On the strength of fibre reinforced soils

Fibre reinforced soils have been investigated for several decades and different models have been suggested to estimate their improved shear strength. Micro and macro mechanical characteristics of both fibres and soils affect the shear strength of such composite materials (e.g. relative sizes of fibres and soil grains, fibres aspect ratio, stress state, mechanical properties of the fibres), even though no model is available to explicitly take all of them into account. The aim of this work is to establish a new expression for the shear strength of the reinforced material, able to consider the main characteristics of the soil and the fibres as well as the effect of fibre to grains relative dimensions. Data from triaxial tests carried out on fibre reinforced soils with distinct grain size distributions (from clayey sands to sandy gravels) and from previous experimental works were considered and have been analysed successfully within the proposed framework.