A comparative study of suction-induced seepage consolidation versus centrifuge consolidation

Abstract

The time required for the preparation of a normally consolidated clay sample, by self-weight consolidation in the centrifuge, is often very long and the process may take up to several days. To save centrifuge time, a hydraulic consolidation method of preparation of normally consolidated clay beds, using seepage forces, is often used prior to final consolidation in the centrifuge. At present, the required hydraulic gradient is usually generated by high-pressure water at the top of the clay bed. This method tends to cause hydraulic fracturing at corners when rectangular containers are used. A simple method of using vacuum suction to induce seepage forces to clay samples is proposed and discussed in this paper. Experience with this method shows practically no incidence of hydraulic fracturing. Comparison of the variation of water content and shear strength with depth of samples prepared by the present method and those prepared exclusively by self-weight consolidation in the centrifuge lends support to the validity and effectiveness of the proposed method. The method can be used to prepare clay samples for prototype depth less than about 17 m. A procedure for estimating the final height, water content, and shear strength profiles of the soil model prepared is also presented.