Abstract
Some of the observations published so far represent that secondary compression arises not only after the dissipation of pore water pressure but also during the stage of primary consolidation. The secondary compression has considerable influence upon the time-strain relation in the process of consolidation and makes the estimate of consolidation difficult, in the case that primary consolidation continues for a long time. Therefore, it is of significance to investigate the secondary compression and its characteristics for the sake of evaluating more reasonably the consolidation of a clay deposit. This technical note is mainly concerned with the characteristics of secondary compression in the stage that pore water pressure is dissipated. From the results of consolidation tests which have been carried out on a clay with three kinds of thickness, the following findings have been derived. (1) The amount of a strain due to secondary compression developed in the stage of primary consolidation enlarges as the thickness of a clay layer increases. (2) Secondary compression occurs during primary consolidation only when the effective pressure is greater than the quasi-preconsolidation pressure and may be expressed as a function of elapsed time and a compression strain. On the other hand, no secondary compression may arise during primary consolidation when a clay stays in an apparently over-consolidated state.
