Effect of Smear on Radial Consolidation with Vertical Drains

This paper describes experimental study of the effect of smear on radial consolidation behavior of soft clay with vertical drains. "Unit cell" model tests that realistically mimic the field situation were conducted in a large scale consolidometer with extensive instrumentation. Using a specially designed double tube mandrel system, the two specific cases of "with smear" and "no smear" were simulated. Detailed isochrones of excess pore pressures during radial consolidation have been quantified. Delay in degree of horizontal consolidation, U_h due to smear effect was experimentally determined to be approximate 10% in the model tests for the insensitive, homogeneous kaolin clay used. The Mandel-Cryer effect was observed and its mechanism was clarified. The discrepancy in U_h assessed with respect to settlement and pore water pressure was examined and the importance of an unambiguous definition of U_h was highlighted.