JEAN CLAUDE MOREL*, KHOSROW GHAVAMI** AND ALI MESBAH* *DGCB-ENTPE **Pontificia Universidade Catolica, Rio de Janeiro

It has been recognised that the presence of fibres in a soil matrix influences the composite ductility in compression to varying degrees, depending on the matrix and the properties of the reinforcing fibres. Not many studies have been reported to elucidate the shearing behaviour of soil composite blocks reinforced with vegetable fibres. This paper presents an experimental and theoretical research programme to establish the behaviour of composite soil blocks subjected to shearing forces. In the experimental study the direct shear behaviour of compacted soil alone and compacted soil fibre blocks were determined. The experimental values have been compared with the predicted results using a theoretical model which is an extension of an earlier model presented for composite material of soil reinforced with fibre mesh. The theoretical model has been first developed for only one fibre in a soil matrix and then extended for random fibres. A good agreement has been found between the experimental and theoretical values.