Earthquake response of arch dams to spatially varying ground motion

Abstract

The response of two arch dams to spatially varying ground motions recorded during earthquakes is computed by a recently developed linear analysis procedure, which includes dam-water-foundation rock interaction effects and recognizes the semi-unbounded extent of the rock and impounded water domains. By comparing the computed and recorded responses, several issues that arise in analysis of arch dams are investigated. It is also demonstrated that spatial variations in ground motion, typically ignored in engineering practice, can have profound influence on the earthquake-induced stresses in the dam. This influence obviously depends on the degree to which ground motion varies spatially along the dam-rock interface. Thus, for the same dam, this influence could differ from one earthquake to the next, depending on the epicenter location and the focal depth of the earthquake relative to the dam site.of computed response with ambient vibration data and known concrete and rock properties, Proulx et al. [3] selected parameter values for the dam-water-foundation rock system as follows: Concrete: elastic modulus = 36 GPa, Poisson's ratio = 0.2, and unit mass = 2400 kg/m 3 ; foundation rock: elastic modulus = 72 GPa, Poisson's ratio = 0.25, and unit mass = 2500 kg/m 3 ; water: unit mass = 1000 kg/m 3 and wave velocity = 1438 m/s; and wave reflection coefficient at the reservoir and in the portion of the dam adjacent to the thrust block, consistent with what happened during the earthquake. In contrast, analyses that ignored spatial variations in ground motion were unable to identify these highly stressed regions.

Direct finite element method for nonlinear earthquake analysis of concrete dams: Simplification, modeling, and practical application

“…For example, viscous damping ratios of 1% and 3% for the dam and foundation, respectively, in the case of Mauvoisin Dam; 2% and 4%, respectively, for Pacoima Dam; and 1% and 2%, respectively, for Morrow Point Dam, combined to provide damping in the overall dam‐water‐foundation system that was consistent with measured damping for these dams: 2% to 3% for Mauvoisin Dam, 6% to 7% for Pacoima Dam and 1.5% to 4% for Morrow Point Dam. Responses computed from the numerical models for Mauvoisin Dam and Pacoima Dam were in good agreement with motions recorded during small earthquakes at these two dams . More recent examples include analyses of Tagokura gravity dam (1% in dam and 0% in foundation) and Kurobe arch dam (1% in dam and 0% in foundation)…”

Linear analysis of concrete arch dams including dam–water–foundation rock interaction considering spatially varying ground motions

“…The material properties (elastic properties and unit weight) of the dam concrete and rock were selected as the values established earlier [6] based on the correlation of computed response with ambient vibration data and known properties of concrete and rock. The damping values for the dam and foundation rock were established [15,17] to be consistent with the viscous damping ratio of 2-3% in the overall dam-water-foundation rock system, determined by ambient vibration tests [18].…”

Investigation of Damping in Arch Dam–Water–Foundation Rock System of Mauvoisin Arch Dam

“…The parameters of the dam concrete and the foundation rock are fixed to z s ¼ 1%, z f ¼ 3%, E s ¼ 36 GPa and E f ¼ 72 GPa, which were selected in the previous investigation [11]. The contribution of damping from the damewater interaction and the reservoir boundary absorption to the overall effective damping of the system is investigated.…”

“…The ground motions at other nodes along the interface were then interpolated from these five records in [11,15]. Among them, five accelerographs recorded the ground motions at the damefoundation interface.…”