Vízügyi Közlemények, 1969 (51. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(45) CONSTRUCTION OF CIVIL ENGINEERING STRUCTURES BY MEANS OF JET SINKING By Ferenc Hallóssy, Civ. Engr. (For the Hungarian text see pp. 190) The objective of the present paper is to offer a practical guide for the construction of cut-off walls of reinforced concrete sheet piles and other vertical elements, or entire structures, by jetting, using water under high pressure for this purpose. Experiments and realizations by the author are described. In these experiments the liquid used for jetting was either lime-water of 1.3 g/cu.cm specific gravity, or a bentonite suspension of 1.06 g/cu.cm specific gravity. The paper is divided into five chapters. In Chapter 1, after a brief description of the method, the soils suitable for jetting work are classified, the possibilities for soil replacement and the uses (advantages) of the method are outlined (Figs. 1 and 2

). In Chapter 2 a detailed description is presented on the principles underlying this method. Special attention is called to the ,.double elements", which enclose the open sides of the contemplated structure in such a manner that after completion the upper portion of the sunk element (sheet pile, or wall) closing the opening (e.g., gate opening) of the structure can be removed without the necessity of disturbing the lower part of the element, which serves as a cutoff. The fields of application of the method are described subsequently, whe e the sunk element forms part of a structure (cutoff-, or wing wall), or constitutes an independent structure (shaft, well, basin, lock, etc.) or cut-off (e.g. in flood levees). Chapter 3 deals with the structural elements used in the method, namely sheet piles, their joints and mounting, the suspended watertight reinforced concrete sheet wall and its mounting, followed by the U-section vertical mantle elements and their mounting. Chapter 4 contains a description of construction methods, the fabrication of elements, the materials used for jetting, the necessary equipment, in particular the construction rig and its accessories. The performance of jet sinking operations and the grouting of joints is outlined in conclusion. In Chapter 5 the results of cost calculation are presented for two jobs of this type. THE GEOELECTRICAL METHOD OF SOIL-RESISTANCE MEASUREMENT IN PROSPECTING FOR MINERAL WATER CONTAINING MAGNESIA SALTS By János Gálfi, Geophysicist, Dr. Kálmán Korim, Geologist, and P. Liebe (For the Hungarian text see pp. 204) With the purpose of extending the areas for the production of mineral waters containing magnesium-, or sodium sulphates, further for exploring new production sites in Hungary, the authors performed soil-resistance measurements in three areas. The three areas, indicated by 1, 2 and. 3 in Fig. 1, developed invariably in flat, waterlogged parts tending to marsh formation. The geological structure of these areas is a fairly simple one, the profiles containing predominantly clay layers in horizontal stratification. Characteristic for these waterbearing formations is that the clay in the profile contains gypsum at certain spots, which forms 1 to 10 mm long individual crystals and aggregations. Characteristic for all three formations was that the mineral water was situated at shallow depth below the terrain (from 2 to 6 m) and was intimately related with the ground-water system. Both concentration and chemical character of the mineral water were found to vary horizontally and vertically even within individual formations.