SMALL DAMS PETITS BARRAGES

Fig. 5.16 – Size range of impervious cores used in zoned embankments.
Table 5.22 – Recommended slope for small homogeneous earthfill dams on stable
foundations.[3]
Type
Subject to rapid
drawdown [1]
Soil
Classification [2]
Upstream
slope
Downstream
slope
Homogeneous
or modified -
homogeneous
No
GW, GP,SW, SP
GC, GM, SC, SM
CL, ML
CH, MH
Pervious, unsuitable
2.5:1 2:1
3:1 2.5:1
3.5:1 2.5:1
GW, GP,SW, SP Pervious, unsuitable
Modified
homogeneous
-
Yes
GC, GM, SC, SM
CL, ML
3:1
3.5:1
2:1
2.5:1
CH, MH 4:1 2.5:1
[1] Drawdown rates of 15cm or more per day after prolonged storage at a high reservoir
levels.
[2] OL and OH soils are not recommended for major portions of homogeneous earthfill
dams. PT soils are unsuitable.
Type
Table 5.23 – Recommended slopes for small zoned earthfill dams on stable foundation.[3]
Zoned with
minimum
core A [1]
Zoned with
maximum
core [1]
Zoned with
maximum
core [1]
levels.
Subject to rapid
drawdown [2]
Not critical [4]
No
Yes
Shell Material
Classification
Rockfill, GW,
GP,
SW (gravelly),
or SP (gravelly)
Rockfill, GW,
GP, SW
(gravelly),
or SP (gravelly)
Rockfill, GW,
GP, SW
(gravelly),
or SP (gravelly)
Core Material
Classification [3]
GC, GM, SC,
SM, CL, ML,
CH, or MH
Upstream
slope
2:1 2:1
Downstream
slope
GC, GM 2:1 2:1
SC, SM 2.25:1 2.25:1
CL, ML 2.5:1 2.5:1
CH, MH 3:1 3:1
GC, GM 2.5:1 2:1
SC, SM 2.5:1 2.25:1
CL, ML 3:1 2.5:1
CH, MH 3.5:1 3:1
[1] Minimum and maximum size cores are as shown on Figure 3.
[2] Rapid Drawdown is 15cm or more per day after prolonged storage at a high reservoir
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