Vízügyi Közlemények, 1972 (54. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(59) During the congress the 5 subjects were discussed in 3 groups of questions; a symposium and a special meeting were held. The subjects on the agenda included irrigation and drainage in deltas, riparian and low areas, the use of plastics in irrigation and drainage practice, the application of automatic equipment in the operation and maintenance of irrigation and drainage systems, the factors affecting river regulation, and the amelioration of flood plains. At the special meeting the fundamental measures promoting the introduction and improvement of irrigation and drainage projects in developing countries were discussed, while the symposium dealt with the design of water management projects with special regard to irrigation, drainage and flood control. On these subjects 124 papers were submitted and the number of participants attained round 800. '2. Papfalvy, F., Civ. Engr. : Research into the density of earth structures in hydraulic engineering (For the Hungarian text see pp. 326) As the result of several years of research new draft standard specifications have been compiled on the density of eartli structures in hydraulic engineering. The fundamentals thereof were provided by the investigations described in the paper. By laboratory tests permeability vs. density relations were established lor different soils. These relations were found to be affected for cohesive soils also by the moisture at compaction ( Figs. 1 — 3). A fair correlation was found to exist between the combined volume ratio of solids and the moisture at placement on the one hand, and the permeability coefficient on the other hand (Fig. 4). In the second stage of tests the influence of cycles of drying and wetting was studied. For granular soils this effect proved negligible, but in cohesive soils it was found to cause a considerable increase in permeability. Field measurements were performed using nuclear density- and moisture probes on 8 flood levees, 6 reservoir embankments and 5 canal dikes (Fig. 6). The method of data processing is illustrated in Fig. 7. Typical data have been compiled in Table 1. Considerable heterogeneity was experienced especially in flood levees, while canal dikes were rather loose. The density of reservoir embankments was rather high and uniform. In the new draft specifications earth structures in hydraulic engineering are classified according to importance, type, structure and dimensions, and densities are specified for different soil types. 3. Bogárdi, ]., Br. Engr. and Szentgyörgyi, G., Civ. Engr.; Soil stabilization applied for slope lining (For the Hungarian text see pp. 338) In soil stabilization local soils arc mixed with an appropriate binding agent for attaining the desired strength or sealing properties. One of the major fields of soil stabilization in hydraulic engineering is the construction of linings serving the purposes of sealing and erosion control. In earlier studies Ihe soil mixtures prepared by stabilizing the soil types in Fig. 1 were examined. The field test described was aimed at the stabilization of a levee slope in typical aeolian sand soil (curve D in Fig. 1). The technology of construction used for the stabilized soil slope lining consisted of preparing the mixture at a nearby mixing plant, transportation to the site, placement on the slope, compaction and curing (Figs. 2 to 11). For stabilization 5% by weight cement Type С 500 and 10% by weight fly ash showing an indifferent chemical reaction were added to the local soil. Over short sections the additives consisted of 10% by weigth cement of Type С 500 and 5% by weight hydrated lime. Which of the solutions is economically superior to the other will depend on their respective durabilities. ï. Varga, Gy., Civ. Engr. : Control oi aquatic plants in England (For the Hungarian text see pp. 349) Based on experiences gained during a study tour, the methods used in England for controlling aquatic weeds are described. The problems arising in the areas of the Avon and Dorset River Authorities in South-England are outlined, together with the solutions found to these (Fig. 1). The relevant research activities at the River Laboratory, Freshwater biological Association are introduced.