Evolution criteria of overall damage of concrete gravity dam body and foundation under near-fault ground motion

Abstract

Strong earthquake cases of concrete gravity dams show that the foundation damage has an important influence on the seismic response and damage characteristics of the dam body. To study the real dynamic damage characteristics of concrete gravity dams under the action of near-fault ground motions, this study establishes a dam-reservoir-foundation system model which can reasonably reflect the dynamic damage evolution process of dam concrete and foundation rock mass. Select three different types of near-fault ground motion records with rupture directional pulse, fling-step pulse and non-pulse, an improved dam damage index evaluation model is proposed, which can reasonably reflect the overall damage degree of the dam, and deep researchon the overall damage evolution law of concrete gravity dams. The results show that the foundation of the concretes gravity dam often get damaged before the dam body under the action of strong earthquakes. Compared with the near-fault non-pulse ground motion, the overall damage index of the dam under the action of the near-fault directivity pulse ground motion is significantly increased, and causes greater damage and displacement response to the dam body. The near-fault fling-step pulse ground motion has the least impact on the dynamic response of the gravity dam structure.