Stress-Strain State of Rockfill Dam Concrete Face Due to Temperature Impact During Reservoir Impoundment

During the reservoir initial impoundment, a rockfill dam concrete face maybe subject to intensive thermal effect. Thermal stresses may considerably change the concrete face stress-strain state (SSS) and induce crack formation in it. With the aid of numerical modeling the author studied the concrete face thermal stresses and deformations for three alternatives of temperature distribution along the face thickness. It was shown that the character of temperature distribution plays an important role in formation of the face thermo-stressed state. At uniform cooling (or heating) due to rockfill low stiffness the face can partially compensate temperature deformations and thermal stresses. Thermal stresses makeup only 15÷30% of the potential ones in constrained conditions. More dangerous is the case of non-uniform distribution of stresses: it causes the face bending deformations. Stresses from bending deformations actually are not compensated. Combination of linear and bending deformations causes high thermal stresses in the face, which may become the reason of crack formation in the face. To provide the face favorable thermo-stressed state without impact from bending deformation sit is necessary to execute the impoundment of the reservoir during a long period. At designing rockfill dams with concrete faces it is necessary to take into account the fact that the less is the face thickness the more is the value of thermal stresses caused by uniform cooling (heating). It is reasonable to revise the recommendations for assigning the face thickness.