Abstract:
Reinforced layered soil system is generally used under the foundations, to make the weak soil
like soft clay safe and stable and to avoid shear failure and excessive settlements due to static
and dynamic loads. Reinforced layered soil system is also used for working platforms which are
required for installing heavy construction machines and vehicles on weak soils like soft clay
which are not suitable for taking so much loads, and show excessive settlements. Provided fill
creates a suitable load bearing surface on which concentrated load may be applied, without the
shear failure and excessive deformations.
In this work static and dynamic analysis have been carried out using Finite Element Software
PLAXIS 2D on the two layer unreinforced and reinforced soil systems to see the effect of
providing geogrid as reinforcement in the two layer soil system and other parameters, on the
bearing capacity and settlement behavior of two layer system. Two layer soil systems consisted
of soft clay soil overlain by compacted granular fill. Loading is applied on a circular plate.
Axisymmetric analysis is performed to simulate the circular plate in 2D. For static analysis
results obtained from numerical analysis are in good agreement with the existing experimental
results. For dynamic analysis, it is required to provide viscous boundaries in PLAXIS to reduce
the boundary effects and to prevent the reflection of waves from boundaries. So a study have
been carried out to compare the various methods of providing silent boundaries and to see the
effectiveness of viscous boundaries used in PLAXIS. Inclusion of geogrid layer as reinforcement
in soil caused a significant improvement in the load bearing and settlement behavior of soil. This
improvement also depends on the position, number and stiffness of geogrid layers.
