Lesson 7 - nptel

modes, which are much different from those of a gravity dam. Hence, the design of an
embankment dam is done in a different way than that of a gravity dam. In fact, the
design procedures are targeted towards resisting the failure of an embankment dam
under different modes, which are explained in the next section.
4.7.1 Embankment dam and appurtenant structures-basic types
and typical layouts
An embankment dam, whether made of earth completely or of rock in-filled with earth
core, has a trapezoidal shape with the shoulder slopes decided from the point of
stability against the various possible modes of failure, discussed in section 4.7.2. The
top crest is kept wide so as to accommodate roadway (Figure1). In order to check the
seepage through the body of the dam, a number of variations are provided. For earthen
embankment dams, these range from the following types:
1. Homogeneous dam with toe drain (Figure 2)
2. Homogeneous dam with horizontal blanket (Figure 3)
3. Homogeneous dam with chimney drain and horizontal blanket (Figure 4)
4. Zoned dam with central vertical core and toe drain (Figure 5)
5. Zoned dam with central vertical core, chimney filter and horizontal blanket
(Figure 6)
6. Zoned dam with inclined core, chimney filter and horizontal blanket (Figure 7)
Version 2 CE IIT, Kharagpur