Discussion on the Safety Factors of Slopes Recommended for Small Dams
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Date
2017-03-06
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Mark
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Mendel University Press
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Abstract
The design and assessment of the slope stability of small embankment dams is usually not carried
out using slope stability calculations but rather by the comparison of proposed or existing dam
slopes with those recommended by technical standards or guidelines. Practical experience shows
that in many cases the slopes of small dams are steeper than those recommended. However, most
of such steeper slopes at existing dams do not exhibit any visible signs of instability, defects or
sliding. For the dam owner and also for dam stability engineers, the safety of the slope, expressed
e.g. via a factor of safety, is crucial. The aim of this study is to evaluate the safety margin provided by
recommended slopes. The factor of safety was evaluated for several dam shape and layout variants
via the shear strength reduction method using PLAXIS software. The study covers various dam
geometries, dam core and shoulder positions and parameter values of utilised soils. Three load cases
were considered: one with a steady state seepage condition and two with different reservoir water level
drawdown velocities – standard and critical. As numerous older small dams lack a drainage system,
variants with and without a toe drain were assessed. Calculated factors of safety were compared with
required values specified by national standards and guidelines.
Practical experience shows that in many cases the slopes of small dams are steeper than those recommended. However, most of such steeper slopes at existing dams do not exhibit any visible signs of instability, defects or sliding. For the dam owner and also for dam stability engineers, the safety of the slope, expressed e.g. via a factor of safety, is crucial. The aim of this study is to evaluate the safety margin provided by recommended slopes. The factor of safety was evaluated for several dam shape and layout variants via the shear strength reduction method using PLAXIS software. The study covers various dam geometries, dam core and shoulder positions and parameter values of utilised soils. Three load cases were considered: one with a steady state seepage condition and two with different reservoir water level drawdown velocities – standard and critical. As numerous older small dams lack a drainage system, variants with and without a toe drain were assessed. Calculated factors of safety were compared with required values specified by national standards and guidelines.
Practical experience shows that in many cases the slopes of small dams are steeper than those recommended. However, most of such steeper slopes at existing dams do not exhibit any visible signs of instability, defects or sliding. For the dam owner and also for dam stability engineers, the safety of the slope, expressed e.g. via a factor of safety, is crucial. The aim of this study is to evaluate the safety margin provided by recommended slopes. The factor of safety was evaluated for several dam shape and layout variants via the shear strength reduction method using PLAXIS software. The study covers various dam geometries, dam core and shoulder positions and parameter values of utilised soils. Three load cases were considered: one with a steady state seepage condition and two with different reservoir water level drawdown velocities – standard and critical. As numerous older small dams lack a drainage system, variants with and without a toe drain were assessed. Calculated factors of safety were compared with required values specified by national standards and guidelines.
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Citation
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis. 2017, vol. Volume 65, issue 2/2017, p. 569-576.
https://acta.mendelu.cz/65/2/0569/
https://acta.mendelu.cz/65/2/0569/
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Peer-reviewed
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en
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Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
http://creativecommons.org/licenses/by-nc-nd/4.0/
http://creativecommons.org/licenses/by-nc-nd/4.0/