Coupled hydromechanical model for high concrete-faced rockfill dams and its application

A coupled hydromechanical (HM) model is established for performance assessment of concrete-faced rockfill dams (CFRD). The non-linear elastic deformation of the rockfills is described by means of the Duncan-Chang’s E-B model, and the non-steady seepage flow behavior is modelled by use of the newly-developed parabolic variational inequality formulation of Signorini’s type. The Kozeny-Carman equation is calibrated to characterize the dependence of permeability of the rockfills on deformation by taking into account the effect of confining pressure. On the basis of back calculation of the permeability of the face slabs, the proposed model is employed to capture the coupled seepage flow and deformation behaviors of Shuibuya CFRD. Comparison of model predictions and in-situ measurements shows that the coupled HM effects in the rockfills are not remarkable due to the high seepage-proof performance of the face slabs, and the present model has an acceptable performance for describing the seepage and deformation behaviors. The limitations of the model are also demonstrated by examining the modeling errors, such as the negligence of the creep effect, wetting effect and size effect of the laboratory parameters of the rockfills, and the negligence of the unsaturated effect of seepage flow in the rockfills as well.