Investigation of reservoir bottom absorption effects on stochastic seismic response of gravity dams

Abstract

The dependence of the dynamic response of gravity dams on various factors governing the reservoir bottom absorption effect has been analysed in detail. The absorption effect is modelled via a damping coefficient in the boundary condition at the reservoir bottom to compute the hydrodynamic forces by solving the wave equation for the reservoir water domain. Hydrodynamic pressure on the upstream face of the dam has been estimated using analytical expressions based on certain idealisations, which are in general valid for most practical situations. Contrary to the common belief as per the past studies, the dam response is not found to be influenced much by the absorption effects due to the sedimentary layer at the reservoir bottom. On the other hand, the reflection from the underlying rock mass is found to have somewhat stronger influence, if the modulus of elasticity of rock is much higher than that of the sedimentary deposits.

Keywords:

• dynamic response
• gravity dams
• reservoir bottom absorption
• power spectrum density function