Abstract: Settlement magnitude and surcharge duration estimations are the main research aspects of the preloading of railroad embankments over soft soils. A railway embankment over the coastal soft soil beach is improved by surcharging with Prefabricated Vertical Drains (PVD). A geotechnical instrumentation program including surface settlement plates, piezometers and extensometers is also implemented during the construction. The subsurface soft soil settlement and pore water pressure characteristics are summarized from the observed data. The hyperbolic curve fitting method was used in predicting the post construction settlement as well as the degree of consolidation of the soft soils. The relationship between the surcharging loading duration and the post construction settlement as well as the degree of consolidation was established. The results indicate that the surcharging with PVD method effectively improves the coastal soft soils. The surcharging duration can be estimated in accordance with the surface and sublayer settlement magnitudes, pore water pressures, post construction settlement as well as the degree of consolidation of soft soils.

Key words: Surcharge Preloading, Surcharge Duration, Coastal Beaches, Soft Soils