UPLIFT IN GRAVITY DAMS

Abstract

The problem of uplift in gravity dams greatly influences the safe and economic design of dams and forms the subject matter of this dissertation. The failure of Bouzey Dam in 1895 brought the problem to lime light and since then a number of research workers 'propounded their own theories in this regard which have been discussed with spe cial reference to the work of Lieckfeldt, Link and Maurice Levy. These theories were based on the assumption that a crack develops in the material of dam through which water enters under pressure causing uplift. This assumption has, however, now been 4tondemned as it has been proved that pores in the material building a dam without a cra-ck are the cause of uplift. The structure of concrete has a bearing on the extent of pores which influences the permeability of the material and consequently the uplift in dam. These factors as brought out by Fillunger and Terzaghi have been explained in detail. The problem has been divided into two parts, viz., (1) Determi nation of the effective uplift area over which the uplift acts and (2) determination of the actual pressure intensities. For the first both theoretical and experimental approaches are available and have been explained with special reference to the experiments carriedout by Leliavasky. For the second, recourse is generally made to the available data of actual measurements of uplift pressure in similar existing structures. Data available for some of the dams of U.S.B.R. TVA and other has been compiled in the form of diagrams with a ment-ion of loc.l characteristics and the general method of measurements Great economy can be achieved from reducing the uplift press-ure by provision of some additional structure, rather than, design-ing the whole dam for full uplift. The various structural devices to reduce the uplift pressure have been explained in detail. The