Vízügyi Közlemények, 1970 (52. évfolyam)
4. füzet - Rövidebb közlemények és beszámolók
(60) 1. Gates in flood, levees, which are required to ensure complete watertightness. 2. Intake gales of irrigation and fisheries, further the delivery-side gates in drainage pumping stations, lor which the rate of allowable leakage must be determined separately. .'5. Other gates, where watertightness is not related to economic interests. Field investigations on standard gate designs have revealed the following facts: 1. There is no standard gate design available which would meet the requirement for perfect closure imposed in group 1. For this reason the development of a new design is recommended, the design principles of which are listed. For the purposes of group 2 the gate types involving wedge closing elements on four sides meet the requirements from among the standard designs. For gates belonging to group 3 the existing standard designs are suitable. For classifying closing elements the concept of the specific leakage coefficient is introduced and the method of its determination is descrihcd. This method has been used to compute the upper limit of the specific leakage coefficient at q st = = 0.347 Xl0~ 3 m 3/ 2/sec, the upper limit average clearance between the gate and the frame was found to be ay = 0.16 mm. In conclusion specifications are suggested for classifying gates with respect to watertightness. tíogárdi, I., Civ. Engr., Ph. D.: Seepage control by soil stabilization in loess soil at Debrecen (For the Hungarian text see pp. 385) The actual permeability of loess soils in their original condition may be greater by several orders of magnitude than the value observed on a sample compacted under laboratory conditions. Experiences gained in roadbuilding indicated the advisability of efforts aimed at the realization of sealing layers by stabilizing the typical soil type of the Debrecen loess region (East-Hungary, east of the Tisza River). The original permeability coefficient of the loess soil is A , = 4 + 10~ 2 cm/sec. To this soil pure cement, a combination of cement and fly-ash, further bitumen was added for stabilization. Of these cement stabilization proved most effective, as it made possible the development of the required strength, a permeability lower than Ar-—106 cm/sec and good frost resistant properties. Owing to the typical granulometry of loess soils stabilization using bitumen, or fly-ash failed to produce the necessary frost-resistance. From these results it is concluded that cement stabilization may be applied successfully on the loess soils east of the Tisza River, with a coat of sprayed cut-back bitumen, applied at the rate of 2 to 4 kg/sq.m.
