Vízügyi Közlemények, 1935 (17. évfolyam)

Kivonatok, mellékletek - Kivonat az 1. számhoz

21 The paddle wheels of the axial pump are made with a profile of aeroplanewheels. The paddle wheel revolves beneath the low water level, and thence it lifts the water to the height desired, therefore no foot valve or air pump is needed. The way of the water in this pump is very simple, thu there are hardly any eddy losses. It can be adjusted to different lifting heights by shifting the revolving propeller wheels, or by changing the speed of revolution. The writer describes a pump of 400 litres per second delivery constructed by himself, and gives the experience gained in its operation. This pump is small, weighing only 450 kg, and is therefore easily transportable. The writer then describes some smaller units prepared for serving irrigation, which have been fitted with minute explosion motors. The axial pump, having good efficiency, simple construction, small weight, and low prime cost, will probably be widely accepted for drainage, irrigation, and fish pond plants. V. GEOLOGY OE THE RÔKUS MOUNTAIN WITH SPECIAL REGARD TO LANDSLIPS. By G. A. POSEWITZ. The Rókus mountain lies to the west of Budapest. On its south-west slope landslips have taken place repeatedly during a long period. At the place in question 71 soil investigation borings in all have been made on four different occasions. From these data thus procured, the geologic formation of the Rókus mountain has been ascertained, especially the extent of the travertine, which plays ко great a part in causing landslips (fig. 1 and 2). Landslips have always occurred in the Kiscell-clay, which was formed in the Middlc-Oligocen (Rupelian) age, as is shown by the fossils found in it. Landslips were caused by the improper removal of clay for brickworks at the foot of the Rókus mountain. This disturbed the usual flow of the ground-water, and the clay layers soaked by it began to slide. Great landslips occourred in 1882, in 1913 (fig. 3), and in 1933 (photographs 1, 2, 3, 4), endangering the building of the Ampelologic Institute. To prevent slidings, stone underdrains have been constructed (fig. 4 : S = stone underdrains). Material taken out of bore-holes were analized, and the size of part icles of clay layers found wet at the time of borings, and then dry farther below, were determined : but the sliding surface could not be ascertained. Both the wet and the dry clay layers showed a plasticity and a quantity of colloidal particles so great that the clay could be considered as practically impervious . The fact that in some places the clay was soaked through to a depth of 10—12 metres and carried water, can be ascribed to the coagulating effect of salts dissolved in ground-water. The effect of chemical processes taking place in the upper layers of the clay in the presence of salty ground-water was to change the physical properties of the clay. The result of the sedimentation process is shown in Table 2 and in figure 6. The samples examined were taken out of the same bore-hole. The sample from a depth of 10 metres

, marked ,A", is dry blue clay ; that from 11 metres, marked