Studying the stress-suction coupling in soils using an oedometer equipped with a high capacity tensiometer

Various works have concerned the hydromechanical behavior of Boom clay. Due to some amount of smectite minerals in the clay fraction, Boom clay exhibits swelling properties when hydrated under low stresses. To investigate some aspects of the hydromechanical behavior of Boom clay, oedometer compression tests, during which the changes in suction with increased vertical stress are monitored by means of a high capacity tensiometer installed at the bottom of the sample, were carried out on samples close to saturation and submitted to an initial suction. Some aspects related to hydromechanical couplings are examined through the investigation of the changes in suction during oedometer compression, a somewhat delicate and poorly documented experimental approach. The experiment allows the determination of the point at which suction is changed to positive pressure during compression and different HM behaviour below and above this point. The suction/stress behavior during unloading is also described and discussed. Finally, an interpretation in terms of microstructure effects is provided. The experimental approach seems to provide interesting further application to better understand hydromechanical couplings in natural soils in relation with suction increase during stress release.