Nonlinear Seismic Response of Concrete Gravity Dams due to Foundation Fault Movement

Abstract

Not only should dams be evaluated for seismic shaking, but their capability to survive potential fault displacements in their foundations should also be assessed. Safety reviews of existing dams suggest the geological-seismic evaluations of some dam sites had failed to recognize the existence of possibly active faults. In this study, nonlinear seismic behavior of concrete gravity dams due to relative fault dislocation occurring in foundation has been investigated. Two types of fault movements including normal-slip and reverse-slip have been considered. These two types, combining with location of fault line respect to toe, middle, and heel of the dam base, angle of the fault, and water elevation in reservoir which result in 36 types of models, have been considered to study their behaviors. Results shows that each type of fault can cause to propagate specific crack pattern; Angle and location of fault beneath the dam are very effective on amount of damage induced; Water pressure of the reservoir can also have increasing or even decreasing effects on the crack propagation rate. Existence of foundation fault movements beneath concrete gravity dams, depending on the conditions of problem, can cause rapid crack propagations in the dam body, jeopardize the stability, and significantly change dam's dynamic response.