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Dam failure
The document discusses the failure of the St. Francis Dam in 1928 near Los Angeles, California. It provides background on the dam's design and construction. On March 12, 1928, the dam catastrophically failed, releasing a flood wave that killed an estimated 450 people and destroyed over 1,000 homes and buildings. The failure was likely due to cracks and leaks that were dismissed by the dam's designer. The document recommends lessons for disaster management, including early warning systems and emergency preparedness.
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Dam failure
- 1. Bonab University Civil EngineeringDepartment Bonab-Iran Dam failure Sajad Behnajad
- 2. The cause offailure may be classified as • hydraulic failures (for all types of dams) • failures due to seepage 1. through foundation (all except arch dams) 2. through body of dam (embankment dam) • failures due to stresses developed within structure Arch dams fail instantaneously, whereas the gravity dams take some multiples of 10minutes
- 3. The percentage distributionof dam breaks and its attributes causes of failure Foundation problems 40 % Inadequate spillway 23 % Poor construction 12 % Uneven settlement 10 % High pore pressure 5 % Acts of war 3 % Embankment slips 2 % Defective materials 2 % Incorrect operations 2 % Earthquakes 1 %
- 4. Dam failures effects •Dam failure results in a catastrophic break followed by a flood wave often with considerable loss of life or property • More than a dozen dams have failed in South Carolina amid catastrophic flooding that has destroyed homes and businesses and left more than a dozen people dead • The structures that have failed in South Carolina are like the vast majority of dams around the world: they are made of earth
- 5. Dam failures aremost likely to happen for one of five reasons • Overtopping • Foundation Defects and Slope Instability • Cracking • Inadequate maintenance and upkeep • Piping
- 6. Overtopping • caused bywater spilling over the top of a dam. Overtopping of a dam is often a precursor of dam failure. National statistics show that overtopping due to inadequate spillway design, debris blockage of spillways, or settlement of the dam crest account for approximately 34% of all U.S. dam failures
- 7. Foundation Defects andSlope Instability • Foundation defects, including settlement and slope instability, cause about 30% of all dam failures
- 8. Piping • It happenswhen seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam • 20% of U.S. dam failures have been caused by piping (internal erosion caused by seepage).
- 9. Failure Prevention Failurecould have been prevented if some of these points had been observed Failure is a complex process Begins with some abnormality in behavior (not detected) Consequent deteriorations (not observed) Further damage or disaster • Inspection and Monitoring of dams as well as data analysis and interpretation has a critical role in the field of dam safety
- 10. St. Francis DamDisaster
- 11. Geography • Located 40miles NE of Los Angeles • In city of Santa Clarita • Developing city • Agriculture, electricity (Edison), mostly immigrants • Inside San Francisquito Canyon
- 12. Background • Designed byWilliam Mulholland, Dept. of Power and Water • 1924 – construction began • Originally • Capacity: 30,000 acre-feet • 180 ft high, 600 ft long • 1st change • 10ft height increase • Capacity: 32,000 acre-feet • 2nd change (July 1925) • 10ft height increase • Capacity: 38,000 acre-feet • Wing dyke added (600ft long) • 1926 – construction complete William Mulholland
- 13. Completed and filled reservoir St.Francis Dam construction http://www.scvhistory.com/scvhistory/scvhistory.htm
- 14. • 1926-1928 • Cracksdeveloping in dam and abutments • Mulholland investigates and dismisses • 7 March 1928 • Reservoir fills to capacity • More leaks develop • Mulholland investigates and dismisses • 12 March 1928 • East side of reservoir roadbed sagging 1 – 5 feet • More leaks and cracks • Mulholland and assistant inspect and dismiss Evidence of leaks http://www.scvhistory.com/scvhistory/scvhistory.htm
- 15. • 12 March1928 – Dam fails 11:57 pm • 12 bill gallons of water • 18 mi/hr initially, 5 mi/hr into Pacific • Traveled 55 miles to the Pacific Ocean • Took 5 ½ hrs Dam after failure http://www.scvhistory.com/scvhistory/scvhistory.htm
- 16. Impacts • Deaths: 450estimated • Many found downstream • Tent residents of unknown count • +900 homes destroyed • 1,200 buildings damaged • 10 bridges knocked out • Power lost in multiple cities • Crops, businesses and livestock affected
- 17. Overturned railroad tracks Debrisand overturned cars http://www.scvhistory.com/scvhistory/scvhistory.htm
- 18. Disaster Management • Awarenessand preparedness • No disaster plan • No one ever thought it would break • Mulholland was aware of cracks/leaks and maximum capacity • Dismissed them because said, “This is typical for a concrete dam of this size.”
- 19. How was thecommunity affected • Many people lost jobs • Edison electric power plants ruined • Agriculture crops devastated • Agriculture devastated • 7,900 acres • Citrus, walnuts, apricots, grapes, alfalfa, pecans • Tent residents • Lost jobs and displaced • Rebuild homes and businesses • Took very long for people to get back on their feet
- 20. Recommendations • Warning systemneeded • You can never be too careful, the risk of failure will always be there no matter the confidence • More response by police force • Efficiency needed with system of communication • Reservoir shouldn’t have been built there • The geography is extremely dangerous
- 21. Sources • http://www.scvhistory.com/scvhistory/scvhistory.htm • http://en.wikipedia.org/wiki/San_Francisquito_Canyon •http://web.umr.edu/~rogersda/st_francis_dam/lessons_learned _from_the_st_francis_dam_failure(geostrata_mar-apr_2006).pdf • http://web.umr.edu/~rogersda/st_francis_dam/reassessment_o f_st_francis_dam_failure.pdf • http://web.umr.edu/~rogersda/st_francis_dam/Mapping%20th e%20St%20Francis%20Dam%20Outburst%20Flood%20with%2 0GIS.pdf • Sharif University Presentation based on dam failure • Outland, Charles F. Man – Made Disaster: the story of St. Francis Dam. Glendale, California: The Arthur H. Clark Company, 1963.
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