Numerical and field study of wick drains performance in soft clay

Abstract

The Soft soil formations are considered huge challenge for geotechnical engineers worldwide. Soft clay soil usually appears in coastal areas. This paper presents a field case study where the extended soft clay layers were a huge geotechnical challenge. The executed site investigation consists of boreholes and cone penetration tests (CPTu). The upper soft clay extends to depths more than 30m. Many field and laboratory tests were performed. The anticipated stresses due to the proposed structures were high for the existing soft soil deposits. The preloading system with vertical drains was selected as soil improvement system in some wide areas. Field instrumentation measurements were conducted in site during the preloading works. The detailed construction activities performed in the site are presented for two different areas. Both two-dimensional and three-dimensional finite element analyses are performed considering the construction activities for both areas. The results of the finite element analyses are compared with field measurement results. In addition, the final consolidation settlement due to the preloading load is estimated by different methods based on the recorded field measurements. The estimated results of final settlement are compared with the finite element analysis results. The presented results show that the use of preloading and vertical drains in the discussed project was successful and that the finite element analysis predictions were accurate.

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