Stress-deformation analysis of a zoned earth dam with elasto-plastic hardening soil models

Zoned earth dams are challenging geotechnical structures for engineers due to the many uncertainties revolving around the behaviour of core and rockfill materials. This research focuses on validation of stress-deformation numerical analyses for better prediction of dam response during construction and first filling. The case study is Montedoglio dam, a 64 m high zoned earth-core dam located on the Tiber River at about 24 km from Arezzo (Central Italy). The construction of embankment dam started in 1977 and finished in 1986 and the reservoir was impounded in 1990. Numerical simulations are conducted using both the finite difference code FLAC2D and the finite element code ICFEP which implement elasto-plastic hardening models. Specifically, two constitutive models were employed for the simulation of the construction and reservoir impounding phases: the Cysoil model (Cap-Yield) implemented in FLAC2D and the Lade’s Double-hardening model implemented in ICFEP. Model parameters for the core and the shoulders were calibrated using laboratory data. The numerical analyses of the construction phase of the dam were carried out with both codes and well captured the monitoring data recorded. The simulation of the reservoir impounding was conducted only using ICFEP with the Double-hardening model and reproduced with reasonable accuracy piezometers measurements and, consequently, stresses and deformations within the dam. Some challenging issues around the model calibration with both codes are presented and discussed.