Embankment Deformations Research Articles

The Seismic Coefficient in Earth Dam Design

The limitations of methods of earthquake-resistant design of embankments based on pseudo-static analysis and incorporating a static seismic force designated by a seismic coefficient are discussed. It is suggested that both from considerations of soil behavior under cyclic loading conditions, and for purposes of assessing embankment deformations due to earthquakes, the development of a method of predicting dynamic seismic forces and their variations with time would provide a more reasonable approach for design purposes. A method of accomplishing this objective is suggested, and representation of the results by an equivalent simplified seismic force series is proposed. For embankments that can be considered to have a uniform shear modulus, charts are presented for determination of the equivalent seismic force series. It is pointed out that limitations in available dynamic response analyses require that some judgment be exercised in selecting design parameters. However, the results presented in the paper provide a useful basis for guiding this judgment. Furthermore, the results show that in designating seismic coefficients for design purposes, it is important to distinguish between embankments of different heights and material characteristics as well as different positions of the potential slide mass within the embankment.

A Method for Earthquake Resistant Design of Earth Dams

A method is presented for analyzing the stability of embankments during earthquakes incorporating(1) a consideration of the time history of forces developed in the embankment during the earthquake, and(2) measurements of soil behavior under simulated earthquake loading conditions. Field experience, analyses, and laboratory investigations all indicate that such innovations are highly desirable in any rational design procedure. The method also follows the concept of earthquake design advocated by Newamrk in which stability is assessed in terms of embankment deformations rather than as a factor of safety developed at some instant during an earthquake. The method is primarily applicable for analyzing the stability of embankments constructed of saturated soil which is sufficiently impervious so that no drainage will occur during the period of earthquake ground shaking. As improved methods for predicting embankment deformation are developed, they can readily be incorporated in the design procedure. /ASCE/