Numerical prediction of bearing capacity and settlement of shallow foundation on overconsolidated clays using the Hardening State Parameter model

A numerical analysis was performed to investigate the bearing capacity and settlement behaviour of shallow foundations on overconsolidated clays. Finite element analyses were conducted in PLAXIS 2D using two constitutive soil models: the Modified Cam Clay and the Hardening State Parameter (HASP) model. The HASP model, implemented as a user-defined constitutive formulation, introduces state-dependent hardening within the critical state framework to represent the stress-strain behaviour of overconsolidated clays. The study reproduced field load tests on two shallow footings (A and B) at the Bothkennar research site, supported by comprehensive measurements of settlements and pore-water pressures. All soil parameters were adopted directly from published laboratory data, without further calibration. The analyses focused on the load-displacement response, time-dependent settlements under sustained loading, and the development and dissipation of excess pore-water pressures. The HASP model provided a realistic prediction of the measured field behaviour, showing good agreement with observations and demonstrating its capability to capture the coupled hydro-mechanical response of overconsolidated clays.