Relation between suction changes in compacted soils and evolution of micro-structure during compression

摘要

Compressibility is closely related to the stability of geotechnical engineering structures made of compacted soils. Most analysis neglects the variation of suction during the compaction. A standard oedometer cell equipped with a tensiometer was used to measure soil suction continuously during the application of different vertical stresses. Measurements were carried out on remolded soil samples obtained by compacting a loamy soil sieved 2 mm and 0.4 mm at an initial dry density of 1.1 g cm'3 and at different initial water suctions. The results showed that the suction remained almost constant until a vertical stress threshold value beyond which the suction decreased as the stress increased. Furthermore, the results obtained highlighted the effect of soil structure on the stress threshold. Variations in soil suction were interpreted in term of processes at pore scale by comparing the evolution of pore-size distribution, measured by mercury intrusion, and the expected distribution of water in the pores.