Interpretation and analysis of a test embankment on soft clay

ABSTRACT: This paper presents the foundation performance of a test embankment constructed on instrumented thick deposits of soft clays in Northern Ontario, with and without prefabricated vertical drain (wick drains) ground improvement. The test site consists of low to high plastic, slickensided, lightly overconsolidated clay deposits. Wick drains were installed in three areas of the test embankment foundation with 2 m, 3 m and 4 m triangular spacings. A fourth area of the test embankment foundation did not have wick drains installed. The embankment was constructed in stages and loaded to achieve normally consolidated condition in the clay foundation. Aspects such as strength gain of the clay deposits due to loading and ground improvement, the effect of wick drain spacing, and consolidation parameters are discussed.