Finite Element Modelling of Foundation on Soft Clay Improved by Geocell and Boulder-Sand Layer: A Comparative Study

Abstract

Rapid infrastructure development urges for sufficient competent ground, which is currently scarce. Thus, the major focus of geotechnical engineers is the development of techniques for improving poor soil. A variety of strategies are used to reduce post-construction settlement, increase the shear strength of the soil, enhance the bearing capacity of the soil system, and improve the stability of superstructures. Among these, soil replacement is the simplest and most widely used method, while geocell reinforcement has been found to be an effective methodology. The three-dimensional structure of geocell provides better lateral confinement to the infill soil, improving its ability to support loads. However, because of its intricate honeycomb structure, numerical modelling of geocell has always proven difficult. Thus, an attempt has been made to generate a three-dimensional model of geocell using PLAXIS 3D. Finite element model was validated using laboratory model test results. A numerical analysis of footing resting over unimproved soft soil and soft soil improved by boulder-sand replacement and geocell reinforcement has been carried out. It was found that by replacement and reinforcement techniques, the performance of the footing can be doubled. The influence of width and depth of the boulder-sand layer and depth of the first geocell layer on bearing capacity improvement has been studied. The effect of the depth of boulder-sand bed on the influence factor was found to be higher compared to the effect of width. Maximum improvement by the inclusion of geocell was observed when it was placed in the middle of the sand layer with an improvement factor of 2.25. Further, using soil investigation data from in situ and laboratory tests, the concept has been extended to a field problem. © Deep Foundations Institute 2025.