Vízügyi Közlemények, 1969 (51. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(48) exceed the value of 10-' metre/sec, yet the removal of the diaphragm wall should present no difficulties. Gravel- and soil concretes are uneconomical for this purpose if a suitable clay soil is available in the vicinity of the construction site. Simple dumping of the coarse clay soil into the slot is the cheapest solution, but then low thixotropy is required. The experiment performed at the site of the future Kisköre Barrage in sandy soil has been demonstrated by the samples taken to be entirely successful, since the core samples showed permeabilities ranging from 7-109 to 1-108 metre per second. The granulometric curve of the clay dumped into the slot is illustrated in Fig. J. The index of plasticity was 25.4%- Settling of the dumped clay in the slot continued for about two weeks, whereafter construction of the connecting slot section (panel) could have been started in all probability. The cost of clay filled into the slot was in the present case from 3 to 4% of plain concrete. Overall costs of the clay diaphragm wall amounted to about 400 Ft/sq.metre. Since the method seems to have many potential applications, including underground reservoirs, it appears worth while to repeat these experiments in another type of subsoil.