1Associate Professor, Civil Eng. Dept., KLEIT, Hubli, Karnataka, India. sharadgjoshi@rediffmail.com
2Honorary Fellow, Indian Institute of Technology, Roorkee, Uttarakhand, India
3Professor, Appld. Mech. Dept., Govt. College of Eng., Aurangabad, Maharashtra, India
Very comprehensive investigations are carried out in this paper to show that the soil-structure interaction effects on the seismic response of gravity dams can be modeled accurately simply by approximating a horizontally layered foundation with an equivalent homogeneous foundation. For this purpose, a dam cross section along with a finite size of foundation block is analyzed by standard finite element method (FEM) for a large number of hypothetical cases of foundation inhomogeneity defined by two and three layers with different combinations of thicknesses and impedance contrasts using FEM software ABAQUS. The displacements and the maximum principal stresses induced under excitation by typical horizontal and vertical acceleration time histories of a real earthquake are compared with the corresponding results obtained for an equivalent homogeneous foundation in each case. Very good matching between the two results has established that the heterogeneity of foundation block does not much govern the soil structure interaction effects on the dam response, and the use of an equivalent homogeneous foundation is sufficient in practical engineering applications. The conclusions are not expected to be dependent on the characteristics of the input excitation.
Gravity dam, soil-structure interaction, acceleration time history, impedance ratio, foundation inhomogeneity
