Hierarchical constitutive modeling of structured clays: Bridging element tests and mechanized tunneling simulations

Mechanized tunneling in natural clays requires accounting for complex soil behavior governed by anisotropy, structure, stress–strain history, and destructuration. This paper develops a hierarchical constitutive modeling framework based on the SANICLAY family within critical state soil mechanics to simulate mechanized tunneling. The framework establishes a clear progression from element-scale model evaluation to boundary-value application, ensuring continuity between constitutive formulation, calibration, and three-dimensional tunnel simulation. Calibration is anchored in well-documented element test datasets and supported by variance-based global sensitivity analysis to identify influential parameters. The resulting calibrated models are then applied in three-dimensional finite element tunneling simulations across normally consolidated and overconsolidated states under both drained and undrained conditions. Results show that destructuration is the dominant mechanism for settlements, most evident in normally consolidated drained cases, while anisotropy and bounding-surface plasticity have more moderate and case-dependent impacts. The tunnel-scale analyses extend the calibrated framework to realistic excavation conditions, maintaining continuity between constitutive formulation and boundary-value response. The study provides practical guidance for model selection and calibration in structured clays, with implications for realistic prediction and the safe design of mechanized tunnels. • Evaluated hierarchical constitutive models for clay using element tests and BVPs. • Quantified effects of anisotropy, destructuration, and bounding surface plasticity. • Simulated tunneling in clay, capturing settlement during key construction stages. • Identified destructuration as the dominant factor shaping settlement and trough. • Provided guidance on selecting model complexity based on governing mechanisms.