Construction of the Dospat-Teshel complex of hydraulic structures in Bulgaria

Abstract

The Dospat-Tesbel complex of hydraulic structures is the first stage of the Vycha sequence, which in the future will consist of six hydroelectric schemes: Teshel, Devin, Tsankov Kamyk, Mikhalkovo, Antonivaanovtsy, and Y4ichim (Fig. 2). The composition of the structures of the Dospatteshel complex, a rockflll dam with a clay core (Fig. 1), forms an alpine reservoir with volume of 445 million ms. The topographic conditions of the dam site and the reservoir basin are favorable. In addition to the flow of the Dospat River, the reservoir collects, by means of a special diversion system, a part of the flow of the rivers Vyshcheritsa, Kanina, Bistritsa, etc. The upstream diversion with a diameter of 3.1 m has a total length of 16,220 m (tunnel 15,060 m and open channel, aqueduct, and siphon 1160 m). A large part of the tunnel runs through granite with a coefficient of elastic resistance of 300-1000 kg/cm s, and the last section is in limestones with evident manifestations of a karsL The head in the diversion increases from 6 atm at the inlet to 11 atrn at the surge shaft; the power-plant complex consists of a twochamber surge shaft with a diameter of four and height of 107 m, an underground chamber for two free-discharge butterfly valves, penstock with a diameter of 2. 6 and length of 560 m with a metal lining, a machine hall for two 30 MW units, and other auxiliary ~tructures.The collection system for diverting the flow of other rivers includes the Vyshcheritsa-Kanina diversion which collects the stream flow of the. Vyshcheritsa and Kanina rivers, tributaries of the Mesta River, in a volume of 74 million m3/year and directed to the Dospat River; the. Zmeitsa diversion which collects the flow of the Karadzha, Selimkhodzhovo, and Beldonovo rivers and delivers it to the main diversion; the Bistritsa diversion which diverts the flow of the Bistritsa River, a tributary of the Mesta River, into the Dospat reservoir in a volume of 21 million mS/year.After completing the Barutin, Lyava, and Dyasna diversions it will be possible to direct into the Dospat reservoir about 160 million m3/year through the main diversion of the Teshel hydroelectric power station which will operate here at a high head. For economic considerations the installed power at the Teshel hydroelectric power station is comparatively small; the generation of electric power is also small: 180 (first line) and 274 million kWh/year after completing the entire complex.The particular value of the complex of hydraulic structures is that the diversion of the flow of the Mesta river basin into the basin of the Vycha River will permit irrigating large areas of heretofore unutilized lands and at the same time will make it possible to create on the Dospat-Vycha sequence economicaily effective hydrnelectric 305 6 Fig. 1. Dosp.atDam. 1) Upstream cofferdam; 2) surcharge; 3) slope stabilization by large stone; 4)rockfill (angle of internal friction q = 35", unit weight ~ = 1.65 t/mS); 5) three-layer fiker; 6) clay core (a= 23 ~ ], = 2.0 t/mS); 7) grouting gallery; 8) surchar...