# Cracks in Arch Dams: An Overview of Documented Instances
## 2 Observational Data/Material: Summary of Case Studies
### Double Curvature Dams
In this respect, 57 joint meters were deployed and cracks in the crest gallery were supervised with crack meters. These cracks opened in winter and closed in summer when the concrete temperature was at its highest in the crest area of the dam. Additionally, some efflorescence was observed on the downstream face, especially near the concrete lifts at the top of the dam that were exposed to seasonal wetting and drying. _Quiebrajano_ dam (1978): The dam suddenly developed horizontal cracks in its connection to the base. During the revision performed in 1996, deformations and deterioration in the concrete were also visible near these cracks, as well as various cracks on the crest of the dam that were separated by a few meters from the joints. _Shuanghe_ dam (1992): While the reservoir was not yet in service, six vertical perforative cracks originated on the downstream face. These cracks formed in the central area of the dam height. Eventually, two of the cracks extended along the crest of the dam, and four of them spread toward the foundation. _Susueda_ dam (1968): After construction, it was not possible to perform the grouting of the joints under optimal conditions, resulting in the filling of enclosures in which hydration heat still remained to be dissipated. As a result, posterior openings of the vertical joints occurred as temperatures reached their cyclic equilibrium process. These openings had a greater impact on the levels of galleries 1, 2 and 3, which were concreted later. In 1988, thin, mostly horizontal cracking was observed, ranging from the upstream face to the gable of the upper gallery. As a consequence, the vertical joints were re-injected with epoxy resins. _Xiaowan_ dam (2010): During construction, numerous cracks originated in the dam structure. To monitor the behavior of the cracks and the concrete, joint gauges and extensometers were placed perpendicular to the plane of the cracks at different depths. The first crack was found after two years, almost parallel to the dam axis, in the 110.5 m inspection gallery. Subsequently, similar large cracks with an average opening of 1 mm were detected by probing. One or two cracks were found in nearly all sections of the dam, mostly located between 29.5 and 139.5 m elevation. _Xiioudu_ dam (2013): During the construction phase at height 245 m above the dam base, the cracks first started to emerge. For that reason, four real-time location systems were implemented at the corners of the 29 monolith 18 pouring block. _Zeuzier_ dam (1957): Since 1978, the dam deflects upstream. In 1979, severe cracks developed across the downstream foundation line at the same time as the contraction joints on the upstream face opened up, and cracks appeared in the corridors, shafts and crest of the dam. In 1982 and 1983, the dam was intervened by injecting epoxy resin into the cracks and contraction joints. _Zillergrundl_ dam (1986): During the first filling to a height of 175 m above the dam base, the elevator shaft was flooded, causing water to seep into the gallery area. Additionally, given the anisotropic permeability of the concrete, the downward-oriented hydraulic forces combined with the weight of the concrete generated a large crack in one of the dam blocks. To correct this, the crack was filled with epoxy resin and, subsequently, the load distributions were adapted to reintroduce a partial uplift pressure into the foundation joint. However, due to excessively high injection pressures, secondary cracks were created.