Numerical analysis of the mechanical behavior of geosynthetic reinforced stone columns in soft soils

BAHI, Selma (2025) Numerical analysis of the mechanical behavior of geosynthetic reinforced stone columns in soft soils. Doctoral thesis, Faculté des Sciences et de la technologie.

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Abstract

Soft soils, characterized by high compressibility and low shear strength, present significant challenges for infrastructure construction, necessitating innovative soil improvement techniques. Among these, geosyntheticencased stone columns (GESC) have emerged as a highly effective solution. This thesis explores the mechanical behavior of GESC in soft soils through advanced three-dimensional numerical analyses using Plaxis 3D, aiming to enhance our understanding and optimize design methods for infrastructure projects. The first part of the study focuses on optimizing ground improvement with encased stone columns through a detailed 3D numerical analysis in very soft clay. Different types of columns were studied, including short and floating columns, ordinary stone columns, and geosynthetic-encased stone columns within a unit cell model. The investigation demonstrates the superior performance of geosynthetic encasement in reducing bulging and settlement compared to ordinary stone columns. The results emphasize the importance of considering realistic installation effects, highlighting how geosynthetic encasement significantly improves performance by preventing lateral expansion and maintaining structural integrity. The second part of the study delves into the advanced 3D modeling of a group of geosynthetic-encased stone columns in soft clay beneath embankments. Using Plaxis 3D software, this analysis evaluates the installation effects using a realistic lateral expansion method alongside the effects of geosynthetic reinforcement. The simulations reveal that geosynthetic encasement, combined with realistic installation methods, substantially enhances the load-bearing capacity and stability of stone columns. The findings validate the effectiveness of the lateral expansion method for simulating installation effects, showing that geosynthetic encasement greatly improves the performance of stone columns under various loading conditions. This thesis significantly advances the understanding of GESC behavior in soft soils, offering practical guidelines for designing more resilient and efficient infrastructure. The findings emphasize the necessity of incorporating realistic installation effects and a comprehensive range of parameters in design practices to achieve optimal performance.

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