Effect of sequential erection and loading on the stressed state of gravity dams

Conclusions

• 1. Erection of a dam of the Bratsk type in stages is advisable. The volume of the first concrete should, according to experimental investigations, constitute 43% of the total volume of the dam section, in which case the normal stresses σ_y on the entire pressure face exceed the normative value σ ^B₁ ≥0.25γH (see SN-123-60). It is stipulated that 65% of the concrete volume in the section will be placed when the reservoir is filled after complete erection of the dam.

• 2. In a dam of the Ust'-Ilimsk type the values of the combined compression normal stresses are close to zero for erection by stages (see variants I and II in Table 1). To ensure a reserve of these stresses σ_y≥σ ^B₁ it is necessary to place in the first stage 67% of the total volume of section concrete, which gives an advantage of only 6–8% as compared with the usual erection procedure. The reduction in the volume of the first concrete placement leads to a reduction to σ_y<σ ¹_B in normal stresses on the pressure face. The possibility of such a reduction must obviously be substantiated by appropriate design and technological measures.