SAFETY PERFORMANCE OF DAMS IN CHILE’S HIGHLY SEISMIC ENVIRONMENT


noted that the Marquesa dam that failed in the 1985 earthquake seems to be a different one from that indicated by ICOLD Chile, the Marquesa de Los Quillayes dam (21m high). There are also mentions of the case of La Viñilla dam (15m high) which suffered similar damage to Lliu LLiu dam, with longitudinal and transversal cracks The Lliu Lliu dam also suffered significant damage in the Maule earthquake of 2010, as is commented later in this paper. Besides Catapilco, Lliu Lliu and Peñuelas dams, the San Alfonso, La Dehesa, Portal de Alcones and Carrizal dams are still identifiable on relatively recent Google images (2017 to 2019), indicating that those dams are still in existence, although no information is available on the eventual damage they could have suffered during the numerous earthquakes which have occurred since their construction. Another earth dam built in that period – El Sauce dam (15m high) near Llolleo coastal town – was not identified and probably also failed in some of the big earthquakes that have hit the area of San Antonio port. It should be noted that before 1928 there was no construction equipment available to guarantee adequate soil compaction, and that soil mechanics was not yet a developed engineering discipline. At the same time most of these dams had been operated by agricultural associations, without external supervision or inspection, and not all of them had been provided with the adequate level of maintenance as well as the necessary repair works needed after strong earthquakes. Also, during periods of drought – which have become more frequent throughout the decades – some of these private water irrigation reservoirs had been abandoned for long periods of time. Consequently, it should not be a surprise that only a part of them have been able to remain operative over almost a century or more.


Catapilco dam is an earth dam with a central impervious core. Originally 13m high, it was raised to 15m in the 1970s, with a crest length of 1800m and 8Mm3 original reservoir capacity[11]. The construction of this dam began in 1853, and was completed in the period 1856-1859. This 171 year-old dam, the oldest registered in the country, was still in operation by a local irrigation association until a few years ago when operation of this reservoir was interrupted by extreme sedimentation. The removal of 250,000m3 of sediment allowed for the recovery of part of the original reservoir capacity. Work started in October 2017 and was completed in June 2018 and also included some repair work to the upstream slope and placement of rip rap on the dam slopes. The strong earthquakes of March 1965 (M = 7.4) and July 1971 (M = 7.8) could have produced some minor damage, which is probably the reason for the repair work carried out in 2017.


Vol XXXI Issue 3


DAM ENGINEERING


195


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