Abstract:
The present investigation is concerned with an experimental
study of the inward radial and vertical flow consolidation
characteristics, and the shear strength behaviour of
the consolidated soil due to installation of vertical central
model drains and imposed load on a soft fine grained soil
of Bangladesh.
A laboratory experimental programme has been setup
and implemented using three different sizes of circular
consolidation moulds. Five open circular model drains were
used for a particular sample and loads were applied in three
increment s. Two types of locally available dra:inagematerials •.
sand and rice husk,were used independently in the vertical
drains.
The effect of drain diameter, for different drainage
materials, on the gain of shear strength measured by different
methods (triaxial and vane. shear) were studied. The
consolidation characteristics e.g. co-efficient of consolidation,
degree of consolidation for radial'and vertical drainage were investigated. Also an attempt was made to
study the effect of water content on shear strength of the
consolidated soil.
The experimental results suggest that the shear
strength reaches a maximum at an optimum value of loading
diameter - drain diameter ratio, n. The optimum value of n
is found to be a function of loading diameter. It is also
found that rice husk filled drain gives a higher strength
than that for a sand filled drain of same dimension for a
particular imposed load. The statistical analyses of the
experimental data show strong correlations between shear
strength and n, shear strength and water content, triaxial
shear strength and vane shear strength. The relations are
proposed in the form of equations. The investigation
suggests that the co-efficient of consolidation increases
upto an optimum value of n and then decreases with n. The
co-efficient of consolidation has a higher value in case
of a rice husk drains than that for a sand filled drains.
