Vízügyi Közlemények, 1980 (62. évfolyam)
4. füzet - Karácsonyi Sándor: Kutak indító igénybevétele
Kutak indító igénybevétele 605 According to the conclusions arrived at concerning the starting rate of pumping, three processes of different character can be distinguished, namely — constant withdrawal and uniform pipe diameter (Section 2 and Fig. 2); — constant withdrawal and variable pipe diameter (Section 3 and Fig. 4); variable withdrawal and uniform pipe diameter (Section 4 and Fig. 8). As regards the forces induced in the layer when pumping is started, the accerelation of flow towards the well is the critical factor, which assumed peak values depending on the particular process. Analysing the starting conditions under the assumption of Q = constant it may be concluded that the acceleration of flow entering the well is highest immediately after pumping has started. The acceleration rate critical to the layer skeleton can be reduced in this case only by increasing the diameter and screen surface area of the well (Fig. 5). Apart from minimizing the forces induced by starting the pump, a well screen of larger diameter may be justified in many instances by other considerations as well. These can be satisfied simultaneously in the first place by using well screens of gradually varying diameter. Adopting for this arrangement screen sections of suitable diameter and length ( Fig. 0), the initial forces, i.e. the critical acceleration Umax can be reduced appreciably. Another method of minimizing the starting forces consists of increasing the pumping rate gradually. Under such conditions the flow towards the well screen will occur in two successive phases, namely the starting phase where Qo = constant ( Fig. 7), followed by normal pumping with Q = constant. In the case of inital pumping with Qo = constant, withdrawal may be increased in a linear manner: Qo = pt , while in practice the increase is almost exclusively nonleniar: Qo = pt n (See: Sections 4.1 and 4.2). The velocity of flow towards the well can be minimized even such cases by extending the period under which the normal pumping rate is attained ( Fig. 10). It will be seen that by proper well design and gradually increasing pumping rates the initial hydraulic load on the well and the effects thereof can be influenced considerably. For this reason the measures aimed at reducing the initial hydraulic load should be applied in combination and in a coordinated manner. * * * Anfangsbelastung von Brunnen von Dr. Sándor Karácsonyi Als eine Bedingung für den sandungsfreien Betrieb eines Brunnens ist nicht nur während der schon ständig gewordenen Wasserförderung, sondern bereits beim Anfang des Brunnenbetriebes notwendig, dass die Auswirkungen dieser besonderen Belastung die Schichtenstruktur nicht zerstöre. Der Betriebsbeginn kann mathematisch gut beschrieben werden. Dies ermöglichte die Durchführung weiterer Berechnungen und bildete die Grundlage der Serienuntersuchungen, die in der Studie anhand einer vergleichenden Analyse besprochen werden. Laut durchgeführter Analyse können vom Gesichtspunkt der Anfangsbelastung drei Prozesse verschiedenen Charakters linterschieden werden, undzwar Wasserentnahme und Bohrabmessungen konstant (Kapitel 2. und Bild 2.); Wasserentnahme konstant, Bohrabmessungen veränderlich (Kapitel 3. und Bild 4.); Wasserentnahme veränderlich, Bohrabmessungen konstant (Kapitel 4. und Bild 8.).
