Consolidation of a very soft clay with vertical drains

The paper analyses the performance of an embankment built on a very soft and extremely compressible organic clay where prefabricated vertical drains have been installed. Co-efficients of horizontal consolidation, ch, obtained from settlement analyses took into account the smear resulting from the installation of the drains and also the vertical drainage. These values of ch are compared with the measurements obtained from special laboratory tests with drains installed in the sample, and from in-situ tests using the piezocone. The three sets of figures showed good agreement with each other, which suggests that the secondary consolidation was negligible compared with the primary consolidation in the case herein, in which vertical drains were used.