Table A3
Summary of Model Test Series
Test Series
Structure
Waves
Tests
A
Single gradation rock
Hs 4 to 10 m
37
Tp 12 to 22 sec
B
Two-layer rock (5H:1V seaward slope)
Hs 4 to 8 m
15
Tp 18 to 22 sec
C
Two-layer rock (3H:1V seaward slope)
Hs 4 to 8 m
7
Tp 18 to 20 sec
D
Two-layer rock (5H:1V seaward slope); 15 cm sand bed
Hs 4 to 8 m
14
Tp 16 to 20 sec
E
Single outer layer rock (5H:1V seaward slope); sand core
Hs 4 to 10 m
7
Tp 18 to 20 sec
F
Geobag
Hs 4 to 10 m
16
Tp 18 to 22 sec
G
Two-layer rock (5H:1V seaward slope); sand slurry matrix
Hs 4 to 10 m
12
Tp 18 to 20 sec
W
None
As in A
34
Damage Analysis
With respect to the rock-armored structure, the total stones displaced per
storm segment can be used to develop an empirical damage function. The
damage function expresses the total number of armor units displaced per hour of
of any given Hs - Tp combination is shown in Figure A16 and the damage
function is shown in Figure A17. Multiplying the damage function by the
expected wave durations yields the expected lifetime damage per 100 ft run of
spur. Integrating the function over all Hs and Tp provides an estimate of the total
stone damage expected in a 25-year life cycle (Figure A18). The results
presented in Figure A18 indicate a total stone damage of 98 stones/100 ft over
25 years. This number is small in relation to the total number of stones
composing the surface of the structure. Typically, there are about 2,000 stones on
the surface of the spur per 100 m length. Therefore, the 98 stones/100 ft equates
to about 5 percent of the stones on the surface of the structure.
Overview of Physical Model Tests
An overview of damage results from the test program is provided in this
appendix. Detailed results are provided in Davies (2001).
Both the rock-armored structure and the geobag structure performed
satisfactorily in the flume tests at CHC. Some stone movement was observed
during the most severe wave and water levels tested. However, stone movements
did not develop to an extent that would detract from the performance of the
structure. No significant degradation of the spur crest was experienced during the
testing.
A22
Appendix A
Stability Analysis of a Submerged Spur, North Jetty, Grays Harbor, WA
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