5.2. RUBBLE-MOUND STRUCTURES
199
5. Tests of Accumulated Storm Impacts. These tests
attempt to reproduce the accumulated impacts of a number of large storm events having different characteristics
but all capable of causing damage. The storm parameters and duration are determined from historical records
or from wave hindcasts. The different storms should be
ran in random order, and if funds allow, the order should
be altered and the test conducted again.
6. Tests of Residual Stability. These tests complete the
testing program by examining what residual stability a
damaged structure has. Some structures, such as those
with steep slopes, may totally fail after initial damage with
only a small increase in the incident wave condition. Such
a possibility should be considered in the overall economic
analysis of the project.
7. Tests of Structures Under Construction. Coastal
structures are particularly vulnerable to a wide range of
wave conditions during construction when portions of the
core and underlayers are not protected by the primary armor layer. Hence most structures are usually built during
months of typically low wave energy. Nevertheless, damaging storms can occur at any time, and tests of partially
completed structures can provide information on potential
extent of damage, or construction sequences to minimize
potential damage.
Hudson, et al. (1979) noted the importance of repeat tests of rubblemound stability. Repeat tests demonstrate the capability of the model to
produce similar results under similar forcing conditions. However, various
factors, particularly nonsimilarity in model armor layer placement, may result in repeat tests that have significantly different stability. In this case,
there is no option but to conduct additional repeat tests to isolate the
problem causing the nonsimilar results. Unfortunately, the expense of conducting stability studies precludes extensive testing necessary to establish
statistical certainty. Differences in rubble-mound stability reported by different laboratories may be explained, in part, by the difficulty of obtaining
statistically valid stability results from a small number of tests.
Owen and Briggs (1985) suggested that each design condition be tested
five times and the post-test rubble slope profiles be compared. Hudson
and Davidson (1975) recommended testing each structure three times with
the armor layer replaced each time. The latter two tests could be limited
to critical wave conditions determined during the first test. Differences
199
5. Tests of Accumulated Storm Impacts. These tests
attempt to reproduce the accumulated impacts of a number of large storm events having different characteristics
but all capable of causing damage. The storm parameters and duration are determined from historical records
or from wave hindcasts. The different storms should be
ran in random order, and if funds allow, the order should
be altered and the test conducted again.
6. Tests of Residual Stability. These tests complete the
testing program by examining what residual stability a
damaged structure has. Some structures, such as those
with steep slopes, may totally fail after initial damage with
only a small increase in the incident wave condition. Such
a possibility should be considered in the overall economic
analysis of the project.
7. Tests of Structures Under Construction. Coastal
structures are particularly vulnerable to a wide range of
wave conditions during construction when portions of the
core and underlayers are not protected by the primary armor layer. Hence most structures are usually built during
months of typically low wave energy. Nevertheless, damaging storms can occur at any time, and tests of partially
completed structures can provide information on potential
extent of damage, or construction sequences to minimize
potential damage.
Hudson, et al. (1979) noted the importance of repeat tests of rubblemound stability. Repeat tests demonstrate the capability of the model to
produce similar results under similar forcing conditions. However, various
factors, particularly nonsimilarity in model armor layer placement, may result in repeat tests that have significantly different stability. In this case,
there is no option but to conduct additional repeat tests to isolate the
problem causing the nonsimilar results. Unfortunately, the expense of conducting stability studies precludes extensive testing necessary to establish
statistical certainty. Differences in rubble-mound stability reported by different laboratories may be explained, in part, by the difficulty of obtaining
statistically valid stability results from a small number of tests.
Owen and Briggs (1985) suggested that each design condition be tested
five times and the post-test rubble slope profiles be compared. Hudson
and Davidson (1975) recommended testing each structure three times with
the armor layer replaced each time. The latter two tests could be limited
to critical wave conditions determined during the first test. Differences