Staged construction of a rockfill dam is the way of regulating the reinforced concrete face stress-strain state

Introduction. Presented the approach to studies of the impact of a rockfill dam staged construction on the reinforced concrete face SSS. Experience in construction of reinforced concrete face rockfill dams (CFRD) shows that at perception of hydrostatic pressure the integrity of the seepage-control element may be broken. By the results of mathematical modeling it was revealed that the tensile stresses appearing in the face concrete may exceed concrete design tensile strength. The causes of appearing tensile stresses are bending deformations and the face longitudinal extension. The urgent issue is selection of the way of improving the stress-strain state (SSS) of the face to provide its safe operation as a seepage-control element. Materials and methods. The studies were conducted on the example of a 100 m high dam with the aid of numerical modeling. Two cases were considered: in the first case the dam was constructed in one stage, in the other in two stages. Rockfill is considered as a lineally deformed material, but computations were conducted for a wide range of the soil linear deformation modulus: from 60 to 480 МPа. Steel reinforcement was considered in the face. Results. Longitudinal stresses in a reinforced concrete face were compared for two cases of the dam staged construction. Analysis was fulfilled with determination of the longitudinal force and bending moment appearing in the face. The obtained maximum values of tensile longitudinal stresses in the face were compared for two cases. Conclusion. It was revealed that construction and loading of the dam by stages on the whole is favorable for the face stress-strain state. The second-stage dam weight transfers to the first-stage face the compressive longitudinal force, which permits decreasing tensile stresses in it. Bending moments in the face vary insignificantly and even may increase to some extent by value. Nevertheless, at dam construction and reservoir filling in 2 stages the maximum values of tensile stresses in the face concrete decrease, therefore, such construction sequence contributes to enhancing safety of the dam seepage-control element.