Towards a predictive model of the shear strength behaviour of fibre reinforced clay

Randomly distributed fibres can be a potential reinforcement material to improve the shear strength of soils. However, gaps remain in experimental research and predictive modelling of the shear strength of fibre reinforced high plasticity clays. In light of this, a series of consolidated undrained triaxial tests were carried out to investigate the shear strength behaviour of London Clay reinforced with 0.3% to 0.9% polypropylene fibre by dry weight of soil. The effects of fibre length and confining pressure were also considered. The results indicated that fibres significantly improve the shear strength of soil. The shear strength improvement increases with the fibre length, but decreases with increasing confining pressure at test scale. The addition of fibres also leads to the increase in the pore water pressure of soil. Using these and other experimental results, a predictive model was developed based on the concept of equivalent confining stress. The model is able to describe the deviator stress-strain and pore water pressure-strain relationship of fibre reinforced clay and can be used efficiently to predict the shear strength of fibre reinforced clay subjected to different confining pressures.