Environmental Engineering Reference
In-Depth Information
Figure 18.12.
Generalised model for seepage through a dam foundation.
Figure 18.13.
Effectiveness of grouting in reducing seepage in a dam foundation.
it is doubtful whether such a low permeability is achievable with cement grouting because
the cement will not penetrate rock with such low Lugeon value.
For high permeability rock (say 100 Lugeon) with wide fracture spacing, the effective
width of the curtain should be larger (say 20 m) and the permeability could be reduced to
that of the secondary fracture system. If this was, say, 5 Lugeons, then the seepage would
be reduced to about 20% of the ungrouted value. If the permeability of the secondary
fractures was, say, 2 Lugeons, the seepage would be reduced to 5% to 10% of the
ungrouted value.
18.2.4
Recommended closure criteria for embankment and concrete dams
From the review of criteria used by others, including Houlsby (1977, 1978, 1982a, 1985),
WRC (1981), Deere (1982), Ewart (1985), Kjaernsli et al. (1992), the authors' experience
