In 1997 a survey was initiated by the USSD Committee on Materials for Embankment Dams (COMED) to determine the "state of the practice" for selecting fill strength parameters used in static and pseudostatic analyses of earthfill embankment dams. A questionnaire was sent to federal and state agencies, consulting firms, and private consultants experienced in the design and safety evaluation of embankment dams. The questionnaire asked each respondent to provide information as to their practice in determining the static strength of embankment materials and analyzing the static stability of embankment dams. The information provided by the respondents included: approach to static stability analyses, loading conditions, shear strength parameters, field and laboratory testing used to determine shear strength parameters, procedures for interpreting test results, factors of safety, and methodologies used for static analyses. In 2006 the information provided by the respondents, combined with updated information and criteria developed since 1997, was summarized by the COMED in a white paper entitled, "Strength of Materials for Embankment Dams," which will be available on the USSD web site. The white paper provides the current criteria used by the U. S. Army Corps of Engineers, U. S. Bureau of Reclamation, Federal Energy Regulatory Commission, National Resources Conservation Service, and Tennessee Valley Authority, along with other state agencies and consultants. The purpose of this presentation, therefore, is to highlight the results for the "state of the practice" presented in the white paper. Among the topics discussed are: 1. Loading Conditions for Embankment Dams, including End of Construction, Steady-State Seepage, Rapid Drawdown, and Earthquake. 2. Determination of Shear Strengths, including total and effective stresses, selection of shear strengths, and the use of cohesion. 3. Static Analyses of Embankment Stability, including the types of potential failures surfaces evaluated and recommended factors of safety.
展开▼
