Parameterization and Application of a Small-Strain Stiffness Hardening Soil Model for Coastal Soft Soils

ABSTRACT The selection of Small-Strain Stiffness Hardening Soil (HSS) model parameters for coastal soft clays remains insufficiently established. This study aimed to determine HSS model parameters for coastal soft clays and evaluate their applicability in finite element analysis. Undisturbed soil samples from three representative soil layers were investigated through standard consolidation tests, Consolidated Drained triaxial (CD) tests, CD tests with loading–unloading cycles, resonant-column tests, and bender-element tests. The derived HSS model parameters were then used in numerical simulations of excavation projects, and the calculated deformation responses were compared with field monitoring data. In addition, sensitivity analyses were conducted to quantify the effects of key HSS model parameters on retaining wall displacements and ground settlements. The results showed that the reference initial shear modulus (G0ref) obtained from resonant-column tests was approximately 96 % of that measured by bender-element tests. The measured failure ratio (Rf) ranged from 0.60 to 0.70, which is notably lower than the default value of 0.90 commonly adopted in finite element analysis. Numerical simulations using the calibrated parameters showed favorable consistency with field monitoring data, confirming their reliability. The sensitivity analyses further demonstrated the critical roles of small-strain parameters (G0ref and γ0.7) and Rf in controlling deformation predictions. This study establishes empirical relationships among moduli and provides practical guidance for HSS model parameter selection in similar coastal soft clays.