Seepage concrete dam foundations

STUDY ON COUPLING INFLUENCES OF CONCRETE DAM FOUNDATION SEEPAGE, STRESS, AND CREEP ON STRUCTURE BEHAVIORS OF DAM BODY... 

Drains of sand and/or gravel installed beneath or within the dam also afford seepage control. Because of their broad base, earth dams impose much lower stresses on the foundation materials than concrete dams. Furthermore, they can accommodate deformation such as that due to settlement more readily. As a consequence, earth dams have been constructed on a great variety of foundations ranging from weak unconsolidated stream or glacial deposits to high-strength rocks. 

In some cases, only one type of soil is readily obtainable for an earth dam. If this is impervious, then the design will consist of a homogeneous embankment, which incorporates a small amount of permeable material in order to control internal seepage. On the other hand, where sand and gravel are in plentiful supply, a very thin earth core may be built into the dam if enough impervious soil is available, othenwise an impervious membrane may be constructed of concrete or interlocking steel sheet piles. However, since concrete can withstand very little settlement, such core walls should be located on sound foundations. 

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