Vízügyi Közlemények, 1965 (47. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

<88) With the lining made in a total length of 61 km favourable experiences were gained. Although in the lining hairline cracks occurred, as a result of winter frost effects, yet watertightness did not change to a considerable degree. Unit price of the linings ranged from 49 to 102 Forint/sq. m. Experimental construction works were performed with three types of concrete shell canals: a profile assembled from flat plates, a paraboloid reinforced concrete section formed by bending, as well as a trapezoid reinforced cement profile were investigated. For making the canal profiles composed of flat plates the application of iron forms proved to be inadequate because of deformations. As to the units formed by bending, difficulties arose concerning sealing and joints. The relatively great costs of concrete shell canals had to be reduced by applying further modifications in technology. Л. B. Máté, civ. eng. : Manufacturing reinforced concrete pressure pipes by vibropressing. (For the Hungarian text see pp. 398) The first costs of reinforced concrete pressure pipes are considerably lower than those of steel pipes (Table 2), and besides, the production of reinforced concrete pipes requires less investment. In addition, r.c. pipes have the advantage of a longer duration of life and smaller friction losses. The first concrete pipes were made 100 years ago, while reinforced concrete pipes were manufactured at first by the firm Bonna at the turn of the century. Prestressed reinforced concrete pipes, and later spun concrete pipes are of more recent origin. The principle of vibro-pressing has been developed by Freyssinet, a wider use of the procedure, however, ensued through the Swedish firm Sentab. The Swedish patent was purchased by the USSR as well and today plants for manufacturing vibro-pressed pipes are established on the basis of Soviet designs, too. Manufacturing has been standardized and pipes of 518.5 cm length and of 500, 700, 900, 1000 and 1200 mm inner diameter are made (Table 3) with moulds that may be disassembled (Figs. 1, 2). The manufacturing process is represented in 10 stages in Fig. 3. Requirements concerning aggregate and reinforcing steel were strictly specified. The production of the plant concerned with prefabricating standard pipes amounts to 11,000 cu.m, which means a pipe quantity of 46,850 running metres. 5. L. Rákóczi: Experiences at the Hamburg Agency of the „Bundesanstalt für Wasserbau". (For the Hungarian text see pp. 407) The activities of the Seaside Agency of the Federal Institute for Hydraulic Engineering in West Germany are mostly concerned with practical investigations as regards development and maintenance of the sea-shore, tidal river estuaries, as well as ports and harbours. One of its most important scopes is associated with studying sediment transport, for which also luminescent and radioactive isotope tracers are used. A special attention should be devoted to the sampler applied by the Station for investigating bed material (Figs. 1 and 2). It may be desirable to introduce these types of examinations and methods in Hungary as well. REVIEWS 1. Activities of the European Association of [Water Protection. Reviewed by /. Holló. (For the Hungarian text see pp. 411) The Seventh Symposium of the "Föderation Europäischer Gewässerschutz" created in 1956 was held in Milan, with 160 reports sent from 10 countries. Unified investigation methods have been worked out and an international committee called into existence in order to develop these procedures. 2. Closure devices of the barrages built on the Pasvikelv River. Reviewed by E. Szabó after Procenko Ju. D. and Vasziljevszkij. (For the Hungarian text see pp. 412) Due to the severe northern climatic conditions prevailing on the Pasvikelv River traversing Finnish, Swedish and Soviet territories, it became necessary to