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A laboratory experimental bench suiting the evolution survey of little concentrated materials in the course of deposition is presented here. The materials concerned can be in formation soils (mud) or any other fine granular materials, however, all characterized by their strong deformability and by their complex behaviour with constant changes from settling to consolidation phases. First, the already available experimental devices are summed up in a state-of-the-art section. The restraints imposed by the material (properties, consistency, quick evolution) have directed the development towards automated settings consisting of a column containing the material studied, a gammadensitometer and a pressure sensor. The device proposed here, the experimental procedures and the result post-processing are described in detail to provide an accurate follow up of the densities and of the interstitial excess pore pressures. The most original feature of the device lies in the possibility to obtain profiles within the first minutes of the evolution. The results, presented here in terms of effective stress and pore pressure, make it possible to delimit the range of validity of the usually adopted constitutive laws better.

The constant silting up of ports and estuaries makes it necessary to carry out dredging operations to ensure free access to port infrastructure. The dredged materials are disposed of at sea, with the creation of a maritime deposit, or stored on land in decantation pools. In each case, this leads to the creation of high water content soil. This paper presents a geotechnical laboratory approach to the formation of high water content soils on an experimental sedimentation/consolidation test bench. The original feature of this test bench is that it is possible to carry out highly accurate pressure and density measurements in a time very close to the beginning of the test. These measurements are used to analyse the changes in the total stress, the pore pressure, and the effective stress. On a diagram showing the void ratio/effective stress, we have highlighted the changes in the intermediate phases of the formation of a natural soil which consolidates under its own weight.