Concrete dam of the Bratsk hydroelectric station

Abstract

The Bratsk concrete dam is a gravity dam with expansion joints, with a slope of the downstream face 1:0.8 on a rock foundation composed of dense, poorly permeable trap rocks [i]. The Bratsk dam is the railroad crossing for the Baikal-Amur Mainline (BAM) and highway trossing for the Bratsk industrial region.Monitoring and Measuring Equipment. There are morethan 3000 pieces of monitoring and measuring equipment (MME). It consists of 760 height marks (together with the powerhouse), 27 direct and reverse plumb lines, 120 visual gap meters, 1800 sensors in the concrete, and 330 piezometers in the foundation (Fig. I) [4].During operation the composition of the observations and MME were constantly changed, improved; the number of height marks and piezometers was increased, the plumb lines and transit lines were improved; new sensors were installed in the concrete in place of those that failed(PTS 60 thermometers, remote strain gauges in the contact zone of the foundation, etc.). Seisometers were installed in 1986 for observing dynamic loads.The composition of the MEE is rather extensive, but has a substantial shortcoming: all sensors in the concrete are concentrated in three nonoverflow sections. The spillway and powerhouse sections do not have such sensors.The upper pool level during 1968-1986 varied within 122-112 m; three times during this period it was close to the normal pool level (NPL), in