The underground position of the hydroelectric and pumped storage power plants has become considerably widespread, mainly in the rock. The paper presents a brief description of a number of existing, under construction and planned underground power plants in the USSR. The.sizes and significance of such structures demand a complex analysis which involves analytical technique, modelling, in-situ investigations, and which takes into consideration the experience gained in construction and operation. principal requirements are formulated for the components and the precision of the geological survey which should pro- vide information on the strength and deformability of the rocks, the systems of joints (Special attention should be paid to the tectonic joints adjacent to the cavern), and of the initial state of stress of the rock mass. The final stage of the studies is both the in-situ measurements of the cavern contour displacements and of the anchor forces, and the analysis. The statements mentioned in the paper are illustrated with specific examples of the powerhouse caverns investigation.
Die unterirdische Anordnung der Maschinenkavernen fuer wasserkraftwerke und pumpspeicherwerke hat sich hauptsachlich in Felsgesteinen immer starker durchgesetzt. Im vorliegenden Bericht werden einige in der UdSSR im Betrieb stehende, im Bau befindliche und projektierte unterirdische Maschinenkavernen kurz beschrieben. Wegen der grossen Dimensionen und der wirtschaftlichen Bedeutung solcher Bauwerke ist eine komplexe Betrachtungsweise unter An- Wendung von Berechnungsverfahren, Modellierung, in-situ-Versuchen und unter Berucksichtigung der langjahrigen Erfahrungen im Bau und Betrieb erforderlich. Es werden grundsatzliche Forderungen an die Zusammensetzung und Genauigkeit der ingenieurgeologischen Erkundungen zusarnmengefasst, die ueber die Festigkeits- und Deformations-eigenschaften der Gesteine, Kluftsysteme (unter besonderer Beachtung der tektonischen Kluefte in der Nahe der Maschinenkaverne), den natuerlichen Spannungszustand des Felsverbandes Aufschluss geben muessen. Der Sachverhalt des Berichtes wird an einigen konkreten Beispielen der untersuchung der Maschinenkavernen fuer die Wasserkraftwerke klargelegt.
Une disposition souterraine des centrales hydroelectriques et des centrales à accumulation par pompage s''est repandue largement, surtout quand il s''agit des terrains rocheux. Dans le rapport les auteurs donnent une breve description de quelques usines souterraines, deja mises en service, à construire et à projeter en URSS. De grandes dimensions et l''importance de tels ouvrages demandent une analyse complexe, qui comporte des methodes theoriques, modelisation et investigations in situ et qui tient compte de l''experience, acqUise pendant la construction et l''exploitation. Les auteurs formulent des exigences essentielles, concernant la composition et la precision de la reconnaissance du terrain qui doit aussurer l''information sur la resistance et la deformabilite des terrains, sur le systeme de joints (une attention essentielle doit etre pretee aux fussures tectoniques à proximite des cavernes), sur l''etat de contrainte initial du massif rocheux. L''expose est illustre par d''exemples concrets relatifs aux etudes des cavernes.
A number of various large under ground workings intended for Accommodation of machine halls, transformer halls as well as of gate chambers of hydroelectric power plants in a variety of geological conditions has been constructed or is at present under construction in the USSR.
Recently the underground machine hall of the Inguri hydroelectric power plant, 127 m long, 22 m wide and 51 m high, has been put into service (Maysuradze & Potskhoveria 1977, 1978). The machine hall is situated in jointed water-bearing limestone and covered with a rein- forced concrete vault, 1 m thick, on which crane beams are suspended.
In the diversion and spillway Tunnels of the Nurek hydroelectric power plant large underground gate chambers (for permanent, emergency and repair gates) are provided (Iliushin 1977; Gurtovnik, Shuten-kov, Mel''nikov 1980). The chambers are 25 m high, 14 m wide and 45 m long and are spaced at 52 m intervals between centre-lines. The chambers are situated in interbedding sandstones and aleurolites of medium hardness and the rock mass around the chambers is rock-bolted.
The underground machine hall ofthe Ust-Khantaisk hydroelectric power plant was built under severe climatic conditions of the North,in dolerite of large-block structure (Kelmi & Vittenberg 1975). Theclear span of the machine room is24 m, the maximum height - 48 m,the length - 148 m. The workingwalls are rock-anchored, the vaultis of reinforced concrete.
