Vízügyi Közlemények, 1971 (53. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(41) not be compensated by the raw water pumps, but rather by the size of the basin storing the treated water. The capacity limits of types recommended for use in Hungary have been determined 011 the consideration that the number of clarifiers at a treatment plant should be at least two for reasons of safety, but it should not exceed four, if possible. The following arrangements have been suggested accordingly : a) For 5 to 15,000 cu.m/day capacity Candy basins. b) For 10—30,000 cu.m/day capacity uniform-flow, e.g. Corridor-type basins. c) For 30 — 80,000 cu.m/day capacity single-level, horizontal-flow basins and the design developed at the Consulting Enterprise for Civil Engineering (MÉLYEPTERV), Budapest, Hungary.' d) For 40 — 200,000 cu.m/day capacity Pulsators. e) For 60 — 160,000 cu.m/day capacity two-level, horitontal-flow basins. f) For 40—250,000 cu.m/day capacity Cyclo floe type clarification in combinanation with the basin design developed at the Consulting Enterprise for Civil Engineering (MÉLYÉPTERV), Budapest, Hungary. BRIEF PUBLICATIONS AND REPORTS 1. Dr. Gasser, M. M., Civ Engr. : The emergence of the phreatic line from earth embankments (For the Hungarian text see pp. 205) Theoretically, the seepage velocity at the point of emergence from the slope of an embankment may assume an infinitely high value. This phenomenon may in many instances adversely affect the stability of the embankment and lead to its failure. The point of energence of the phreatic surface on the slope of the embankment has been determined with the help of experiments performed using a Hele—Shaw model ( Figs. 1 and 2

). Sixteen different embankment cross-sections ( Fig. 3) of uniform material have been examined in order to determine the effect of embankment shape on the position of the phreatic line. The position of the point of emergence was found to depend on the gradient, as well as on the upstream and downstream slopes of the embankment (Table II). The base width of the embankment proved to be of no appreciable influence on the height of emergence, which was found to increase in direct proportion with the increase in gradient, to increase slightly as the downstream slope becomes steeper and to reduce as the upstream slope increases. The following notations have been used in the paper: H

x = the upstream depth, H„ = the downstream depth, H = the height of the point of emergence of the phreatic line, II = the differential head = H

1—H„, i/

0 = the height of the embankment, a=the height of the seepage front = #

3 —© = the angle of the upstream slope, @ = the angle of the downstream slope, m = cotan ©, m = cotan 0, i = the crest width of the embankment, L = the base width of the embankment, T = lhe thickness of the permeable layer, A- = the permeability coefficient. 2. Dr. Hamvas, Ferenc, Civ. Engr.: The uplift force acting on hydraulic structures (For the Hungarian text see pp. 212) The changes in the uplift force acting on hydraulic structures founded of permeable alluvial soils must be taken into consideration in dimensioning. The causes responsible for the difference in the uplift force over the value determined by the static approach are: — the particular properties of water and the soil particles (Fig. 1 ), — the transition between the hydrostatic and the hydrodynamic uplift force ( Figs. 2 and 3), — the impervious contact between the structure and the soil particles (Fig. 4), — the structural changes clue to the action of the seeping water (Figs. 5 and 0

), such as internal suffosion, contact suffosion and internal sealing, — the settlement of structures (Figs. 7 and S

), — the sealing due to sediment (Fig. 9),