CUTOFFS FOR EMBANKMENT DAMS

Abstract

Dams are man-made structures put across streams/rivers to impound water for storage, diversion etc. In the past most of the geologically good sites have been utilised and sites having geologically less soundness are being left with for the present and future development. The versatality and flexibility of embankment dams have drawn attention of dam designers and construction Engineers to develop so called geologically less sound dam sites. As a result the number of embankment dams under construction and proposed, have outnumbered concrete/ masonry dams. While naturally available materials e.g. silt & clay, sRnd, gravel, boulders, rocks etc, are utilised under controlled condition by the help of modern machineries and technical-know-how, for the construction of embankments to ful-fill desired criteria, the foundations are accepted as provid-ed by Nature and have to be improved upon to meet the basic requirements by interposing man-made structures, One of the basic requirements is reduction of underseepage. This dissertgtion makes a review of the existing practices of provision of cutoffs, their classification and suitability of different types of cutoffs for different situations. Theore-tical analysis for evaluation of efficiency of various types of cutoffs have also been presented. Basing on theoretical and practical considerations suggestions regarding selection of suitable cutoffs for various foundation conditions have been made.