INFLUENCE OF CONCRETE FACE ON SEISMIC RESPONSE OF CONCRETE FACED ROCKFILL DAM

Abstract

Concrete-faced rock-fill dams (CFRD) are widely used in large-scale hydraulic projects. Understanding the behaviour of a high concrete-faced rock-fill dam is critical for the design and safety evaluation. The face slab, the key seepage-proof structure is of great concern, which has a strong interaction with the neighbouring gravel layer due to significant difference in their stiffness. The seismic behaviour of concrete-faced rock-fill dam is studied by realistic modelling of materials & their interface. This contact analysis method regards dam body and concrete slab as two independent deformable bodies. These two deformable bodies follow Coulomb friction law at contact. The rock-fill materials in dam body are assumed to be non-linear and time-dependent but concrete slab is elastic. A nonlinear static & nonlinear earthquake analysis has been carried out with a set of historic earthquake records of 0.60g PGA. Numerical results highlight key aspects of the seismic response of CFRD with emphasis on the internal forces developing in the slab. The analysis showed that the interface model describes a significant effect on the stress response of the face slab under different conditions. The top of the face slab exhibited a significant separation from the dam body during seismic excitation. Finite element - software ANSYS 11.0 has been used for all the computation.