Seismic Response and Damage Characteristics of RCC Gravity Dams Considering Weak Layers Based on the Cohesive Model

Abstract

Due to the construction technology of roller compacted concrete (RCC) gravity dams, there are many weak layers that have the potential to affect the seismic performance of dams. However, research on the seismic response and failure characteristics of RCC dams considering their layered characteristic is still lacking. In this paper, the zero-thickness cohesive element is presented to model the mechanical behavior of the RCC layers. An impacted concrete beam is selected to verify its effects on simulating crack propagation. Subsequently, the concrete damaged plasticity model is utilized to model concrete under seismic loading. The dynamic interaction in the gravity dam-reservoir-foundation system is considered by coupled acoustic-structural method, whose rationality is validated by seismic failure mode analysis of the Koyna dam under the 1967 Koyna earthquake. The validated algorithms are applied to investigate the influence of the weak layer at different elevations on the seismic response and the failure process of the Guandi RCC gravity dam. On this basis, the effects of well-bonded RCC layers set at intervals along the dam on the nonlinear response and failure modes under strong earthquakes are further investigated. The results reveal that the weak layer will influence the anti-seismic capacity of RCC gravity dams, and the damage characteristics of the dam are significantly changed. In addition, well-bonded RCC layers still affect the seismic response of RCC gravity dams. Increasing displacement response and energy dissipation can be observed. Meanwhile, RCC layers lead to more severe damage to the dam under the same seismic input.