An Analytical Study on the Performance of Basal Reinforcement in an Embankment Placed Over a Soft Clay Bed

The civil engineering infrastructure such as roads and railways require embankments to maintain the designed gradient all along its alignment and also for flood protection. These embankments pass over different types of natural ground and when they pass over soft clay beds, several challenges are to be addressed in terms of lower bearing capacity, excessive settlements, and lateral deformations. When the unconfined compressive strength of clay bed is less than or equal to 5 kPa, traditional techniques such as stone columns, pre-loading with strip drains, and other modification techniques are considered to be time-consuming and uneconomical for a project. In such cases, piles are being adopted to support the embankment to keep pace with the project duration. However, the soft soil between the piles remains weak and the load transfer is to be facilitated by using a basal reinforcement at the top of piles. The basal reinforcement enables the system to develop the necessary arching action so that the load transfer takes place to the piles. In order to understand the load transfer mechanisms, several investigators have been working using numerical techniques. The present work is an attempt to study the influence of pile spacing, basal reinforcement stiffness, and its tensile strength in mobilizing the optimum soil-arching in order to facilitate the load spreading from the embankment to the piled clay bed using Plaxis-3D. The input parameters were kept as the cohesion of soft clay bed and pile material properties such as the modulus of elasticity (E) and Poisson’s ratio (µ). The pile spacing, reinforcement stiffness, and tensile strength were kept as variables.