occur due to the self-weight of the sample. The effectiveness of the USSH in minimizing sample disturbance is demonstrated using comparative laboratory tests conducted on relatively soft soil specimens prepared with and without the USSH. The observed axial strains during specimen preparation, volumetric strains during consolidation, and stress-strain-pore water pressure response during undrained triaxial shear testing show that the USSH contributes to the preparation of undisturbed soil specimens for element testing.