Response and Stability of Earth Dams during Strong Earthquakes.
Final rept. Nov 74-Nov 76,
IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (ENGLAND) DEPT OF CIVIL ENGINEERING
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This earth dam study considers the response of an earth dam resting on a layer underlain by a rigid base and subjected to a strong ground motion. The dam and the layer are assumed to be elastic, homogeneous, and of simple geometric form. The properties of the dam and the layer may be different. Several combinations of the properties of the dam and the layer, as well as several ratios of the height of the dam to the depth of the layer, are studied. All of these are subjected to nine strong motion acceleration recrods, and their response is calculated. At the same time, seismic coefficients for various sizes of sliding wedges are computed. The results of individual cases and their envelopes are presented in the spectral form for design purposes. Methods of stability analysis for static and pseudostatic conditions are examined, and two new methods are presented. One of these methods is suitable for analyzing existing slip surfaces, and the other for quick computation of the critical acceleration for a given surface. Since pore water pressure developed in the dam during an earthquake is an important factor, a method of stability analysis is developed that takes the excess dynamic pore water pressure into account. The method is based on limit equilibrium principle. Pore water pressures are introduced in the form of dynamic parameter A sub n. The result is obtained in the form of a critical acceleration required to cause failure as a function of the number of cycles of earthquake load.
- Civil Engineering