Long-term behaviour of dams that have experienced internal erosion (sinkholes)
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Rockfill dams |
Earthfill dams |
Timing of internal erosion incident: |
Generally during first filling or within first year. There are also rockfill dams where incidents occurred years into operation. |
Generally a few years into operation or after several years. |
Possible early-warning sign: |
Increase in leakage, Muddy leakage, Pore-pressure variations |
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Possible warning-time between first sign and internal erosion incident: |
Account for the majority of dams with no warning, or up to days–weeks “warning-time”. However, there are also rockfill dams where there have been months or longer “warning-time”. |
Generally months or longer between first sign and the incident. |
Location of internal erosion incident: |
Higher incidence where dams: i) abut to concrete structures and/or sheet pile walls, and ii) are placed on irregular foundation. |
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