Environmental Engineering Reference
In-Depth Information
Figure 16.24.
Effect of joint apertures and continuity on uplift pressure (Adapted from EPRI, 1992).
curtain upstream of the drains, or that the weight of the dam closes discontinuities in the
foundations.
16.6.2.3
Design of drains
Foundation drainage is provided by the provision of boreholes drilled into the dam and
the foundation from the drainage gallery. ANCOLD (1991) recommend the following to
achieve the uplift coefficient of 0.33 which is commonly assumed:
(a) The line of drains should be located at a distance from the upstream face of 5% to
15% of the maximum reservoir head at the dam;
(b) The lateral spacing of the drains in the dam should not exceed 10% of the maximum
reservoir head at the dam and preferably not exceed 3 m. (However, drains in the body
of the dam should not be so closely spaced as to encourage cracking between them);
