Soft soils have a low bearing capacity and a high compressibility. If the loading process is so slow, that the soil can consolidate under each loading step, the embankment can be constructed in safe conditions. Consolidation means dewatering, what depends on the water permeability of the soil.
Geotextiles as separation layers separate a coarse grained fill from a fine grained subbase, allows the rise of water from the subbase into the fill. Both soils can react unchanged after the laws of soil mechanics. The separator equalises and helps against local subsidence. Geotextiles or geogrids as reinforcement can hinder a slipform failure. The reinforcement of foundations by one or more layers equalises the conditions and allow the foundation of small bridges and culverts as integral part of an embankment. Geosynthetic drains as vertical drains accelerate the dewatering of soft soils and accelerate the consolidation.