EXPERIMENTAL AND NUMERICAL INVESTIGATION OF DAM-RESERVOIR-FOUNDATION INTERACTION FOR A LARGE GRAVITY DAM

Forced-vibration tests were completed on Outardes 3 gravity dam, locat ed in northeastern Quebec, Canada. The experimental results were subse quently used as a basis for a numerical correlation study to evaluate the performance of state-of-the-art finite element programs far earthq uake analysis of concrete dams. The experimental procedure is presente d and involved the recording of acceleration responses on the 84-m-hig h dam under harmonic loading. Hydrodynamic pressures were also recorde d at several locations in the reservoir, up to a distance of 90 m from the dam face. Extensive studies were carried out with two- and three- dimensional models. The effects of several calibration parameters are discussed, including the dam and foundation stiffnesses and damping as well as water compressibility. Numerical results are compared with co mplete frequency responses for accelerations and pressures obtained on site. ft is demonstrated that the two-dimensional approach could only predict the fundamental resonance of the system, and that a three-dim ensional model for the dam-reservoir-foundation system including water compressibility could reproduce the experimental behaviour with accur acy. This project complements similar work carried out on a large arch dam, and constitutes direct evidence of water compressibility effects for a large gravity dam.