The influence of grouting contraction joints on the stress-strain state concrete dam during the filling water reservoir of Boguchan HPP

The monolithic of concrete gravity dams is one of the important features of their construction. As shown by field observations, almost all concrete dams have cracks in one way or another, and the successful operation of gravity dams in the presence of a large number of cracks indicates large reserves of their strength. As a result of the erection of a concrete dam by the method of column cutting, a structural joints is technologically provided for. The static work of the column in this construction scheme is not monolithic, the creation of monolithic concrete columns at the time of filling the reservoir is carried out by cementing these joints and in this case the dam can be considered a massive unified structure. For the best transfer of forces between the columns, as well as the subsequent qualitative unification of the said joints, a so-called keys is made in them. In the present paper, the effect of cementing of joints with keys on the stress-strain state of a concrete dam during the filling of a reservoir is considered. To determine the stress-strain state, the main loads and impacts are taken into account: own weight of concrete, hydrostatic pressure, filtration pressure, and seasonal temperature variation. For calculations, a typical section of the concrete dam of the Boguchanskaya HPP was selected. Analysis of field data for the opening of the joints of the concrete dam at the Boguchanskaya HPP showed that the conducted primary cementing did not fully allow the dam to be made monolithic. Thus, part of the joints, which emerges on the bottom face of the dam, was subjected to alternating temperatures of ambient air with a sufficiently wide amplitude. In connection with this, the periodic nature of the state of the joints appeared, namely, “closing-opening”. Calculations carried out within the framework of this work confirmed the seasonal nature of the joints, which allowed to check the stress-strain state of concrete columns in case of incomplete cementation and to give recommendations on further cementation of joints. Materials and methods: analysis of stress-strain state, finite element method. Results: the behavior of concrete column of a gravity dam is analyzed taking into account the incompleteness monolithic of inter-columnar joints by calculating the non-stationary heat conduction problem with subsequent determination of the stress-strain state of concrete column. Seasonal places of opening of inter-columnar joint were identified and their unevenness in the opening of the seam height was revealed. Conclusions: practical application of the methods used to take into account the real configuration of the fine seams of the performed calculations allows us to more accurately determine the stress-strain state of the concrete columns of the dam, as well as the effect of omonivation on the stress-strain state.