The Effect of Reservoir Compressibility on The Earthquake Performance of Gravity Dams
Gravity dams are solid barriers to impound the reservoir water and the weight alone is large enough
to prevent them from tipping over. Their failures may result in disastrous consequences causing significant loss of life and
property. The dams should be reliable for which they are entrusted and also competent to take care of seismic forces apart
from the designed static loads. This study aims on the seismic response of concrete gravity dam, considering reservoir water
compressibility. In this respect the reservoir boundary is truncated to an extent of three times the height of the dam. Dam –
reservoir system is modeled considering Lagrangian - Lagrangian approach in finite element analysis. Nine-node
quadrilateral elements are used to model the complete system. The effect of foundation flexibility is investigated by
considering three cases of dam-foundation interaction ratios. The responses of the inquiry based on the compressibility of
water are compared with the incompressibility of impounded water modeled as an added mass by Westergaard Method. 2D
seismic analysis of Sunkesula concrete gravity dam monoliths located in the state of Andhra Pradesh, India is performed by
using 1967 Koyna shock record for the present case study. The responses at the heel, toe and u/s slope changes are found to
be reduced due to the fluid compressibility.
Key words- Gravity dam, Water Compressibility, Seismic Analysis , Finite elements.