A Study on Precompression, by Separate-Type-Consolidometer

In the stabilization of soft subsoils before constructing structures on them, preloading techniques such as sand drains with surcharge load, are commonly used. But ordinary method of calculating consolidation settlement is not applicable to this case, because of the complex nature of stress path which differs very much in any part of a clay layer, under compression-rebound-recompression process. Johnson took into account the effects of surcharge loading on secondary compression settlement after removal of the surcharge. However there must be further researches to establish the theory for estimating residual settlements, especially on the effects of secondary compression which have not sufficiently been recognized. In this paper, several experimental data concerning the effect of surcharge loading on residual settlements are referred, using a separate-type-consolidometer. From the precise measurement of strain and pore pressure inside a consolidating specimen, several interesting experimental facts have been made clear.