Fabric evolution during hydromechanical loading of a compacted silt

A study was undertaken on a compacted silt to determine fabric modifications induced by suction and/or stress variations. The link between fabric and hydromechanical behaviour was also investigated. A suction-controlled oedometer, using air overpressure, was developed for this purpose and mercury intrusion porosimetry was employed to determine sample fabric. The initial samples fabric was made of macro and micropores. It was shown that suction increase produced a strong decrease in the macroporosity associated with an increase in microporosity. However, some macropores were not significantly affected by the suction increase; this phenomenon might be related to the initial fabric of the samples. Second, it appears that loading under saturated conditions also produces strong fabric modification: the higher the applied stress, the lower the macroporosity. Soil fabric depends on the maximum stress experienced by the soil. Finally, some tests have shown the influence of suction, as well as the role of the degree of saturation, on the deformation process and the mechanical behaviour. The test results show that in the case of unsaturated mechanical loading, all macropores are not destroyed by the mechanical loading. Copyright © 2004 John Wiley & Sons, Ltd.