Characteristic features of the cap on the service spillway at the Bureya hydroproject and some results of its laboratory and field investigations

Abstract

Characteristic features of the cap on the service spillway at the Bureya hydroproject are examined. Some results of laboratory and field investigations are presented. Tests during passage of the 2009 spring flood indicated that the cap and its air-conducting system function in conformity with design requirements and results of its laboratory investigations.The cap on the spillway dam at the Bureya hydroproject [1] (Fig. 1) possesses the following characteristic features: -a large difference between heads on the crest residing at elevation 243.0 m with a normal backwater level of 256.0 m and forced backwater level of 263.4 m;-as a rule, passage of the basic design flow at the normal support level is ensured in conformity with Construction Rule and Regulation [2, Section 5.4.3]. Passage of a flow with a probability P » 5% of being exceeded is provided through the Bureya hydroproject at the normal support level; here, 9400 m 3 /sec is passed through the eight bays of the spillway. For passage of the 1000-year design flood, the elevation of the forced backwater level must be increased to 259.5 m;-the cap is configured on the basis of Kriger -Ofitserov coordinates for the head at the forced backwater level, the probability of the occurrence of which is extremely low. It is proposed, however, to use the spillway primarily when the elevations of the forced backwater level are close to the normal backwater level;