Calibration of a constitutive model for volcanic sands under simple shear conditions

Abstract The simple shear response of air-fall volcanic (pyroclastic) soils under both saturated and unsaturated conditions is interpreted through an elastoplastic constitutive model with hydraulic-hardening porosity-dependent critical state. Extensive experimental data collected various testing protocols (i.e., shear, direct triaxial tests) enable the theoretical identification variability fundamental physical properties frictional resistance, dilatancy, water retention behavior) a band admissible values for prescribed confidence levels. In this paper, specifically developed to account loading adopted calibration parameters performed accounting such scatter. procedure led single set 3 main steps. range variation each parameter carried out using derived from laboratory tests. Then, sensitivity analyses are on parameters. Mathematical indicators quantifying difference between measurements predictions proposed investigate role material evaluate performance. Furthermore, optimization algorithm identify optimal which best fits all considered tests wetting tests). results imply that hydro-mechanical must be satisfactorily simulate behaviors variety regimes.