ABSTRACT
In the laboratory, the negative pore water pressure, or suction (uc = ua − uw), is not easy to measure in coarse materials and their derivation requires the use of elaborate tests.
Several authors have studied the effect of the negative pore water pressure on the small strains behavior of partially saturated soils (Brull 1980, Wu et al., 1989, Kheirbek-Saoud 1994, Picornell and Nazarian 1998, Balay et al., 1998). In most cases, the analysis of the results is made in total stresses, and the role of the stress tensor is considered separately from that of the negative pore water pressure. Other authors (Wu et al., 1989, Biarez et al., 1991, Coussy & Dangla 2002, Fleureau et al., 2003) showed that an effective stress approach could be used to take in account the effect of the capillary pressure in the interpretation of the data in the very small strains domain.
