SAFETY PERFORMANCE OF DAMS IN CHILE’S HIGHLY SEISMIC ENVIRONMENT
its 85 years of operation. This dam has been subjected to the Illapel earthquakes of 1943 (M = 8.2) and 2015 (M = 8.4) and was recently inspected after the 2015 earthquake, identifying only minor slides of the downstream rip-rap and deformation at the crest[15]. The dam is about 125km from the epicentre of these earthquakes. In 2017 a lateral wall, built by the operators over the lateral spillway, allowed the water level in the reservoir to go over the spillway crest, and the additional wall was overtopped, bringing the dam to the risk of a much serious major failure, fortunately not realized. The additional wall was later removed and the original design conditions were restored.
Figure 14. General view of Recoleta dam
3.3 Earth dams built after 1950
After 1950 earth dams were designed and built following in an increasing way the international practice and recommendations from organizations such as the US Bureau of Reclamation and ICOLD. Dam design practice was gradually improving based on the continuous development of soil mechanics, engineering geology, rock mechanics, hydrogeology, seismology, earthquake engineering and numerical analysis as well as the development of construction equipment and geotechnical investigation tools.
Most of the earth dams (24) constructed after 1950 have been built either by private
irrigation associations (6), by the MOP (10), by the state-owned electric company Endesa (established in 1943) or other companies (8).
The six earth dams designed and built by private irrigation associations have heights varying from 15m to 20m, which is a typical range for this type of dam. These dams are apparently in operation, but no information was available in relation to eventual damages during earthquakes. The 18 earth dams built by the MOP and hydroelectric companies have heights varying between 20m and 116m, with the exception of Tucapel dam with a height of 15m. The tallest
Vol XXXI Issue 3 DAM ENGINEERING 199
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