Geoscience Reference
In-Depth Information
14.17 Crest levels based on revetment type
•
The crest levels are based principally on design wave heights (based on fetch, wind
and water depths).
•
Significant water depth
=
H
s
.
•
Other controlling factors are slope and revetment type.
•
The required freeboard is then based on consideration of all of the above factors.
•
Design wave height factored according to the next 2 tables.
Table 14.17
Design wave height, H
D
(McConnell, 1998).
Revetment type
Crest configuration
Design wave height, H
D
Concrete/Masonry
-
0.75 H
s
Rockfill
Surfaced road
1.0 H
s
Earthfill with reinforced downstream face
Surfaced road
1.1 H
s
Earthfill with grass downstream face
Surfaced road
1.2 H
s
Grass crest
1.3 H
s
All embankment types - no still water or
1.67 H
s
wave surcharge carryover permitted
14.18 Crest levels based on revetment slope
•
The design wave height is factored according to the run-up factor
×
H
D
.
•
The run-up factor is based on the dam slope provided in table below.
Table 14.18
Run-up factor based on slope (adapted from McConnell,1998).
Dam slope
Run-up factor
Maximum
Intermediate
Minimum
(smooth slope)
(rough stone or shallow rubble)
(thick permeable rip-rap)
1V: 5H
1.0
0.85
0.65
1V: 4H
1.25
1.05
0.8
1V: 3H
1.7
1.35
1.05
1V: 2.5H
1.95
1.55
1.2
1V: 2H
2.2
1.75
1.35
•
Different overtopping limit apply based on the access requirements, type of
structure and land use immediately behind.
14.19 Stable slopes underwater
•
Slope stability analysis alone does not capture the stability of slope under water.
•
Slopes fully underwater tend to be stable at much flatter angles than indicated
by slope stability analysis.
•
This is due to the activity of the water and continuous erosion effects under water.
Search WWH ::
Custom Search