Volume 29, Issue 5 (September 2006)
A New Centrifugal Testing Method: Descending Gravity Test
This paper presents a new centrifugal testing method that has been developed to observe the effects of void ratio and overconsolidation ratio on the generation of undrained shear strength in cohesive soils. This new method provides soil profiles of constant overconsolidation ratio and varying void ratio throughout the sample profile. Combinations of this method with various in situ shear strength tests such as the cone penetration test and the vane shear test constitutes a new methodology which is named the “descending gravity test” (DGT). When DGT is repeated for different acceleration levels during centrifuge testing, it provides the void ratio-undrained shear strength relationship for various magnitudes of overconsolidation ratio. Therefore it renders the observation of the uncoupled effects of void ratio and overconsolidation ratio on the generation of shear strength feasible. Additionally the method requires the unloading of the clay cake, and since swelling of a sample is more rapid than its consolidation the test takes a relatively short time, hence the method is efficient.