75th Anniversary |
Progress, problems, and solutions
Bayardo Materón reflects on his experience of working with compacted rockfill dams. Problems may occur, he says, but solutions are always found
Right: Bakun Dam in Malaysia
Above: Looking across Karahnjukar Dam in Iceland
ACROSS AUSTRALIA, COLOMBIA, BRAZIL, Mexico, and China, compacted rockfill dams began to evolve and grew in height over a short period, from 110m to concrete-faced structures approaching 300m high. Table No. 1 presents the record of CFRD and Asphalt Core type dams built with compacted rockfill, indicating the years in which they were the highest dams in the world. All of these dams worked relatively well, with small leaks, except for Brazil’s Campos Novos Dam which had noticeable breaks. At 202m high, Campos Novos was built with the following characteristics: L 592m; L/H 2.93; A/H2 2.60 – Basalt. The dam had a rapid lowering of the reservoir due to problems in the diversion tunnels, but this allowed us to see the arrangement of the central and lateral cracks that affected the slab. From 2000 to 2006, slab fractures also occurred at other CFRD type dams, including Tiangshengqiao (Tsq1). Built in China it was 178m high with the following characteristics: L 1104m; L/H = 6.2; A/H2 5.68. This dam presented fractures in the central part which were repaired during lowering of the reservoir.
Table No. 1 Evolution in height of CFRD and ACRD Name
Cethana
Alto Anchicaya Foz do Areia Aguamilpa
Campos Novos Shuibuya
Country Australia Colombia Brazil
México Brazil China
Height 110m 140m 160m 187m 202m 233m
28 | May 2024 |
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When the reservoir was raised again, the same type of breakage could be observed, which was corrected using a compressible membrane that would mitigate the movement of the slabs, avoiding the transfer of forces that would break the slab. The treatment used worked relatively well. It should also be noted that the rockfill of this dam is made of limestone that tends to produce a well-graded rockfill with good compaction characteristics. Other slab fractures also occurred at the 185m high Barra Grande Dam in Brazil. Built with the following characteristics: L -665m L/H 3.59; A/H2 3.16 – Basalt, it had breakage in the central compression joints, with high leaks. Table 2 identifies a group of CFRD type dams that
were identified as possibly having problems with fracturing of the main slab and were studied and corrected to avoid breaks in the slab. The Bakún dam slab was built in two stages. The lower stage 1 from the middle to the river bed and the upper stage 2 to the crown of the dam. Observations of the fractured dams indicated lower slab breaks
Year + hight 1971 a 1974 1974 a 1980 1980 a 1993 1993 a 2006 2006 a 2009 2009
Table 2. Evolution of CFRD type dams Name Bakún
Karahnjukar El Cajón La Yesca Chaglla
Country Malaysia Iceland Mexico Mexico Peru
Height 205m 196m 188m 220m 211m
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