Refinement of the design models for evaluating the stress state of the Sayano-Shushenskoe hydrostation dam with consideration of the data of on-site observations

Abstract

During the 30 years of designing, constructing, and initial operation, the Sayano-Shushenskoe hydrostation dam has been repeatedly calculated and experimentally investigated for strength by various methods under various premises. Such a thorough and long calculated substantiation is due to two reasons. First, the Sayano-Shushenskoe dam is a unique structure constructed at the limit of the capabilities of the material (concrete) and structural members. The two-dimensional design models of the 1970s, when intense designing was being carried out, were imperfect and could not reflect many features of the static behavior of the structure. Only in the second half of the 1980s, when three-dimensional design models entered practice and made it possible to take into account the inelastic behavior of structural members, did the real possibility of a reliable calculated substantiation of the strength of the dam appear. Second, during construction there were deviations from the design sequence of constructing the dam which had a substantial effect on the formation of its stress-strain state. As a result of this, the data of on-site measurements during initial operation of the dam revealed a number of discontinuities in the dam -foundation system not predicted by the design calculations: decompression of the rock under the upstream shoulder of the dam and horizontal cracks of great depth and length in the body of the dam. Discontinuities of the dam and foundation led to a considerable increase of seepage discharges, both organized, into the drainage system, and unorganized. Suppression of water shows in the body of the dam required repair -injection of special grouts into the cracks that formed [1]. The occurrence of horizontal cracks that "cut" the cantilever as well as decompression of the foundation rock beneath the upstream face of the dam led to a decrease of the rigidity of the dam in the cantilever direction and to an increase of stresses in the arch zones of the dam. Repair also affected the stress-strain state of the damfoundation system.The aforementioned circumstances required detailed static calculations with refinement of the design models. Each design model and factors taken into account in the calculations had their own limitations and, naturally, could not reflect all features of the behavior of the structure. However, the change from relatively rough two-dimensional calculation schemes that schematized the behavior of the materials of the dam and foundation as an elastic linearly deformable shell to a sequence of calculations modeling the real scenario of constructing and loading the dam within the framework of three-dimensional inelastic design models taking into account the occurrence and development of discontinuities in the dam -foundation system made it possible to reduce substantially the difference between the results of static calculations and data of on-site observations.A brief review of the stages of investigating the stress-strain state of the Sayano-Shushenskoe dam and a brief characterization of...