Retention Properties and Compressibility of a Compacted Soil

Soil-water retention properties and compressibility are closely related to the stability of geotechnical engineering structures made of compacted soils. In the present study, the water retention curve of a compacted soil from Northern France was characterized using either suction control method or suction measurement. The results obtained showed a good correspondence between the two methods. Then, these two experimental methods were used in oedometer compression test to highlight the factors influencing the compression properties, especially in terms of changes in compression index as a function of initial suction and initial structure (i.e. density). In the case of low density (1.1 Mg/m3), the results evidenced different zones for the variations of compression index, separated by a stress threshold. Compression index did not change significantly when suction values were relatively high and the applied vertical stresses were lower than the identified threshold stress.