LUIS VALENZUELA P, RAMON VERDUGO A, JOSE CAMPANA Z & CARMEN G OPAZO A
not induce any additional movement of the upstream slope. Figure 13 shows low water level in the reservoir, a situation that has become common in several irrigation reservoirs because of the severe drought that has been present in the last decades in the Northern and Central regions of Chile.
Of the eleven large earth dams registered by ICOLD as being built during this period, four of them are still operating and are in relatively good conditions. Two of them were destroyed by earthquakes, one has not been found and four still exist although probably with some limitations and lack of proper maintenance. This result is not surprising since all these dams, except Peñuelas dam which was designed and built by MOP, were built privately with a lack of proper construction equipment and probably also a lack of technical supervision.
3.2 Earth dams built between 1928 and 1950
This period includes earth dams designed mostly by the Irrigation Department of MOP. The 15 earth dams registered by ICOLD Chile[1] as being constructed during this period have heights varying between 15m and 47m, with the exception of Bullileo dam (70m high). Fourteen of them are operated by irrigation associations and one (Sauzal dam) was built and operated by a hydroelectric company.
It has been reported that at least two of these earth dams have been seriously affected by the 1985 earthquake of M = 8.0[13]. Cerrillos (19m) and Perales de Tapihue (15m) dams presented longitudinal and transversal cracks, with Perales de Tapihue dam also affected by localized upstream slope failure. There has also been mention[9,12,13] of a Huechún dam that suffered longitudinal cracks during this earthquake, but apparently it is referred to as Huechún Bajo, a 10m∗ high dam, which is different from the Huechún 15m high dam included in the ICOLD Chile register, which has not been reported as affected by earthquakes, at least significantly. Bullileo dam is still in operation but was repaired about 1983 after a serious piping erosion developed within the central impervious core, probably caused by cracks in its core due to differential deformations near one of the abutments. No information was found of damages caused by earthquakes, although this dam is within one of the more seismic zones of the country.
The Illapel earthquakes of 1943 (M = 8.3) and 2015 (M = 8.4) impacted the Central-North region of Chile where three important earth dams are located: Recoleta (47m), La Laguna (41m) and Culimo (36m). According to MOP[15], none of these dams suffered any significant damage. At the Culimo dam, built between 1929 and 1933, a diaphragm wall through the central clay core, down to the rock foundation, was implemented in 2007 to diminish excessive seepage through the foundation.
Recoleta dam (47m high), an earth dam in the Central-North region of Chile (Coquimbo), was built in 1934 and is a good example of the dams designed by MOP for irrigation purposes. At the time it was the highest dam built in Chile and in its design can be recognized some features that were starting to be adopted from other countries, especially the US. Rock foundation was another aspect that contributed to the dam’s good seismic performance over
198 DAM ENGINEERING Vol XXXI Issue 3
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