Location

St. Louis, Missouri

Session Start Date

4-2-1995

Session End Date

4-7-1995

Abstract

Seismic design of tailings dams in present times has to provide satisfactory solutions to fulfill environmental protection requirements and to assure proper behavior after closure and abandonment. The requirements to protect the environment include control of seepage and other forms of pollution of the air, waters and soils, under normal conditions, and also under the most extreme events which may be foreseen to occur. The worst possible form of pollution under such extreme conditions is a liquefaction failure involving breaching of the dam and flooding of the valleys downstream. The probability of occurrence of maximum events obviously increases with the period of time considered, therefore, for the abandonment period of a tailings dam, a maximum credible earthquake has to be considered and a 500 year period is normally requested for such prediction. Relatively large areas become endangered, under these conditions, around every tailings dam built in a seismic region. As time passes important parts of such areas shall be inhabited or developed for agricultural or industrial production, increasing their values, due to increase of population and growth of the economy. The combination of maximum earthquake, increasing demands for environmental protection and increasing values of the risks associated to tailings deposits, pose severe requirements for seismic design of the dams. If these requirements are confronted with the dynamic properties determined by tests performed in laboratory prepared specimens of tailings soils, as is normal today for a new dam, they result in very expensive designs. On the other hand, recent observations of real seismic behavior of abandoned deposits of tailings and investigation of dynamic properties of tailings soils suggest that age has some favourable effects in the stability of these structures and that consideration of such effects may produce significative improvements in their design. Therefore, the emphasis of this paper shall be placed on those aspects of seismic design specifically related with environmental protection, abandonment and time effects.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Third Conference

Publisher

University of Missouri--Rolla

Publication Date

4-2-1995

Document Version

Final Version

Rights

© 1995 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 2nd, 12:00 AM Apr 7th, 12:00 AM

Design and Behavior of Tailings Dams Under Seismic Conditions

St. Louis, Missouri

Seismic design of tailings dams in present times has to provide satisfactory solutions to fulfill environmental protection requirements and to assure proper behavior after closure and abandonment. The requirements to protect the environment include control of seepage and other forms of pollution of the air, waters and soils, under normal conditions, and also under the most extreme events which may be foreseen to occur. The worst possible form of pollution under such extreme conditions is a liquefaction failure involving breaching of the dam and flooding of the valleys downstream. The probability of occurrence of maximum events obviously increases with the period of time considered, therefore, for the abandonment period of a tailings dam, a maximum credible earthquake has to be considered and a 500 year period is normally requested for such prediction. Relatively large areas become endangered, under these conditions, around every tailings dam built in a seismic region. As time passes important parts of such areas shall be inhabited or developed for agricultural or industrial production, increasing their values, due to increase of population and growth of the economy. The combination of maximum earthquake, increasing demands for environmental protection and increasing values of the risks associated to tailings deposits, pose severe requirements for seismic design of the dams. If these requirements are confronted with the dynamic properties determined by tests performed in laboratory prepared specimens of tailings soils, as is normal today for a new dam, they result in very expensive designs. On the other hand, recent observations of real seismic behavior of abandoned deposits of tailings and investigation of dynamic properties of tailings soils suggest that age has some favourable effects in the stability of these structures and that consideration of such effects may produce significative improvements in their design. Therefore, the emphasis of this paper shall be placed on those aspects of seismic design specifically related with environmental protection, abandonment and time effects.