Multilevel schemes for the layout of temporary and permanent spillways are presently used in the construction of high-head hydrodevelopments.Such schemes, corresponding to the technical level attained by Soviet gate construction, provides the release of considerable flows over a wide range of heads up to 100-130 m. The number of levels of spillway structures at high-head hydrodevelopments can be reduced by using high-head gates.This can effect a considerable economy, especially in the case of spillway tunnels, since the cost of each level amounts to 10-20 million rubles.At present designs have been developed for deep, mainly vertical-lift and radial gates which can operate satisfactorily under heads to 200 m for opening areas of up to 30 m 2. However, if the temporary discharges during construction are great, the spillway is built with a large number of openings, which adversely affects the hydraulics and leads to an increase in the spillway face, rock excavation, and capital expenditures. Therefore, the need for creating high-head gates covering openings greater than 30 m 2 at heads to 200-300 m is quite pressing.
Future increase in the unit capacity of hydraulic turbines and in hydroelectric-station heads are making it necessary to increase in the turbine-penstock characteristic P x D (product of pressure and penstock diam.), which basically determines the required strength of the penstock material [i, 2]. For the penstocks of modern high-capacity hydraulic turbines, the strength properties of the usual low-carbon and low-alloy steels are practically exhausted because the shell thickness of turbine penstocks in this case reaches critical values (60-70 ram). A further increase in penstock wall thickness is associated with a reduction in the technological and brittle strength of welded joints and the reliability of welded construction, in general, also with a sharp increase in the labor required for assembly and welding work.
At present the wide introduction of high-speed methods of construction is underway in hydrotechnical construction along with an increase of the parameters of hydro developments. An increase of the parameters of hydro developments (Rogun, Khudoni, Kambarata, and other hydrostations) required the creation of new types of hydraulic drives, and high-speed construction necessitated a new approach to the design, manufacture, assembly, and start of operation of hydraulic drives.As is known, hydraulic drives for operating gates represents a complex multicomponent system consisting of an oil-pressure system, hydraulic operating and control panels, hydraulic accumulators, hydraulic cylinders and their support structures, control units, main pipelines, gate connection components, electrical equipment, etc.As a rule, only individual components of hydraulic drives undergo assembly and testing at the manufacturing plant, and the bulk of these works is performed during installation and startup at the construction site, which requires large expenditures of time on the part of highly skilled personnel and special equipment.
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