Study on the influence of the sediment at reservoir bottom on dynamic damage of gravity dam

Abstract

Traditional linear elastic model or elastic-plastic DP model can hardly reflect the damage and failure law of the concrete and rock foundation when the tensile and compressive strengths exceed the limitation. Therefore, the concrete damage model is used to simulate the dynamic damage of gravity dam body. According to the similarity of concrete and rock mass materials, the damage model of concrete is extended to rock mass materials. The sediment at the bottom of reservoir is simulated by viscous and high density compressible fluid. Based on this, a multi-coupling simulation model is established, which can reasonably reflect the dynamic damage evolution process of the dam concrete and dam foundation rock mass. Based on the Koyna gravity dam project, taking the thickness of sediment at the bottom of the reservoir as a variable, FEM transient analysis is carried out in this paper. By comparing the damage areas of the model, the displacement of the key points of the dam body along the river and the energy dissipation index, the influence of different thicknesses of the sediment is quantified on the damage of the multi-coupling system of the gravity dam. The calculation results obtained are close to the actual earthquake damage, which verifies the feasibility and rationality of the calculation method. The results of the analysis also show that: the seismic damage of the gravity dam can be consistently reduced with the increase of the thickness of the reservoir bottom sediment. Compared with the dam body, the change of thickness of sediment has less influence on dam foundation damage.