Seismic analysis of earth-core and concrete-face rockfill dams.

摘要

The objective of this thesis is to study theoretically aspects of analysis and design of earth-core rockfill and concrete-face rockfill dams against strong seismic shaking.; 1. To evaluate the earthquake-induced permanent displacement for dams and embankments, a method is presented that assumes a pre-existing (potentially) sliding interface which obeys Coulomb's friction law, and whose location is fixed, although varied parametrically. The error introduced by the "Decoupled" method (which is based on the simplifying assumption that the computation of dynamic response and the resulting sliding displacement can be decoupled) is also examined. Both sinusoidal and real earthquake ground motions are employed as excitation. When the predominant frequencies of the input motion lie in the proximity of the fundamental frequency of the dam the slip based upon the decoupling assumption may exceed the exact value severely. The error decreases as the threshold acceleration (required to initiate slip) and damping (in the soil and rockfill) increase.; 2. The limitations of the Equivalent Linear Method in representing dynamic rockfill behavior is reviewed and a nonlinear elasto-plastic constitutive model for rockfill under dynamic load is discussed. A procedure for identifying the necessary elasto-plastic model parameters using the results of laboratory testing is detailed. The capability of the model to reproduce realistically dynamic rockfill behavior (hysteretic damping, permanent deformations, and history-dependent properties) is shown.; 3. The problem of analyzing the seismic behavior of concrete-face-rockfill dams under different levels of earthquake shaking is discussed. The principal objective is to estimate earthquake-induced strains and stresses in the face slab using a linear viscoelastic finite element model, in which the slab-rockfill interface obeys Coulomb's friction law.; 4. Presently, there hardly exists analytical or observational evidence on the behavior of concrete face slabs during strong seismic shaking. The choice of slab thickness and steel reinforcement is based solely on precedent, and performance under static load is the only consideration. A simple but realistic dynamic analytical model is developed for analyzing the seismic behavior of concrete-face-rockfill dams. (Abstract shortened by UMI.)