Description
Construction unit of soft soil foundation improvement
The use of prefabricated vertical drains with preloading is now
common practice and is proving to be one of the most effective
ground improvement techniques known.
Preloading of soft clay with vertical drains is one of the most
popular methods used to increase the shear strength of soft soil
and control its post-construction settlement. Since the
permeability of soils is very low, consolidation time to the
achieved desired settlement or shear strength may take too long.
Using prefabricated vertical drains (PVDs), means that the drainage
path is shortened from the thickness of the soil layer to the
radius of the drain influence zone, which accelerates
consolidation. This system has been used to improve the properties
of foundation soil for railway embankments, airports, and
highways.
Over the past three decades the performance of various types of
vertical drains, including sand drains, sand compaction piles,
prefabricated vertical drains (geosynthetic) and gravel piles, have
been studied. Prefabricated band shaped drains and cardboard wick
drains for ground improvement. Typically, prefabricated band drains
consist of a plastic core with a longitudinal channel surrounded by
a filter jacket to prevent clogging. Most vertical drains are
approximately **0 mm wide and 4 mm thick.
To study consolidation due to PVDs, unit cell analysis with a
single drain surrounded by a soil cylinder has usually been
proposed. PVDs under an embankment not only accelerate
consolidation, they also influence the pattern of subsoil
deformation. At the centre line of an embankment where lateral
displacement is negligible, unit cell solutions are sufficient but
elsewhere, especially towards the embankment toe, any prediction
from a single drain analysis is not accurate enough because of
lateral deformation and heave.
Construction unit of soft soil foundation improvement
