A. Koliji

Effective stress in double porous media with two immiscible fluids

Note: Sols Reference LMS-ARTICLE-2005-006doi:10.1029/2005GL023766View record in Web of Science Record created on 2006-11-09, modified on 2016-08-08

Structural characterization of unsaturated aggregated soil

Despite the recent experimental studies of soil structure, a comprehensive understanding of the macroscopic response of a soil in relation to its structure has not yet been achieved. This lack of understanding reveals the need for further assessments of soil structure and its evolution under loading. In this work, the structure of an aggregated soil under various conditions of saturation and mechanical loading is studied. We also compare the aggregated soil structure, which shows a double porous fabric, with that of the same soil when reconstituted. The experimental methods selected for this study are a combination of mercury intrusion porosimetry (MIP), environmental scanning electron microscopy (ESEM), and neutron computed tomography (CT). Using MIP and ESEM, we first examine the soil fabric at the intra-aggregate scale. Then, we quantify the structural evolution of the soil using neutron tomography and link it to the macroscopic response of the soil. Based on the experimental evidence, the main features of the soil structure and its evolution are outlined for unsaturated aggregated soil under different loading conditions.

Assessment of structural evolution of aggregated soil using neutron tomography

The advanced non-destructive method of neutron tomography, together with image analysis, is used to evaluate the structural evolution of an aggregated soil during one-dimensional compression tests. Aggregation of primary particles is a commonly observed phenomenon in natural and compacted soils that causes an open soil structure with two dominant pore sizes corresponding to macro (inter-aggregates) and micro (intra-aggregate) pores. The evolution of macro porosity and the degradation of structures are evaluated by means of morphological parameters such as volume fraction, size distribution and chord length. Change in the structure is then linked to the macroscopic soil response. It is observed that the major structural modifications are associated with irreversible strains in soil.

Structure degradation of dry aggregated soils: experimental evidence and model formulation.

Note: Sols Reference LMS-CONF-2006-005 Record created on 2006-11-09, modified on 2017-11-20