Vízügyi Közlemények, 1962 (44. évfolyam)

4. füzet - IX. Könyvismertetés

(28)* ii. PLACEMENT OF HYDRAULICALLY CONVEYED MATERIAL By D. Pásztor and A. Szivák (For the Hungarian text see pp. 192) Hydraulic material conveyance and the placement of hydraulically conveyed material is described in the paper with special regard to hydraulic construction. Materials that can be conveyed hydraulically are generally considered in Chapter I, while more attention is devoted to the material of hydraulic earth structures, as well as to various other materials which are conveyed by hydraulic methods to the place of their eventual disposal. The methods applicable for the placement of hydraulically conveyed material are detailed in Chapter II, whereby the construction of embankments is considered separately from large surface fillings. Embankments can be constructed by half-sided silting, where the placement of the fill is commenced and continued under the protection of the pilot dyke, respectively auxiliary dykes, the latter being constructed from the material already deposited. With this method the coarser fractions of the material are deposited along the dyke, above the watersurface, while the finer fractions in the settling pond (Fig. 1 ). With the full-section silting method material is deposited from both sides, along the pilot dykes constructed along both toe lines of the embankment. The auxiliary dykes are also constructed along both sides and the settling pond is formed at the embankment axis (Fig. 2). In this case the coarse particles depositing along the dykes form the structural frame of the embankment, while the fines at the center act as the impermeable core. The combined silting method has been developed as the combination of the abovementioned ones, while in the case of the coffered method of construction the solid content of the slurry is settled in caskets formed of pilot dykes at the place of the earth structure to be built. In the case of area filling the half-sided silting method is practicable for disposing of industrial wastes (Fig. 5), while for fine-grained materials the radial silting method should be used. Technological methods of hydraulic construction are described in Chapter III. A prerequisite for a good embankment is Lhat the fill material should be homogeneous and uniform in any longitudinal profile. This requirement should be satisfied by the method of construction. Embankments built at an earlier date do not comply with this specification, the corresponding construction method having not been developed then. In order to prevent longitudinal classification slurry is discharged from the pipeline not only at the underside of the pipe, but also through openings at the side and directed gradually downward. The composition of the slurry discharged at individual points can 'be made approximately uniform thereby (Fig. 8). A more practicable solution is to install a contraction into the pipeline at every point of discharge (Fig. 9). Distribution by troughs placed under the slurry line is a solution rather frequently encountered (Fig. 10) but this is very expensive. In the trestle system the pipeline is supported on trestles located at the internal, or external side of the embankment (Fig. 11). A modified alternative of this system is, where the pipeline is laid on the pilot dyke, and only the lateral pipes must be extended in pace with the increasing embankment (Fig. 12). The so-called trestle-less system is known as the most up-to-date solution (Fig. 13), where the pipeline is at the top of the embankment being built, and can be extended, shortened, or raised according to the rate at which silting proceeds. An embankment of approximately uniform cross section can be realized by the mosaic construction method, where the slurry line is placed at the lop of the embankment with numerous discharging openings (Fig. 14). If it is necessary to classify the solid material before placement, this can be performed expediently by a hydrocyclone.