Abstract This study was carried out in an instrumented and monitored embankment divided into two symetrical sections and constructed with compacted treated soils (i.e., a silty soil and a clayey soil) exposed to the same atmospheric conditions in a continental climate, with oceanic influences. It aimed to investigate changes of bare soil surface moisture (w) and corresponding suction (s) as result of soil water evaporation processes on a monthly time scale. Seasonal variations in the w (and s) measurement in both soil surfaces show overall consistency with the meteorological measurement within the study area. The paper also examines the ability of four air temperature-based potential evaporation (PET) formulations to capture the process of evaporation at the site. Results indicated that soil water evaporation is controlled by both atmospheric and soil conditions. And, during the most significant drying time period, the measured s consistently increased and the corresponding w decreased suggesting a relatively significant water evaporation effect. However, the monthly predicted PET data varied from a maximum of over 120 mm/month to less than 50 mm/month during the drying time, depending on the used method. The continuously monitored soil surface suctions are used for discussing the variations of evaporation according to the predicted PET method and time period at the site.

El uso del ensayo edométrico para determinar la respuesta volumétrica de muestras de suelo data de los orígenes de la mecánica de suelos. Por lo general, el uso del ensayo ha estado enmarcado en el estudio de muestras naturales talladas en anillos de pared delgada, sin generar un estado de esfuerzos iniciales que perturbe la respuesta volumétrica del material. Sin embargo, en el marco del estudio del comportamiento de barreras de arcilla para el aislamiento de desechos nucleares se presenta la necesidad de ensayar materiales expansivos altamente compactados, por lo que este ensayo se ha estado utilizando con muestras compactadas directamente en el anillo edométrico, introduciendo un estado inicial de esfuerzos que afecta la respuesta volumétrica del material por efectos de roce lateral. En este artículo se presentan resultados de ensayos de hidratación, sobre muestras de una arcilla expansiva compactada, realizados para mostrar dichos efectos y que permiten mostrar la importancia del protocolo de preparación de las muestras, lo cual es el objetivo principal de este trabajo.

The use of oedometer test to determine the volumetric response of soil samples dates from the beginnings of soil mechanics. Currently, the use of the test has been focused in the study of natural samples that are trimmed in thin wall rings, which do not generate initial stress states that could perturb the volumetric response of the sample. However, due to the increasing interest in studing highly compacted swelling soils, in the case of engineered barriers for nuclear waste disposal, this test has been conducted on samples directly compacted in the oedometer ring. This practice introduces an initial stress state that affects the volumetric response due to frictional effects. In this paper, some results of hydration tests on compacted swelling clay are presented to point out such effects, permitting to show the relevance of the way the samples are prepared, which is the goal of this work.