Assessment of Prefabricated Vertical Drains and Surcharge for Accelerated Consolidation of Soft Marine Clay beneath an Embankment

This study assesses the use of prefabricated vertical drains (PVDs) combined with surcharge preloading for accelerating consolidation of a thick soft marine clay deposit beneath an embankment in Kuala Langat, Selangor, Malaysia. The site comprises approximately 20–25 m of soft clay beneath fill, creating a significant settlement and construction-time constraint. A field investigation consisting of five boreholes and laboratory testing was used to establish the subsoil and consolidation parameters. PVDs were installed to approximately 25 m depth at 1.0 m spacing in a triangular arrangement, and a 3.5 m fill comprising platform fill and surcharge was considered. One-dimensional consolidation theory was used to estimate settlement, while the radial consolidation response of the PVD system was assessed using the Hansbo modification of Barron's solution. The calculated total settlement for the 3.5 m fill was 1419 mm, with 90% of the predicted primary consolidation settlement corresponding to 1277 mm. The analysis indicated that the 90% consolidation target could be achieved in approximately four months under the adopted PVD and surcharge arrangement.

Soft soil; Marine clay; Prefabricated vertical drains; PVD; Surcharge preloading; Consolidation; Settlement; Ground improvement

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