Repair of CFRDS in the Dry and Underwater:Salt Springs and Turimiquire
In CFRDs deterioration of the face slabs and of the waterstops due to climatic factors,or to poor construction procedures,or to insufficient resistance to settlements and differential movements,often causes unacceptable leakage rates.Synthetic geomembranes are used worldwide to restore imperviousness to CFRDs,because with their elongation and weathering properties can resist large movements and maintain imperviousness over time. The paper describes two significant examples of rehabilitation of high CFRDs,one in the dry and one underwater.Salt springs,USA,the 5th oldest CFRD in the world and the first CFRD to reach 100 meters in height,in its70 +years history required repairs 19 times.In 2001,when seepage exceeded the level set by the safety authorities,Pacific Gas and Electric Company (PG&E),owner of the dam,decided to make a permanent rehabilitation the upstream face with an exposed PVC geomembrane system. A seepage analysis was performed to ascertain the areas of geomembrane system installation that would maximize the seepage reduction.Installation was carried out in winter 2004 and winter 2005 to minimise impact on operation.Seepage has been reduced from 1,150 L/s to 130 L/s,well within the allowed limits.Las Canalitas CFRD in Venezuela,better known as Turimiquire,was designed by Barry Cooke and built between 1976 and 1980. The dam,113 m high and used for potable water supply,was impounded in 1988. A first repair was carried out in 1989 when leakage attained 300 L/s,a second repair in 1994 when leakage increased again up to 2,500 L/s.In 1996,when leakage had attained 3,173 L/s,a natural repair was carried out by a land slide that occurred at the left abutment and reduced leakage to 1,255 L/s.Repairs were made again in 1999 when leakage up to 6,500 L/s was experienced,and in 2000. Also the result of these repairs was very poor.In 2008,beeing the rate of leakage in the range of 9,800 L/s,the owner selected an exposed PVC geomembrane system to provide a permanent solution to continuing leakage problems. The geomembrane system will be installed for its most part underwater,installation will be staged according to the extent of deterioration and leakage.In 2009 the most crucial area requiring immediate repair is being lined,in total about 14,930 m2 of exposed geomembrane. The paper discusses problems,technical solutions,installation methods,results and lessons learned.
geomembrane geocomposite,tensioning underwater installation
Sequera R Perazzo P Scuero A Vaschetti G
Ministeriodel Poder Popular para El ambiente,Centro Simon Bolivar,Caracas,Venezuela MWH Consultant,CCCT,Torre C,Ofc 1308,Caracas,Venezuela Carpi Tech,Corso San Gottardo 86,6830 Chiasso,Switzerland
国际会议
The 1st International Symposium on Rockfill Dams(第一届堆石坝国际研讨会)
成都
英文
25-35
2009-10-18（万方平台首次上网日期，不代表论文的发表时间）