INFLUENCE OF LOAD INCREMENT RATIO ON PRECONSOLIDATION PRESSURE

Abstract

Consolidation tests were conducted on preconsolidated samples of highly plastic clay. Load increment ratio was varied during preconsolidation as well as during consolidation tests from 2 to 1/16. Preconsolidation pressure as determined by Casagrande1s graphical method was compared with actual pre-consolidation pressure for various tests. Prediction of preconsolidation pressure was fairly accurate when load increment ratios were kept same for pre-consolidation as well as for consolidation tests, however, they were more when load increment during conventional test was less than that for preconsolidation. At large load incre-ment ratios, during laboratory consolidation tests, higher compressibility of soil was observed, which resulted in lower values of predicted preconsolidation pressures. It was surprising to note that in case of overconsoli-dated clays, the maximum quasi preconsolidation effect did not exceed 20 to 3c7/, whereas Ohri (1966) reported 100'/ quasi pre-consolidation effect in the same clay.