The Rogun hydro project [i] --a multipurpose irrigation and power facility --is the uppermost s=age of the Bakhsh network and is located 70 km upstream from the Nurek hydroelectric plant.The plant's rated capacity for six units is 3,600,000 kW, its average annual generation of electric power is 13 billion kwh, and the full and useful volumes of its reservoir are 13.3 and 8.6 km s, respectively.In geologic respects, the segment containing the site is a single tectonic block bounded by the second-order Ionakhsh and Gullzindansk fractures and the deep flrst-order Vakhsh fracture. The section is subject to nlne-polnt earthquakes.The bedrocks --Lower Cretaceous sandstones, siltstones, and argillltes--beyond the weathered zone are distinguished by hlgh-strength properties, regardless of the appurtenances to this or any other blocks; in the saturated state, the average compressive strength under a unlaxially applied load reaches 105 MPa for the sandstones, and 60 MPa for the siltstones and argillites.The entlre mass in the vertical profile is divided into four zones according to its physicochemlcal and seepage properties as a function of embedment depth and the extent of the effect of weathering and unloading processes on the rock mass: I --zone of severe weathering and unloading; If--zone of weathering and unloading; Ill--zone of unloading; and IV --zone of virtually unchanged rock.The following comprise the Rogun hydro project (Fig. 1): structures of a steady-head facility with an underground powerhouse and open distribution device, construction tunnels, and an underground-type operational sluice, a structure for protecting the salt stratum from scour in the foundation bed of the dam, structures to protect the agricultural complex on the Obi-Shur dry bed, and service tunnels.The structures of the underground complex, whose overall length of excavation reaches 60 km, occupy a speclal place in the design of the Rogun plant~ In designing the underground structures for the plant, we encountered many problems caused by the unique parameters of the structures, and by the complex natural conditions of a portion of the construction. To resolve these problems, we conducted the necessary designresearch work, which resulted in new progressive solutions that produced a positive effect expressed as the technical feasibility of the problem solution, savings in construction materials and labor outlays, a reduction in construction costs and time, improvement in the operational reliability of the structures, etc.Construction Tunnels. The use of gates that operate under heads of up to 200 m in the construction Gunnels makes it possible to discharge from one tube (third stage) of the construction tunnel.Routing of the construction tunnels from the left to right bank along the shortest path with a transition to reinforced-concrete pipes through the river channel, and also the combination of these tunnels with the plant's discharge tunnels (Fig. 2) made it possible to reduce the overall length of both tunnels by 1500 m. With this routing,...

Water exerts a decisive effect on the further economic and social development of the productive forces of Central Asia. In connection with the need for expanding the irrigated area, there arises the problem of ensuring water supply. Basic additions to the irrigated land are to be made in the expanses of virgin soil in the Amudar'ya River basin. In the near furore, the diversion of water for irrigation and other needs from the Amudar'ya River and its tributaries will increase to 59 billion m 3 per year, which represents about 90% of the Amudar'ya runoff at the Kerki site. These water needs are insufficiently satisfied by the Nurek and Tyuyamuyunsk reservoirs, now under construction, which are intended for seasonal flow regulation and ensure the utilization of only 52 billion m 3. The increasing water need for 59 billion m 3 can be economically and expediently satisfied through deeper flow regulation of the Amudar'ya River system. The resulting shortage of 7 billion m 3 is to be covered in accordance with the general scheme for utilization of the Amudar'ya River by constructing the multipurpose Rogun hydraulic development on the Vakhsh River.Placing the Rogun hydraulic development in operation will make it possible to organize the effective control of the Amudar'ya River according to the required regimes, and to expand the irrigated area. In addition to flow regulation for irrigation, this hydraulic development will also supply cheap electric energy, with an annual output -,k/,f"..- Fig. 1. Plan of hydraulic development. 1) Dam; 2) flu-st-level diversion tunnel; 3) second-level diversion tunnel; 4) plant intake; 5) powerhouse; 6) transformer chamber; 7) transformer tunnel; 8) cable tunnel; 9) switching station to switchyard; 10) tailrace tunnels; 11) 500-kV switchyard; 12) emergency spillway; 13) surface intake; 14) deep intake; 15) installations for protecting rock salt against scour, which include holes for hydraulic protection and for grouting and chemical stabilization of the rock.Translated from Gidrotekhnicheskoe Stroitel'stwo, No. 4, pp. 10-13, April, i975. 320

A meeting of the joint council of Ail-Union Planning, Surveying, and Scientific-Research Institute (Gidroproekt) on underground structures for evaluating the current state of the underground machine hall under construction at the Rogun hydroelectric station was held at the end of 1990. The reason for raising the question was the numerous negative features in the state of the workings of the machine hall (MH) observed both visually and by means of on-site measurements. The main points and results of analysis of the state of the MH and its causes examined by the joint council are given below. Description of the Object -Engineering-Geological Data, Main Designs, Predictive Evaluations. The object was already characterized earlier on pages of the journal [1, 2], and therefore only data about it needed for understanding the essence of the problem are presented below. The machine hall of the underground powerhouse of the Rogun hydrostation, designed by the Tashkent branch of Gidroproekt, is an underground working unique in size: span 21 m, height 70 m, length 220 m. Parallel to it, at a distance of 63 m at the axes, is an also rather large working -the transformer room (TR): span 19 m, height 37 m, length 182 m. In conformity with the design, in addition to functional transverse tunnel workings (busbar ducts, draft tubes), the rock mass enclosing the powerhouse is weakened by a number of auxiliary workings. The most significant with respect to effect on the stress-strain state of the MH are the access adit P-lb driven in the pillar between the workings of the MH and TR, parallel to them (Fig. 1), and the 12 x 20-m assembly chamber (AC) for assembling the shells of the penstocks of units 5 and 6. The set of workings of the powerhouse is located at a depth of more than 400 m in a single tectonic block bounded by active faults No. 1 (Ionakhsh) and No. 35. Within this block is also noted a lower tectonic disturbance, fault No. 70, extending at an angle of 45 ~ to the longitudinal axis of the MH.

The complex of underground structures of the Rogun hydroelectric station is unique not only in Soviet but also in foreign practice of underground hydrotechnical construction.The specific features of the structures are characterized by the parameters of the hydrostation and by the natural conditions of the zone of its site [i, 2].In a geological respect the zone of the site represents a single tectonic block bounded by several faults.The seismicity of the zone of the hydrostation, as of the entire region, is rated at intensity 9.Relative displacements of the walls are occurring along the sutures of the faults -the Ionakhsh and No. 35 --at a rate of 1-2 mm/yr.It is presumed that in the case of an intensity 9 earthquake the one-time displacement along the suture of fault No. 35 can reach 10-15 cm and along the Ionakhsh fault a few tens of centimeters.A characteristic feature of the rock mass of the hydrostation zone is the presence of high tectonic compressive stresses in it. The values of the vertical stresses exceed by a factor of 1.3-2 the stresses from the overlying rock stratum; the horizontal stresses exceed the vertical by a factor of 1.4-2.3.

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