A modified elasto-plastic model with double yield surfaces and considering particle breakage for the settlement analysis of high rockfill dams

Abstract

This paper improves the elasto-plastic model with double yield surfaces in the context of the hardening soil model for the simulation of the settlement behavior of high rockfill dams. The stress-dependent stiffness values (E50 and Eoed control the shear hardening and the cap yield surfaces, respectively) are modified to exhibit different degrees of evolution with changes in the stress state. A modification of Rowe’s stress-dilatancy theory is proposed to account for the influence of particle breakage. Good quantitative agreement between simulated and measured stress-strain relationships can be achieved; in particular, the volumetric strain is much improved from the original model. The developed model is applied to predict the settlement of Nam Ngum 2, a 182 m high rockfill dam, during the construction stage, in conjunction with a three-Dimensional (3D) Finite Element (FE) analysis. The findings show that a good agreement between computed settlements and dam field monitoring data can be achieved.