Volume 31, Issue 2 (March 2008)
Experiment Setup for Shear Wave and Electrical Resistance Measurements in an Oedometer
The development of a new laboratory oedometer cell, which includes bender elements and an electrical resistance probe, is documented. The apparatus is used to evaluate consolidation characteristics such as primary consolidation, anisotropy, void ratio, and the preconsolidation stress by using the elastic and electromagnetic waves. Bender elements are installed on the top cap and the bottom plate and are also mounted on the wall of the oedometer cell. The electrical resistance probe is positioned onto the top cap of the oedometer cell. The primary consolidation time can be assessed with the evolution of shear wave velocity and the slope of the resistance-log time curve. The increment of the shear wave velocity, which propagates along the long axis of particles, is higher when the vertical effective stress is higher than the preconsolidation stress. The preconsolidation stress is confirmed by the relationship between the void ratio and the electrical resistance, and cementation and stress controlled regions are confirmed with the shear wave velocity. The electrical resistance linearly increases with the vertical effective stress in the stress controlled region. This study suggests that the shear wave velocity and electrical resistance provide complementary information about primary consolidation, anisotropy, void ratio, and the preconsolidation stress.