Modelling Geosynthetic Reinforced Three-Layered Soil System Under Monotonic Loads Considering Shear and Vertical Deformations of Layers

Researchers have developed various simple and robust mechanical models to study the characteristics of granular fill- reinforced soft soil system. In most of these models, granular fills are assumed to be incompressible, and only the foundation soil is considered to be compressible. However, the granular layers in reality are compressible. In the present study, a mechanical model is developed to simulate the behaviour of geosynthetic-reinforced granular beds with soft soil foundation considering the compressibility of granular layers. The proposed system uses a set of Winkler springs to model the compressibility of granular layers and foundation soil, while the shear behaviour of granular layers is modelled using a Pasternak shear layer. A rough elastic membrane is used to model the behavior of the geosynthetic material. An iterative finite difference approach is used to obtain the solution. The proposed mechanical model is used to obtain the load-settlement response of a geosynthetic reinforced three-layered soil system. A parametric study is carried out for different load intensities, compressibility characteristics of granular and foundation soil layers, and geosynthetic tensile stiffness. The present study helps in understanding the behavior of reinforced three-layered soil system and can form a basis to model different cases of reinforced beds. The study concludes that the compressibility of individual granular layers significantly influences settlement profile of the layered soil system. A five-fold increase in the spring constant of the top granular layer with respect to foundation soil resulted in reducing the maximum settlement by 16%.