Vacuum Preloading on Structured Clay: Field, Laboratory, and Numerical Studies

Abstract

A full-scale vacuum preloading test was performed for an embankment construction on a Canadian structured clay deposit at Saint-Roch-de-l’Achingan. Accordingly, extensive instrumentation was used to monitor field behavior over eight months. A multidrain finite-element analysis was also carried out using a plane strain configuration with which the structured soft clay behavior was simulated using the S-CLAY1S constitutive model. The numerical analyses were then compared with the field measurements in terms of settlements, horizontal displacements of the clayey foundation, and pore pressure developments in the soft clay deposit. The results showed that compression curves obtained numerically at two different depths compared reasonably well with both field and laboratory curves. Effective stress paths at different points in the clay layer clearly demonstrated the benefit of vacuum preloading in comparison with traditional embankment construction (i.e., without vacuum preloading). In addition, the results suggested that the finite-element approach was consistent with laboratory and field behavior.