INVESTIGATIONS ON A GEOSYNTHETIC REINFORCED BEARING LAYER UNDER STATIC AND DYNAMIC LOADING

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.