Determination of HSS Model Parameters for Soft Clays in Hangzhou: Statistical Analysis and Engineering Validation

The hardening soil model with small-strain stiffness (HSS model), capturing nonlinear stiffness of soils at small strains, offers advantages for deformation analysis of tunnels or deep excavations in soft clay areas such as Hangzhou City. However, its complex parameters are rarely determinable via conventional tests, and regional geological differences render parameter determination methods of other areas inapplicable to Hangzhou. To address this issue, this paper summarizes the geological genesis, spatial distribution, and physical–mechanical properties of Hangzhou soft clays, and clarifies significance and acquisition of HSS model parameters. Via statistical analysis of existing literature data, the relationships between key HSS model parameters and physical indices (e.g., void ratio) were established. A 3D finite element (FE) simulation of a Hangzhou excavation validated the proposed parameter determination method: simulated lateral retaining structure displacement and surface settlement closely matched field measurements. The simulation results employing the model parameters proposed herein are closer to the measurements than those based on the method of Shanghai, providing guidance for excavation design and geotechnical parameter selection in Hangzhou soft soil region.