Finite Element Analysis of Shear Strength Improvements in Fibre-Reinforced Soils Using the Mohr–Coulomb Model

With increasing emphasis on sustainable construction, fibre reinforcement of soils presents a viable approach for enhancing mechanical performance while minimising environmental impact. This study investigates the influence of fibreglass fibres (0–3% by dry weight) on soil behaviour under triaxial loading using finite element modelling. The results demonstrate that fibre inclusion improves peak deviator stress and reduces volumetric strain, with the magnitude of enhancement dependent on both fibre content and confining pressure. Optimal performance was observed at 2% fibre content, which increased performance by approximately 20% under low confining pressures (50–100 kPa). At higher pressures (200–500 kPa), optimal performance was from 3% fibre content, which increased performance by approximately 5%. Improvements are attributed to mechanisms reported in the literature, including the ability of fibres to redistribute stresses and bridge microcracks. These findings provide insights into the behaviour of fibre-reinforced soils for applications such as slope stabilisation, foundations, and retaining structures, supporting more sustainable geotechnical engineering practices. These findings are not intended for direct design application.