Shear behaviour of sandy soil from Chlef river reinforced with different types of fibres

Direct shear box tests were carried out in order to evaluate the effect of different types of randomly distributed fibres; two synthetic fibres (Polypropylene and Glass fibre) and one natural fibre (Sisal fibre) on the improvement of Chlef sandy soil shear strength. All of the inclusions were randomly distributed in the soil mass with a length of 12 mm and fibre contents of (0, 0.25, 0.5, 0.75 and 1% by dry soil mass). Samples were prepared at a relative density of 50% representing medium dense state and performed at normal stresses of 50, 100 and 200 kPa. The present work is conducted in order to study the effect of material properties and fibre content on the shear strength of sand. The experimental results show that all types of fibre greatly improved the shear strength, cohesive intercept and friction angle of Chlef sand. However, samples reinforced with sisal fibres have shown a more pronounced increase in strength parameters than those reinforced with glass or polypropylene fibres. The effect of the soil initial state was also discussed.