ВОПРОСЫ РЕКОНСТРУКЦИИ КРУПНЫХ КАНАЛОВ И ОЦЕНКА ИХ ЭФФЕКТИВНОСТИ

Abstract

Purpose: to define the efficiency of large irrigation canals on the example of the Donskoy main canal and the Bolshoy Stavropol canal during their reconstruction. Materials and methods. The use of geocomposite materials is of interest to creating combined linings of large canals. A geocomposite anti-seepage structure made without a protective layer at the bottom and part of the slope and a concrete-film element in the zone of wave and ice impact is considered. The application of such a combined lining makes it possible to reduce the cost of the anti-seepage screen, to shorten the construction time, to reduce the canal roughness and to increase its water-carrying capacity. The method of hydraulic research is based on the field data of the Bolshoy Stavropol and the Donskoy main canals for average and maximum values of hydraulic parameters. In particular, it was necessary to determine the roughness coefficients of the canal in the area between the sections. Results. A feature of the reconstruction of the most dangerous sections of the Donskoy main canal is the close location of the groundwater level to the surface, which leads to the transition of free filtration to a banked-up one. According to the results of calculations, the total losses are 13.7×10³ cubic meters/day in the section 57–70 km, and with canal lining – 0.504 cubic meters/day, which is 2.09 times less than with banked-up filtration in the earthen bed. Conclusions. The most effective types of linings with the use of geocomposites which, as shown by field surveys, are reliable combined coatings, are presented. Anti-seepage facilities made of concrete and reinforced concrete have high impermeability, though at the same time they are destroyed over time under the influence of water and freezing-thawing processes.