The challenging structural integrity of dams in cold climates

Abstract

The design of concrete dams for cold climates has its specific features. Particularly, the operation of dams is characterised by openings of horizontal construction joints on the downstream face due to significant temperature differences over the winter period between the downstream surface and the interior of the dam. The opening of joints increases further due to the changes in the thermal properties of concrete as it freezes. The effect of thermal stresses may induce the growth of tensile stresses on the upstream face because the dam decreases its profile. Thus, there is a problem of the effectiveness of reinforcement of the dam's downstream face. Numerical models that were developed made it possible to evaluate the strain state of a typical cross section of a gravity dam by (i) considering changes in the properties of concrete as it freezes; (ii) excluding changes in the properties of concrete; and (iii) considering changes in the properties of concrete plus reinforcement of the dam faces. As a result of this research, it has been possible to assess the actual stress-strain state of the downstream face of the dam (the average depth/width of joints openings) and evaluate changes of concrete properties at subfreezing temperatures.