Vízügyi Közlemények, 1934 (16. évfolyam)

4. szám - XI. Szakirodalom

22 VIII. REPAIR OF THE PUMPING PLANT AT KARAPANCSA. BY D. IHRIG. The article deals with an examination and repair of the pumping plant at Karapancsa, serving the surface drainage system of the Margitta Island in the Danube near Mohács, which has a surface area of about 26.000 hectares. The engine house of the pumping plant, built in 1904, was founded on a concrete floor underlain by silt. The suction bay and discharge canal are joined to the building (fig. 2). In 1926 the suction bay was replaced by a deeper one. In 1929, when the suction bay and the engine house were subjected to an examination, it was found that the bottom and the side walls of the suction bay were full of chinks, and were separated from the wall of the engine house. As it was supposed that the percolation of water between the discharge canal and the suction bay, in consequence of a waterhead of 2-8 metres in depth, had undermined the engine house and the suction bay, the measure of the undermining was also taken by experimental cement pressing. The points of this examination are indicated by the numbers 1, 2, and 3, on figure 3. The examinations showed that there was a horizontal hole under the engine house and a vertical one under the suction bay. Then the following repair works were carried out : The holes in the underground were filled up by cement pressing, great attention being paid to the abolition of groundwater movement, the choice of material and pressure applied, the disposition and number of pressing pipes, the establishment of the depth and time of pressing, and the significance of control pressings. The cement pressing is shown in figure 3, where the numbers beside the pressingspots indicate the order of pressing, and the squares symbolize the quantity of cement mortar pressed in. Through 44 pressing pipes 320 quintals of cement were driven in under 0-5—1-0 atmospheric pressure during 21 labour-days, which amounts to 35-8 cubic metres of compact cement mortar with a mixing rate of 1:1. The cost of pressing came to 197 pengő per cubic metre of cement mortar. The pit next the engine house was filled up, and the discharge canal lengthened with a pipe of 10 millimetre wrought-iron sheets, 1300 millimetres in diameter (fig. 5). The walls of the suction bay were strengthened so that they should be adequately strong and impervious. This work was carried out by the Torcretmethod. To carry out the works, the groundwater was lowered by four tubular wells, the walls of the suction bay were cut up, and the reinforcement was placed, a wall of 20 cm thickness was built in addition to the wall of the engine house, leaving an interspace between the two walls, and a concrete layer of 8 cm upon the side walls and another of 12 and 25 cm on the bottom were blown by the Torcret-method. As materials of concrete, Danube sand of 8 millimetres in size, and bauxite cement were used with good results and comparatively small expense. The cost of production of Torcret reinforced concrete amounted to 255 pengő per cubic metre.