Earth and Rockfill Dams
The seepage of reservoir water through the body of earth and rock fill dam or at
interfaces of dam seat with ground/steep ground surface or abutment or both,
creates the following two problems, apart from causing excessive water loss and
thereby reducing usable storage of reservoir:
1. Seepage force in the form of pore water pressures, and
➢ The drainage system should be so devised that it tackles the problems mentioned.
➢ The design is mostly governed by type and permeability of base materials as well
as filter materials, water depth in reservoir, topographical features of dam site, etc.
The conventional type of seepage control and drainage features generally adopted
for the embankment dam are:
➢ Impervious core, Inclined/vertical filter with horizontal filter, Network of inner
longitudinal drain and cross drains, Horizontal filter, Transition zones/transition
filters, Intermediate filters, Rock toe, and Toe drain.
Selection Of Site:With a decision made about the necessity of having the dam across a river near
about a broad area, attention is focused on narrowing down into one, or preferably
two or three alternate sites that may be apparently suitable from visual inspection.
Detailed investigations are carried next to examine the option that satisfies as being
most economical, technically more suitable, convenient for construction etc. The
various investigations that are carried out for finalizing a particular dam,
specifying its type, height, method of construction, etc. are mentioned below.