Influence of the hydric solicitations and mechanical complexes on the behaviour compacted expansive soil

The main objective of the paper is to present a study on compacted expansive soil strains generated by complex hydric or mechanical loadings and their consequences on tested soil compressibility. In the first part of the paper, the suction-controlled testing devices are described (osmotic and salt solution methods). All the presented tests were performed in the range of suctions between 0 and 40 MPa. The consequences of the strains induced by wetting as a function of the applied mechanical stress were analyzed. The results showed that, under these conditions, strain depends on the followed hydraulic path, whereas the slope of the plastic compression line lambda(s) was only affected by the suction applied during the mechanical loading. The second test series demonstrated that the stress path influenced both deformation and slope lambda(s) if suction higher than the initial sample suction was imposed during the test. As a conclusion, it could be stated that the slope lambda(s) depends on the suction applied during a mechanical loading and on the maximum suction experienced by an expansive material during its past "history".