Evaluating the Constrained Modulus and Collapsibility of Loess from Standard Penetration Test

Argentinean loess has mechanical properties highly dependent on moisture content. Sand and silt particles jointed by clay bridges and precipitated salts form macropores which undergo high volume decrease when loaded or wetted. The constrained deformation modulus is an important parameter for the assessment of settlement and to characterize loessical formations. This work analyzes experimental results obtained in double-oedometer test and standard penetration tests (SPT) performed in silty loess. Typical behaviors observed in double-oedometer test are related to the decrease of soil modulus, collapsibility, cementation, and presence of disseminated cementing nodules. Correlations between the constrained modulus, collapsibility, and the blow count from SPT are presented. The influence of disseminated nodules, moisture content, and collapsed soil structure on the constrained modulus and collapsibility of loess is highlighted.