Full-scale observations on the Bukhtarma hydroelectric station dam during the erection and operation periods

Abstract

1. The formation and nature of variations in the temperature conditions of a high-mass-concrete dam are governed by several factors of a design and construction, technical, and climatic nature. Natural cooling of the inner zones of this type of dam is very slow in the absence of expansion joints. Even under severe climatic conditions it continues for not less than 4–5 years. With a moderate section thickness (on the order of 10–12 m), expansion joints are an effective means for cooling the mass concrete, accelerating the cooling process on the inside by a factor of 3–4. 2. Observations on the Bukhtarma dam indicate that, with correct design and the observance of a set of design technology measures, construction of a mass concrete dam is completely feasible under severe climatic conditions without appreciable cracking, even in the absence of artificial cooling of the concrete masonry. 3. The measured total stresses in the concrete are governed mainly by the temperature stresses. It is practically impossible to establish what proportion of the total stress is due to the external load. 4. Expansion joints between sections in contact with the tailrace are an effective means for reducing the seepage uplift on the base of the dam. They almost completely absorb the excess uplift under a large part of the dam. 5. The nature and extent of the joint opening between sections are governed mainly by temperature variations in the concrete. 6. The results of the observations point to the completely satisfactory condition of the Bukhtarma hydroelectric station dam. Uplift on its base is either substantially less than the design value (river bed sections) or does not exceed it (shore sections). There is no hazard therefore as regards stability.