Consideration of moisture effects on the upstream face of concrete dams

Conclusions

• 1. Investigations of the saturation of concrete of the Sayano-Shushenskoe dam showed that during five years of operation of the structure moisture penetrated into the concrete to a depth of 4–6 m, and the maximum change in the moisture content of the concrete of the upstream face was 1.5%. The moisture-induced strains at a depth of 0.5 m from the upstream face reached a value of 4.5–5.5×10⁻⁵ and at a distance of 4.5–5 m a value of 0.6–1.0× 10⁻⁵. The change both in the depth of penetration of moisture into the structure and in the degree of saturation occurred most intensely during the first 1–1.5 years after a rise of the head.

• 2. Calculation of moisture-induced stresses on the basis of the data of on-site investigations of the moisture content and moisture-induced strains with the use of the physical and mechanical characteristics of concrete determined under laboratory and on-site conditions showed that compressive stresses, which reached 0.95–1.52 MPa, occurred on the upstream face of the dam. The width of the zone of compression is 3–4 m for concrete located below the seasonal drawdown of the reservoir and up to 2 m in the zone of the variable water level.

• 3. Consideration of the additional compressive stresses on the upstream face of the Sayano-Shushenskoe dam during the 1982 flood made it possible to raise the elevation of filling the reservoir and to increase the production of electric energy by 127 million kWh.

• 4. A generalization of the results of investigating saturation of concrete in the zone of the upstream face of the Sayano-Shushenskoe dam and also of the additional data obtained at the Krasnoyarsk and Zeya dams made it possible to establish a general regularity for determining stresses occurring on the upstream face of dams of various types due to swelling of concrete, which can be recommended for inclusion in SNiP 2.06.06-85 “Concrete and Reinforced-Concrete Dams.”