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

Karimi, Zana | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41464 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen
  7. Abstract:
  8. Generally concrete dams have not been sited at location where there were faults classified as active. However, there may be sites suitable for concrete dams where there is some possibility of fault displacement occurring underneath the dam. In addition, there may be situations where an existing dam was constructed over a fault thought to be inactive and later determined to be active, due to different approaches of classification of a fault whether it is active or not. Also some discontinuities may be observed during construction. For these cases nonlinear analysis and criteria will be required to assess the capability of concrete dams to safely withstand fault displacements. In this thesis, we are going to assess nonlinear seismic behavior of concrete gravity dams due to relative fault dislocation occurring in foundation beneath the dams. If the axis of the dam and the fault line lie on the same direction, two dimensional modeling of the dam-foundation-reservoir can be adopted. We may consider two types of fault movements in two dimensional problems including normal-slip and reverse-slip. These two types of movements, combining with location of fault line respect to toe, middle, and heel of the dam, angle of the fault, and water elevation in reservoir which result in 36 types of models, are considered to study their behaviors. By introducing split node technique in to 2D and nonlinear finite element computation, we can apply fault relative movement to the foundation. The splitting nodes can displace under other forces and boundary conditions applied to the system and the technique induces no spurious or net forces and moments on the finite element grid when isoparametric elements are used. Dam-foundation-reservoir interaction is considered in finite element simulation. Comparing results of analyses shows that each type of fault can cause to propagate specific crack pattern in the dam monolith; Angle and location of fault beneath the dam are very effective on amount of damage induced on dam; Water pressure of the reservoir can also have increasing or even decreasing effects on the crack propagation rate, depending on the magnitude of fault relative displacement or boundary conditions of the problem. Existence of foundation fault movements beneath concrete gravity dams (even that one of a small dislocation), depending on the conditions of problem, can cause rapid crack propagations in dam body, jeopardize the stability, and significantly change dynamic properties and behaviors of concrete gravity dams
  9. Keywords:
  10. Concrete Gravity Dam ; Finite Element Method ; Dam-Reservoir-Foundation Interaction ; Nonlinear Seismic Behavior ; Foundation Fault Movement ; Split Nodes Technique

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